Verification of Underground Coal Mine Operators' Dust Control Plans and Compliance Sampling for Respirable Dust

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: March 6, 2003 (Volume 68, Number 44)]
[Proposed Rules]
[Page 10783-10884]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06mr03-29]

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DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Parts 70, 75 and 90
RIN 1219-AB14

Verification of Underground Coal Mine Operators' Dust Control
Plans and Compliance Sampling for Respirable Dust

AGENCY: Mine Safety and Health Administration (MSHA), Labor.
ACTION: Proposed rule; notice of public hearings; close of record.

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SUMMARY: This proposed rule supercedes the proposed rule published by
MSHA on July 7, 2000. Under this proposed rule mine operators would be
required to verify and periodically monitor, through sampling, the
effectiveness of the dust control parameters for each mechanized mining
unit (MMU) specified in the mine ventilation plan. For samples to be
valid, the operator would be required to sample on a production shift
during which the amount of material produced by a MMU is at or above
the verification production level using only the dust control
parameters listed in the ventilation plan. The use of approved powered,
air-purifying respirators (PAPRs) and/or verifiable administrative
controls would be allowed as a supplemental means of compliance when
MSHA determines that all feasible engineering or environmental controls
are being used. MSHA is also proposing to rescind operator compliance
sampling in underground coal mines. The use of a personal, continuous
dust monitor (PCDM), once developed and approved, could be used by an
operator in conjunction with the dust control parameters specified in
the mine ventilation plan. The proposed rule would significantly
improve miners health protection by limiting the exposure of individual
miners to respirable coal mine dust.

DATES: Comments on the proposed rule should be submitted on or before
June 4, 2003.
MSHA also is announcing that the Agency will hold public hearings
on the proposed rule. The hearing dates and times will be announced by
a separate document in the Federal Register.

ADDRESSES: Comments must be clearly identified as such and transmitted
either electronically to comments@msha.gov, by facsimile to (202) 693-
9441, or by regular mail or hand delivery to MSHA, Office of Standards,
Regulations, and Variances, 1100 Wilson Blvd., Room 2313, Arlington,
Virginia 22209-3939. You may contact MSHA with any format questions.
Comments are posted for public viewing at http://www.msha.gov/
currentcomments.htm.

Information Collection Requirements

Send written comments on the information collection requirements to
both the Office of Management and Budget (OMB) and MSHA as follows:
(1) To OMB: If under 10 pages, by facsimile (202) 395-6974 to Attn:
Desk Officer for MSHA; or by email to: cathomas@omb.gov. All comments

may be sent by mail addressed to the Office of Information and
Regulatory Affairs, Office of Management and Budget, New Executive
Office Building, 725 17th Street, NW., Washington, DC 20503, Attn: Desk
Officer for MSHA; and
(2) To MSHA: Comments must be clearly identified as comments on the
information collection requirements and transmitted either
electronically to comments@msha.gov, by facsimile to (202) 693-9441, or
by regular mail or hand delivery to MSHA, Office of Standards,
Regulations, and Variances, 1100 Wilson Blvd., Room 2313, Arlington,
Virginia 22209-3939.

FOR FURTHER INFORMATION CONTACT: Marvin W. Nichols, Jr., Director,
Office of Standards, Regulations and Variances, MSHA; phone: (202) 693-
9440; facsimile: (202) 693-9441; E-mail: nichols-marvin@msha.gov.
This proposed rule is also available on MSHA's webpage at http://
www.msha.gov, under Statutory and Regulatory Information;
Federal Register Documents; Proposed Rules. You can view comments filed
on this rulemaking at http://www.msha.gov/currentcomments.htm.

SUPPLEMENTARY INFORMATION:

I. Table of Contents
II. Background
A. Procedural History
B. Overview of Proposed Rule
1. New Proposed Respirable Dust Sampling Program
2. Verification of Ventilation Plan Effectiveness
3. Measures to Supplement Engineering Controls to Reduce
Exposures
C. Control of Coal Mine Respirable Dust
D. Coal Mine Respirable Dust Task Group
E. NIOSH Criteria Document
F. Advisory Committee on the Elimination of Pneumoconiosis Among
Coal Mine Workers
III. General Discussion
A. Proposed Reforms to the Respirable Dust Monitoring Program
a. Compliance Sampling
b. Abatement Sampling
c. Operator Verification Sampling and Quarterly Sampling
d. Advantages of MSHA Sampling Over the Existing Program
B. Procedures for Setting the Applicable Dust Standard When
Quartz is Present
1. Proposed Procedures
2. Validity of Averaging Percentages
C. Respirable Dust Control Program for Underground Coal Mines
1. Proposed Procedures for Evaluating, Approving, and Monitoring
Plan Requirements
D. Hierarchy of Dust Controls
1. Primacy of Engineering Controls
2. Administrative Controls
3. Limitations of Engineering Controls
4. Respiratory Protection
a. Selection of Respirators: Powered Air-Purifying Respirators
(PAPR)
b. PAPR Protection Program
c. PAPR Protection Factor
E. Guidelines for Determining What is a Feasible Dust Control
F. Application of New Technology for Monitoring Coal Mine Dust
Levels
IV. Section-by-Section Discussion of Proposed Rule
A. Part 70
B. Part 75
C. Part 90
V. Health Effects
A. Introduction
B. Hazard Identification
1. Agent: Coal
2. Physical State: Coal Mine Dust
3. Biological Action: Respirable Coal Mine Dust
C. Health Effects of Respirable Coal Mine Dust
1. Description of Major Health Effects
a. Simple Coal Workers' Pneumoconiosis (Simple CWP) and
Progressive Massive Fibrosis (PMF)
b. Other Health Effects
2. Toxicological Literature
3. Epidemiological Literature
a. Simple Coal Workers' Pneumoconiosis (Simple CWP) and
Progressive Massive Fibrosis (PMF)
b. Other Health Effects
VI. Quantitative Risk Assessment
VII. Significance of Risk
VIII. Feasibility Issues
A. Technological Feasibility
B. Economic Feasibility
IX. Preliminary Regulatory Economic Analysis
A. Costs and Benefits: Executive Order 12866
1. Compliance Costs
2. Benefits
B. Regulatory Flexibility Certification and Regulatory
Flexibility Analysis
X. Other Statutory Requirements
A. Unfunded Mandates Reform Act of 1995
B. Paperwork Reduction Act of 1995
C. National Environmental Policy Act
D. Executive Order 12630: Governmental Actions and Interference
with Constitutionally Protected Property Rights
E. Executive Order 12988: Civil Justice Reform
F. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks
G. Executive Order 13175: Consultation and Coordination with
Indian Tribal Governments

[[Page 10785]]

H. Executive Order 13132: Federalism
I. Executive Order 13211: Energy
J. Executive Order 13272: Proper Consideration of Small Entities
in Agency Rulemaking
XI. Public Hearings
Appendix A. Derivation of the Critical Values
Appendix B. Model Powered Air-Purifying Respirator (PAPR)
Program
Appendix C. Citation Threshold Values (CTV)
Appendix D. References
Appendix E. Supplemental References
XII. Regulatory Text

II. Background

A. Procedural History

On July 7, 2000, the Mine Safety and Health Administration
published a Notice of Proposed Rulemaking (NPRM) in the Federal
Register: Verification of Underground Coal Mine Operators' Dust Control
Plans and Compliance Sampling for Respirable Dust (65 FR 42122). A
notice of public hearing and close of record was also published in the
Federal Register (65 FR 42186) on July 7, 2000. During August 2000,
three public hearings were conducted in Morgantown, West Virginia;
Prestonsburg, Kentucky; and Salt Lake City, Utah. Transcripts of those
proceedings were made available to the public. The close of the
rulemaking record was originally scheduled for August 24, 2000. In
response to requests from commenters, an extension of the comment
period for the NPRM was published in the Federal Register (65 FR 49215)
on August 11, 2000; the rulemaking comment period was extended to
September 8, 2000. Supplementary statements and data postmarked on or
before the close of the record, September 8, 2000, were included in the
rulemaking record and made available to the public.
Many commenters on the proposed rule urged MSHA to withdraw the
proposed rule and publish another. In their opinion, the agency failed
to adequately address the concerns of mine operators and ignored other
reforms in the dust sampling program urged by coal miners since the mid
1970s or that were recommended by the Secretary of Labor's Advisory
Committee on the Elimination of Pneumoconiosis Among Coal Workers (Dust
Advisory Committee) and the NIOSH Criteria Document addressing
respirable coal mine dust.
After carefully considering all the facts, issues, and concerns
raised by commenters during this rulemaking, MSHA concluded that, to
proceed to a final rule would not be in the best interest of miners'
health or the mining community. The Agency is re-proposing for further
public comment, the rule which is the subject of this rulemaking.

B. Overview of Proposed Rule

In preparing this proposed rule, MSHA has responded to comments
that were made to the July 7, 2000 proposed rule. However, since this
proposed rule differs from the earlier proposed rule in several areas,
the agency may not have addressed each concern that was identified by
the earlier commenters.
MSHA believes that the proposed rule would significantly improve
miners' health protection from the debilitating effects of occupational
respiratory disease by limiting their exposures to respirable coal mine
dust to no more than the applicable dust standard on each shift.\1\
Accordingly, this proposed rule revises 30 CFR part 70, subparts A, B,
and C; amends two existing sections of part 75; and revises part 90,
subparts A, B, C, and D.
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\1\ For details, see the Quantitative Risk Assessment and
Significance of Risk Sections.
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Under this proposed rule, MSHA would be responsible for all
compliance and abatement sampling, which is currently being carried out
by the operator. This includes frequent sampling of each mechanized
mining unit (MMU) and part 90 miner, sampling of outby Designated Areas
(DAs) and occupations, and abatement sampling. This proposed rule
specifies that compliance and abatement determinations will be based on
the results of single samples. Also, only MSHA samples would be used to
set a reduced dust standard when the quartz content of the respirable
dust exceeds five percent.
In response to comments raised in the earlier proposed rule, mine
operators will continue to play a role in monitoring the mine
environment. The proposed rule requires each underground operator to
verify, through sampling, that the dust control parameters specified in
a mine ventilation plan are effective in controlling the concentration
of respirable coal mine dust and quartz dust at or below the
verification limits of 2.0 mg/m3 and 100 [mu]g/m3
respectively. For a sample to be valid for verification purposes, the
amount of material produced must be at or above the ``verification
production level'' or VPL. The VPL is defined as the tenth highest
production level recorded in the most recent 30 production shifts. In
addition, the engineering or environmental control parameters must not
exceed 115% of the quantities specified in the ventilation plan and the
sampling must take place over the entire production shift.
The dust control parameters specified in mine ventilation plans
must be designed to maintain dust concentrations at or below the
applicable standard on each shift. If during the initial verification
sampling, the VPL is achieved and dust concentrations are sufficiently
low, the district manager could approve a plan based on one shift of
sampling. However, if dust concentration measurements are higher, or if
the actual production was less than the VPL, MSHA will require the
operator to sample additional shifts. All verification samples would be
submitted to MSHA for analysis. However, mine operators would not be
cited if sample results show an overexposure so long as the operator
takes steps to identify and correct the condition that caused the
verification limit to be exceeded.
Also, to confirm the continued effectiveness of the plan
parameters, mine operators would be required to sample quarterly each
producing MMU designated by MSHA under the same conditions that were in
place when the plan parameters were initially verified. As in the
earlier proposed rule, mine operators would be required to maintain
records of the total amount of material produced by shift for each MMU.
In the earlier proposed rule, commenters expressed concern about a
provision in the July 7, 2000 proposed rule allowing the use of
supplementary controls (powered, air-purifying respirators (PAPRs) and
administrative controls), on an interim basis, in mines utilizing
longwall mining technology. Commenters offered a wide range of opinions
on this part of the proposed rule. Some commenters supported MSHA's
decision to allow the use of supplementary controls, but criticized the
proposed rule for being too restrictive. Other commenters objected to
the proposed provision, claiming that the requirement was inconsistent
with the provision of the Mine Act which prohibits respirators to be
used as substitutes for engineering controls. These commenters were
also concerned that operators would have no incentive to implement
available engineering controls once they are permitted to use
supplementary controls as proposed.
This proposed rule recognizes that there may be circumstances
where, even after implementing all feasible engineering or
environmental controls, a mine operator may be unable to maintain
concentrations at or below the verification limits. This includes
operations that employ longwalls or other mining systems. In those

[[Page 10786]]

instances, the proposed rule would allow a mine operator, with the
approval of the Administrator of Coal Mine Safety and Health, to use
either PAPRs or administrative controls or a combination of both to
supplement engineering or environmental controls to reduce the dust
exposure of individual miners. Approval to use supplementary control
measures would be contingent on the mine operator adopting new
engineering and environmental controls when they become available. The
proposed rule also recognizes that there may be special situations that
occur intermittently and for short periods of time where the approved
dust control measures may not protect miners from overexposure. An
example would be where the operator is required to mine through a rock
parting with high quartz content. In these situations, the district
manager may allow the operator to use PAPRs for a period not to exceed
30 calendar days.
This proposed rule would require that the mine operator provide a
copy of any request for supplemental controls to the representative of
the miners. This would provide an opportunity for miners' input prior
to MSHA making any determination.
A full discussion of these and other provisions is provided in the
section-by-section analysis of this proposed rule.
A number of commenters stated that MSHA's earlier proposed rule was
incomplete because it did not address some key recommendations of by
the Dust Advisory Committee, and by NIOSH in its Criteria Document (see
sections II.E. and II.F. of the preamble). Some of these commenters
expressed concern that the proposed rule failed to recognize and
consider alternatives involving continuous dust monitoring technology.
Since publication of that earlier proposed rule, technology has
advanced to a point that will likely allow for continuous monitoring of
dust exposures in the near future. Accordingly, this proposed rule has
provisions that would allow mine operators to adopt such technology to
meet the requirements for operator monitoring of dust control
effectiveness and miner exposure.
The recommendations regarding exposure limits for respirable coal
mine dust and crystalline silica were beyond the scope of either the
single sample or plan verification rules. In the interim, MSHA
enforcement efforts continue to focus on lowering the quartz exposure
of miners as recommended by the Dust Advisory Committee.
1. New Proposed Respirable Dust Sampling Program
In order to improve miner confidence in the respirable dust
sampling program, the proposed rule revises the existing operator
sampling requirements for underground mines and for part 90 miners
under 30 CFR parts 70 and 90, respectively, and provides that MSHA
conduct compliance and abatement sampling.
This proposed rule would result in fewer shifts being sampled than
under existing requirements. However, MSHA believes that the amount of
sampling it will conduct under the proposed rule will be more
protective because a greater number of individual compliance
determinations would be made. MSHA samples the Designated Occupation
(DO) and at least four other occupations, if available, on each
sampling inspection. Also, since all MSHA sampling is unannounced,
sampling will occur under conditions that are more typical of the
actual mining environment. In addition, compliance determinations would
be based solely on a single-sample measurement and not on an average of
multiple shift measurements. Multiple shift measurements can mask
overexposures by diluting a measurement of high dust exposure with
lower measurements made on different shifts or at different
occupational locations.
Commenters to the July 7, 2000 proposed rule also criticized MSHA
for failing to fully incorporate the preamble discussion on the
Agency's sampling procedures into the proposed regulation to prevent
those procedures from being changed or modified in the future. MSHA
does not believe that it would be appropriate to incorporate agency
enforcement procedures into rules that are designed to regulate the
mining industry. It is necessary for MSHA to retain the ability to
modify its enforcement policies and procedures in response to, among
other things, case law, new health or safety concerns, major mine
emergencies, or changes in technology which may require the agency to
redirect its efforts to protect miner health and safety.
In order to provide the mining community with an understanding of
how the agency intends to enforce this proposed rule, MSHA has
published a draft of Chapter 1 (Respirable Dust) of MSHA's health
inspection procedures (see http://www.msha.gov) which it intends to
adopt as its enforcement strategy when the final rule becomes
effective.
2. Verification of Ventilation Plan Effectiveness
The proposed rule requires that each underground coal mine operator
must have a mine ventilation plan verified by operator sampling. The
verified plan must be effective in controlling respirable dust in each
MMU under typical mining conditions prior to approval of the plan by
the district manager. In addition, mine operators would be required to
sample quarterly each producing MMU designated by MSHA to determine if
the dust control measures specified in the approved ventilation plan,
continue to protect miners from overexposure. No citations would be
issued to mine operators based on the results of this sampling as long
as the operator takes steps to eliminate the conditions which caused
any overexposure identified through such sampling.
Consistent with the Mine Act and its implementing regulations, this
proposed rule preserves the primacy of engineering controls to the
extent that they are technologically and economically feasible.
The dust control parameters specified in the mine ventilation plans
should be designed to control respirable dust and prevent overexposures
on individual shifts. These plans should accurately reflect the
engineering or environmental controls that are suitable to the mining
system and operating conditions at the MMU.
Under the proposed rule, the mine operator will collect respirable
dust samples to demonstrate the adequacy of the dust control parameters
specified in the mine ventilation plan in maintaining the concentration
of respirable coal mine and quartz dust at or below the ``verification
limits'' of 2.0 mg/m3 and 100 [mu]g/m3,
respectively. The adequacy of the dust control parameters must be
demonstrated on shifts during which the amount of material produced is
at or above the ``verification production level'' (VPL) or the tenth
highest production level recorded in the most recent 30 production
shifts, and using only the engineering or environmental control
parameters proposed in the ventilation plan, at levels not exceeding
115 percent of the quantities specified in the plan.
The proposed rule would require mine operators to: (a) Set and
maintain the dust control parameters during verification sampling at
levels specified in the plan; (b) maintain and make available to MSHA
records of the amount of material produced by each mechanized mining
unit during each production shift; (c) provide additional

[[Page 10787]]

information in mine ventilation plans such as the VPL, shift length,
etc.; and (d) provide the miners' representative the opportunity to
participate in the plan verification process.
During sampling to secure plan approval, the district manager could
approve a plan based on one shift of sampling if the VPL is achieved,
and respirable dust concentrations are sufficiently low. However, if
dust concentration measurements are higher, or if the actual production
was less than the VPL, the mine operator would be required to sample
additional shifts.
3. Measures To Supplement Engineering Controls to Reduce Exposures
Under the proposed rule, if a ventilation plan cannot be verified
using all feasible engineering or environmental controls, the mine
operator may be permitted to use either powered, air-purifying
respirators (PAPRs) or verifiable administrative controls, or a
combination of both, as a supplemental means of control (see section
III.D. Hierarchy of Dust Controls). MSHA may, under certain conditions,
approve such use only after the Administrator for Coal Mine Safety and
Health has determined that all feasible engineering or environmental
controls have been adopted in the ventilation plan, but miners continue
to be at risk of overexposure. District managers may also approve the
use of supplementary controls for limited periods of time when unusual
or intermittent adverse conditions could result in miners not being
fully protected by the approved dust control plan.
These and other provisions of the proposed rule are explained in
more detail in the Section-by-Section Discussion of this preamble.

C. Control of Coal Mine Respirable Dust

Maintaining a work environment free of excessive levels of
respirable coal mine dust and quartz dust (hereafter referred to as
``respirable dust'') is essential for long-term health protection.
Section 202(b)(2) of the Federal Mine Safety and Health Act of 1977
(Mine Act) requires each operator to continuously maintain the average
concentration of respirable dust in the mine atmosphere, during each
shift to which each miner in the active workings of such mine is
exposed, at or below 2.0 milligrams of respirable dust per cubic meter
of air (mg/m3). Under the Mine Act and the implementing
regulations, when respirable coal mine dust contains more than five
percent quartz, the applicable dust standard is further reduced by
means of a formula. Although MSHA does not enforce a separate standard
for respirable quartz dust, the formula (10 divided by the percentage
quartz) used to establish an applicable dust standard, in effect,
limits respirable quartz concentrations to 100 [mu]g/m3 (as
an MRE equivalent).
Consistent with the Mine Act and MSHA regulations, the primary
focus of the federal respirable dust program is on controlling the
concentrations of respirable dust in the environment where miners work
or travel through the application of feasible engineering or
environmental control measures. Engineering or environmental controls
for respirable dust in the mine environment are the proven dust-control
techniques and the principal methods for protecting miners' health.
These include all methods for controlling the quantity of respirable
dust in the air that a miner breathes by either reducing dust
generation, or by suppressing, diluting, capturing, or diverting the
dust that is being generated by the mining process. Under the Mine Act,
the mine operator has primary responsibility for implementing a program
to control respirable dust so that all miners work in an environment
free of excessive levels of respirable dust. Mine operators must
develop, implement, and maintain effective measures to control the
level of respirable dust in the mine environment, and evaluate these
control measures at regular intervals to ensure that they function as
intended. These control measures, or ``dust control parameters,'' are
required to be specified in the dust control portion of the operator's
mine ventilation plan under Sec. 75.370.
Mine ventilation plans are a long-recognized means of addressing
health issues that are mine-specific and for achieving work
environments that are free of excessive concentrations of respirable
dust. Currently, section 75.370 requires each operator of an
underground coal mine to develop and follow a ventilation plan that is
designed to control methane and respirable dust in the mine. The plan
must be suitable to the conditions and mining systems employed at the
mine. Although ventilation plans must be designed to control respirable
dust, there has been no requirement that the plan's effectiveness be
verified.
The dust control portion of the mine ventilation plan is a key
element of the operator's strategy to control respirable dust in the
working environment of each mechanized mining unit (MMU) during each
shift. Existing section 70.2 defines, in part, a MMU to mean ``a unit
of mining equipment, including hand loading equipment, used for the
production of material.'' The plan provides a description of the
specific engineering control measures in use. The plan also contains
procedures for maintenance of specific dust control equipment, such as
scrubbers, dust collectors on roof bolters, and spray nozzles, or for
the replacement of cutting picks to minimize dust generation. Once
approved by the district manager, the dust control parameters must be
employed on a continuous basis to provide protection from the hazards
of respirable dust to coal miners. By insuring that the parameters are
being maintained on each production shift, miners can be assured that
respirable dust levels are being adequately controlled without the need
to continuously monitor respirable dust levels in the mine environment.
Implementing dust control parameters that have been determined
effective under typical mining conditions, and maintaining these
controls in proper working order, provides reasonable assurance that no
miner will be overexposed. Because technology that continuously
monitors respirable dust and displays dust concentrations in real-time
is not yet available for use in underground coal mines, the
implementation of effective ventilation plans is the only practical
means of reasonably ensuring, on a continuous basis, that miners are
not overexposed.
In 1996, MSHA implemented revised ventilation standards which,
among other provisions, required an on-shift examination of the dust
control parameters before coal production begins on each MMU to assure
compliance with the dust control parameters specified in the
ventilation plan. Based on the recommendations of MSHA's Coal Mine
Respirable Dust Task Group (MSHA, 1992), this requirement is intended
to focus attention on the need for properly functioning dust controls
before production begins. On-shift examinations of dust control
parameters under existing Sec. 75.362 are one important component for
an effective respirable dust control strategy. Recent advances in
technology make it feasible to continuously monitor certain parameters,
such as air quantity and velocity and spray water flow rate and
pressure (Spencer, et al. 1996). Existing Sec. 75.362 encourages the
use of such monitors as it would eliminate the need for periodic
physical measurements of some dust controls to verify if they are
operating properly. Although current technology allows real-time data
to be obtained on certain dust control parameters such as air
quantities,

[[Page 10788]]

MSHA is not aware of its use by any operator.
Since establishment of the first comprehensive dust standards in
1969, the implementation of ventilation plans by mine operators and
their enforcement by MSHA has had a significant impact on control of
dust levels in underground coal mines. For example, based on federal
mine personnel sampling results, the average dust concentration in the
environment of a continuous miner operator (occupation code--036) has
been reduced by 87 percent over the past 32 years, from 7.7 mg/
m3 to approximately 1.0 mg/m3. This accounts for
the significant decline in the percentage of operator continuous miner
designated occupation (DO) samples with concentrations of 2.1 mg/
m3 or higher, from 49 percent (over 32,000 samples/shifts)
in 1971, to 7 percent (over 1,250 samples/shifts) during the first
three quarters of 2002. Analysis of all valid operator DO samples
collected during the same time period as above indicates that in 1971,
53,463 (44 percent) of the 122,404 shifts sampled, were at or above 2.1
mg/m3, compared to 1,450 (7 percent) of the 19,336 shifts
sampled in 2002 (MSHA, DO Samples by Calendar Year, 2002). Despite this
progress, MSHA has found evidence that a significant number of
overexposures still occur on the shifts sampled during which the
approved dust control parameters are operating at or above approved
levels. This evidence suggests that it is highly probable that some
miners are overexposed to respirable dust on shifts not sampled by
either the operator or by MSHA. In addition, recent medical
surveillance data suggests that miners continue to be at risk of
developing simple coal workers' pneumoconiosis (CWP), progressive
massive fibrosis (PMF), and silicosis (Elam, April 1999).
Two expert panels, that reviewed the federal program designed to
prevent pneumoconiosis among coal miners, found that certain aspects of
the current respirable dust program limit MSHA's ability to determine
the adequacy of the dust control parameters under typical mining
conditions. Both the Coal Mine Respirable Dust Task Group, (Task Group)
an interagency task group established in 1991 by the Assistant
Secretary for Mine Safety and Health, and the Advisory Committee on the
Elimination of Pneumoconiosis Among Coal Mine Workers, (Dust Advisory
Committee) established in 1995 by the Secretary of Labor, considered
all aspects of the respirable coal mine dust control program and made
recommendations for improvement. In addition, in November 1995, NIOSH
issued a criteria document that contained recommendations to improve
miner health protections.

D. Coal Mine Respirable Dust Task Group

In response to concerns about the Federal coal mine dust program
(MSHA, 1992), MSHA's Task Group undertook an extensive review of the
program to control respirable coal mine dust and made recommendations
to improve the program in 1991. As part of that review, MSHA developed
a special respirable dust ``spot inspection program'' (SIP). This
program was designed to provide the Agency and the Task Group with
information on the dust levels to which underground miners are
typically exposed.
The Task Group found that MSHA's current program did not promote
the development and implementation of quality plans. Based on its
review of a representative number of dust control plans, the Task Group
found that some plans lacked specificity or did not include all the
dust control parameters actually used. For example, the plans for three
major underground coal mines listed the air quantity, the primary means
of controlling concentrations of respirable coal mine dust, to be
18,000 cubic feet per minute (cfm) in the mining section. The actual
quantities measured by MSHA samples at these mines during the SIP
varied from 40,000 cfm to over 120,000 cfm.
Based on a review of MSHA Form 2000-86 (Revised), Respirable Dust
Sampling and Monitoring Data, similar differences were found between
air quantities specified in approved ventilation plans and the levels
observed at a number of longwall MMUs inspected in 1999. For example,
20 of the 47 longwall MMUs were using significantly more air than
specified in the ventilation plan (MSHA, September 1999). Under these
circumstances, it would be impossible to assess whether the air volume
specified in the plan was adequate to maintain dust concentrations at
or below the applicable dust standard. It should be noted that air
quantities, air velocities, water spray pressures, and other control
parameters, specified in the plan are considered to be minimum
requirements and MSHA encourages mine operators to exceed their plan
parameters, but only after the levels specified in the plan have been
shown to be effective under the conditions in effect during sampling.
In addition, a lack of specificity in some plans made it difficult for
MSHA samples to determine whether the operator was complying with the
approved plan. Although several plans indicated that the mining
equipment was to be provided with water sprays, the plan did not
specify the location of the sprays or the water pressure at the spray
nozzle.
Currently, MSHA relies on information provided by the operator to
determine at what production level the plan should be evaluated. No
production records are required for each MMU. Although operators must
submit production data on a quarterly basis, the data is compiled for
the entire mine. In addition, these quarterly reports provide
information on the amount of clean coal produced, which are much lower
than the tonnage of total material produced, and are not useful for
establishing what constitutes ``normal production shifts'' for sampling
purposes.
The Task Group determined that the use of low production levels for
evaluating the effectiveness of dust control parameters can result in
marginal or inadequate plans. Therefore, the Task Group recommended
that MSHA require mine ventilation plans to be effective under typical
mining conditions. A more detailed discussion of the impact of
production on the quality of dust control parameters specified in mine
ventilation plans is contained in sections III.C.1. and IV.B. of this
preamble.
A survey conducted by MSHA in August of 2002 found that 48 percent
of producing MMUs worked at least a 9-hour shift. The Task Group
concluded that current regulations limiting the duration of sampling to
eight hours do not provide for adequate assessment of respirable dust
exposure during nontraditional shifts of more than eight hours.
Implementation of the Task Group recommendations would have
required regulatory change. The effort to implement these changes was
suspended pending the deliberations and recommendations of the Advisory
Committee on the Elimination of Pneumoconiosis Among Coal Mine Workers,
which was convened in 1995.

E. NIOSH Criteria Document

On November 7, 1995, MSHA received the document, Criteria for a
Recommended Standard: Occupational Exposures to Respirable Coal Mine
Dust, (Criteria Document) from the National Institute for Occupational
Safety and Health (NIOSH). That document contains recommendations to
minimize the health risks encountered by surface and underground coal
miners due to their occupational exposure to respirable coal mine dust
and

[[Page 10789]]

crystalline silica, hereafter referred to as ``quartz.''
According to NIOSH,

By means of criteria documents, NIOSH communicates these
recommended standards to regulatory agencies (including the
Occupational Safety and Health Administration (OSHA) and MSHA) and
to others in the community of occupational safety and health * * *.
In addition to transmitting these documents to the Department of
Labor, NIOSH also distributes them to health professionals in
academic institutions, industry, organized labor, public interest
groups, and other government agencies. (NIOSH, 1995, p. iii).

Pursuant to the Mine Act, MSHA was required to issue a public
response to this criteria document within 60 days. The statutory
deadline for MSHA's response fell on January 7, 1996. In the fall of
1995, there was a lapse in funding for the Federal government, and the
Department of Labor was unable to take timely action on this matter (61
FR 731). On April 25, 1996, MSHA published its response to the Criteria
Document in the Federal Register (61 FR 18308) stating it would develop
its regulatory response to the Criteria Document in conjunction with
its response to the outcome of the Dust Advisory Committee. (See
section II.F.).
Some commenters criticized the earlier proposed rules for not
addressing all the recommendations of the Criteria Document. During the
August 2000 hearings when these comments were made, a NIOSH
representative stated, ``* * * strong steps are necessary * * *
oftentimes they do need to be incremental in nature.'' Among the
relevant recommendations from the Criteria Document raised by
commenters were the following:
? Sampling should be conducted with a device that operates in
accordance with NIOSH Accuracy Criteria Document, using the
international definition of respirable dust.
? Single-shift measurements should be used to determine
noncompliance.
? The exposure limit for respirable coal mine dust should be
limited to 1.0 mg/m3 as a time-weighted-average (TWA)
concentration for up to 10 hours per day, during a 40-hour workweek.
? There should be a gravimetric standard for silica of 0.05
mg/m3 as a TWA for up to 10 hours per day, for a 40-hour
workweek.
? Sampling goals should include determining the effectiveness
of a dust control system and determining compliance with exposure
limits to ensure that exposure conditions are comparable between shifts
which are sampled and those which are not.
? Engineering controls and work practices should reflect
reasonable efforts to reduce exposures to respirable coal mine dust
below the exposure limit.
? MSHA should not make an upward adjustment of the exposure
limit to account for measurement uncertainties (i.e., citation
threshold values (CTV)). (See section III.A.4.a.).
? Continuous monitoring devices should be developed for use
in sampling respirable coal mine dust.
? Sampling frequency should be enough that a significant and
deleterious change in the contaminant generation process or exposure
controls is not permitted to persist.
MSHA has carefully considered the applicability of each NIOSH
recommendation to reduce miners' exposure to respirable coal mine dust,
and the agency has integrated these recommendations into our programs,
policies, and promulgation of standards. The proposed rule published
today are, in part, responsive to NIOSH's recommendations.
For example, the single sample rule, for which the record is
reopened in today's Federal Register notice is responsive to the
Criteria Document. This rule was jointly developed with NIOSH.
The two recommendations regarding exposure limits for respirable
coal mine dust and quartz dust are beyond the scope of either the
single sample or plan verification proposed rules.
MSHA and NIOSH agree that the level of ``coal production
significantly affects the amount of airborne respirable coal mine
dust'' (NIOSH 1995, p. 86). NIOSH recommended that ``The mine operator,
therefore, should establish a production-level threshold to ensure that
exposure conditions are comparable between sampled and unsampled
shifts'' (NIOSH, 1995, p. 86). NIOSH recommended that, for a production
shift to be considered a normal production shift, it must produce at
least 80% of the average production, over the last 30 production
shifts.
Through this plan verification proposed rule, MSHA would require
operators to design their ventilation plan to be effective in
controlling respirable coal mine dust at or above the ``verification
production level'' (VPL). The VPL is defined as the tenth highest
production level recorded in the most recent 30 production shifts. This
quantity generally exceeds the production criteria recommended by NIOSH
by a substantial amount.
In addition, for MSHA to approve an operator's mine ventilation
plan, the plan's dust control parameters must be shown to be effective
in meeting the verification limits of 2.0 mg/m3 for
respirable coal mine dust and 100 [mu]g/m3 for respirable
quartz dust, under typical mining conditions. MSHA expects that most
ventilation plans will be verified at or below those values. Therefore,
for most mechanized mining units (MMUs), engineering controls will be
in place that can control respirable coal mine dust at or below the
exposure limit. (See chapter IX. Costs in the Preliminary Regulatory
Economic Analysis (REA) for details).
Citation threshold values (CTV) are calculated to ensure that
citations are issued only when a single sample measurement
demonstrates, with at least 95-percent confidence, that the applicable
dust standard had been exceeded.\2\ Thus, before issuing a citation,
the Secretary requires a high level of confidence that there has been
an overexposure. Even so, a dust concentration measurement that falls
between the applicable dust standard and the corresponding CTV does not
demonstrate that the sampled environment is in compliance. MSHA would
identify such environments for further sampling to determine if
engineering controls are adequately protective.
------------------------------------------------------------------------

\2\ CTVs are listed in Table 70.2
------------------------------------------------------------------------

As mentioned earlier, several commenters to the 2000 proposal
expressed concern that, under MSHA's proposed sampling program, the
number of shifts to be sampled would be less than under the current
operator and MSHA sampling programs combined. Although MSHA will sample
fewer shifts than what was recommended by the Dust Advisory Committee,
the number of compliance determinations per MMU will not decrease.
Under the existing sampling programs, each MMU averages 10 compliance
determinations per year.\3\ Each of these compliance determinations is
based on the average

[[Page 10790]]

of five 8-hour exposure measurements. (See III.A.2. Post-1980 Sampling
Program). Under this proposed rule, each MMU will average significantly
more compliance determinations annually using the results of single
sample measurements taken by MSHA personnel (30 CFR 70.202).\4\ This
increase does not reflect the additional compliance determinations that
will be made as a result of sampling, concurrently with MMUs, each
intake DA, roof bolter DA and outby occupations.
------------------------------------------------------------------------

\3\ Currently, six of the ten compliance determinations are
based on the average of five operator, ``designated occupation''
(DO) exposure measurements. Each of these measurements is collected
on a different shift within a bimonthly cycle. The remaining four
determinations are based on the average of five inspector samples
taken quarterly on different occupations from a MMU. Since the
publication of the earlier proposed rule, the number of yearly MSHA
sampling inspections at each MMU was reduced from six to four. This
was the result of the impact on Agency resources due to a decision
by the Federal Mine Safety and Health Review Commission that
violations of the applicable dust standard must be based on samples
taken on multiple shifts. Prior to that decision, MSHA compliance
decisions were based on multiple samples taken on a single-shift.
Accordingly, there has been a need to increase the number of shifts
of MSHA sampling at MMUs where overexposures are found on the first
sampling shift. This results in fewer sampling inspections being
available at other MMUs.
\4\ On a re-occuring basis MSHA will sample an average of five
different occupations on each producing MMU. Since every measurement
will be compared with the CTV corresponding to the applicable dust
standard in effect, MSHA will be making significantly more
compliance determinations yearly than under the current operator and
MSHA sampling programs combined.
------------------------------------------------------------------------

The new sampling program will be far more effective in monitoring
the quality of the mine air that miners must breathe, and in preventing
overexposures on individual shifts, because MSHA will be making
compliance determinations using measurements that are more
representative of the dust concentrations to which miners are exposed
on individual shifts. As such, MSHA believes the new MSHA sampling
program addresses the NIOSH recommendation that sampling be conducted
``frequently enough that a significant and deleterious change in the
contaminant generation process or exposure controls is not permitted to
persist'' (NIOSH, 1995, p. 85).
Significant progress in monitoring technology has been made since
MSHA published the earlier proposed rule on plan verification. The
agency has been informed by NIOSH that a continuous dust monitor may be
available for in-mine use by the middle of 2004. Accordingly, as
recommended in the criteria document, MSHA is proposing a new standard
that would permit operators to use this new technology in conjunction
with existing dust controls specified in the ventilation plan to
prevent overexposures on individual shifts.
Today's proposed rule does not adopt all the Criteria Document
recommendations since many of the recommendations are outside the scope
of these rules. However, MSHA continues to be committed to the
principles that ``preventive efforts [must]
be focused primarily on
reducing work exposures (NIOSH, 1995).''
The Secretary of Labor and the Secretary of Health and Human
Services believe that miners' health will be further protected from the
debilitating effects of occupational respiratory disease by limiting
their exposures to the applicable dust standard through the
implementation of the single sample rule which conforms to the NIOSH
Accuracy Criteria. Furthermore, as stated by NIOSH during the hearings:

NIOSH does support efforts by MSHA and anyone else that will
reduce miners' exposures to dust and silica dust and also eliminate
or at least reduce significantly the incidence of the diseases * *
*.

MSHA believes that this proposed plan verification rule provides an
improved program for measuring, monitoring, and reducing overexposures
to respirable coal mine dust and quartz dust, under typical mining
conditions. As such, it greatly advances the level of health protection
afforded underground miners and is consistent with recommendations
issued by NIOSH in its Criteria Document.

F. Advisory Committee on the Elimination of Pneumoconiosis Among Coal
Mine Workers

On January 31, 1995, the Secretary of Labor established the
Advisory Committee on the Elimination of Pneumoconiosis Among Coal Mine
Workers (Dust Advisory Committee). The Dust Advisory Committee was
chartered to ``make recommendations for improving the program to
control respirable coal mine dust in underground and surface mines in
the United States.'' The Dust Advisory Committee identified and
addressed many of the same issues considered by the Task Group.
Findings and consensus recommendations were developed for each issue
(MSHA, 1996). The Dust Advisory Committee concluded that the dust
control portion of the mine ventilation plan is the key element of an
operator's strategy to control respirable dust in the work environment.
They concluded that the initial evaluation, approval, in-mine
verification and monitoring to demonstrate the effectiveness of the
operator's proposed dust control plan is critical for the protection of
miners from lung disease. Also, believing that the credibility of the
current system of mine operator sampling to monitor compliance with
exposure limits has been severely compromised, the Dust Advisory
Committee concluded that restoration of miner and mine operator
confidence in the respirable coal mine dust sampling program should be
one of MSHA's highest priorities. Accordingly, there was unanimous
agreement that in order to restore confidence in the program MSHA
should take full responsibility for all compliance sampling currently
being carried out by mine operators under 30 CFR parts 70 and 90.
The November 1996 Dust Advisory Committee Report recommended
numerous improvements for the federal program to protect miners from
simple CWP, PMF, and silicosis. Of these, the following have been
incorporated in this proposed rule:
1. MSHA will take full responsibility for all compliance sampling
(periodic and abatement) at a level which ensures that representative
samples are collected of respirable dust exposures under usual
conditions of work without adversely impacting the Agency's resources
and responsibilities.
2. Operators would be required to verify, through sampling, the
effectiveness of the dust controls in the ventilation plan prior to
approval by MSHA. The plan must be verified utilizing only those
controls that are listed in the plan. In addition, mine operators would
sample designated MMUs quarterly to ensure that the dust controls
continue to protect miners from overexposure.
3. MSHA will redefine the range of production levels which must be
maintained during sampling to verify the plan. The value will be
sufficiently close to maximum anticipated production levels in order to
reasonably ensure that the plan is effective under typical operations.
4. MSHA will review compliance and production records to determine
when there is a need for plan verification and modification.
5. MSHA would allow mine operators to use newly developed
technology to continuously monitor the work environment and prevent
overexposures on individual shifts.
This proposed rule is intended to eliminate overexposures on
individual shifts and to restore the confidence of miners and mine
operators in the respirable coal mine dust sampling program by
addressing the shortcomings identified by the Task Group and the Dust
Advisory Committee in the current respirable coal mine dust program.
This proposed rule would revise the operator dust sampling programs
under 30 CFR parts 70 and 90 and require the implementation of mine
ventilation plans demonstrated to be effective in maintaining
respirable dust at or below applicable dust standards on each shift.
These ventilation plans will be verified through sampling by the mine
operator, and the plans' effectiveness may be monitored on a quarterly
basis by the operator. MSHA intends to periodically monitor operator
verification sampling and on a recurring basis will conduct sampling on
each MMU to assure

[[Page 10791]]

compliance with the provisions of the ventilation plan and the
applicable dust standard. A notice reopening the record regarding the
use of single-shift sample measurements of respirable coal mine dust to
determine average concentration is also published in today's Federal
Register.
MSHA recognizes that the Dust Advisory Committee made several
recommendations that also impact on surface coal mine workers. These
surface coal mine issues are beyond the scope of this proposed rule and
will be addressed by the Agency at a later date.
In response to comments received, MSHA has specifically stated in
this proposed rule that the representative of miners has the right to
observe MSHA sampling with no loss of pay as recommended by the Dust
Advisory Committee. The proposed rule also allows the miners'
representative the opportunity to participate in operator sampling to
verify the ventilation plan. However, such participation would be with
no loss of pay, only when MSHA personnel are present to observe that
sampling. This proposed rule does not specifically address the
committee's recommendations concerning specialized miner training on
verification sampling procedures. However, MSHA does intend, during the
implementation of any final rule, to provide training to miners,
miners' representatives and mine operators on the requirements of the
new regulations. In addition, agency personnel are available to provide
training to miners and their representatives on the verification
procedures as needed.
This proposed rule does not incorporate full-shift sampling as
recommended by the Dust Advisory Committee. In this proposed rule, MSHA
does require that verification and operator quarterly sampling occur
for the entire production shift since the purpose of that sampling is
to evaluate the effectiveness of the dust controls on the MMU.
Therefore, outby travel time is not included. With regard to compliance
sampling by MSHA, the agency believes that sampling portal to portal
for the entire shift or eight hours, whichever is less, provides the
agency with sufficient data to determine if the dust control measures
outlined in the ventilation plan are adequate and being followed or to
determine if overexposures are occurring.
Although the Dust Advisory Committee also recommended that MSHA
adjust the exposure limit to account for extended work weeks, such a
change is considered to be outside the scope of this rulemaking.
MSHA has clarified in this proposed rule that the Secretary will
cite for overexposure when an MSHA sample demonstrates that the
applicable dust standard has been exceeded, based on the citation
threshold value (CTV). In response to concerns that, by using a CTV,
MSHA is increasing the standard, MSHA has clarified that respirable
dust concentration levels must always be maintained at or below the
applicable dust standard. In order to obtain ventilation plan approval
from MSHA, operators must demonstrate that the dust control parameters
adequately prevent excessive dust concentrations on individual shifts.
The plan's effectiveness is evaluated against the applicable dust
standard itself--not the CTV--and must be demonstrated at a high level
of confidence.
This proposed rule also provides for the limited use of measures to
supplement engineering or environmental controls for exposure control.
These supplemental measures would be permitted at certain times when
the Administrator for Coal Mine Safety and Health has determined that
all feasible engineering and environmental controls have been applied
and the mine operator is unable to verify the ventilation plan.
Supplementary controls may also be approved by MSHA for short-term use
to protect individual miners when operators encounter intermittent,
adverse conditions under which exposures cannot be maintained within
the applicable standard using the approved dust control parameters.
Finally, MSHA received comments suggesting that this rule address
the Dust Advisory Committee recommendation to establish a separate
silica standard. This issue is outside the scope of this rule.

III. General Discussion

A. Proposed Reforms to the Respirable Dust Monitoring Program

One of the Dust Advisory Committee's key recommendations was that
MSHA take full responsibility for all compliance sampling at a level
which assures representative samples of respirable dust exposure under
usual conditions of work. This was based on the belief that one of
MSHA's highest priorities must be to restore the confidence of miners
and mine operators in the respirable coal mine dust sampling program.
Accordingly, MSHA is proposing to revise the operator dust sampling
programs under current 30 CFR parts 70 and 90 and to take full
responsibility for all compliance sampling (i.e., periodic and
abatement sampling) in a manner that it believes will be more
protective than the current operator sampling program. MSHA intends to
monitor miners' dust exposure and compliance with the dust control
provisions of the approved mine ventilation plan, or with the
respirable dust control plan for a Part 90 miner at underground mines,
in accordance with the procedures and guidelines established in Chapter
1 of the Coal Mine Health Inspection Procedures Handbook.
(a) Compliance Sampling
MSHA will routinely collect samples from the working environment of
the DO, Part 90 miners and, if available, four or more other
occupations working in each producing MMU. The data from this sampling
will be utilized by MSHA to formulate an effective compliance sampling
strategy that focuses on the performance of individual sampling
entities and to target MMUs for operator quarterly sampling. The
strategy will be detailed in the Agency's respirable dust inspection
procedures.
Each DA inby the section dump point, such as intake and roof bolter
DAs, and other DAs that can be sampled concurrently with the MMU will
also be sampled routinely. If the MMU sampled is operating with
approved supplemental control measures, the five or more occupations
sampled will include the DO and all miners whose exposure is being
controlled through the use of PAPRs or verifiable administrative
controls.
Since MSHA's inspections are unannounced, the primary objective is
to assess the respirable dust conditions to which miners are exposed
under the operating conditions in effect at the time of sampling (i.e.,
production level, air quantities and velocities, etc.). All respirable
dust samples collected will be considered valid, unless voided by MSHA
for other reasons, such as a malfunctioning pump. Because the primary
purposes are to measure the quality of the mine air miners breathe and
to evaluate the operating conditions on a particular shift, the Agency
believes there is no reason to invalidate any sample if a certain level
of production is not attained as under the previous sampling
procedures. Compliance sampling results, however, will provide MSHA
personnel with sufficient information to make a sound engineering
judgement about the effectiveness of the dust control parameters in
use.
Also, since the purpose of this sampling is not intended to
evaluate plan effectiveness, the term ``full shift'' for purposes of
compliance and

[[Page 10792]]

abatement sampling will continue to mean the entire work shift
including travel time but excluding any time in excess of 480 minutes.
This is different from the definition of ``full shift'' that is
proposed for verification sampling. For purposes of verification
sampling, ``full shift'' would mean an entire work shift during which
material is produced by a MMU. MSHA solicits comments on whether full
shift for compliance sampling should be defined in the same way as for
verification sampling.
MSHA is proposing to continue the current policy of sampling outby
locations only once per year. The historical data that has been
collected by MSHA personnel at outby locations confirms our belief
that, if the working sections are in compliance with the applicable
dust standard and if controls are in place at outby dust generating
locations, workers throughout the mine are being protected from
overexposure. MSHA personnel will continue to sample each DA located
outby the section dump point on a production shift and any other dust-
generating sources that can be sampled concurrently with the DA.
MSHA will issue a citation for noncompliance when a valid single
sample measurement, expressed as an equivalent dust concentration,
meets or exceeds the Citation Threshold Value (CTV) corresponding to
the applicable dust standard in effect.
The current CTVs are contained in Table 70.2 of this proposed rule.
The CTVs and an explanation of how they were derived was originally
published in the Federal Register notice of February 3, 1998 (63 FR
5687), entitled ``Coal Mine Respirable Dust Standard Noncompliance
Determinations.'' As explained in that notice and in Appendix ``C'' of
the current notice of proposed rulemaking, each CTV is calculated so
that citations are issued only when a single-shift measurement
demonstrates noncompliance at least at a 95 percent confidence level.
Noncompliance determinations based on single-shift measurements
will reduce the chances for failure to cite cases of noncompliance.
According to the federal sampling inspections conducted in 1995, only
132 MMUs were found to be in violation of the applicable dust standard.
These MMUs were cited under the existing enforcement policy of
measurement averaging, compared to 545 MMUs that would have been
citable using single sample measurements in combination with the CTV
table. This clearly demonstrates that the new enforcement strategy will
not compromise miners' health, instead it would have identified 413
additional instances of overexposure. Otherwise, these overexposures
would continue to go uncorrected under the previous policy of
measurement averaging.
Many commenters believed that miners would receive greater
protection if MSHA cited for noncompliance whenever any single-shift
measurement exceeded the applicable dust standard. MSHA has carefully
considered, but rejected this suggestion. Such citations may not be
sustained with a sufficient degree of confidence for enforcement
action. If the mine environment is sufficiently controlled, the
likelihood that a particular measurement exceeds the applicable dust
standard, but not the CTV, due to measurement error, can actually
exceed the likelihood that the measurement exceeds the standard due to
excessive dust concentration. A thorough technical discussion of this
issue is provided at 63 FR 5709-5712 (Appendix D of the Federal
Register notice cited above) and is incorporated into this notice by
reference. Basing noncompliance determinations on a single sample
measurement, in conjunction with the CTV table, will improve working
conditions for miners.
Many commenters contended that a policy of citing in accordance
with the CTV table, rather than citing whenever a measurement exceeds
the applicable dust standard, would effectively increase the allowable
dust concentration limit. These commenters expressed concern that MSHA
was raising the applicable dust standard when it proposed to cite
violations only when the measurement demonstrated noncompliance at a
high level of confidence.
The CTVs do not raise the applicable dust standard. Instead, MSHA
must ensure a sufficiently high level of confidence in noncompliance
determinations to withstand a legal challenge. For those MMUs with
measurements above the applicable dust standard but below the CTV, MSHA
will thoroughly review their dust control parameters. Special emphasis
will be directed to working environments required to comply with
standards below 2.0 mg/m3. As a result of such reviews MSHA
may initiate additional sampling.
The Secretary has concluded that using single sample measurements
for noncompliance determinations in accordance with the CTV table
neither increases nor decreases the applicable dust standard. Operators
are required to maintain compliance with the applicable dust standard
at all times. Dust controls must be verified as adequate to maintain
dust concentrations at or below the applicable dust standard on all
shifts, not merely at or below the CTV. If a measurement exceeds the
applicable dust standard by an amount insufficient to warrant
citation--that is, the level does not meet or exceed the CTV--MSHA will
target that mine or area for additional sampling to ensure that dust
controls are adequate.
(b) Abatement Sampling
Under this proposed rule, MSHA would also assume responsibility for
all abatement sampling. As recommended by the Dust Advisory Committee,
MSHA would utilize single samples to demonstrate abatement. Since the
criteria under which the effectiveness of ventilation plans are
required to be verified are significantly more stringent than those for
compliance sampling, MSHA does not anticipate issuing many citations to
MMUs and sectional DAs.
When a mine operator is cited for violation of the applicable dust
standard, MSHA will require that approved respiratory equipment be made
available to the affected miners in accordance with existing Sec.
70.300 of this part. The mine operator also will be required to review
the dust control practices to identify the cause of the excessive dust
concentration and correct any deficiencies within the abatement period
fixed in the citation.
The mine operator must notify the district manager of the
corrective measures taken within 24 hours of implementation to enable
MSHA to determine whether abatement or verification sampling should be
scheduled. This determination will be based on the review of the
information the mine operator provides and the latest inspection
reports documenting the measured quantities of the dust control
parameters that were in use at the time the citation was issued.
If it is determined that the existing dust control parameters are
likely to be adequate to maintain compliance, the district manager will
initiate abatement sampling under Sec. 70.218. For example, if the
operator believes that the overexposure was caused by improper work
practices, the proper course of action would be to review these work
practices with the affected miners rather than requiring the operator
to upgrade the engineering or environmental controls. Since there was
no need to change the plan parameters, MSHA would initiate abatement
sampling in this particular case.
If, on the other hand, the district manager determines that the
dust control parameters may not maintain respirable dust levels at or
below the

[[Page 10793]]

applicable dust standard, the mine operator will be notified to revise
the dust-control portion of the mine ventilation plan as specified in
this Part.
When MSHA samples a MMU for abatement purposes, single samples will
be collected from the working environment of the cited occupation and,
if available, four other occupations that will include the DO. Like
compliance sampling, abatement sampling will be conducted portal to
portal, for the entire shift or 8 hours, which ever is less.
When sampling DAs and outby occupations, MSHA will collect a
similar single-shift abatement sample from the environment of the cited
DA or occupation.
A citation for excessive dust will be terminated when all valid
abatement samples collected are at or below the applicable dust
standard. The subsequent action form will clearly and fully describe
the action taken to abate the violation. Mine operators may be required
to revise the ventilation plan in accordance with Sec. 75.370(a)(2) of
this title depending on the type of corrective measures taken to abate
the violation. This includes, at a minimum, the actual dust control
parameters that were in effect when MSHA sampled.
If the district manager requires the mine operator to initiate the
plan verification process under Sec. 70.206 of this part instead of
abatement sampling, the citation for excessive dust will be terminated
after a revised plan has been verified to be effective for the current
mining conditions.
(c) Operator Verification Sampling and Quarterly Sampling
Mine operators are required, under this proposed rule, to verify,
through sampling, the effectiveness of the dust control parameters for
each MMU prior to receiving MSHA approval of the mine ventilation plan.
In addition, certain mine operators must sample quarterly each DO, any
occupation required to wear a PAPR or using administrative controls,
and any other occupation designated by the district manager. The
purpose of the quarterly sampling is to evaluate the continued
effectiveness of the approved dust control parameters. These provisions
are discussed elsewhere in this proposed rule.
(d) Advantages of MSHA Compliance Sampling Over the Existing Program
Under section 101(a)(9) of the Mine Act, no health standard
promulgated under the Act shall reduce the protection afforded miners
by an existing mandatory health standard. The joint promulgation of
this proposed rule and the proposed single sample rule, would provide
protection to miners from the debilitating effects of occupational
respiratory disease by limiting their exposures to respirable coal mine
dust and quartz dust on every shift:
? Providing and maintaining a work environment free of
excessive levels of respirable dust is essential for long-term health
protection. While monitoring of the work environment provides an
indication of how effective the existing dust control measures are,
monitoring alone does not control dust levels. Requiring mine operators
to implement and maintain dust control parameters which have been
determined effective under typical mining conditions, will provide
reasonable assurance that no miner will be overexposed on individual
shifts.
? Implementing single-shift sample determinations will more
likely detect excessive dust concentrations and thus protect miners.
Averaging samples taken on multiple shifts can mask overexposures on
individual shifts. Although fewer shifts will be sampled under this
proposed rule, MSHA believes the revised sampling methodology will
provide a more accurate representation of dust conditions to which
miners are exposed.
? Under the existing operator sampling program, only the DO
is sampled. Under the new sampling program, MSHA will sample multiple
occupations on the same shift. As a result, MSHA will make several
times as many compliance determinations as under the previous operator
and MSHA sampling programs combined, providing a more comprehensive
assessment of dust conditions to which miners are exposed.
? Since MSHA will be conducting all compliance sampling, the
Agency will be able to monitor the dust control parameters and work
practices in effect during sampling. This will enable MSHA to determine
the effectiveness of the mine operator's dust control program.
? Unlike the current sampling program, which allows
operators' control over when to sample and under what operating
conditions, MSHA's visits for compliance sampling will be unannounced.
As a result, all phases of the mining cycle are likely to be sampled
eventually (i.e., construction activity, longwall start-up, turning
crosscuts, etc.), and samples should be more representative of typical
mining conditions.
? The miners' representative will have walkaround rights
during all MSHA sampling, thereby increasing miners' confidence in the
dust sampling program.

B. Procedures for Setting the Applicable Dust Standard When Quartz Is
Present

1. Proposed Procedures
Consistent with MSHA's proposed rule to assume full responsibility
for compliance sampling, the Agency also proposes to rely only on MSHA
samples, i.e., compliance or abatement samples, as the basis for
setting the applicable dust standard when quartz is present. As
discussed below, while today's proposed rule would reduce the burden
and cost on mine operators to take and submit optional samples, it
would not diminish the advantages afforded operators under the current
program. In particular, it continues to consider temporal variability
associated with quartz determinations by averaging three MSHA samples
collected on different shifts.
MSHA believes that results under this revised process will be more
representative of the quartz levels to which miners are exposed. Unlike
the current process, which may cause a standard to be set based on the
quartz content of an individual MSHA sample, three valid MSHA samples
would be used to set a reduced standard under the revised procedures
(64 FR 65671).\5\ Since, under the rules being proposed today, MSHA
intends to frequently sample underground mines and surface mines, MSHA
personnel will have no difficulty in collecting the required number of
samples to arrive at the average quartz percentage. If initial sampling
shows that miners may be exposed to excessive levels of quartz, MSHA
intends to sample at a greater frequency to ensure that miners are
being protected. This level of sampling should also allay any operator
concerns regarding the collection of ``misleadingly high'' samples
during atypical periods. MSHA also intends to begin reporting quartz
levels to the nearest tenth of a percent. This will be more protective
for the miner than the current truncation of results to a full
percentage point.
------------------------------------------------------------------------

\5\ Unlike MSHA's objective in compliance sampling, the
objective in measuring quartz content is to establish a reduced
standard that will apply to all shifts. This enables an operator to
design a ventilation plan that will be protective on every shift.
Therefore, it is appropriate to estimate the quartz content by
averaging quartz measurements obtained over an extended time period.
------------------------------------------------------------------------

Under the revised procedures, when an MSHA sample contains more
than five percent quartz, the agency will average the percent of quartz
present in three most recent MSHA respirable coal mine dust samples to
set the applicable

[[Page 10794]]

dust standard. If a MMU, DA, Designated Work Position (DWP) at an
underground mine, or Part 90 miner is already on a reduced standard, a
new applicable dust standard will be established by averaging the
results of the first two MSHA samples, taken under the revised
procedures, with the quartz percentage associated with the reduced
standard in effect. If fewer than two MSHA samples are taken, the
existing reduced standard will continue to remain in effect.
Assume a MMU is on a 1.0 mg/m\3\ standard (10 percent quartz). If
the first MSHA sample contains 7.2 percent of quartz, the existing
standard of 1.0 mg/m\3\ would continue to remain in effect. If,
however, the next sample contains 16.1 percent, the average quartz
percentage would be 11.1 percent [(10.0% + 7.2% + 16.1%) 3 = 11.1%],
resulting in a 0.9 mg/m\3\-standard (10 11.1% = 0.9 mg/m\3\). For any
MMU, DA, DWP, or Part 90 miner not on a reduced standard, MSHA will
collect and analyze three samples for quartz to determine if a reduced
standard is warranted.
Under the revised procedures, if the newly-established standard is
lower than the one in effect, the new standard will become effective
seven days after the date of the notice informing the mine operator of
the change in the applicable dust standard. However, if it is higher
than the current standard, the newly-established applicable dust
standard will become effective on the date of the notice.
As published elsewhere in today's Federal Register, MSHA is
proposing to take enforcement actions on the basis of single-shift
sample measurements. For entities on reduced standards, MSHA would
delay enforcement action until the sample is analyzed for quartz. If an
exposure measurement significantly exceeds the existing standard and
the quartz content of that sample would cause the standard to be
lowered below the existing reduced standard, the operator will be cited
for violation of the applicable dust standard currently in effect. On
the other hand, if the quartz content of the sample would cause the
applicable dust standard and the corresponding citation threshold value
(CTV) to increase so that the single-shift sample measurement would no
longer indicate noncompliance, no citation will be issued. This is
illustrated by way of the following example.
For example, suppose that the MMU is on a 1.3 mg/m\3\ standard and
a single-shift sample measurement of 1.6 mg/m\3\ is obtained. Since
this measurement exceeds the CTV value, the operator is in violation of
the standard. However, analysis of the DO sample shows that the sample
contained 5.6 percent quartz which, if averaged with the previous two
MSHA quartz levels, would result in a 1.7-mg/m\3\ standard. This
indicates that the quartz level in the environment of the DO has
changed, indicating that the current standard is no longer valid.
Therefore, since the original measurement of 1.6 mg/m\3\ is less than
the 1.7-mg/m\3\ standard that could have been in effect for the shift
sampled, a citation would not be issued.
Since MSHA samples are viewed to be more representative of the
respirable dust concentration to which miners are exposed, MSHA is
proposing to revise section 70.101 to clarify that the Secretary will
determine the quartz level by sampling. Operator samples would no
longer be submitted to determine the applicable dust standard. It is
our belief that the procedures being proposed today for setting reduced
standards will be more protective for the miners than those in effect
at this time. The revised approach provides for stringent monitoring of
miners' exposure to quartz which is consistent with the Dust Advisory
Committee's recommendation that MSHA increase surveillance and reduce
exposure to this serious health hazard.
As under the current program, if operating conditions change
following establishment of a lowered applicable dust standard and
affect the level of quartz in the working environment, MSHA intends
that mine operators or miners' representatives will be able to request
MSHA to conduct a quartz reevaluation.
2. Validity of Averaging Percentages
The average quartz percentage that MSHA intends to use to set the
applicable dust standard for a particular sampling location or area of
a mine would be determined in accordance with accepted mathematical
procedures for arriving at an average value from a set of values (i.e.,
adding together the individual quartz percentages and dividing by the
number of analyses that are in the set). MSHA believes that this is the
most appropriate method to use.
One commenter who responded to a draft 1999 program policy letter
(November 23, 1999, 64 FR 65671) concerning this issue contended that
MSHA's approach of arriving at the average quartz percentage was
mathematically incorrect. This commenter recommended that, to more
accurately reflect the true quartz concentration, the average quartz
percentage be calculated by dividing total mass of quartz in micrograms
by the total mass of dust collected (based on three samples in the
example submitted). In the commenter's example, the average percentage
obtained using MSHA's proposed averaging method was larger than that
obtained using the commenter's approach.
The following two scenarios in Table III-1 clearly demonstrate that
MSHA's intended averaging method does not always result in a larger
average quartz percentage value.

[[Page 10795]]

[GRAPHIC]
[TIFF OMITTED]
TP06MR03.000

These examples show that for situations where MSHA would have
determined a quartz percentage of 8.0 percent, the commenter's method
would yield 9.2 percent in one case and 7.7 percent in the other.

C. Respirable Dust Control Program for Underground Coal Mines

The primary focus of the underground coal mine respirable dust
program is to limit the concentration of respirable dust to which
miners are exposed in the work environment. To ensure that miners are
not being exposed to excessive concentrations of respirable dust,
current regulations require mine operators to:
? Design a mine ventilation plan that effectively controls
respirable dust under typical mining conditions;
? Implement the plan's dust control parameters when approved
by MSHA before commencing production;
? Maintain the dust control parameters specified in the
approved plan and monitor their function and operation through required
on-shift examinations; and
? Evaluate the effectiveness of dust control parameters with
bimonthly samples in order to provide reasonable assurance that such
parameters continue to function as intended.
In addition, each plan must be suitable to the conditions and
mining system in use at the mine. These plans provide detailed
requirements for the protection of miners by specifying engineering
controls. These engineering controls may include:
? The quantity and the velocity of the air current used to
ventilate the MMU;
? The number, type, and location of water sprays;
? The pressure and quantity of water delivered by the sprays;
and
? Additional environmental controls, such as dust scrubbers
or devices which collect mine air and filter out dust particles.
Plans also contain procedures for maintenance of dust control
equipment used on the mining machine and roof bolter. Mine operators
frequently do not describe all dust controls in use at the mine. If
such information is not included in the plan, it is impossible for MSHA
to enforce those provisions or to determine if the ventilation plan
provisions as approved are adequate to protect miners from
overexposure.
When an operator submits a proposed mine ventilation plan or
revision in accordance with Sec. 75.370, the MSHA district office
reviews it for completeness and adequacy. The district manager will
approve the plan if it meets MSHA requirements, and he or she is
confident that the dust control parameters specified will have a
reasonable likelihood of maintaining dust concentrations within the
allowable limits. Most proposed plans or revisions are approved
immediately, or tentatively approved, based on engineering judgement,
or experience, or both, until they are assessed by MSHA sampling or, to
a lesser extent and only under certain circumstances, by mine operator
bimonthly sampling. Generally, MSHA takes samples within 60 days of
plan approval. Current regulations prohibit a mine operator from
initiating any mining activity without an approved ventilation plan.
MSHA allows operators to commence mining by granting tentative
approval. However, under the existing process, plans may be implemented
which are later determined to be inadequate under typical mining
conditions.
1. Proposed Procedures for Evaluating, Approving, and Monitoring
Ventilation Plan Requirements
The dust control portion of the mine ventilation plan is the key
element of an operator's strategy to control respirable dust in the
work environment, thereby protecting miners. In recognition of this,
MSHA is proposing to make a number of changes to the process for
evaluating, approving, and monitoring mine ventilation plans, many of
which are based on the Dust Advisory Committee's recommendations. These
are addressed in detail under proposed Sec. Sec. 70.201 through 70.220
of the preamble.
Consistent with the Dust Advisory Committee recommendations, MSHA
is proposing to add provisions to verify the effectiveness of the
ventilation plan in controlling dust, at a production level which will
demonstrate the plan's effectiveness under typical operating
conditions. Dust control parameters and production associated with
samples on a given shift would be recorded in order to demonstrate that
parameters specified in the ventilation plan continue to be effective
in controlling respirable dust.
This proposed rule requires a ventilation plan to include all
engineering or environmental controls necessary for maintaining dust
concentrations at acceptable levels. A plan must also include any
specific work practices or other means used to supplement these
controls in order to minimize the dust exposure of individual miners.
Unlike plans under the existing program, mine operators will have to
identify all measures necessary for achieving continuous

[[Page 10796]]

compliance with the applicable dust standard in the plan.
MSHA would require mine operators to include information on the
length of each normal production shift in Sec. 75.371(f) and to
specify the VPL, as defined in Sec. 70.2, in every ventilation plan.
The VPL is the tenth highest production level recorded in the most
recent 30 production shifts. This value will represent the minimum
production level at which effectiveness of the plan must be
demonstrated.
MSHA believes that the current production criteria used to evaluate
plan effectiveness may not adequately represent typical conditions
under which miners work. Requiring that plans be verified at or above
the VPL will provide assurance that excessive dust concentrations will
be avoided, even on shifts with higher-than-average production. This is
far more protective of miners than the current practice of evaluating
plan adequacy based on MSHA samples taken when production can be as low
as 60 percent of the average production.
Some commenters on the earlier proposed rule expressed confusion
about the relative magnitude of the VPL, compared to average production
or other possible production criteria. Figure 1 shows a typical
distribution of 30 shift production levels recorded at a longwall MMU.
As illustrated by this example, the VPL, defined as the 10th highest
production achieved during 30 shifts, generally exceeds the average
production by a substantial amount.
BILLING CODE 4510-43-P

[[Page 10797]]
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.001

BILLING CODE 4510-43-C
MSHA proposes to require mine operators to maintain records of the
amount of material produced by each MMU during each shift. This will
enable operators to establish the VPL. Because verification of a plan's
effectiveness is conditioned on the VPL, these records are necessary to
ensure that the VPL continues to represent typical production levels.
Although a VPL must be included in the ventilation plan, MSHA will not
cite mine operators for producing at levels exceeding the VPL.
MSHA considers the VPL to be a plan design criteria, not a minimum
plan parameter that must be in effect on every shift. The Agency would
expect production on a MMU to exceed the VPL on about 33 percent of all
production shifts. If the district manager determines that an
operator's actual production exceeds the VPL on more than 33 percent of
the production shifts over a six-month period and the operator or MSHA
samples exceed the applicable standard, the district manager may
require that the adequacy of the plan parameters be verified under

[[Page 10798]]

different operating conditions of production.
Under the proposed plan verification procedures, mine operators
will be required to verify through sampling the effectiveness of the
dust controls specified in the ventilation plan prior to approval of
that plan by the district manager. Sampling would occur when production
is at or above the VPL specified in the plan and using only those
control parameters and other measures listed in the plan. The sampling
pumps must be turned on upon arrival on the MMU and remain operational
during the entire production shift. The pumps must be turned off upon
leaving the MMU. Samples would be collected on multiple occupations
which are specified in proposed Sec. 70.206. All verification samples
must be transmitted to MSHA. However, no citations would be issued to
mine operators if the verification sample results show that the
applicable dust standard has been exceeded. Operators would be cited
only if they fail to take steps to determine the cause and take
corrective action to eliminate the overexposure. The agency would
approve a plan only when a sufficient number of verification samples
demonstrate, at a high level of confidence, that the plan is effective
at production levels at or above the VPL.
Unlike the existing program, this proposed rule would allow certain
longwall and other operations to use either approved PAPRs,
administrative controls, or both, to supplement engineering or
environmental controls if the mine operator is unable to verify the
ventilation plan. This will be permitted only after the Administrator
for Coal Mine Safety and Health determines that the operator has
exhausted all feasible engineering or environmental controls. District
managers also may allow mine operators to use PAPRs to achieve
compliance with the applicable dust standard when unusual operating
conditions are encountered briefly and intermittently and the operator
believes that the approved plan parameters will not adequately protect
all miners from overexposure. The period of time when PAPRs may be used
cannot exceed 30 calendar days under this proposed rule. An example of
when such approval may be granted is when an operator periodically must
mine through rock strata with high quartz content.
Finally, under this proposed rule, mine operators also would be
required to sample each DO and occupation using PAPRs or administrative
controls at least once every three months to evaluate the continued
adequacy of the approved plan parameters. As with verification samples,
operators would only be cited if they fail to take corrective action to
eliminate any overexposure identified through such sampling.

D. Hierarchy of Dust Controls

1. Primacy of Engineering Controls
Consistent with the Mine Act, engineering or environmental controls
have been the principal method used for preventing or minimizing
miners' exposure to both primary and secondary dust sources in the
workplace over the past 30 years. Engineering controls that are able to
manage the amount of dust throughout the work environment give
reasonable assurance that all miners in the area will be adequately
protected. Well-designed engineering or environmental controls provide
consistent and reliable protection to all workers because they are not
dependent upon constant human supervision or intervention, except for
the periodic checks, to ensure that they are functioning as intended.
Under this proposed rule, operators would be required to utilize, on
each production shift, all engineering or environmental controls as
specified in their mine ventilation plans. These controls will maintain
concentrations of respirable dust in the work environment of MMUs at or
below the applicable dust standard. Engineering or environmental
controls include all methods that control the level of respirable dust
by reducing dust generation (e.g., machine parameters) or by
suppressing (e.g., water sprays, wetting agents, foams, water infusion,
etc.), diluting (e.g., ventilation), capturing (e.g., dust collectors),
or diverting (e.g., shearer clearer, passive barriers, etc.) the dust
being generated by the mining process.
The importance of using engineering or environmental controls was
recognized by the Dust Advisory Committee and by NIOSH in Occupational
Exposure to Respirable Coal Mine Dust (NIOSH, 1995). NIOSH recommended
that such controls must continue to be relied upon as the primary means
of protecting coal miners. The primacy of engineering or environmental
controls would be preserved under this proposed rule. The proposed rule
requires a mine operator to utilize all feasible engineering or
environmental controls, specified in the approved ventilation plan, to
reduce concentrations of respirable dust to a level at or below the
applicable dust standard.
2. Administrative Controls
Administrative controls are another method of avoiding
overexposure. Administrative controls refer to work practices that
reduce a miner's daily exposure to respirable dust hazards by altering
the way in which work is performed. They consist of such actions as
rotation of miners to areas having lower dust concentrations,
rescheduling of tasks, and modifying work activities. The Task Group
found that administrative controls were used increasingly, even when it
was feasible to implement additional engineering or environmental
controls. The use of administrative controls was found to be increasing
at mines employing longwall mining systems.
The most frequent administrative control in use consisted of
restricting the activities of miners required to work downwind of the
longwall shearer operator, the occupation designated as 044 by MSHA.
This particular form of administrative control was in use at some of
the 51 longwall MMUs that were operating on October 28, 1999. MSHA has
observed the use of this particular administrative control, even after
changing the location of the DO from the 044 to the 060 occupation--the
miner who works nearest the return air-side of the longwall working
face. Unlike engineering or environmental controls, to be effective,
administrative controls rely on the ability of miners to follow
specified procedures. However, difficulty in ensuring that miners
adhere to the administrative controls, labor/management agreements, and
limitations on the number of qualified miners capable of handling
specific tasks may limit the use and effectiveness of such controls.
The Dust Advisory Committee Report stated that the use of
administrative controls does not reduce the operator's responsibility
to maintain ambient dust levels in active workings at or below the
applicable dust standard. However, the Dust Advisory Committee noted
that ``while not a substitute for engineering controls, administrative
controls, which restrict the amount of time that miners spend in an
area with uniform exposure level, can result in lower personal
exposures (MSHA, 1996).''
3. Limitations of Engineering Controls
It is MSHA's position that technology is generally available to
control respirable dust to, or below, the applicable dust standard at
MMUs employing continuous and conventional methods of mining. However,
where unusual or adverse conditions are encountered it is possible that
available

[[Page 10799]]

controls may be inadequate to continuously protect all miners from
overexposure. This is most likely to occur in areas where high levels
of quartz are encountered that may result in the setting of lowered
standards on a MMU.
However, MSHA recognizes that, unlike other mining systems,
longwall MMUs may have acute dust problems. These problems can be
caused by the face-ventilation airstream carrying the shearer-generated
dust over the miners working along the face downwind of the longwall
shearer operator (occupation code 044). This makes it more difficult to
control the work environment downwind of the longwall shearer operator
on a consistent basis.
Improvements in dust control technology have not kept pace with
increases in production technology associated with high-production
longwall MMUs. Average longwall shift production reported during
bimonthly sampling has increased more than six-fold since 1980, from
approximately 890 tons per shift (tps) to 5,500 tps in 2002. In fact,
49 percent of the shifts sampled averaged 4,000 to 8,000 tps, while
approximately 8 percent of the shifts exceeded 8,000 tps. A major
milestone in mining production was achieved in 1997 when a single
longwall mine produced more than 1 million tons of coal in a single
month (Fiscor, 1998).
Unfortunately, as more coal is mined, greater quantities of
respirable dust are generated. The increase in longwall production
levels has resulted in the generation of far more dust which must be
controlled (Webster, et al., 1990; Haney, et al., 1993; O'Green, 1994).
According to published literature, several thousand milligrams of
respirable dust per ton of coal cut can be formed and liberated during
the cutting process (National Research Council, 1980). Of course, the
quantity of respirable dust produced by the cutting process can vary
greatly, depending on the type of coal, its moisture content, the
amount of rock bands in the coal, sharpness of the cutting bits, the
particular mining machine, and many other factors. Although a
considerable amount of respirable dust is formed by the cutting
operation, not all of it becomes airborne. Nevertheless, given the
amount of dust that is produced per ton of coal mined, a larger
quantity of respirable dust would be generated and released to the mine
environment from cutting 8,000 tons of coal than from cutting 4,000
tons. Currently, an operator is not required to produce, on a sampled
shift, more than 50 percent of the average production reported during
the last bimonthly sampling period. Therefore, dust concentrations on
sampled shifts may be substantially lower than what is typical on
nonsampled shifts.
While significant efforts have been made to implement available
control technology, no significant new advancements in longwall dust
control technology have been reported since 1989 (U.S. Bureau of Mines,
undated). From 1989 to 2002 (Jan.-Sept.), the percentage of operators'
longwall DO samples with concentrations of 2.1 mg/m3 or
higher dropped from 22 percent to 14 percent, reflecting the impact of
implementing the pre-1990 advances in longwall control technology.
Although this represents a significant improvement, especially in view
of the six-fold increase in average shift production, the 2002 data
suggests that miners continue to be overexposed on a significant number
of shifts.
Over the past ten years, MSHA and the former U.S. Bureau of Mines,
now part of NIOSH, have made unsuccessful efforts to conduct a joint
research program that would evaluate the effectiveness of available
longwall dust control technology. The objective of such research would
have been to quantify the effects of employing all state-of-the-art
dust control technology available for a longwall operation.
Unfortunately, the two agencies have been unsuccessful in finding an
industry partner to participate.
MSHA has worked with mine operators on an individual basis to
determine the effectiveness and feasibility of existing and additional
respirable dust controls on a particular longwall. However, the design
and goals of those studies were neither intended nor sufficient to meet
MSHA's broader research objective. Rather, the scope of those studies
was to evaluate the effectiveness of control technology that both MSHA
and the mine operator agreed were applicable to that one particular
longwall MMU. The objective of the cooperative research program that
MSHA and the Bureau of Mines were attempting to conduct, was to
establish the combined efficiency of the various control technologies
that the Bureau of Mines had developed through their ongoing dust
control research program.
However, even though no such study has been conducted, based on our
experience, MSHA's position remains that feasible engineering or
environmental controls exist for maintaining dust exposures at or below
the applicable dust standard, for most, if not at all longwall
operations. MSHA believes that the plan verification provision
contained in this proposed rule will foster further improvements in the
design and quality of mine ventilation plans for longwall MMUs.
4. Respiratory Protection
While the Mine Act provides that operators ``make available''
approved respirators to miners during periods of noncompliance, when
miners may be overexposed, the Act specifically prohibits using such
devices as a substitute for environmental controls in the active
workings of the mine. As previously discussed elsewhere in the
preamble, this is because environmental or engineering controls are
reliable, provide consistent levels of protection to large number of
miners, allow for predictable performance levels, can be monitored
continually and inexpensively, and can remove harmful levels of
respirable coal mine dust from the workplace. MSHA recognizes that
approved respirators, such as the powered air-purifying type (e.g.,
Racal[reg]
Airstream helmet or air helmet),\6\ can be effectively used
as an interim method of protecting miners from respirable dust hazards
when properly selected, used, and maintained. Although a respirator may
achieve satisfactory air quality in the miner's breathing zone when
used in a good respirator program, their use will not achieve the
intent of the Act, which is to control the level of respirable coal
mine dust in the mine atmosphere in the active workings at or below
specific limits. Accordingly, consistent with the intent of the Act and
general industrial hygiene practice, it has been MSHA's long-
established practice to rely on the strict adherence to a hierarchy of
controls that prefers engineering controls over dependence on
supplementary control measures (e.g., respirators, work practices or
both) to achieve compliance with the applicable dust standard.
Nevertheless, the mining industry has urged MSHA over the years to
accept the use of powered air-purifying respirators (PAPRs) or air
helmets as an alternative method of complying with the applicable dust
standard when engineering controls did not adequately control
respirable exposure or were not feasible. Most recently, Energy West
Mining Company (Energy West) petitioned the Secretary of Labor:

\6\ References to specific equipment, trade names or
manufacturers does not imply endorsement by MSHA.
------------------------------------------------------------------------

[t]o amend the mandatory health standards for underground coal mines
contained in the Secretary's regulations at 30 CFR part 70 in order
to allow the use of airstream helmets or other types of powered air-
purifying respirators (PAPRs) approved by the National Institute for
Occupational Safety and Health (NIOSH) as a supplemental means of

[[Page 10800]]

compliance with the respirable dust standards of subpart B of part
------------------------------------------------------------------------
70. (Energy West, September 1997).

Energy West contended that PAPRs are necessary as a supplemental means
of controlling respirable dust because even the most diligent
application of feasible engineering or environmental controls could not
always prevent overexposure. This proposed rule responds to Energy
West's petition for rulemaking.
Although, as stated above and elsewhere in the preamble, the Agency
does not believe that supplementary controls are as effective or as
safe as engineering controls, MSHA believes, on balance, that under
certain circumstances reliance upon the limited use of such measures is
appropriate. Accordingly, MSHA is proposing to permit the limited use
of either approved PAPRs, administrative controls, or a combination of
both, for compliance purposes, in those circumstances where further
reduction of dust levels cannot be reasonably achieved using all
feasible engineering controls. In these situations, the burden of proof
of infeasibility is appropriately placed on the operator. Also, as
provided for under proposed Sec. 70.212, MSHA recognizes that the use
of PAPRs as a supplementary control may be appropriate on an
intermittent basis when unusual operating conditions are encountered
that adversely impact the ability of the previously verified plan
parameters to effectively control respirable dust under prevailing
conditions. MSHA will permit the use of PAPRs for a period not
exceeding 30 calendar days if the operator demonstrates that the
particular circumstances that necessitate the use of PAPRs occur only
intermittently and are beyond the control of the operator.
While the conditions under which MSHA would permit supplementary
controls to be used introduces an added element of complexity to the
proposed standard, the Agency believes that it will provide operators
the flexibility to select the most appropriate option for supplementing
the engineering controls which best meet the needs of the miners under
the prevailing operating conditions.
MSHA believes that the use of these supplementary control measures,
under the conditions of use set forth in the proposed rule, will
enhance the level of health protection for miners by preventing
overexposures on all shifts when engineering controls cannot achieve
the necessary reduction to or below the applicable dust standard. The
combination of engineering and supplementary controls will provide
reliable and effective exposure control when used in accordance with
the approved plan provisions. This proposed rule, which provides for
expanded use of supplementary controls under limited circumstances to
protect individual miners, is not a departure from the Agency's long-
standing practice of relying on engineering controls to achieve
compliance, since these measures would not be used as a substitute or
replacement for engineering control measures in the active workings.
Rather, it is a recognition that, in those limited instances where
supplementary controls may be used, engineering controls alone may not
protect some miners from overexposure.
a. Selection of Respirators: Powered Air-Purifying Respirators (PAPR)
By choice, underground coal miners wear various styles of
respirators to protect themselves from exposure to respirable coal mine
dust including: disposable filtering facepieces, tight-fitting
elastomeric masks, and PAPRs. Currently, over 50 percent of the
operating longwall mines have miners who have chosen to wear PAPRs
(MSHA, Longwall Summary, January, 1999) for added protection.
The Racal[reg]
Airstream, or air helmet as referred to by miners,
is a type of loose-fitting PAPR which has long been the respirator of
choice in underground coal mines. Due to the weight of the device, its
use has generally been limited to mines with coal seam heights
exceeding six feet. The functional and physical characteristics of air
helmets, as described below, make them especially well-suited to
underground coal mining conditions. Accordingly, MSHA has chosen PAPRs
as the type of respirator to be used when such devices are approved
under this proposed rule.
The air helmet has been in use in underground coal mines since the
late 1970s. Developed primarily for mining use by the Safety in Mines
Research Establishment (SMRE) in England, this respirator combines
face, head, and respiratory protection in a single convenient unit. The
support hardware, which provides the filtered air, is enclosed within
the air helmet. Power for the system is provided by a belt-mounted
battery. Mine air enters the helmet through a rear entrance port,
passes through a pre-filter assembly that removes the coarse material,
and then passes through the fan and into a final-filter assembly that
is located between the head of the wearer and the outer helmet shield.
The filtered air then sweeps down across the wearer's face, behind the
face-shield visor, imposing minimal breathing resistance, and exits at
the chin. A partial seal between the visor (inlet covering) and the
face is accomplished using a flexible medium which contours to the
wearer's neck and face. The original air helmet has undergone numerous
design improvements since it was first introduced in British coal
mines. The unit is now produced by the Minnesota Mining and
Manufacturing Company (3M) (3MTM Helmet-Mounted
AirstreamTM series).
Unlike other styles of PAPRs (e.g., hoods) and negative pressure,
tight-fitting respirators, the air helmet is better able to provide
various types of required personal protective equipment in an efficient
package. For example, in addition to protecting the lungs, the helmet
and visor (the inlet covering) of a PAPR can simultaneously protect the
face and head from high-velocity nuisance dust, spray, and small pieces
of coal from the cutting drums and face. PAPRs do not require fit-
testing, unlike tight-fitting respirators.
By definition, for PAPRs to be approved for use under this proposed
rule, the visor must form a partial seal with the face, limiting entry
of unfiltered mine air. Because this style of respirator does not have
a tight-fitting facepiece, miners are not required to be clean shaven
in order to wear this respirator correctly. MSHA's allowance of facial
hair with this style of PAPR is also consistent with the Occupational
Safety and Health Administration's (OSHA) regulation that facial hair
prohibition applies only to tight-fitting respirators (29 CFR 1910.134
(g)(1)(i)(A) as discussed in 63 FR 1152). MSHA recognizes that there
may be facial conditions which may prevent the proper fit of a PAPR.
However, a well-designed respirator protection program should identify
and address any extreme facial conditions, including excessive facial
hair, which prevent the partial seal of the inlet covering and the face
as intended, and thereby compromise the efficacy of the PAPR. For
example, a miner could have exceptionally bushy sideburns which prevent
the inlet covering from forming an appropriate partial seal with the
face, and leave a significant gap between the inlet covering (visor)
and chin. This situation would have to be rectified in order for the
PAPR to be worn properly.
Greenough (1978) summarized limitations of other styles of
respirators as follows:

[T]he objections to conventional face-mask respirators arise
primarily from the mask being clamped to the wearer's face, often
causing irritation and soreness: also the breathing resistance,
though small, can affect the wearer's capacity to work over long

[[Page 10801]]

periods (Johnson, 1976). Speech is impeded and if the respirator
harness fits under the wearer's safety helmet it is necessary to
remove the helmet when replacing the respirator.

Greenough's description illustrates how other styles of respirators
are less compatible with the other safety requirements for miners, as
well as miners' comfort, and their need to communicate. It would be
more difficult for a miner to perform his/her job effectively and
communicate with fellow workers, wearing a tight-fitting respirator
their entire work shift. Voice transmission through a tight-fitting
respirator can be difficult, annoying and fatiguing. In addition,
movement of the jaw in speaking can cause leakage, thereby reducing the
efficiency of the respirator and decreasing the protection afforded the
wearer. While voice communication is somewhat easier with a PAPR than
with other respirator styles, the face shield is generally raised to
communicate. Also skin irritation can result from wearing a tight-
fitting respirator in hot, humid conditions. Tight-fitting respirators
have straps which go across the crown and back of a miner's head which
is under a miner's helmet (i.e., hard hat). Because miners are required
to wear hard hats at all times while in the mine (30 CFR 75.1720(d)),
each time a miner needs to break the seal of a tight-fitting
respirator, to eat, or to speak, or to relieve the discomfort of the
seal, he/she would have to remove the hard hat. Similarly, each time a
miner would need to put a tight-fitting respirator back on he/she would
have to remove their hard hat. It should be noted that both tight-
fitting elastomeric respirators and disposable facepieces, if worn
correctly, would require the wearer to be clean shaven. A large
proportion of miners have a tendency to wear facial hair, especially
during the fall and winter season.
The unique qualities of the PAPR identified within this proposed
rule are such that it could fall into either the helmet or loose-
fitting facepiece categories. ANSI defines a loose-fitting PAPR with a
helmet to be ``a hood that offers head protection against impact and
penetration (ANSI, 1988).'' ANSI defines a loose-fitting PAPR with a
loose-fitting facepiece as ``A respirator inlet covering that is
designed to form a partial seal with the face, does not cover the neck
and shoulders, and may offer head protection against impact and
penetration (Ibid.).'' In this proposed rule, a powered air-purifying
respirator (PAPR) is defined as an air-purifying respirator that uses a
blower to force ambient air through the air-purifying elements to the
inlet covering, which provides a partial seal with the face. This
respirator must be approved by NIOSH under 42 CFR part 84 and by MSHA
under 30 CFR 18 and offer head and face protection in compliance with
30 CFR 75.1720(a)and(d).
A current list of equipment, including PAPRs, approved under 30 CFR
18 can be obtained from MSHA's Approval and Certification Center on the
internet at http://www.msha.gov/TECHSUPP/ACC/lists/18instrm.pdf. A
searchable index of approved respirators is available from NIOSH at
http://www2.cdc.gov/drds/cel/cel_form.asp. As of 2002, the 3M
Airstream Air-Purifying Helmet (MSHA Approval 2G-3143, originally
issued to Racal 3/29/1979), was the only approved PAPR model suitable
for use under this proposed rule.
b. PAPR Protection Program
In an underground coal mine, the degree of respiratory protection
that a properly functioning PAPR will provide the wearer is a function
of the type and condition of the air-purifying medium used to filter
out the respirable dust particles from the mine air, the workplace
environment (i.e., nature and concentration of the respirable coal mine
dust), the work activity of the wearer in that environment, how the
wearer uses the device (i.e., how often is the visor raised during the
shift), and the care and maintenance of the PAPR's functional
components and power source. These parameters are required to be
addressed in the approved PAPR protection program (see example in
Appendix B).
In 1998, to increase the efficiency of the filtering medium used in
PAPRs, NIOSH began requiring PAPRs to be equipped with a high
efficiency particulate air (HEPA) filter. This change introduced a
denser medium to filter the air, providing an extra margin of safety at
all levels of respirable coal mine and quartz dust exposure. However,
as a result of this change, the PAPR's average airflow dropped from
about 9 cubic feet per minute (cfm) to 7 (cfm). While the current
airflow still exceeds the required minimum airflow of 6 cfm (42 CFR
84.1152(b)), the drop in airflow reduced the level of comfort the PAPR
provides to the miner.
MSHA realizes that miners' comfort with a particular respirator is
an important determinant to miners' proper use of it. Several previous
commenters testified that PAPRs were not being used as approved.\7\
Many of these examples related to reports that visors were fogging.
These commenters attributed the fogging problem to NIOSH's recent (mid-
1998) improvement in the filtering medium for PAPRs. One commenter
testified:

\7\ NIOSH requirements for PAPR performance, including airflow
are specified in 42 CFR subpart kk. Although Sec. 84.1136 specifies
that facepieces, hoods, and helmets shall be designed and
constructed to provide adequate vision which is not distorted by the
eyepiece, NIOSH does not have requirements for a visor's
predisposition to fogging.
------------------------------------------------------------------------

I would have to answer honestly and say they [PAPRs]
are being
used in a modified condition. Miners some, you know, have typically
removed the shroud * * * [miners]
raise the face piece to
communicate and so on * * *. We've had that [fogging of the visor]
problem recently, * * * since we've been required [by NIOSH]
to use
the new version of the filter [the HEPA filter]. There has been what
seems to be reduced flow in the unit and that has also resulted in
more fogging. And we've worked real hard to try to--[work]
with 3-M
to try to resolve that.

MSHA's experience has shown that fogging of PAPRs has been an
intermittent problem since the introduction of PAPRs in underground
mines. This is due to the inclement conditions of underground mining
such as: High humidity, fluctuation in temperature, and physical
exertion by miners.
Some miners indicated that they had to replace the HEPA filters
with socks to increase the PAPR airflow. Using socks in lieu of
required filters is unacceptable. This one example of PAPRs being used
outside the manufacturer's recommendations and the requirements of an
approved respiratory protection program. Various approved remedies are
available to control fogging of visors including: intermittent wiping
down of the visor, ``anti-fogging'' visors, application of anti-fogging
sprays, and the use of a new visor design with an anti-fog impregnate
baked directly into the visor. A properly functioning respiratory
protection program would address this issue, with respect to the
appropriate selection and maintenance of a respirator.
MSHA recognizes that for a PAPR protection program to be effective,
the miner must be properly trained to wear the respirator, to know why
the respirator is needed, and to understand the limitations of the
respirator. Appendix B contains a model PAPR protection program to
assist an operator in developing a mine-specific program in accordance
with the provisions of the American National Standards Institute's
``Practices for Respiratory Protection ANSI Z88.2-1969'' as required by
30 CFR 72.710. Additionally, mine management must regularly conduct
reviews to ensure continued effectiveness of the PAPR protection

[[Page 10802]]

program. Under this proposed rule an operator will not be permitted to
use PAPRs as a supplementary control without an MSHA approved
respiratory protection program which meets the requirements of Sec.
72.710 and incorporates the information required by proposed Sec.
70.210(a)(2).
c. PAPR Protection Factor
The degree of workplace respiratory protection provided to the
wearer by a properly functioning PAPR when correctly worn and used
depends on the unit's ability to prevent the contaminant from entering
the wearer's breathing zone. In general, the protection factor (PF)
expresses PAPR performance as the ratio of the respirable dust
concentration outside the respirator facepiece to the concentration
inside the facepiece. It reflects the effectiveness of a respirator
used in conjunction with a good respirator protection program. For
example, a PF of 4 means that the particular respirator will reduce the
concentration of respirable dust actually breathed to one forth of the
concentration outside the respirator.
In terms of worker health, there are various forms of the PF. One
form is the assigned protection factor (APF). Terry Spear, et al.,
2000, defined an APF as follows:

APF is a special application of the general protection factor
concept, defined as a measure of the minimum nominal anticipated
workplace level of respiratory protection that would be provided by
a properly functioning respirator or class of respirators to a high
percentage (usually 95% or more) of properly fitted and trained
users * * *. The maximum specified use concentration for a
respirator is generally determined by multiplying the exposure limit
for the contaminant by the protection factor assigned to a specific
class of respirator.

In the NIOSH Respirator Decision Logic (May 1987), based on
simulated laboratory tests and some workplace protection tests (none of
which replicated conditions in underground coal mines), NIOSH assigned,
helmeted PAPRs, properly worn, a protection factor (APF) of 25. NIOSH
made the following cautionary statement:

Despite the fact that some of the PF's [APFs]
have a statistical
basis, they are still only estimates of the approximate level of
protection. It must not be assumed that the numerical values of the
APF's presented in this decision logic represent the absolute
minimum level of protection that would be achieved for all workers
in all jobs against all respiratory hazards. The industrial
hygienist or other professional responsible for providing
respiratory protection or evaluating respiratory protection programs
is therefore encouraged to evaluate as accurately as possible the
actual protection being provided by the respirator (NIOSH, May
1987).

Furthermore, in its Guide to Industrial Respiratory Protection
(September 1987), published after the NIOSH Respirator Decision Logic,
NIOSH offered an additional caution with regard to the effectiveness of
PAPRs:

Until recently, powered air-purifying respirators were
considered positive pressure devices. Field studies by NIOSH as well
as others, have indicated that these devices are not positive
pressure, and that their assigned protection factors are
inappropriately high. (NIOSH, September 1987).

There is virtually no positive pressure in the PAPR. Respirable
dust may enter the miners' breathing zone through openings along the
side and bottom of the visor, even when it is in the full lowered
position. The extent to which respirable dust enters a miner's
breathing zone, depends, in part, on the velocity of air provided to
the MMU and on the miner's work rate and his or her angle of
orientation to the airflow.
NIOSH recommended in their 1987 Respirator Decision Logic an APF of
25 for all loose-fitting hood or helmet PAPRs. However, the
environmental conditions assumed in NIOSH's estimation of an APF for
PAPRs are not consistent with those in underground longwall mining
operations, where high air velocities for methane and dust control are
common. Other, unique conditions of coal mining (obstructed views and
difficulty communicating) will compel miners to lift their visors. Once
the visor is raised, the respirator is no longer being worn in
accordance with conditions required for an APF of 25.
The actual fit or seal of the respirator helmet to the wearer,
repeated work-task motions in confined work spaces, raising the visor,
and high air velocities along the longwall face all may significantly
reduce the actual degree of respiratory protection provided in the
workplace. Therefore, it is imperative that such factors be taken into
account when estimating the degree of workplace respiratory protection
a PAPR provides to the wearer.
According to Spear (2000) a workplace protection factor (WPF) is:

[a]
measure of the actual protection provided in the workplace under
conditions of that workplace by a properly functioning respirator
when correctly worn and used * * * samples [are]
taken * * * while
the respirator is being properly worn and used during normal work
activities. In practice, the WPF is determined by measuring the
concentration inside and outside the donned [worn]
respirator during
the activities of a normal workday.

An effective protection factor (EPF) is another form of estimate of
efficacy of a respirator given its typical use. According to Spear
(2000) an EPF is:

[a]
measure of the actual protection provided in the workplace under
the conditions of that workplace by a properly functioning
respirator, defined as the ratio of concentration outside to
concentration inside * * * samples [are]
taken * * * during normal
work activities, while the respirator is being worn and not worn.
Because concentration outside and concentration inside are measured
during periods of use as well as during periods of non-use, EPFs are
considered as estimates of the effectiveness of respirator use
policies, rather than of intrinsic respirator performance
capability.

A fourth type of protection factor, a program protection factor
(PPF) was presented by 3M. In addition to the variables accounted for
in an EPF, a PPF reflects factors affecting the respirator programs
effectiveness including:

* * * respirator selection, the respirator design, training,
maintenance, storage, supervision, program administration and
monitoring, and any other variable that affects program
effectiveness. If any of these program elements are deficient, the
program protection factor will be adversely affected.

An EPF is predicated upon proper fit and maintenance of a
respirator, where a PPF is not. Unlike an APF or a WPF, an EPF reflects
the degree of respiratory protection provided by a respirator over an
actual work shift given specific occupational environmental conditions,
such as the velocity of air provided to control methane and respirable
dust, and the time when miners must raise their visors to speak or see,
given that a miner performs typical work activities and uses the
respirator in a typical manner. Based on MSHA experience and miners'
testimony, it is not reasonable to expect underground coal miners to
always wear the visor down. Due to this eventuality and MSHA's
requirement for an approved respiratory protection program, an EPF
study or studies, which reflect the conditions on longwall MMUs, such
as high air velocities (i.e., exceeding 800 feet per minute (fpm)),
would provide suitable data for determining the effectiveness of PAPRs
used there.
Although not specifically discussed in the 2000 proposed rule, MSHA
had reviewed each of the more than one dozen protection factor studies
submitted in Energy West's 1997 petition for rulemaking. The Agency
also reviewed the additional relevant studies submitted by commenters
in response to the previous proposed rule, as well as studies MSHA
identified. A review of the literature identified the fundamental fact
that effectiveness of

[[Page 10803]]

PAPRs in longwall mines is mediated by the high velocities of air
customarily found there. Those velocities are not comparable to the air
velocities experienced in most industry sectors nor in those
represented in the studies used to determine the APF of 25, nor in the
majority of studies submitted by Energy West in 1997.
The headgate and tailgate air velocities observed by MSHA at 55
longwall MMUs were reviewed in 1999. These velocities ranged from 365
to 1,645 fpm and from 200 to 1,400 fpm, respectively. More importantly,
headgate velocities at 60 percent of the MMUs exceeded 500 FPM and some
18 percent exceeded 800 fpm. Approximately 55 percent of tailgate
velocities exceeded 500 fpm and 11 percent exceeded 800 fpm.
Laboratory and in-mine studies (EPF studies) show that air velocity
is the single biggest factor affecting the degree of respiratory
protection provided by a PAPR. While important at longwall MMUs, air
velocity does not significantly affect PAPR performance at non-longwall
MMUs where the velocity of air provided to control methane and
respirable dust is normally less than 100 fpm. There, the primary
concern is the PAPR's ability to protect the miner from exposure to
excessive quartz levels. Cecala, et al., (1981) found protection of
Racal[reg]
Airstream helmets to be inversely related to
ambient air velocity in both laboratory and in-mine settings (Ibid). In
other words, increased air velocity leads to decreased effectiveness of
the PAPR.
The expected degree of workplace respiratory protection that would
be provided by a properly functioning PAPR is also affected by the
orientation of the helmet to the airflow. Cecala's wind tunnel tests
clearly showed that, at the higher airflow rates, helmet efficiency was
greatest when facing directly against the airflow and was reduced when
the helmet was oriented in other directions. This is extremely
important since miners are more likely to orient their heads at an
angle to the airflow, or to face downwind, than to face directly into
the airflow.
Cecala's in-mine testing of the PAPRs produced an EPF confirming
the inverse relationship between air velocity and the level of
protection provided by PAPRs shown during wind tunnel testing. Under
air-velocity conditions less than 400 fpm, the Airstream helmet
averaged a respirable dust reduction of 84 percent, which is equivalent
to an EPF of 6.4. However, under higher air-velocity conditions (1,200
fpm), the helmet's dust reduction performance decreased significantly,
averaging only 49 percent, which is equivalent to an EPF of 2. The
higher face air-velocity conditions in this study best represent the
higher velocities observed on longwalls. Today, the face air velocity
in over 60 percent of the longwall MMUs exceed 500 fpm (MSHA, October
1999). Thus, it is critical to take into account the air velocity
conditions when determining a PF for PAPRs used in underground coal
mines.
Other researchers have reported that helmeted PAPR systems are
vulnerable to inward leakage into the wearer's breathing zone (Howie,
et al., 1987; Sherwood, 1991). For example, Howie, et al., found that
increasing airflow velocities from approximately 400 to 800 fpm doubled
the inward leakage of the helmet when the airflow impinged on the
wearer's head only, and increased the leakage further when the airflow
impinged on the wearer's body and head (Howie, 1987). Subsequent
testing of a redesigned unit at a wind velocity of approximately 700
fpm showed decreased inward leakage, yielding a PF of 6.3. This met the
target PF of 5, which was subsequently proposed by the European
Community to be the standard for powered helmet respirators.
More recent studies conducted by Bhaskar, et al. (1994) at four
western longwall MMUs indicated that, under these workplace conditions,
PAPRs had an average dust reduction efficiency of 83.8 percent (Ibid.).
Although a different sampling procedure was employed, this result is
consistent with the performance (average value of 84 percent) obtained
by Cecala, et al., under air-velocity conditions less than 400 fpm.
During the test period, Bhaskar reported headgate face velocities
ranging from 345 to 500 fpm, with approximately 88 percent of the
recorded velocities falling below 500 fpm. The tailgate face velocities
ranged from 280 to 550 fpm and only one exceeded 500 fpm. None of these
tests were conducted under face-velocity conditions that exceeded 800
fpm. As such, this study provides information on their effectiveness at
lower velocity applications (i.e., under 500 fpm).
In summary, there is consensus among studies that the effectiveness
of the PAPR is reduced when air velocities are increased. The Cecala
(1981) study alone, provided reasonable estimates of the degree of
respiratory protection that PAPRs would provide to a wearer working on
a longwall MMU where the face velocity exceeds 800 fpm. Consequently,
this study provides the best data from which to estimate PAPR
performance or the PF that should be assigned to PAPRs authorized for a
particular MMU. As discussed elsewhere in this proposed rule, MSHA is
proposing to allow the use of PAPRs only as a supplementary control
measure after all feasible engineering controls have been applied to
reduce exposure to the lowest possible level. In our view, these
measures, when properly applied and maintained, will control respirable
dust to a level reasonably near the applicable dust standard.
Therefore, it would not be in the miner's best interest or necessary
for compliance purposes to apply the highest PF suggested by these
studies. Accordingly, MSHA is proposing that a PF factor of 4 be
applied when using a PAPR under air velocity conditions of 400 fpm or
less and a PF of 2 when the air velocity is equal or exceeds 800 fpm.
This approach recognizes the increased level of respiratory protection
that PAPRs afford at lower air velocities and, based on our engineering
judgement, will allow operators to achieve compliance with the
applicable dust standard on longwalls and other MMUs. Furthermore, the
level of protection provided by a properly used PAPR will assure miners
that they are being protected from overexposure.
For example, if the air velocity to be maintained in the headgate
and tailgate of a longwall MMU ventilated head to tail is 400 fpm and
300 fpm, respectively, then PAPRs used there would be assigned a PF of
4. If on the other hand, the ventilation plan calls for 850 fpm to be
maintained in the headgate location and 450 fpm in the tailgate
location, then the applicable PF would equal 2. Because of the lack of
data on PAPR performance under air-velocity conditions ranging between
400 fpm and 800 fpm, MSHA has proposed that, whenever plan velocities
fall in that range, PAPRs used in the MMU be assigned a corresponding
PF falling between 2 and 4 which would be determined using an
interpolation formula [2 x (800/air velocity)]. For example, if the air
velocity to be maintained in the headgate location is 700 fpm, then the
applicable PF would equal 2.3 [2 x 800fpm/700fpm].
The following example is meant to illustrate the application of the
PF to determine the dust concentration to which the wearer of a PAPR is
expected to be exposed. Assume for purposes of the example that the
applicable dust standard is 1.5 mg/m3 and the airborne
concentration of respirable dust is 2.6 mg/m3. Therefore,
using a PAPR with a PF =4 is expected to reduce the miner's exposure to
0.65 mg/m3 (2.6 mg/m3 4).
The range of PFs that MSHA will allow to be assigned to PAPRs under
this proposed rule will provide a margin

[[Page 10804]]

of safety for the miner. However, regardless of the particular PF
allowed by MSHA, full compliance with the provisions of the approved
respiratory protection program is necessary to ensure that a PAPR's
protective value is not compromised.

E. Guidelines for Determining What Is a Feasible Dust Control

This proposed rule requires a mine operator to implement all
feasible engineering or environmental controls that are technologically
and economically feasible to control respirable coal mine dust. The
Federal Mine Safety and Health Review Commission (Commission) has
addressed the issue of what MSHA must consider when determining what is
a feasible control for enforcement purposes. In cases involving the
noise standard for metal and nonmetal mines, the Commission has held
that a control is feasible when it: (1) Reduces exposure, (2) is
economically achievable, and (3) is technologically achievable. See
Secretary of Labor v. Callanan Industries, Inc., 5 FMSHRC 1900 (1983),
and Secretary of Labor v. A.H. Smith, 6 FMSHRC 199 (1984).
In determining technological feasibility of an engineering control,
the Commission has ruled that a control is deemed achievable if through
reasonable application of existing products, devices, or work methods
with human skills and abilities, a workable engineering control can be
applied to the exposure source. The control does not have to be ``off-
the-shelf'' or already available but, it must have a realistic basis in
present technical capabilities. Further, the Commission has held that
MSHA must assess whether the cost of the control is disproportionate to
the ``expected benefits,'' and whether the cost is so great that it is
irrational to require its use to achieve those results. The Commission
has expressly stated that a cost-benefit analysis is unnecessary in
order to determine whether an engineering control is feasible.
According to the Commission, an engineering control may be feasible
even though it fails to reduce the exposure to permissible levels in
the standard, as long as there is a significant reduction in exposure.
Consistent with the Commission case law, MSHA would consider three
factors in determining whether engineering or environmental controls
are feasible at a particular mine: (1) The nature and extent of the
overexposure; (2) the demonstrated effectiveness of available
technology; and (3) whether the committed resources are
disproportionate to the expected results. As explained in the
discussion of Sec. 70.209 in Section IV of this proposed rule, the
formal determination of whether all feasible engineering or
environmental controls have, in fact, been implemented at a specific
mine to prevent excessive dust concentrations will be made by the
Administrator for Coal Mine Safety and Health based on the best
available information, experience, and engineering judgement.

F. Application of New Technology for Monitoring Coal Mine Dust Levels

Because of the ever changing mining environment, more timely
feedback on current dust conditions in the workplace should enhance
miner health protection from coal workers' pneumoconiosis (CWP) and
silicosis. To obtain such feedback requires a type of dust monitoring
instrument designed to directly measure on a continuous basis the
amount of respirable coal mine dust that is present in the work
environment. The availability of this information on a real-time basis
would enable mine personnel to optimize mining procedures and dust
control parameters when dust levels approach the applicable dust
standard, thus averting possible overexposure. Knowing the actual dust
levels during the shift would also empower the miner to be more
directly involved in the dust control process to safeguard their
health.
The current monitoring program, which has been in effect since
1970, lacks this capability. Samples results are not known by mine
personnel until days after completion of sampling. If there is an
overexposure, corrective action does not occur until the overexposure
has been confirmed by the dust processing laboratory and communicated
to the operator and MSHA. Consequently, any corrective action that may
be taken would only impact exposures on subsequent shifts. Therefore,
the ability to continuously monitor and display dust concentrations
during the shift, rather than depend solely on periodic measurements
under the existing program, has been a goal for nearly two decades.
Recent advancements in personal dust monitoring technology make this
goal achievable within the next two years, presenting opportunities to
further improve miner health protection from disabling occupational
lung disease.
The health benefits of continuous monitoring were recognized by
both the Task Group and the Dust Advisory Committee. In 1992, the Task
Group concluded that continuous monitoring of the mine environment and
dust control parameters offered the best long-term solution for
preventing occupational lung disease among coal miners. Similarly, the
Dust Advisory Committee found that:

Worker exposure to excessive levels of dust can be prevented by
implementing a hazard surveillance program that provides mine
personnel with current information on actual dust levels in the work
environment at all times, and on the status of key dust control
parameters.

The Dust Advisory Committee's final report issued in 1996 made the
following recommendation with regard to continuous dust monitors:

Once the technology for continuous dust monitors has been
verified, these measures should be broadly applied in conjunction
with other sampling methods for surveillance and determination of
dust control at all MMUs and other locations at high risk of
elevated dust exposure.

Over the past decade significant progress has been made as a result
of the R&D efforts sponsored by the former U.S. Bureau of Mines in
conjunction with MSHA. These efforts have advanced the technology for
directly measuring and displaying the amount of respirable coal mine
dust contained in mine air in real time, based on an inertial
microweighing method called tapered element oscillating microbalance
(TEOM[reg]). The development and commercialization of this technology
was pioneered by Rupprecht & Patashnick Co., Inc. (R&P).
A TEOM-based monitor consists of a filter mounted on the end of a
hollow tapered tube. The other end of the tube is fixed rigidly to a
base. The tube with the filter on the free end is oscillated at its
natural frequency. This frequency depends on the physical
characteristics of the hollow tube and the mass on its free end. Mine
air is drawn through the filter that removes the respirable coal mine
dust and then through the hollow tube. As more respirable dust
particles are removed and deposited on the filter, the mass of the
filter increases which causes the frequency of the tapered element to
decrease. Because of the direct relationship between mass and frequency
change, the amount of respirable coal mine dust deposited on the filter
is determined by accurately measuring the frequency change. By
combining the mass of dust and the known volume of air that was drawn
through the filter during the period sampled yields a measurement of
the respirable dust concentration.
While the capabilities of the TEOM method have been applied to a
variety of particle monitoring applications, the first instrument
designed specifically for mine use based on this technology was

[[Page 10805]]

a machine-mounted continuous respirable dust monitor (MMCRDM). In-mine
testing of the prototype MMCRDM in the late 1990s demonstrated the
capability of the TEOM system to produce dust measurements in a mining
environment. However, because instrument accuracy could not be
determined by in-mine testing and questions about the comparability of
fixed-site versus personal sampling, NIOSH decided to discontinue final
development of the MMCRDM.
In 1999, at the urging of labor and industry, NIOSH, in conjunction
with MSHA, funded the development of a personal dust monitor (PDM)
based on the TEOM technology used in the MMCRDM. The ability to
miniaturize the TEOM dust sensor without compromising its performance
made it possible in 2000 to develop the first PDM capable of directly
measuring in real-time and displaying the concentration of respirable
coal mine dust. The PDM-2, as it was called, was a two-piece unit
consisting of a belt-mounted dust monitor battery/pump pack with a
display and the TEOM dust sensor that was attached to the lapel like
the standard sampling device in use today. Although laboratory and in-
mine tests showed the PDM-2 to be dependable and capable of accurately
measuring the amount of dust that accumulated on the filter, concern
was expressed by miners about the size of the instrument. Specifically,
miners believed that since they were already required to carry a cap-
lamp battery and a self-contained self rescuer on their belt, there was
no room for a separate dust monitor battery/pump pack. They also
indicated that the TEOM dust sensor was too bulky, heavy and interfered
with work activity. As a result of these concerns, further efforts to
refine the PDM-2 were suspended by NIOSH.
In 2001, NIOSH contracted the development of a one-piece version of
the PDM that would be less cumbersome to mine workers. Efforts to date
have produced a belt-worn instrument (PDM-1) that contains the dust
monitor and the miner's cap lamp battery in a single package. To
improve wearer convenience and to simplify the monitor, the sample
inlet for the instrument was moved from the traditional lapel location
to the cap lamp of the hard hat. A pump mounted in the instrument
transports the dust-laden air that enters the inlet to the instrument
through a conductive silicone rubber tube that runs parallel to the
lamp cord. Unlike the PDM-2 which employed a 10-mm Dorr-Oliver nylon
cyclone used in the approved sampling device, the PDM-1 uses a Higgins-
Dewell cyclone to separate the non-respirable dust. The redesigned cap-
lamp battery pack contains all the components, including two separate
batteries, to enable the instrument and cap lamp to be operated
independently. To accommodate monitoring over an extended shift, the
PDM-1 was designed to operate continuously for 12 hours.
The PDM-1 is designed to continuously measure dust levels on real-
time basis and provide information on (1) the cumulative average dust
exposure during the shift; (2) the current exposure level based on
entire shift duration (projected end-of-shift exposure); and (3) the
time-weighted average concentration (total mass of dust collect divided
by the length of time the unit was operated) within 15 minutes after
the end-of-shift. The unit is capable of being used either in a shift
mode in which the instrument is programmed to operate for a specific
shift length (e.g., 8, 10, 12 hours) or in an engineering mode. When
operated in the engineering mode, the miner could program periods
during the shift to record dust levels during specific mining cycles or
at specific dust-generation sources in the mine. The display on the
instrument has various screens that show the (1) current time of day,
(2) elapsed time since beginning of the shift, (3) total amount of dust
accumulated on the filter since the start of sampling which is stored
in an internal memory for analysis, (4) dust concentrations, and (5) a
bar graph that shows the average dust concentration of the last 30
minutes. The PDM-1 is also capable of showing whether the instrument
was bumped significantly or tipped beyond 90 degrees. This information
will be stored along with information on the amount of dust that has
accumulated on the filter and the concentration data which can be
accessed with a personal computer at the end of the shift and analyzed.
While the performance of the PDM-1 to accurately and precisely measure
respirable coal mine dust in the mine environment and its durability
under in-mine conditions has yet to be extensively evaluated,
preliminary indications from the limited testing performed to date are
that the PDM-1 has the potential to provide timely information on dust
levels and miner exposure. Although MSHA has confidence in this
technology, a final determination of the applicability and suitability
of PDMs under the conditions of use being proposed is not expected
until after completion of the scheduled laboratory and in-mine testing
and evaluation at the end of 2003. Both NIOSH and MSHA recognize that
to be accepted by the mining community, the PDM must reliably monitor
respirable dust concentrations in the mine environment with sufficient
accuracy to permit exposures to be effectively controlled on each
shift.
Accordingly, as recommended by the Dust Advisory Committee and
urged by the mining community, MSHA is encouraging deployment of
personal continuous dust monitoring technology once verified as
reliable under in-mine conditions by proposing a new standard for the
use of such monitors as part of a comprehensive dust control program.
As discussed under proposed Sec. 70.220, operators would be permitted
to use PDMs capable of continuously measuring and displaying dust
levels during the shift in conjunction with engineering and
administrative controls. Each miner would be required to wear such a
device on each shift, unless the operator successfully demonstrated
during verification sampling that the exposure of each miner working on
the same shift is represented by sampling the DO and/or another
occupation under administrative control. For additional specific
details regarding the proposed application of PDM under this proposed
rule refer to the discussion of Sec. 70.220 in section IV of the
preamble.

IV. Section-by-Section Discussion of Proposed Rule

A. Part 70

The following explains, section-by-section, each provision of the
proposed rule. The text of the proposed rule is included at the end of
the document.
Section 70.1 Scope
Under the proposed rule, the existing scope will remain the same.
It sets forth mandatory health standards for each underground coal mine
subject to the Federal Mine Safety and Health Act of 1977.
Section 70.2 Definitions
The technical terms that were developed for use in this part are
defined in the proposed rule. These include ``citation threshold
value,'' ``dust control parameters,'' and ``engineering or
environmental controls.'' Some existing definitions of terms such as
``certified person'' and ``respirable dust'' have been modified to more
clearly convey the intended meaning under the proposed rule. These and
other modifications discussed below reflect changes resulting from the
removal of existing paragraphs, the transfer of other paragraphs, and
the

[[Page 10806]]

addition of new regulatory text. Other changes were made in response to
previous commenters to make them consistent with the common usage of
such terms. For example, under this new proposed rule, the Agency's
definition of the term ``concentration'' has been changed to reflect
the conventional definition. In doing so, it was necessary to include
and define a new term ``equivalent concentration,'' which originally
appeared within the proposed definition of the term ``concentration''
in the previous proposed rule.
This proposed rule also defines new terms to clarify the process of
verifying the adequacy of the dust control parameters specified in a
mine ventilation plan in controlling respirable dust in a mechanized
mining unit. Specifically, MSHA provides definitions of ``critical
value,'' ``protection factor,'' ``verification limits,'' and
``verification production level.'' Finally, the definition of ``normal
production shift'' would be removed to be consistent with the proposed
revocation of operator sampling requirements for purposes of
determining compliance with the applicable dust standard.
The proposed rule also includes other terms like ``feasible'' for
example, which have not been defined. The term as used applies to the
suitability of the types of engineering or environmental controls
required to control respirable dust under prescribed operating
conditions. Since individual mine conditions would dictate the type of
engineering or environmental controls to be considered as suitable
candidates, MSHA has refrained from providing an explicit definition of
this term. Instead, as noted in the discussion under section III.E. of
this preamble, MSHA intends to follow the Federal Mine Safety and
Health Review Commission case law as to what constitutes a feasible
control for enforcement purposes. The Agency further notes in that
discussion that the final determination of whether a particular
operator has implemented all feasible engineering or environmental
controls would be made by the Administrator for Coal Mine Safety and
Health. That determination would be based on the best available
information and on the combined experience and engineering judgement of
an MSHA expert panel.
The following explains the new and revised definitions of terms
that are used in the proposed rule. Please closely examine the context
of the term as used in each proposed section.
Administrative Control
``Administrative control'' would mean a work practice intended to
reduce an individual miner's exposure to respirable dust at the
assigned job position or occupation by altering the way in which the
assigned work is performed. Examples include rotation of miners to
areas having lower concentrations of respirable dust, altering the way
in which specific tasks are performed, rescheduling of tasks, and
modifying work practices to reduce exposure. An ``administrative
control'' must be (1) capable of being objectively reviewed and
monitored to confirm that it has been properly implemented, (2) clearly
understood by the affected miners for the controls to be effective, and
(3) applied consistently over time.
Approved Sampling Device
``Approved sampling device'' would mean a sampling device approved
by the Secretary and the Secretary of Health and Human Services under
part 74 (Coal Mine Dust Personal Sampler Units) of this title; or
approved by the Secretary when it has been demonstrated that a
respirable dust concentration measurement can be converted to a
concentration measurement equivalent to that obtained with an approved
sampling device. Under the proposed rule, MSHA will continue to use
sampling devices approved by NIOSH pursuant to existing 30 CFR part 74.
To accommodate the adoption of advanced sampling devices in the future
such as continuous respirable dust monitors, the proposed rule would
permit the Secretary to approve and use any technologically advanced
sampling device that should become available in the future but could
not be approved under the regulatory requirements of 30 CFR part 74.
Therefore, under the proposed rule, any newly developed sampling
instrument would be considered an approved device pursuant to this
definition when the Secretary demonstrates that the respirable dust
concentration measured by the new instrument can be converted to a
concentration measurement equivalent to that obtained by a device
approved under 30 CFR part 74 of this title.
To encourage greater innovation in sampler design without
compromising accuracy, comments are specifically solicited on this
approach of approving sampling devices. MSHA also solicits comments on
an alternative approach based on the International Standards
Organization (ISO) definition of respirable dust.
Certified Person
The existing definition would be modified by removing references to
existing Sec. Sec. 70.202 and 70.203. The provision requiring the use
of a certified person to conduct sampling is being transferred to
revised Sec. 70.201. Existing Sec. 70.203 which requires approved
sampling devices to be maintained and calibrated by a certified person
will be retained and redesignated as Sec. 70.202.
Citation Threshold Value (CTV)
``Citation threshold value'' would mean the lowest acceptable
equivalent dust concentration measurement demonstrating that the
applicable dust standard has been exceeded at a high level of
confidence and at which MSHA would cite an operator for a violation of
Sec. Sec. 70.100 or 70.101 under proposed Sec. 70.218. Since MSHA
would be assuming responsibility for all compliance sampling under this
proposed rule, a determination of noncompliance would be based solely
on the results of single-shift samples collected by MSHA. Appendix C
explains how each critical value listed in Table 70-1 was derived. Each
CTV is calculated to ensure that a citation will be issued only when a
single-shift sample demonstrates noncompliance with at least 95 percent
confidence.
Concentration
The existing definition would be modified by replacing the term
``substance'' with ``respirable dust'' to more clearly convey the
meaning under the proposed rule.
Control Filter
``Control filter'' would mean an unexposed or clean filter cassette
of the same design and material as the exposed filter cassette used for
sampling that is pre- and post-weighed on the same day as the exposed
filters. Its use is intended to eliminate the potential for any bias
that may be associated with day-to-day changes in laboratory conditions
or introduced during storage and handling of the filter capsules. The
control filter is used to adjust the resulting weight gain obtained on
each exposed filter capsule. That is, any change in the weight of the
control filter will be subtracted from the change in weight of each
exposed filter.
Critical Value
``Critical value'' would mean the maximum acceptable equivalent
dust concentration measurement demonstrating that the applicable
verification limit has been met at a high level of confidence. Appendix
A

[[Page 10807]]

explains how each critical value listed in Table 70-1 was derived.
Designated Area (DA)
The existing definitions would be modified to certify that the
Secretary may identify DAs which is consistent with existing procedures
that have been in effect since 1980. Once identified, the location of
these DAs and the respirable dust control measures to be used at the
dust generating sources for these locations must be contained in the
operator's approved mine ventilation plan as provided for under Sec.
75.371(t) of this title. However, the operator would not be required to
sample these areas under the proposed rule. MSHA is also proposing to
transfer the requirement for identifying each DA as specified in
existing Sec. 70.208(e) to revised Sec. 70.2.
Dust Control Parameters
``Dust control parameters'' would mean the respirable dust control
provisions specified in an approved mine ventilation plan, including
specific engineering or environmental controls, maintenance procedures,
and other measures designed to control respirable dust levels in the
working environment. These may also include, if approved by MSHA,
supplementary controls such as powered air-purifying respirators and
administrative controls. These measures are required for the protection
of miners from excessive levels of respirable dust and must be in use
on every production shift.
Engineering or Environmental Controls
``Engineering or environmental controls'' would mean methods that
are designed to control the quantity of respirable dust that is
released into the work environment by affecting the rate of generation
or by suppressing it at the source of generation, or by diluting,
capturing or diverting the generated dust. Examples include improved
cutting tools, deep-cutting, water-spray delivery systems and
orientation, air quantities and velocities, dust collectors, and
passive barriers. Throughout the proposed rule, the terms
``engineering'' and ``environmental'' controls are used
interchangeably.
Equivalent Concentration
``Equivalent concentration'' would mean the concentration of
respirable dust, as measured by an approved sampling device, converted
to an 8-hour equivalent concentration as measured by a Mining Research
Establishment (MRE) sampler. This conversion is normally accomplished
in two steps, unless powered air-purifying respirators (PAPRs) are
used, and then an additional adjustment is made to account for the
expected workplace level of respiratory protection being provided the
wearer. In the first steps, the concentration measurement is multiplied
by a constant factor prescribed by the Secretary specifically for the
approved sampling device. In the second step, that result is then
multiplied by t/480, where t is the sampling time in minutes if longer
than eight hours, to make it equivalent in dosage to the concentration
as measured by an MRE sampler on an 8-hour work shift. Since
verification sampling will be conducted over the course of a full
production shift of the MMU only, and not over the miner's entire work
shift which includes travel to and from the MMU, except when employing
personal continuous dust monitors (PCDM), t will also be equal to the
length of a full production shift. If the full production shift is
eight hours or less, then t must equal 480 minutes.
In cases where PAPRs are used, the equivalent concentration
measurement obtained following step two is adjusted further to account
for the expected workplace level of respiratory protection being
provided the wearer. This is accomplished by dividing the equivalent
concentration by the protection factor specified in the approved
ventilation plan for the mechanized mining unit under a PAPR protection
program. The result represents a surrogate measure of the respirable
dust concentration to which the miner is exposed while wearing the
PAPR.
The current U.S. coal mine applicable dust standard is based on
epidemiologic studies of British coal miners. In these studies, miners
routinely worked 8-hour shifts and their respirable dust exposures were
assessed based on 8-hour measurements using an instrument known as the
MRE instrument. Work shifts in U.S. coal mines now frequently exceed
eight hours. Therefore, to provide the intended level of protection to
miners working longer than eight hours, it is necessary to convert dust
concentration measurements to equivalent, 8-hour values as measured by
the MRE instrument.
The first step in the conversion from ``concentration'' to
``equivalent concentration'' is intended to make the measurement
equivalent to the concentration measured by an MRE instrument. This
instrument was designed to selectively collect airborne dust in a way
that would approximate the deposition of inhaled particles in the lung.
Because the MRE instrument was large and cumbersome, other more
portable samplers were developed for use in U.S. coal mines. Currently
approved sampling devices use a 10-mm nylon cyclone to separate the
respirable fraction of airborne dust, instead of the four horizontal
plates used in the MRE instrument. Such differences in instrument
design lead to systematic differences in the amount of dust collected.
Since 1980, measurements made using the currently approved cyclone-
based devices operating at a flow rate of 2.0 liters per minute (lpm)
were multiplied by the constant factor of 1.38 prescribed by the
Secretary for the approved sampling device used. Application of this
factor compensates for the difference in dust collection
characteristics and makes the measurements equivalent to what would be
obtained using an MRE instrument.
Similarly, the second step in the conversion from ``concentration''
to ``equivalent concentration'' is intended to compensate for
differences between current conditions and conditions under which the
existing applicable dust standards were developed. Specifically, it is
designed to ensure that miners working shifts longer than eight hours
will be afforded the same level of protection as miners working an 8-
hour shift. MSHA developed the existing standards from 8-hour shift
exposure measurements. Therefore, MSHA will adjust the measured
concentration to be equivalent, in its effect on cumulative exposure,
to a concentration over an 8-hour exposure period. This is accomplished
by multiplying the concentration measurement by t/480, where t is the
sampling time (i.e., length of the sampled shift) in minutes.
The formula for an equivalent concentration is:
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.002

[[Page 10808]]

where t = sampling time in minutes and airflow rate = 0.002
m3/min). The product of t and the airflow rate is the total
volume of air from which dust is accumulated on the filter.
The following example is meant to illustrate the effect of the
second step in the conversion, multiplication by t/480, which adjusts
for the full length of the sampled shift. Suppose a DO sample is
collected over a 9-hour shift and that the amount of dust accumulated
during the shift is 1.5 mg. If the concentration were not adjusted to
an 8-hour equivalent concentration, the MRE-equivalent concentration
would be calculated as 1.92 mg/m\3\. Under the proposed definition of
``equivalent concentration,'' this quantity is then multiplied by 540/
480, yielding an equivalent concentration measurement of 2.16 mg/m\3\.
Let us suppose now that this concentration measurement was for a
longwall occupation under a PAPR protection program with an applicable
protection factor of 2. Therefore, the concentration measurement of
2.16 mg/m\3\ is divided by 2, which yields 1.08 mg/m\3\, the equivalent
concentration to which the wearer of the PAPR is exposed.
This adjustment does not change the daily limit on the accumulated
dose of respirable coal mine dust as intended by the existing exposure
limit for coal mine dust. Since the current limit was based on the
assumption that exposure occurs over an 8-hour shift, it corresponds to
a daily cumulative dose of respirable coal mine dust of 8 x 2.0 = 16
mg-hr/m\3\ as measured by the MRE instrument. The proposed definition
of equivalent concentration will maintain this same MRE-equivalent 16
mg-hr/m\3\ daily limit, regardless of the length of the working shift
being sampled.
To continue the example, the exposure accumulated during the
sampled working shift is the same, whether over 8 hours at an average
of 2.16 mg/m\3\ or over 9 hours at an average of 1.92 mg/m\3\. In
either case, the MRE-equivalent exposure accumulated during the sampled
shift is 17.3 mg-hr/m\3\, which exceeds the intended limit of 16 mg-hr/
m\3\. Under the definition of ``equivalent concentration'' provided
here, this will be reflected by the fact that, when more than 16 mg-hr/
m\3\ (MRE-equivalent exposure) is accumulated over the course of the
particular shift sampled, the equivalent concentration will exceed 2.0
mg/m\3\, regardless of the shift's length.
Similarly, using a currently approved sampler, the plan
verification limit for respirable quartz dust (i.e., 0.1 mg/m\3\) will
be exceeded when the total amount of quartz dust amassed on a filter
during the full production shift exceeds 0.07 mg, regardless of the
shift's length. For example, if 0.08 mg of quartz dust were accumulated
over the course of a 12-hour shift, then the equivalent concentration
of respirable quartz dust would be calculated as:
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.003

This is exactly the same value of the equivalent concentration that
would be obtained if 0.08 mg of quartz dust were accumulated on an 8-
hour shift.
MSHA originally proposed a different but mathematically equivalent
method of adjusting concentrations to an 8-hour equivalent and
solicited comments on the proposed method. The proposed method would
have defined ``concentration'' to mean what is here defined as
``equivalent concentration.'' Instead of making an explicit adjustment
to the concentration, using the factor of t/480 as in the present
definition, the proposed rule would have substituted 480 for the actual
sampling time in the definition of respirable dust concentration. The
proposed definition of ``equivalent concentration'' is meant to both
preserve the ordinary definition of ``concentration'' and to clarify
the adjustment to an 8-hour equivalent.
MSHA believes that the proposed adjustment to an ``8-hour
equivalent concentration'' is necessary to protect miners, who normally
work nontraditional or extended shifts, from excessive exposures. A
miner working for ten hours at an average concentration of 2.0 mg/m\3\
will inhale and retain more respirable coal mine dust as a result of
that specific shift than a miner working for eight hours at the same
average concentration. By comparing the adjusted concentration to the
concentration limit originally intended for miners working an 8-hour
shift, the same cumulative exposure limit is applied on individual
shifts for all miners.
It should be noted that the American Conference of Governmental
Industrial Hygienist (ACGIH) approach of reducing the permissible
concentration to compensate for the extension of a shift beyond eight
hours is similar in its effect to the approach taken here of adjusting
the equivalent concentration upwards and comparing it to a fixed limit.
MSHA makes similar adjustments for extended work shifts in the
enforcement of exposure limits in metal and nonmetal mines under 30 CFR
56.5001 and 57.5001. Taking into account the reduced recovery time that
results from an extended work shift would have led to a numerically
greater and more protective adjustment, but this would also have
introduced additional complexities in the calculation of equivalent
concentration measurements. The Secretary believes that the method
proposed strikes a reasonable balance between no adjustment at all, and
a far more complex adjustment that would attempt to model clearance,
deposition, and retention mechanisms.
Material Produced
``Material produced'' would mean the amount of coal and/or any
other substance(s) extracted by a mechanized mining unit during a
production shift. In order to properly assess the effectiveness of the
ventilation plan requirements for respirable dust control and for
subsequent monitoring purposes, MSHA proposes to require that the
operator record and make available records of the amount of material
produced by each mechanized mining unit each shift under a new
paragraph (h) of Sec. 75.370.
Mechanized Mining Unit (MMU)
The existing definition would be modified by deleting the reference
to Sec. 70.207(e) (Bimonthly sampling; mechanized mining units), and
replacing it with proposed Sec. 70.206(d); and by transferring the
requirements for identifying each MMU specified in existing Sec. Sec.
70.207(f)(1) and (f)(2), to revised Sec. 70.2.
MRE
``MRE'' would mean Mining Research Establishment of the National
Coal Board, London, England.
Personal Continuous Dust Monitor (PCDM)
``Personal continuous dust monitor'' would mean a type of approved

[[Page 10809]]

instrument capable of accurately measuring the concentration of
respirable dust on a continuous basis during an entire shift and
displaying in real-time the measured dust exposure information. To meet
the definition of ``approved device,'' the Secretary must demonstrate
that the respirable dust concentration measured by such an instrument
can be converted to a concentration measurement equivalent to that
obtained by a device approved under 30 CFR part 74 of this title.
Comments are solicited on the practice of tying the performance of new
sampler designs to the currently approved sampling device.
The PCDM must be capable of displaying (1) the cumulative average
dust exposure during the shift; (2) the current exposure level based on
entire shift duration (projected end-of-shift exposure); and (3) the
time-weighted average concentration (total mass of dust collect divided
by the length of time the unit was operated) within 15 minutes after
the end-of-shift. The entire unit must comply with MSHA intrinsic
safety regulations and pass tests for electromagnetic interference for
emissions using ANSI C95.1-1982 and 47 CFR part 15 and for immunity/
susceptibility using IEC 61000-4. Since work shifts longer than 8 hours
are common in mining, the PCDM must have sufficient battery capacity to
operate continuously for up to 12 hours. To ensure that air monitoring
results are sufficiently accurate across the relevant range of exposure
levels, the PCDM must meet an accuracy criterion of +/-25% of a
reference value determined using the currently approved sampling device
(P/N 45243) with 95% confidence.
The Agency solicits comments on how continuous dust monitors could
be applied to limit exposure of coal miners to respirable coal mine
dust. Specifically, comments are solicited on the proposed performance,
accuracy, and approval requirements for personal continuous dust
monitoring devices, and whether less stringent requirements should be
imposed on devices designed for surveillance and not for compliance
purposes. What would be an acceptable level of accuracy of such a
device if used for surveillance purposes (i.e., identifying dust-
generating sources and magnitude of dust concentrations), for
compliance determinations, or for control enhancement purposes (i.e.,
provide a means to take corrective measures in response to instrument
readings by adjusting specific controls)? Comments are also solicited
on the performance requirements for continuous dust monitors used
primarily for surveillance purposes to prevent an individual miner from
being overexposed on a particular shift and whether such devices need
to be first approved by MSHA for use in underground mines.
Powered Air-Purifying Respirator (PAPR)
``Powered air-purifying respirator'' (PAPR) would mean a type of
air-purifying respirator that uses a blower to force ambient air
through air-purifying elements to the inlet covering (a visor), which
provides a partial seal with the face, to deliver filtered air to the
miner's breathing area. This category of respirator must be approved by
the National Institute for Occupational Safety and Health under 42 CFR
part 84 and by MSHA under 30 CFR part 18; and, offer head and face
protection in compliance with 30 CFR 75.1720(a) and (d) of this title.
The reasons for excluding other types of approved respirators are
discussed in section III.D.4. of the preamble.
Protection Factor
``Protection factor'' (PF) would be a measure of the expected
degree of workplace respiratory protection that would be provided to
the wearer by a properly functioning PAPR when correctly worn and used.
The PF expresses PAPR performance as the ratio of the respirable dust
concentration outside the respirator facepiece to the concentration
inside the facepiece. It reflects the effectiveness of a respirator
used in conjunction with a good respirator protection program. For
example, a PF of 4 means that the respirator is expected to reduce the
concentration of respirable dust actually breathed to one fourth of the
concentration outside the respirator.
Factors such as air velocity at the working face and raising of the
visor during the shift significantly impact the effectiveness of a
PAPR. Therefore, such factors should be taken into account when
estimating the degree of respiratory protection a PAPR provides in the
workplace. Although NIOSH has recommended that loose-fitting hood or
helmet PAPRs should be assigned a PF of 25, the environmental
conditions observed in the studies used in NIOSH's estimation of an
assigned protection factor (APF) are not consistent with those found in
underground coal mines, where high air velocities for methane and dust
control are common.
Under this proposal, the PF that would be assigned to PAPRs
authorized for a particular MMU depends on the air velocity that will
be maintained at the working face. The applicable PF would be included
in a written PAPR protection program, which must be approved by the
district manager before it can be implemented. Based on the available
technical information and sound engineering judgement, MSHA would
permit a PF ranging from 2 to a maximum of 4 to be assigned to a
particular MMU, depending on air velocity.
If, according to the ventilation plan, the minimum air velocity to
be maintained in the headgate of a longwall MMU ventilated head-to-tail
is less than 400 feet per minute (fpm), then PAPRs used in the MMU
would be assigned a PF equal to 4. If the minimum air velocity to be
maintained in the location specified in the plan exceeds 800 fpm, then
the assigned PF would be 2. If the minimum air velocity specified in
the plan falls between 400 fpm and 800 fpm, then PAPRs used in the MMU
would be assigned a corresponding PF falling between 2 and 4.
Because there is a lack of data on the performance of PAPRs under
actual air-velocity conditions ranging between 400 and 800 fpm, MSHA is
proposing an interpolation formula [2 x (800/air velocity)]
for
determining the PF to be assigned to a MMU when the specified air
velocity to be maintained falls in that range. For example, if the
minimum air velocity to be maintained in the headgate is 550 fpm, then
the assigned PF would be calculated as: 2 x (800fpm/550fpm) = 2.9. A
reasonable alternative interpolation formula, 6--(air velocity/200),
would yield somewhat higher protection factors for velocities between
400 fpm and 800 fpm. However, given the absence of supporting data,
MSHA selected the proposed interpolation formula because it yields a
more conservative PF.
Comments are invited on the proposed method of establishing the
applicable PF and on the interpolation formula proposed for specified
air velocities ranging between 400 fpm and 800 fpm. Data are requested
in support of any recommendations that different protection factors
should be assigned to MMUs authorized to use PAPRs.
Quartz
The existing definition would be modified by specifying the
analytical method that MSHA has been using since 1983 to determine the
quartz content of respirable dust samples. The reason for this
modification is to standardize the analytical procedure, thereby
enabling other certified laboratories to produce quartz determinations
compared to those made by MSHA. Also, to accommodate the adoption of
improved

[[Page 10810]]

or other quartz analytical techniques in the future, the definition of
``quartz'' has been expanded in the proposed rule to provide MSHA the
flexibility to use alternative analytical techniques once these
techniques have been demonstrated to provide quartz measurements that
are equivalent to the currently used analytical method.
Respirable Dust
The existing definition has been modified by transferring the
requirement for what constitutes an approved sampling device to the
proposed new definition of the term ``approved sampling device'' above.
Verification Limits
``Verification limits'' would mean the maximum equivalent dust
concentration for which the dust control parameters, specified in the
ventilation plan for a particular MMU, have been verified as effective
in maintaining dust levels during the entire production shift. Under
the proposed rule, MSHA will require mine operators to address both
respirable coal mine dust exposure and the potential for exposure to
quartz when designing the dust control parameters specified in a mine
ventilation plan by proposing two separate respirable dust limits--2.0
mg/m3 for respirable coal mine dust and 100 [mu]g/
m3 for respirable quartz dust for verification sampling.
The Dust Advisory Committee recognized that a significant quartz
exposure hazard continues to exist in coal mines, especially for
operations such as roof bolting. Based on recent MSHA data (April 23,
2002), 298 or (58 percent) of the 517 producing underground coal mines
are operating on a reduced applicable dust standard due to the presence
of high quartz levels in the working environment. This data also shows
that 65 percent of the more than 470 roof bolters and 27 percent of the
MMUs required to be sampled bimonthly by mine operators must comply
with a reduced dust standard. The number of reduced standards in effect
indicates that quartz exposure remains a significant health risk for
miners.
Under the current program, miners can be exposed to excessive
quartz levels during the period of time necessary to establish the
applicable dust standard that would apply to a particular MMU. For
example, consider a recent situation where an MSHA dust sample of a
roof bolter was 0.9 mg/m3, which complied with the
applicable dust standard of 1.3 mg/m3. However, the results
of quartz analysis indicated that the actual concentration of quartz
dust in the mine environment at the time of sampling exceeded 270
[mu]g/m3, or more than two and a half times the permissible
level of 100 [mu]g/m3. The only action that MSHA could take
in this particular situation is to initiate the process of establishing
a new applicable dust standard, which, on average, can take at least
one month or longer. During this period, the existing applicable dust
standard remains in effect.
Under the proposed rule, MSHA would require operators to
incorporate dust control parameters in mine ventilation plans that are
designed to effectively control exposure to both respirable coal mine
dust and quartz dust. To ensure the adequacy of the operator's dust
control strategy, MSHA would determine the mass of quartz contained in
each verification sample and express the concentration of quartz in the
mine air as an airborne concentration and not as a percentage as has
been the long-standing practice.
MSHA believes that by requiring operators to anticipate exposure to
quartz dust in the initial design of the dust control parameters,
especially at those operations with a quartz exposure history, and by
adopting the new procedures for setting a reduced dust standard as
outlined in section III.B., the level and quality of miner health
protection in the workplace will be significantly enhanced.
Verification Production Level (VPL)
``Verification production level (VPL)'' would mean the tenth
highest production level recorded in the most recent 30 production
shifts. It is an estimate of the 67th production percentile within a
MMU. Under the proposed rule, the VPL is the minimum production level
at which the operator must demonstrate the adequacy of the plan
parameters in controlling respirable dust. To enable the operator to
establish the VPL required under proposed Sec. 75.371(f), the operator
would be required to begin maintaining records of the amount of
material produced by each MMU during each shift in accordance with
proposed Sec. 75.370(h) of this title.
If records for 30 production shifts are not available to establish
a VPL, as in the case of a new MMU, the operator would use the minimum
production actually achieved on any shift used to verify the adequacy
of the plan parameters as the VPL. For example, assume an operator
initiates verification sampling at a longwall MMU. If the dust
concentration measurements obtained on the first shift exceed either
1.85 mg/m3 for respirable coal mine dust or 93 [mu]g/
m3 for quartz dust but not the verification limits, the
operator would need to sample at least two more shifts according to
Table 70-1 to verify the adequacy of the plan parameters, provided that
no sample exceeds 1.93 mg/m3 for respirable coal mine dust
or 97 [mu]g/m3 for quartz dust. If the highest production
level was achieved on the third shift sampled and the dust
concentration measurements obtained on that shift were low enough
according to Table 70-1 to verify the plan parameters on a single
shift, the operator would establish a VPL equal to the production
achieved on that shift. If, on the other hand, the dust concentration
measurements obtained on the third shift with the highest production
level were not low enough to verify the plan parameters on a single
shift and a determination of the plan's adequacy was based on these
three shifts, the operator's VPL would be the minimum production
achieved during verification sampling. In any case, the VPL would
become part of the operator's ventilation plan.
Working Face
``Working face'' would mean any place in a coal mine in which work
of extracting coal from its natural deposit in the earth is performed
during the mining cycle.

Sections 70.100 Through 70.101

Respirable Dust Standards

Section 70.100 Respirable Dust Standards When Quartz Is Not Present
MSHA is proposing no substantive changes in existing Sec.
70.100(a) and (b), except for removing the reference to Sec. 70.206
(Approved sampling devices; equivalent concentrations) from existing
paragraphs (a) and (b) and replacing it with revised Sec. 70.2. The
requirements contained in revised Sec. 70.2 are similar to the
previous standard in Sec. 70.206. The proposed rule retains the
applicable dust standard of 2.0 mg/m3 in existing paragraph
(a) and the intake air standard for respirable dust of 1.0 mg/
m3 in existing paragraph (b), which have been in effect
since 1972.
Section 70.101 Respirable Dust Standard When Quartz Is Present
MSHA is proposing to retain the existing formula (10 divided by the
concentration of quartz, expressed as a percentage) for reducing the
applicable dust standard below 2.0 mg/m3 in proportion to
the percentage of quartz when the quartz content of the respirable dust
in the mine atmosphere exceeds 5.0 percent. However, the Agency is
proposing to change the

[[Page 10811]]

procedures for determining the average quartz percentage used to
calculate the applicable dust standard. Only the results of MSHA
samples would be used to establish the applicable dust standard. The
quartz results of the three most recent valid MSHA samples would be
averaged and the resultant percentage would be used to set the new
applicable dust standard. However, if an entity is already on a reduced
standard when these revised procedures become effective, a new
applicable dust standard will be established by averaging the results
of the first two MSHA samples taken under the revised procedures with
the quartz percentage associated with the reduced standard in effect.
If fewer than two MSHA samples are taken, the existing applicable dust
standard will continue to remain effect.
Application of the revised procedures will result in the setting of
reduced standards that will (1) more accurately represent the quartz
percentage of the respirable dust in the environment at the time of
sampling; (2) reflect the dynamics of the mining process and the
changing geologic conditions of the mine strata; and (3) continue to
protect miners over multiple shifts.
Under the proposed rule, MSHA would also begin reporting the quartz
content to the nearest tenth of a percent, instead of the current
practice of truncating results to the nearest full percent. This is
more protective for the miner because it will permit MSHA to also set
reduced standards at such levels as 1.1 mg/m3, 1.4 mg/
m3, 1.6 mg/m3, 1.8 mg/m3, and 1.9 mg/
m3. Setting these particular standards was not
mathematically possible using the above formula due to the practice of
truncating the average quartz percentage.
Section 70.201 Sampling; General and Technical Requirements
MSHA is proposing to modify the general requirements for operator
sampling under existing Sec. 70.201. The proposed rule would remove
existing paragraph (d), revise and redesignate (b) as (c) and existing
(c) as (g), revise paragraph (a), and add new (b), (d), (e), (f), (h),
and (i).
To minimize repetition and to streamline the proposed requirements,
paragraph (a) would be modified by removing the reference to part 74
approval (Coal Mine Dust Personal Sampler Units), and replacing it with
``approved sampling device,'' as defined under revised Sec. 70.2.
Respirable dust sampling under this proposed rule could also be
conducted with sampling devices that can give a continuous readout of
dust concentrations provided that the measured concentration can be
converted to an equivalent concentration as measured with another
sampling device approved under part 74 of this title.
Proposed new paragraph (b) would retain the requirements in
existing Sec. 70.202(a) and (b) that sampling required under this part
be conducted by an individual certified by MSHA and the manner by which
a person would be certified. Therefore, existing Sec. 70.202(a), (b),
and (c) would be removed.
While the sampling device would continue to be worn or carried to
and from the MMU as required by existing Sec. 70.201(b), proposed
Sec. 70.201(c), the existing requirement that sampling devices be
operated portal-to-portal and for a period no longer than eight hours
would be removed. Instead, since the objective is to assess the
adequacy of the dust control parameters in effect in each MMU under
proposed Sec. 70.206 and Sec. 70.215, except when using a personal
continuous dust monitor (PCDM) under proposed Sec. 70.220, the
sampling device would be operated only during the period that the
production crew spends in the MMU. That is, under proposed Sec. 70.206
the sampling device would (1) be turned ``ON'' when the production crew
arrives at the MMU, regardless if any actual mining is taking place;
(2) remain operational during the entire shift that the production crew
remains in the MMU, regardless of the number of hours worked; and (3)
be turned ``OFF'' at the end of the shift as the production crew exits
the MMU.
On the other hand, if using a PCDM under proposed Sec. 70.220, the
sampling device would be operated portal-to-portal and would remain
operational during the entire work shift or for 12 hours, whichever
time is less, to ensure that the miner's entire work shift is
controlled. Because the use of a PCDM will permit the operator to make
adjustments in administrative controls, without MSHA approval, at
anytime during the work shift, the duration of sampling is not limited
to the time period the production crew spends in the MMU as discussed
in the previous paragraph but, instead, must be carried out over the
entire work shift to ensure that each miner using a PCDM was not
personally overexposed. Simply stated, the PCDM would be turned ``ON''
when the miner enters the mine and remain operational while traveling
to the MMU, during the entire time period spent working in the MMU, and
while traveling back to the mine entrance, at which time the device
would be turned ``OFF.'' Since most non-traditional work shifts in
underground coal mines are less than 12 hours in length, the PCDM
currently under development is being designed with sufficient battery
capacity for one 12-hr work shift of operation.
It should be pointed out that the duration of MSHA sample
collection will continue to be limited to 480 minutes. The sampling
device will be operated portal-to-portal and remain operational during
the entire shift or for 8 hours, whichever time is less.
Consistent with accepted industrial hygiene practice, proposed
paragraph (d) will require the operator to use control filters when
verifying the adequacy of the plan parameters under proposed Sec.
70.206 or Sec. 70.220(c). A control filter is an unexposed filter of
the same design as the filter cassette used for sampling, that is pre-
and post-weighted on the same day as the filter cassettes used for
verification sampling. MSHA first began using control filters in its
enforcement program in May 1998 and continues this practice today. The
reason for requiring their use by operators is to improve the accuracy
in making weight-gain measurements of the exposed filter cassettes by
eliminating the effect of differences in pre- and post-exposure
laboratory conditions, or changes introduced during storage and
handling of the filter cassettes. The control filter will be used to
adjust the weight gain obtained on each exposed filter by subtracting
any change in the weight of the control filter from the change in
weight of each exposed filter. This is especially important since the
filter cassettes to be used by operators will be pre- and post-weighed
to the nearest microgram (0.001 mg). The other modification to the
procedures for processing operator samples will be to discontinue the
practice of truncating (to 0.1 mg) the recorded weights used in
calculating dust concentrations. This means that Mine Safety Appliances
Company (MSA), which upgraded its weighing equipment in 1996 and uses
the same balance as MSHA's Coal Dust Processing Laboratory, will be
permitted to follow MSHA and use all significant digits associated with
the weighing capability of the balance (0.001 mg) when pre-weighing
operator dust cassettes. These changes will enhance the proposed
process of verifying the adequacy of plan parameters. This will also
eliminate the need for operators to sample multiple shifts in order to
obtain sufficient dust mass on the collection filter for quartz
analysis. Since the use of a control filter adjusts for differences
that may exist in laboratory conditions on the days of pre- and post-
weighing, it is no longer necessary to pre- and post-weigh the filter
cassettes in the same laboratory. To ensure the precision and accuracy
of the pre-weight of filters

[[Page 10812]]

used by the operator and federal mine personnel, MSHA will institute a
program to monitor the daily production of filter cassettes weighed to
the nearest microgram ([mu]g) by the manufacturer, MSA. The program
will conform to MIL-STD-105D, which defines the criteria currently used
to monitor the quality of pre-weighed filters used in the current
operator bi-monthly sampling program.
Since the control filter will be used to adjust the resulting
weight gain obtained on each exposed filter cassette, the control
filter must have the same pre-weight date as the filter cassettes to be
used for sampling on the same shift. The pre-weight date is noted on
the dust data card. Failure to follow these instructions will be cause
for voiding the sampling results. Only one control filter will be
required for each MMU per shift sampled. To prevent exposure to the
mine environment, the plugs attached to the inlet and outlet side of
the cassette must not be removed. Also, it is important that the
control filter be exposed to the same time, temperature, and handling
conditions as the ones that are used for sampling, i.e., carry the
control filter in a shirt or coverall pocket while underground. While
the control filter can be carried by any miner assigned to the MMU
being sampled, it would be preferable if that miner performed the job
of the DO. Finally, the control filter cassette must be kept together
with the exposed samples after sampling and treated in the same manner
as the exposed filters prior to being transmitted to MSHA. For
processing purposes, the dust data card for the control filter must be
marked with a large capital ``C'' for ``CONTROL'' in the middle of the
card and enter a ``9'' in the ``Type of Sample'' box. The remaining
items on the dust data card must be completed in the same manner as
under the previous operator bimonthly sampling program. These
procedures are identical to the ones followed by MSHA.
To ensure that the plan parameters are designed to control
respirable dust and are suitable to the conditions and mining system at
the mine as required under Sec. 75.370(a) of this title, the proposed
paragraph (e) prescribes minimum mining activity that must be ongoing
during sampling, as well as the operating parameters for use of the
engineering controls specified in the plan. Therefore, when sampling
under proposed Sec. 70.206, Sec. 70.215 or Sec. 70.220(c),
respirable dust samples must be collected on a production shift during
which the amount of material produced by the MMU is at least equal to
or exceeds the verification production level (VPL) as determined in
accordance with Sec. 70.2. If the VPL is not achieved, the samples for
that shift will be voided by MSHA. However, any sample that exceeds
either verification limit or the applicable dust standard by any amount
would be used to determine the equivalent concentration for that
occupation, regardless of production. Also, if the MMU being sampled
under proposed Sec. 70.215 is authorized to use PAPRs under special
circumstances (see Sec. 70.212) and those circumstances prevent the
operator from achieving the VPL, the sample(s) for that shift will be
used to determine the equivalent concentration for the affected
occupations.
In addition to minimum production activity, limits must also be set
on how much the specified engineering control parameters can deviate
during sampling from the quantities specified in the ventilation plan.
Failure to meet either criterion will undermine miner confidence in the
ability of the approved plan parameters to effectively control
respirable dust under the conditions at the MMU. Accordingly, paragraph
(e) requires each operator to use only the engineering controls and
other measures specified in the plan. Recognizing that engineering
parameters such as air quantity and velocity and water pressure are
subject to measurement error and can vary because they cannot be easily
controlled with absolute precision, proposed Sec. 70.201(e) would
permit the measured levels to be up to 115 percent of the minimum
quantities specified in the plan.
Since miners play an important role in the implementation and
maintenance of the approved plan parameters, MSHA recognizes the need
for miners to have full confidence in the sampling process used to
approve and evaluate the continued adequacy of the plan parameters.
Therefore, consistent with the underlying purposes of the Mine Act,
proposed paragraph (f) would require the operator to provide affected
miners and their representatives with an opportunity to observe any
sampling required by this proposed rule. In addition, the operator
would be required to give prior notice to miners and their
representatives of the dates and times when the operator intends to
conduct sampling. If the exposure of individual miners is monitored on
a daily basis using a PCDM, the operator would be exempt from this
requirement since all affected miners would already be aware that they
were being monitored on a continuous basis. To make miner participation
more effective, it is important that miners and their representatives
are knowledgeable in those features of the sampling program specified
in the proposed rule. This will enable them to make sound and
knowledgeable judgements on the conduct of operator sampling under the
proposed rule.
While section 103(f) of the Mine Act requires the operator to
compensate representatives of miners who accompany MSHA personnel
conducting inspections, it would not apply to operator sampling as
proposed, unless conducted on the same shift that MSHA chooses to
monitor operator sampling. Therefore, unless accompanying MSHA
personnel, section 103(f) would not authorize ``walkaround pay'' for
time spent by a representative of miners observing the operator
conducting sampling required by this part. MSHA believes that providing
the representative of miners with an opportunity to accompany MSHA
personnel monitoring operator sampling required by this part with no
loss of pay is consistent with section 103(f) of the Mine Act. Under
the guidance of the Interpretive Bulletin (43 FR 17546, April 25,
1978), walkaround rights arise when: (1) An ``inspection'' is made for
the purposes set forth in section 103(a), and (2) the inspector is
physically present at the mine to observe or monitor safety and health
conditions as part of direct safety and health enforcement activity.
MSHA sampling required by this part would be unannounced and
conducted to determine if the operator is in full compliance with both
the operating conditions and sampling requirements of this part, as
well as with all other health and safety standards. Consequently, the
representative of miners would have the right to accompany the MSHA
personnel with no loss of pay for the time during which the
representative exercises this right.
Existing paragraph (c) which requires the operator to submit, when
requested by the district manager, the date and time when sampling
required by this part will begin would be redesignated as paragraph
(g). This requirement enables MSHA to monitor operator sampling on a
case-by-case basis to verify compliance with both the operating
conditions and sampling requirements of this part.
The requirement that operators take corrective action during the
time for abatement fixed in a citation for violation of Sec. Sec.
70.100 or 70.101 specified in existing paragraph (d) of Sec. 70.201
would be transferred to proposed Sec. 70.218(b)(2). The requirement
that the operator sample each production shift until five valid samples
are taken under existing

[[Page 10813]]

paragraph (d) would be removed since MSHA is proposing to revoke
operator sampling requirements under existing Sec. Sec. 70.207 and
70.208, and assume full responsibility for all compliance sampling.
Section 70.202 Approved Sampling Devices; Maintenance and Calibration
In an effort to consolidate the requirements that address
maintenance and calibration procedures of approved sampling devices,
MSHA is proposing in Sec. 70.202(a) through (e) to retain the
requirements in existing Sec. 70.203(a) and (b) and Sec. 70.204(a)
through (e), with minor changes. These standards require the sampling
device be maintained as approved and calibrated only by a certified
person in accordance with MSHA Informational Report IR 1240 (1996).\8\
If using a PCDM under proposed Sec. 70.220, the device would be
calibrated to the manufacturer's specifications. The process of
certifying an individual for maintenance and calibration would remain
unchanged. It would continue to require an individual to successfully
complete the applicable MSHA examination. Scheduling information for
MSHA training courses and examinations would be available from MSHA
District Offices.
------------------------------------------------------------------------

\8\ On September 3, 1998, MSHA published a proposed rule in the
Federal Register (63 FR 47123) requesting public comment on our
intention to update the incorporation-by-reference in title 30 of
the Code of Federal Regulations, Sections 70.204, 71.204, and
90.204. The Agency allowed 60 days for public comment and received
no comments, no requests for an extension of the comment period, and
no requests for a public hearing. On August 10, 1999 the final rule
was published and became effective on October 12, 1999 (64 FR
43283).
------------------------------------------------------------------------

These standards require approved sampling devices to be calibrated
at a flowrate of 2.0 liters of air per minute. They also establish the
flowrate and testing and examination requirements for approved sampling
devices. Careful examination and testing of sampling devices would
continue to be required immediately prior to the start of a shift
during which samples would be collected for purposes of this proposed
rule. This would include testing the battery voltage and examining all
external components of the sampling devices to be used. Any necessary
external maintenance to assure the sampling devices are clean and in
proper working condition should be performed at this time by a
certified person. Temporary certification of persons provided under
existing Sec. 70.203(b) would not be retained under the proposal.
If using a PCDM in accordance with Sec. 70.220, the operator under
proposed Sec. 70.202(f) would be exempt from the examination
requirements of paragraphs (d)(1) through (d)(5) of this section.
Instead, the operator would be required to follow the examination
procedures recommended by the manufacturer or prescribed by MSHA and
NIOSH for the particular device.
Section 70.203 Approved Sampling Devices; Operation; Air Flowrate
Proposed Sec. 70.203(a) through (c) retains the operation and
flowrate requirements for approved sampling devices in existing Sec.
70.205(a) through (d), with minor changes. Since MSHA has defined an
approved sampling device in revised Sec. 70.2 to mean a device
approved in accordance with part 74 of this title, proposed paragraph
(a) excludes reference to part 74. Similarly, for purposes of
simplification, reference to Sec. 70.202 (Certified person; sampling)
would be removed and, replaced by certified person as defined in
revised Sec. 70.2.
MSHA believes that the two on-shift examinations of sampling
devices under proposed paragraphs (b)(1) and (b)(2), which are
identical to the examinations required under existing Sec. 70.205(b)
and (c), continue to be an important part of a reasonable and prudent
sampling program. The first examination would be made by a certified
person during the second hour after the sampling devices are placed in
operation. This examination would assure that each sampling device is
operating properly and at the proper flowrate. If the proper flowrate
is not maintained, necessary adjustments in the flowrate would be made
at this time by the person certified to collect samples. The second
examination would be made during the last hour of operation of the
sampling devices. If the proper flowrate is not maintained, the
certified person is required to make a notation on the dust data card
for that sample stating that the proper flowrate was not maintained.
Because it is unclear where on the dust data card such a notation
should be made, proposed paragraph (b) would require all notations
regarding failure to maintain proper flowrate or other events occurring
during sampling that may impact the validity of the sample to be made
on the back of the dust data card.
If using a PCDM under proposed Sec. 70.220, the operator would not
be required to examine the device during the second and last hour of
operation as required under paragraph (b) of this section. Instead, the
operator would be required to follow the procedures recommended by the
manufacturer or prescribed by MSHA and NIOSH to assure that the PCDM is
operating properly and at the proper flowrate.
Section 70.204 Demonstrating the Adequacy of the Dust Control
Parameters Specified in a Ventilation Plan; Verification Sampling
Existing Sec. 75.370(a)(1) of this title requires the operator to
develop and follow a mine ventilation plan that is designed to control
methane and respirable dust. It further requires the plan to be
suitable to the conditions and mining systems at the mine. Accordingly,
a properly-designed mine ventilation plan continues to be the most
reliable means for ensuring that the work environment in each MMU is
free of excessive concentrations of respirable dust.
MSHA recognizes that the operator has the legal responsibility for
developing a ventilation plan that is designed to control respirable
dust. Consequently, the operator has the obligation to demonstrate that
the dust control parameters specified in the plan will effectively
control respirable dust as required by Sec. 75.370(a)(1). Therefore,
within 12 months after the effective date of this rule, each operator
of an underground coal mine must have an approved ventilation plan in
which the dust control parameters specified for each MMU have been
verified to be adequate in controlling respirable dust. Proposed
Sec. Sec. 70.205 through 70.208 set forth the specific steps an
operator must follow to verify the adequacy of the plan parameters. To
demonstrate adequacy, the operator would be required to collect valid
respirable dust samples in accordance with proposed Sec. 70.206 or
Sec. 70.220(c) if using a PCDM. Approval of the plan parameters for a
particular MMU would be granted when these samples, called verification
samples, demonstrate at a high level of confidence, in accordance with
the limits specified in Table 70-1, the adequacy of the plan parameters
in maintaining the equivalent concentration of respirable dust coal
mine dust and quartz dust at or below the verification limits of 2.0
mg/m3 and 100 [mu]g/m3, respectively.
Section 70.205 Verification Sampling; When Required; Time for
Completing
Proposed Sec. 70.205 specifies the various ways in which the
process of verifying the adequacy of the dust control parameters for a
MMU would be initiated. The operator would trigger the process by
submitting a new ventilation plan under Sec. 75.370. This process
would also be initiated if the district manager requires the operator
to amend the plan parameters in a previously approved ventilation plan
after determining, based on dust sampling results or other

[[Page 10814]]

evidence, that the dust control parameters in effect are no longer
suitable to the current conditions at a particular MMU.
Once the dust control parameters for a MMU have been verified as
adequate, it would not be necessary to reverify the plan parameters as
part of the MSHA six-month review under Sec. 75.370(g), unless the
district manager determines these parameters are unsuitable for the
current conditions at the MMU. However, the operator may be required to
make changes to the parameters based on (1) results of the MSHA six-
month review, (2) excessive dust concentrations measured by either MSHA
or operator monitoring samples, or (3) a new reduced applicable dust
standard which is less than the highest respirable coal mine dust
concentration that was previously used to verify the adequacy of the
plan parameters. For example, if an operator was cited for exceeding
the applicable dust standard when the approved plan parameters were
being met or exceeded, the district manager may have cause to question
the adequacy of the previously-approved dust control parameters.
Also, depending on sampling results and production records, if the
production exceeds the VPL specified in the plan, the district manager
may require the operator to verify the plan parameters at the higher
production level. For example, suppose the VPL is 10,000 tons and all
five concentration measurements taken during MSHA sampling exceed the
applicable dust standard on a shift for which the production is 12,000
tons. Then, if the production records indicate that the operator has
exceeded the VPL on more than 33 percent of all production shifts
during the previous six months, that evidence would demonstrate that
the VPL specified in the plan is no longer valid. The district manager
would then require the operator to verify the plan parameters under
current operating conditions.
Under the proposed rule, the operator would be required to verify
the adequacy of the dust control parameters for each MMU within 45
calendar days after obtaining provisional approval from the district
manager. This should be ample time for an operator to demonstrate the
adequacy of the plan parameters, even when starting up a new MMU, such
as a longwall panel. Should an operator experience difficulty in
establishing the desired VPL or encounter other unexpected breakdowns
or unforseen circumstances affecting the operational status of a MMU
after obtaining provisional approval, the district manager may grant an
operator an extension of up to 30 days to complete verification
sampling. Before receiving provisional approval, the operator may be
required to modify the plan parameters if the district manager
determines that the particular parameters are inadequate or unsuitable
for the current conditions in the MMU. If provisional approval is not
granted, the operator may not operate the affected MMU.
Under the proposed rule, the adequacy of all previously approved
dust control parameters would need to be verified by the operator
within 12 months after the final rule becomes effective. Before
submitting these plan parameters to the district manager for review and
approval to commence verification sampling, proposed paragraph (b)
would require the operator to provide additional information. The
additional information is described under revised Sec. 75.371(f) of
this proposed rule. The operator will be permitted to operate a MMU
under the previously approved dust control parameters until the amended
plan parameters are either provisionally approved or denied.
To minimize delays in the verification process, MSHA will develop
and issue appropriate compliance guides and provide adequate training
on the new rule prior to its implementation. MSHA will also be
available to provide guidance to individual mine operators once the
rule becomes effective. The Agency intends to make every effort to
ensure an orderly and efficient transfer from the previous plan
approval process to the new process of validating the adequacy of dust
control parameters for each MMU prior to implementation.
Section 70.206 Verification Sampling; Procedures for Sampling
This proposed section establishes the sampling procedures that each
operator would follow when conducting verification sampling. Described
are the specific occupations and areas to be monitored in a MMU, and
the operation and placement of each sampling device during sampling.
The specific operating conditions under which these occupations and
areas would be sampled are discussed under Sec. 70.201. These will be
covered again for the benefit of the reader.
Proposed paragraph (a) would require the operator to sample
specific occupations assigned to a MMU. These occupations were selected
because, based on MSHA experience over the past 20 years, miners
required to work in those occupations are likely to be exposed to the
greatest respirable dust concentration and, consequently, would be at
significant risk of overexposure. Therefore, the operator would be
required to sample the environment of: (1) The DO in accordance with
proposed paragraphs (d)(1) through (d)(10), which are identical to
existing Sec. 70.207(e)(1) through (e)(10); (2) the roof bolter
operator(s) (occupation codes--012, 014 or 046); (3) the longwall jack
setters (occupation code--041); and (4) any other occupation that the
district manager may designate for sampling after reviewing the
operator's plan parameters.
Unless otherwise directed by the district manager, when an operator
samples a longwall MMU, the DO sample required by this part would be
collected by placing the sampling device on the miner who works nearest
the return air-side of the longwall working face. Since 1987, this work
location has been assigned the 060 occupation code by MSHA for sampling
and tracking purposes in accordance with existing Sec. 70.207(e)(7).
Therefore, when sampling the 060 DO, the sampling device would remain
at all times with the miner working nearest the return air-side of the
longwall face. If individual miners rotate out of the DO position
during sampling, as is the common practice at some operations, the
sampling device must be transferred to and worn by the new miner
rotated into the DO position. For example, if all other miners are
working upwind of the tailgate-side longwall operator, the miner
performing that particular job becomes the DO and wears the sampling
device since that individual is working nearest the return air-side of
the longwall face. However, if during the shift being sampled another
miner, such as the face mechanic, travels past the tailgate-side
longwall operator toward the return air-side, the face mechanic would
then become the DO and must wear the sampling device for the period of
time that individual works nearest the return air-side of the longwall
face. When the face mechanic returns upwind of the longwall operator,
the sampling device must then be transferred back to the longwall
operator, as that individual will now be the miner working nearest the
return air-side.
This is compatible to sampling any other DO, whether it is the 036
DO (continuous miner operator) or the 044 DO (tailgate-side longwall
operator). The sampling device must remain at all times in the
environment of the DO and not with the individual miner, regardless of
how many miners work in that location during the shift. Sampling the DO
in this manner preserves the long-standing high-risk occupation

[[Page 10815]]

sampling concept which the Agency adopted in 1970.
Under these procedures the sampling device must remain in the
environment of the miner who works nearest the return air-side of the
longwall working face. However, in certain circumstances, MSHA may not
require transfer of the sampling device if the amount of time a
particular miner spends inby or downwind of the DO is known to be
infrequent and of short duration, limited to 20 minutes or less.
However, transfer of the sampling device is required if the same miner
travels inby the DO routinely during the shift.
There are other ways to reduce the number of times that a sampling
device needs to be transferred from one miner to another during a
shift. This depends on the particular mining practices of the operator.
By fully utilizing the operational capabilities designed into
currently-employed longwall equipment or altering the mining cycle, the
need for miners to work routinely inby the shearer can and should be
minimized, thereby reducing the number of necessary pump transfers, and
the potential for miners to be overexposed to respirable dust. Another
approach has been used successfully at longwall MMUs employing a type
of water-spray system called ``shearer-clearer.'' This involves
limiting the movement of miners to a certain region or distance inby of
the shearer. In some instances this distance can reach 40 feet inby if
samples indicate dust levels are similar to the levels in the
environment of the tailgate-side shearer operator (Occupation code
044).
If a properly designed shearer-clearer system is installed and
maintained, it is very effective in confining the shearer-generated
dust to the face for some distance downwind of the shearer and prevents
migration to the walkway where miners are located. Therefore, miners
who are required to spend time inby the shearer can be protected from
exposure to excessive dust levels if their work is limited to this
particular area. This area, however, is normally established through
sampling on a mine-by-mine basis. The area can vary depending on the
quantities and velocities of air delivered to the longwall face, type
of cut sequence, water flow rates and spray pressures, and tonnage
produced.
If any of these approaches are not suitable or if the miner working
furthest downwind refuses to wear the sampling device for any reason,
the proposed rule provides for the placement of the sampling device in
a specified location on the return side within 48 inches of the corner
of the longwall face, which MSHA has designated as the 061 DO. Placing
the sampling device at this location is comparable to placing the
sampling device on the continuous mining machine within 36 inches inby
the normal work position of the machine operator. It should be noted,
however, that since dust concentrations at this location are typically
the highest, no longwall MMUs are currently submitting bimonthly
samples taken at the 061 DO.
The proposed approach, which involves sampling the ``high risk
occupation,'' currently referred to as the DO, is not new and has been
in use since inception of the mandated sampling program in 1970. This
sampling approach is designed to monitor the mine atmosphere with the
greatest concentration of respirable dust exposure, in the areas where
miners are working during their shift, to prevent excess exposure of
miners to respirable coal mine dust. The goal has never been to measure
the exposure of an individual miner for the duration of a shift, but
rather to determine if the mine atmosphere in the active workings is
free of excessive concentrations of respirable dust in order to protect
each miner required to work in that environment.
Based on the various dust generating sources and the manner in
which the face is ventilated, the return air-side of a longwall face is
the area on a longwall MMU with the greatest concentration of
respirable dust. Accordingly, since miners are required to work in this
area, operators are required to maintain the mine atmosphere in this
area or location in compliance with the applicable dust standard on
each shift. By doing so, it can be concluded that other miners in less
risky occupations are protected from excessive dust concentrations.
While these measurements will not show a particular miner's dust
exposure, the results will indicate if the air that miners are
breathing is in compliance with the applicable dust standard. The
objective of the proposed sampling scheme is to control the
concentration of respirable dust in the workplace. The method of
sampling the DO on a longwall MMU was determined to be reasonable and
consistent with the Mine Act in American Mining Congress v. Marshall,
671 Fed 12151 (10th Cir. 1982). MSHA believes that the method of
sampling being proposed will effectively serve the health protection
goal of achieving and maintaining good air quality in each MMU.
Therefore, the long-standing practice of sampling the DO in each
longwall MMU or any other DO would be continued under the proposed
rule.
Since the objective is to verify the adequacy of the dust control
parameters in effect at a MMU, proposed paragraph (b) would require
sampling devices to be turned ``ON'' when the production crew arrives
at the MMU to be sampled, regardless if any actual mining is taking
place, and not at the portal as required in existing Sec. 70.201(b)
for bimonthly sampling. The operator would continue to examine each
sampling device at least twice during the sampling shift in accordance
with proposed Sec. 70.203(b)(1) and (2). Each sampling device would
remain operational during the entire shift that the production crew
remains in the MMU, regardless of the number of hours worked. The
sampling devices would be turned ``OFF'' at the end of the shift as the
production crew, assigned to the occupation(s) being sampled, exits the
MMU to travel back to the mine portal.
Each operator would be required to use one control filter for each
shift of sampling as required by proposed Sec. 70.201(d). As explained
earlier, the control filter will be used to adjust the weight gain
obtained on each exposed filter by subtracting any change in the weight
of the control filter from the change in weight of each exposed filter.
Its use in accordance with Sec. 70.201(d) will enhance the decision-
making process involving the approval or denial of the dust control
parameters by the district manager.
To qualify as a valid sample for verification purposes, the amount
of material produced by the MMU during the shift being sampled must
equal or exceed the VPL as required by proposed Sec. 70.201(e). If the
VPL is not achieved, the sample(s) will be voided by MSHA. However, any
sample that exceeds either verification limit or the applicable dust
standard by any amount would be used to determine the equivalent
concentration for that occupation, regardless of production.
Proposed Sec. 70.201(e) also requires the operator to utilize only
the dust control parameters that were provisionally approved by the
district manager. Recognizing that engineering parameters such as air
quantity and velocity and water pressure are subject to measurement
error and cannot easily be controlled with absolute precision, MSHA
would allow the measured levels to be up to 115% of the quantities
specified in the plan.
If a measured level exceeds the corresponding quantity specified in
the plan by more than 15 percent, the operator would have the option to
either (1) adjust the engineering parameter(s) to what is specified in
the plan before beginning verification sampling or (2)

[[Page 10816]]

make no adjustment to the parameter(s) prior to verification sampling.
Under the second option, final approval of the plan parameters would be
contingent on the operator incorporating in the plan the maximum
quantities of parameters measured during verification sampling. If
verification samples were collected on a shift when a plan parameter
exceeded 115 percent of the quantity specified in the plan, then
(assuming none of the verification samples exceeded the critical
values) that parameter quantity, as measured, would be incorporated
into the plan parameters ultimately approved by the district manager.
If an operator chooses to sample multiple shifts, they would not
have to be consecutive shifts as under the previous bimonthly sampling
program. The operator would be required to submit for processing all
samples collected by the operator, regardless of the operating
conditions under which verification sampling was conducted.
The number of shifts that the operator would need to sample to
verify the adequacy of the plan parameters depends on two factors:
First, the actual operating conditions in effect during the shift being
sampled; and, second, the individual sample results. As discussed
earlier, for a respirable dust sample to be valid for verification
purposes, the amount of material produced by the MMU must equal or
exceed the VPL, and the dust control parameters must be at levels not
exceeding 115 percent of the quantities specified in the plan.
Therefore, the number of shifts depends largely on how quickly and
consistently the operator would be able to achieve these operating
conditions. The operator may need to sample several shifts before the
production level on any single shift qualifies for verification
purposes. The operator could verify the adequacy of the plan parameters
based on this single shift--but only if all sample results are at or
below the critical values listed in Table 70-1 that correspond to the
number of shifts sampled. This would demonstrate the adequacy of the
plan parameters at a high level of confidence. If any of the sample
results exceed the appropriate critical value, then the operator would
need to collect verification samples taken on one to three additional
shifts, depending on the concentrations measured on those shifts. Since
these additional shifts would also need to meet the production
criteria, and use only the dust control parameters specified in the
plan, some operators would need to sample a total of more than four
shifts.
Assuming that the operator makes no special effort to meet the VPL
during verification sampling, there is a 67-percent probability that a
randomly selected production shift would not meet the VPL.
Consequently, if the operator made no special effort to achieve the
desired production, there would be a 13-percent chance the operator
would need to sample more than five shifts and a 1.7-percent chance the
operator would have to sample more than 10 shifts.\9\ On the other
hand, again assuming no special production effort, there would be a 98-
percent chance the operator would need 10 or fewer shifts and a 70-
percent chance that the operator would need to sample three or fewer
shifts.\10\ This assumes that the sample results for each shift do not
exceed the critical value corresponding to the number of shifts
sampled. If the operator should make a concerted effort to achieve the
VPL on the sampled shifts and meet the other criteria, then sampling of
fewer shifts would be needed to verify the adequacy of the dust control
parameters.
------------------------------------------------------------------------

\9\ Assuming no special production effort, the probability of
needing more than n shifts to be sampled before meeting the minimum
production level required to verify the plan: P(X£n)=
(.667)\n\; for example, the probability of more than 10 shifts being
needed, P(X£) 10) = (.667)\10\ = 1.7 percent.
\10\ Assuming no special production effort, the probability of
needing n or fewer shifts to be sampled before meeting the minimum
production level required to verify a plan: P(X<=n)=1-
P(X£n); for example, the probability of 10 or fewer shifts
being needed, (1-(.667)\10\) = 98 percent.
------------------------------------------------------------------------

Section 70.207 Approval of Dust Control Parameters by District Manager;
Revocation of Approval
This proposed section establishes the criteria or ``critical
values'' that the district manager would use to determine whether the
operator's dust control parameters should be approved or denied. These
critical values, which differ according to the number of shifts sampled
by the operator, are listed in Table 70-1. Appendix A explains how the
critical values were derived. When verification sample results do not
exceed the applicable critical values, the district manager can be
confident that the dust control parameters in use during verification
sampling successfully prevented overexposures at the sampled locations.
The district manager would approve the operator's plan parameters
when the amount of material produced is at or above the VPL, the
parameters and other measures in place during verification sampling do
not exceed 115% of the quantities specified in the plan, and no
equivalent concentration measurement exceeds the applicable critical
values corresponding to the number of shifts sampled.

Table 70-1.--Critical Values for Determining Compliance With
Verification Limits.
[The result of each verification sample collected must be less than or
equal to the applicable critical values.]
------------------------------------------------------------------------
Critical Critical
value for value for
Number of shifts meeting criteria for coal mine quartz dust
verification sampling dust (mg/ ([mu]g/
m\3\) m\3\)
------------------------------------------------------------------------
1............................................ 1.71 87
2............................................ 1.85 93
3............................................ 1.93 97
4 or more.................................... 2.0 100
------------------------------------------------------------------------

The proposed criteria would allow the district manager to base
approvals on a reasonably small number of sampled shifts, while
maintaining a high level of confidence that approved dust control
parameters adequately prevent excessive dust concentrations on
individual shifts.
The following two examples illustrate how the district manager
would apply the proposed criteria or ``critical values'' to determine
if the operator's plan parameters for a MMU should be approved.

Example 1: Suppose valid verification samples were taken on two
shifts. According to Table 70-1, the district manager would approve
the operator's dust control parameters if all coal mine dust and
quartz measurements obtained on the two shifts were less than 1.85
mg/m\3\ and 93 [mu]g/m\3\, respectively. On the other hand, if one
roof bolter sample indicated a quartz concentration of 95 [mu]g/
m\3\, then the district manager would not approve the operator's
plan parameters based on these two shifts alone. Instead, at least
one additional shift of sampling would be needed. Valid verification
samples from only one additional shift would be sufficient if none
of the coal mine dust measurements on that shift exceeded 1.93 mg/
m\3\, and none of the quartz measurements exceeded 97 [mu]g/m\3\.
Example 2: Suppose valid verification samples were taken on four
or more shifts. The district manager would approve the operator's
plan parameters as proposed if no measurement taken over those four
or more shifts exceeded 2.0 mg/m\3\ of coal mine dust or 100 [mu]g/
m\3\ of quartz dust.
The district manager may revoke approval of the dust control
provisions if either MSHA samples or operator samples collected in
accordance with proposed Sec. 70.215 indicate that miners are being
overexposed to respirable coal mine dust.
Section 70.208 Follow-up Action When Either Verification Limit Is
Exceeded
This proposed section would require the operator to take certain
actions when a verification sample exceeds either the respirable coal
mine dust or quartz verification limit. The operator

[[Page 10817]]

would be required to stop verification sampling, provide approved
respiratory equipment, identify the cause of the high dust
concentration, and take corrective action to prevent miners from being
overexposed on subsequent shifts.
When the operator receives notification from MSHA that a
verification sample exceeded either verification limit, the operator
must stop sampling and immediately make approved respiratory equipment
available to affected miners in accordance with Sec. 70.300. The use
of respiratory equipment should be encouraged until the operator
determines the cause of the overexposure and takes corrective measures.
If deficiencies are identified in the operator's dust control program,
appropriate corrections must be made under proposed paragraph (b) to
lower dust concentrations in the work environment of the affected
occupation or location to a level no greater than the applicable
verification limits.
MSHA recognizes that, given the rigorous nature of the verification
test conditions, such as requiring higher production levels to be
maintained and the application of stringent approval criteria, some
failures will occur. If some attempts prove to be less than successful,
it would not necessarily be due to the lack of good faith effort on the
part of the operator, but could be due to the inability to predict
accurately the effectiveness of particular dust control parameters
under the proposed test conditions. For example, assume the VPL
proposed is significantly higher than that which has been recorded
during previous sampling inspections. In this instance, it would be
difficult to predict in advance that the proposed dust control
parameters would be effective unless the VPL was more representative of
the previous production levels. Therefore, MSHA is proposing not to
cite the operator when samples exceed the verification limits. However,
an operator would be cited under proposed paragraph (b) of this section
for failure to take action required to address the cause of the
excessive dust levels once notified of the results of verification
sampling. This is consistent with the Dust Advisory Committee's
recommendation that:

MSHA should not issue citations for violation of the applicable
dust standard based on operator verification sampling. Operator
inaction to protect miners where dust values are in excess of the
PEL should be citable by MSHA.''

The operator would also be required under proposed paragraph (c) to
document the corrective actions taken and submit this information to
the district manager within five days of receiving MSHA notification
that one or both of the verification limits were exceeded. The
documentation must describe the specific corrective measures taken and
the manner that these measures would be used to prevent overexposures
on subsequent shifts, including the proposed changes in dust control
parameters. The operator would be encouraged to seek technical
assistance from the district manager to help in determining what
additional measures are reasonably likely to help in meeting the
verification limits.
The district manager would notify the operator and the
representative of miners if the proposed revisions to the plan are
provisionally approved and whether the operator should either resume or
initiate verification sampling in accordance with Sec. 70.206. The
district manager may require the operator to make additional changes to
the plan parameters based on the results of verification sampling
before the operator begins the verification sampling process over
again. If no additional changes are required by the district manager,
the operator would be instructed to resume the verification process by
continuing the sampling from the point at which it was stopped.
The district manager would determine whether the operator should
either resume verification sampling or start plan verification anew on
a case-by-case basis. MSHA would not necessarily require the operator
to revise the plan parameters nor require the verification process to
start over again because a valid sample exceeded the verification limit
by a small amount, such as 0.05 mg/m\3\, unless the district manager no
longer felt confident in the ability of the plan parameters to
effectively control respirable dust under the proposed operating
conditions. The decision to resume sampling to verify the adequacy of
the current plan parameters or start over again with totally revised
plan parameters would be based on the information the operator provides
regarding the cause of any excessive dust concentration measurements
and the steps taken to prevent similar occurrences in the future. For
example, suppose the concentration measurements are excessive due to a
deviation in the operator's established operating procedures. It should
be possible for the operator to prevent this from occurring in the
future without requiring changes in the dust control parameters. If the
district manager finds this to be the case, and concurs with the
operator's proposed action to prevent similar occurrences, the operator
would be directed to resume verification sampling. However, if the plan
parameters are found to be inadequate for the proposed operating
conditions and the operator was notified to upgrade the parameters, the
operator would be instructed to start the verification process over
again.
Section 70.209 Use of Supplementary Control Measures; Types and
Conditions for Use; Request for Approval
This proposed section would require the operator to take certain
actions when verification samples exceed either verification limit
after the operator implemented all feasible engineering or
environmental controls. It would permit an operator to use approved
powered air-purifying respirators (PAPRs), administrative controls, or
a combination of both, after MSHA has determined that further reduction
of dust levels cannot be reasonably achieved using accepted engineering
controls. The decision-making process for determining whether feasible
engineering controls should be augmented by supplementary controls
(personal protective equipment and/or work practice controls) to
maintain the personal work environment of the affected miners at a safe
exposure level will consider the various factors involved in each
specific situation. Some of the factors to be taken into account
include: (1) The severity and magnitude of the exposure; (2) number of
affected miners, their job location and assignment; (3) types and
location of dust-generation sources; (4) range of effectiveness and
reliability of the implemented engineering controls; (5) availability,
suitability, reliability, and cost of other feasible engineering
controls; (6) operational conditions such as the method of mining,
mining height, etc.; (7) compliance history; (8) effectiveness and
reliability of supplementary control measures; (9) concerns of
individual miners and their representatives; and (10) ability to
measure and ensure the adequacy of exposure control.
Section 202(h) of the Mine Act does not prohibit the use of PAPRs
and administrative controls under the specific circumstances set forth
in the proposed rule. These measures would be used only as
supplementary controls and not as a substitute or replacement for
engineering control measures in the active workings. The use of these
supplementary control measures under the conditions of use set forth in
the proposed rule will enhance the level of health protection for
miners by preventing overexposures on all shifts.

[[Page 10818]]

The combination of engineering and supplementary controls will provide
reliable and effective exposure control when used in accordance with
the approved plan provisions.
Consistent with the Mine Act and the Dust Advisory Committee's
recommendation, engineering controls continue to be recognized as the
primary means to control exposure to respirable dust under this
proposed rule. Therefore, if verification samples for a MMU continue to
exceed either verification limit after implementing all feasible
engineering controls, including such measures as required by the
district manager, the operator must continue to use these control
measures to reduce the concentration of respirable dust as low as
possible.
MSHA believes that it is feasible to control respirable dust to an
acceptable level as required by Sec. 75.370(a)(1) at most non-longwall
operations using available engineering controls. Currently, over 90
percent of the approximately 720 continuous miner operations employ
extended cut techniques and, therefore, are being operated remotely. As
a result, the continuous miner operator, the occupation normally
identified as the DO, is no longer required to work near the face area
where material is being extracted and respirable dust generated.
Likewise, roof bolting machines, a major generator of respirable quartz
dust on continuous miner MMUs, are now required to be equipped with
suitable drill dust controls. Under Sec. 72.630 of this title, drill
dust must be controlled by either permissible dust collectors, by
water, water with a wetting agent, by ventilation, or by any other
method approved by MSHA. However, the Agency also recognizes that some
non-longwall MMUs continue to have difficulty maintaining consistent
compliance with reduced standards even at production levels that are
significantly lower than the proposed VPL because of the high quartz
content of the adjacent roof rock, which is drilled to install roof
bolts, or of the coal seam being mined.
With regard to mining operations employing the longwall mining
method, MSHA recognizes that technological advances have boosted
longwall production to record levels. According to MSHA data, the
average production reported by operators during bimonthly sampling of
longwall MMUs has increased over 6 fold between 1980 and 2002, from 890
to 5500 tons/shift. Unfortunately, as discussed in section III.D. of
the preamble, dust control technology has not kept pace, rendering
available, acceptable controls less effective, which increases the
miner's risk of being overexposed on any given shift. Given the state
of longwall dust control technology, the engineering controls currently
available may not be effective in achieving and maintaining continuous
compliance at certain locations along the longwall face such as
downwind of the longwall operator (occupation code--044) at some high-
production longwall MMUs. If the operator believes that all feasible
engineering controls have been installed, maintained, and operated as
specified in the ventilation plan, the operator may submit a written
request to MSHA's Administrator for Coal Mine Safety and Health, asking
for authorization to augment the implemented engineering controls with
supplementary controls to maintain the personal work environment of the
affected miners at a safe exposure level and to achieve compliance with
the verification limits and Sec. Sec. 70.100 and 70.101. If such a
request is made, a copy must be provided to the representative of
miners and posted on the mine bulletin board in accordance with
proposed Sec. 70.217(b)(3) at the time it is submitted to MSHA.
When the Administrator receives such a request, guidance would be
immediately solicited from a panel of experts specifically established
to address such matters. Members of this panel would have extensive
knowledge in respirable dust control and would represent the following
organizations within MSHA: Technical Support, Division of Health, the
MSHA District having jurisdiction over the mine making the request, and
another MSHA District. In some cases, MSHA may solicit advice from
NIOSH, an Agency with significant experience in dust control. As part
of their deliberations and on a case-by-case basis, the expert panel
may visit the mine to observe various controls in operation. This panel
will also consider all comments MSHA receives from the representative
of miners, as well as individual miners, and provide copies of these
comments to the operator upon request. Any recommendations reached by
this panel would be based on the (1) review of all the facts gathered,
(2) consideration of the various factors involved in each specific
situation as outlined above, (3) their combined practical and technical
experience in dust control, and (4) sound engineering judgement.
Recognizing the urgency of such a request, the Administrator would
either approve or deny the operator's request within 30 calendar days
or as soon as practical after receiving the request. If approval is
denied, the operator will be notified in writing of the specific
reasons for disapproval. If approval is granted, the operator would be
permitted to use either PAPRs approved by NIOSH under 42 CFR 84 and by
MSHA under part 18 of this title, administrative controls, or a
combination of both, as supplementary controls to protect those miners
assigned to occupations that continue to exceed either verification
limit, provided the operator meets the conditions specified in
Sec. Sec. 70.210 and 70.211 or Sec. Sec. 70.213 and 70.214 of this
part.
If the affected occupation involves the 060 occupation, the
operator would also be informed that the DO would be changed from the
060 to the 044 occupation, or another occupation designated by the
district manager depending on how the particular longwall MMU is
ventilated. While it may be difficult to lower the dust levels to the
applicable dust standard in the environment of some miners working on
the longwall face under certain operating conditions, MSHA believes
that, using available engineering controls, an acceptable work
environment can be provided for the tailgate-side longwall operator
(Occupation code--044) and other miners on a continuing basis.
Therefore, unless demonstrated otherwise through verification sampling,
the operator would be required to maintain the environment of the new
044 DO at or below the verification limits or below the applicable dust
standard using engineering controls. This should have a significant
effect on the quality of the mine atmosphere downwind of the 044 DO
where miners, wearing PAPRs or under administrative controls, are
required to work.
Under the proposed rule, the operator would be permitted to
continue to use supplementary controls to reduce dust exposure of
individual miners assigned to specific occupations until such time when
other feasible engineering controls become available and are
implemented or until the district manager revokes the operator's
approval to use supplementary controls for failure to comply with the
requirements of proposed Sec. 70.211(b) or Sec. 70.214(b).
As discussed above, MSHA will continue to require that all feasible
engineering controls be installed. While the proposed rule provides for
expanded use of supplementary controls, such control measures should
only be used as an interim method of protection since their
effectiveness remains secondary to that of engineering controls.

[[Page 10819]]

Section 70.210 Through 70.212

Use of Powered Air-Purifying Respirators (PAPRs)

These sections would establish the requirements for using PAPRs as
a supplementary control to maintain the personal work environment of
the affected miners at a safe exposure level when MSHA has determined
that further reduction in respirable dust concentrations cannot be
achieved using all feasible engineering or environmental controls or
under special circumstances.
Section 70.210 Powered Air-Purifying Respirators (PAPRs); Requirements
for Approval
If the operator chooses to use PAPRs as a supplementary control
measure, the operator must submit a revision to the ventilation plan to
the district manager within five days of receipt of MSHA's written
approval in accordance with proposed Sec. 70.209(b). The proposed
revision would specify the feasible engineering controls that are
capable of (1) reducing the concentration of respirable dust as low as
achievable in every occupational environment where a PAPR is required
to be worn, and (2) maintaining other occupational environments in the
MMU at or below the verification limits. The proposed revision must
reflect the engineering controls that were in use at the time that the
determination was made by MSHA to permit the use of supplementary
controls.
In addition to specifying all feasible engineering controls to be
used, proposed paragraph (a)(2) would require the operator to develop a
written PAPR protection program which meets the requirements of Sec.
72.710 and incorporates the following information: (1) The protection
factor as determined in accordance with proposed Sec. 70.2 that would
be assigned to the affected MMU; and (2) the specific occupation(s),
work locations or tasks where PAPRs must be worn by the affected
miners. A model PAPR protection program to guide the operator in
developing a mine-specific program that complies with the requirements
of this section is described in Appendix B. The district manager may
require the operator to modify the PAPR protection program before
granting provisional approval of the proposed plan revision.
Also, consistent with the NIOSH Criteria Document and section
101(a)(7) of the Mine Act, proposed paragraph (a)(3) would require the
operator to post warning signs with the statement ``RESPIRATORY
PROTECTION REQUIRED IN THIS AREA'' in locations where PAPRs must be
worn. Since the presence of excessive dust concentrations is not
readily discernible, MSHA believes that the use of warning signs is
necessary to protect miners. The posting of warning signs is an
appropriate vehicle to inform or remind miners, regardless of their
familiarity with the workplace environment, that they are entering a
high dust area where the use of PAPRs is mandatory. The Agency
recognizes that Sec. 75.370(e) requires that operators instruct
persons affected by a revision to the ventilation plan prior to
implementation. Section 75.370(f)(3) also requires approved revisions
to be posted on the mine bulletin board for the period that the plan is
in effect. MSHA is soliciting comments on whether it should require the
posting of warning signs when PAPRs must be worn, or should it be
optional and left to the discretion of the operator.
Proposed paragraph (b) requires the operator to verify, in
accordance with proposed Sec. 70.206(b) through (e), the adequacy of
the revised plan parameters, incorporating the use of PAPRs, within 30
calendar days of obtaining provisional approval from the district
manager. Accordingly, the operator would be required to collect
verification samples in the environment of (1) the occupation(s) where
PAPRs must be worn by miners assigned to work in those job positions,
(2) the DO, and/or (3) other occupation(s) that may be designated by
the district manager.
Section 70.211 Powered Air-Purifying Respirators (PAPRs); Approval and
Conditions for Continued Use; Revocation of Approval
This proposed section establishes the criteria that the district
manager would use to determine whether the operator's proposed plan
revision incorporating the use of PAPRs should be approved. As
previously discussed under proposed Sec. 70.207, approval of the
proposed revision would depend on the results of verification sampling
and the operating conditions in effect for each sample.
The district manager would approve the operator's revised plan
when: (1) The amount of material produced is at or above the VPL, the
parameters and other measures in place during verification sampling do
not exceed 115% of the quantities specified in the plan, and no
equivalent concentration measurement exceeds the critical values listed
in Table 70-1 that correspond to the number of shifts sampled; and (2)
the revision incorporates the dust control parameters used during
verification sampling.
To account for the expected workplace level of respiratory
protection provided the wearer of the PAPR, the equivalent
concentration measurement must be adjusted further in accordance with
Sec. 70.2. This requires the equivalent concentration to be divided by
the protection factor (PF) specified in the PAPR protection program for
the particular mechanized mining unit (MMU). The PF represents the
minimum reduction in dust concentration that a respirator would be
expected to provide. In the absence of a direct measure of the dust
concentration inside the PAPR (in the miner's personal work
environment) while under the conditions of the workplace, the adjusted
equivalent concentration represents a surrogate measure of the
respirable dust concentration inside the PAPR facepiece to which the
wearer is exposed. Since the PFs assigned to MMUs under this proposed
rule incorporate a margin of safety, the resulting equivalent
concentration measurement represents a conservative estimate of the
dust concentration in the miner's breathing zone.
For example, assume that a MMU, which was assigned a PF = 3, was
sampled one shift and the concentration measurement for the sampled
occupation under a PAPR protection program is 3.54 mg/m3 for respirable
coal mine dust and 174 [mu]g/m3 for respirable quartz dust.
Under the definition of ``equivalent concentration,'' these
measurements are divided by 3, which yields an equivalent concentration
of 1.18 mg/m3 [3.54 mg/m3/3]
for respirable coal
mine dust and 58 [mu]g/m3 [174 [mu]g/m3/3]
for
respirable quartz dust to which the miner assigned to that occupation
is exposed. If no other valid equivalent concentration measurement
obtained on one shift exceeds 1.71 mg/m3 or 87 [mu]g/
m3 according to Table 70-1, the district manager would
approve the revised plan incorporating the use of PAPRs.
MSHA believes that this strategy provides far more health
protection to miners than is available under current regulations, which
only requires operators to make available approved respiratory
equipment to miners when exposed to excessive dust concentrations.
There is no requirement that miners actually wear the respirator when
issued. Under the proposed rule, not only must PAPRs be worn at all
times but must also conform to specific requirements consistent with an
acceptable respiratory protection program.
Proposed paragraph (b) establishes the requirements for the
continued use of

[[Page 10820]]

PAPRs as a supplementary control. To continue to use PAPRs and operate
under the same conditions that were in effect during verification
sampling, the operator would be required to comply with the approved
revised plan parameters on each production shift, in particular, the
provisions of the PAPR protection plan. MSHA believes that the
effectiveness of a PAPR is dependent upon proper training and continued
maintenance, which are critical elements of an acceptable PAPR
protection program. Necessary maintenance includes examining the PAPR
for defects prior to use, charging the batteries properly, and
appropriate replacement of parts including, but not limited to, the
filter elements, visors, batteries, blowers, and face seals.
In addition, the operator would be required to ensure that no
occupation where PAPRs must be worn by the miners required to work in
those particular job positions, the DO and other occupations in the
affected MMU, are exposed to an equivalent concentration of respirable
coal mine dust that exceeds the applicable dust standard.
Finally, since the use of PAPRs as a supplementary control is not
intended to be permanent and their use is being permitted until
feasible engineering controls become available, proposed paragraph
(b)(3) would require the operator to continue to seek and implement
additional improvements when they become available. To ensure
conformance with these requirements, MSHA will review the operator's
approved plan parameters, including the operator's compliance history,
every 6 months to determine if the operator is using all feasible
engineering controls and if the plan parameters continue to be suitable
to the current operating conditions. If MSHA determines that other
acceptable controls have become available which would be suitable to
the particular MMU, MSHA would notify the operator and the
representative of miners of its findings.
MSHA approval to use PAPRs as a supplementary control may be
revoked if the operator failed to meet the requirements of proposed
paragraphs (b)(1), (2) and (3) of this section. If the operator's plan
provisions are revoked, the operator would be required to submit a
revision to the plan parameters for the affected MMU that would include
a VPL at which compliance with the applicable dust standard would be
achieved.
Section 70.212 Powered Air-Purifying Respirators (PAPRs); Conditions
for Use under Special Circumstances
Section 70.212 sets forth the special circumstances under which an
operator would be permitted to use, on an intermittent basis, PAPRs to
protect individual miners from excessive dust concentrations and for
compliance purposes. Such use is only permitted after the plan
parameters have been verified without the use of supplementary controls
and additional remedial actions will not be practical or feasible
because of the intermittent nature and duration of a special condition.
Because of the dynamic nature of mining, it is not uncommon for a
MMU to occasionally encounter operating conditions which directly
impact the ability of the previously verified plan parameters to
effectively control respirable dust. This is especially true when the
particular condition encountered varies from the operating conditions
under which the adequacy of the plan parameters was originally
demonstrated. It is not because an operator may have failed to
adequately take such conditions into account when designing the plan
parameters, but because the proposed verification process requires the
adequacy of the plan parameters to be demonstrated only under typical
operating conditions. For example, encountering a significant rock band
in the coal seam containing a high percentage of quartz would be
considered a unusual circumstance since its occurrence is not routine.
While this may have occurred in the past and may occur again, the
operator cannot predict with certainty when this condition might
reoccur. Because of the unpredictable nature of such an occurrence, it
may not be practical to factor this into the design of the plan
parameters.
While the Mine Act and implementing regulations intend for the
working environment to be free of excessive dust at all times, MSHA
recognizes that it may not be practical or feasible to implement
additional engineering controls whenever these unusual conditions
occur, especially when they occur intermittently for a brief period of
time. Even if the operator makes a concerted effort to implement
additional engineering controls, it may require an extended period of
time to complete and verify the effectiveness of the adjustments,
during which time some miners may not be adequately protected from
excessive dust.
Before MSHA will grant authorization to use PAPRs for compliance
purposes, the operator must show that the particular condition or
situation is atypical, occurs only occasionally, and is beyond the
control of the operator. Increased production levels which exceed the
VPL and any other situations which are more routine and therefore under
the operator's control would not be characterized as unusual
conditions. However, because of the difficulty in maintaining proper
ventilation along a longwall face, during start-up, MSHA will consider
and encourage the use of PAPRs at longwall MMUs until the first gob
fall. The types of evidence MSHA would consider when the unusual
condition encountered involves cutting rock occasionally, would include
information on quartz levels, the duration and frequency of reduced
standards, and/or on the reject rate for a particular MMU.
MSHA anticipates questions regarding what constitutes special
circumstances under this proposed section. It is not possible or
appropriate to set forth all circumstances which might be covered by
this proposed rule. Each request will be considered by the district
manager on a case-by-case basis. The district manager will rely on past
in-mine experience and the information provided by the operator in
determining whether the special circumstances under which the applicant
is seeking authority to use PAPRs, occurs intermittently and is the
best way to protect the affected miners during such periods. The Agency
specifically solicits comments on these issues, especially, with regard
to what other special circumstances in mining may necessitate the
immediate use of PAPRs.
Under proposed paragraph (a), an operator can file a written
request seeking MSHA approval to use PAPRs under special circumstances:
(1) When submitting a ventilation plan under Sec. 75.370 of this
title, (2) when required to verify a previously approved ventilation
plan that was revised in accordance with Sec. 75.370(f), or (3) after
the district manager approves the plan parameters based on the results
of operator verification samples. To the extent possible, the operator
must submit a written request prior to encountering special
circumstances to assure prompt review, and revision to the ventilation
plan. A copy of the request must be provided to the representative of
miners at the time of submittal and posted on the mine bulletin board
to alert the miners working in the affected MMU. The district manager
will consider all comments and, if requested, provide copies of these
comments to the operator.

[[Page 10821]]

In addition to showing that the particular circumstances
necessitating use of PAPRs occur occasionally and are beyond the
control of the operator, proposed paragraph (b) requires the operator
to revise the previously approved plan provisions to incorporate the
provisions proposed in Sec. 70.210(a)(1), (2) and (3).
Once approval is granted by the district manager, proposed
paragraph (c)(1) through (3) sets out the requirements for the use of
PAPRs. The operator will be required to notify, in writing or by
electronic means, the district manager and the representative of miners
within 24 hours of determining that current operating conditions
necessitate use of PAPRs. This would enable MSHA to follow-up with an
in-mine visit to verify the operating conditions under which PAPRs are
being used and whether the operator is in full compliance with the
letter of approval and with the provisions of proposed Sec.
70.211(b)(1) and (2). It is the responsibility of mine management to
ensure that PAPRs are worn for all required periods and to see that the
conditions stipulated in the plan, which are necessary to protect miner
health, are followed.
When PAPRs are used during MSHA compliance sampling, the
determination of compliance with the applicable dust standard will be
made in accordance with proposed Sec. 70.218(a). For occupations under
a PAPR protection program, compliance would be assumed if the
equivalent concentration measurement, as determined in accordance with
Sec. 70.2 and as discussed under Sec. 70.211, is less than the
citation threshold value (CTV) listed in Table 70-2 that corresponds to
the applicable dust standard in effect.
Unusual operating circumstances do not normally last for an
extended period of time. Therefore, use of PAPRs for compliance
purposes is limited to 30 consecutive days. The district manager may
revoke the operator's authority to use PAPRs under special
circumstances for failure to comply with this requirement. If the
operator exceeds this time period or if respirable dust samples taken
by either the operator or MSHA indicate miners are being overexposed,
the operator must revise and verify the adequacy of the proposed plan
parameters under the prevailing operating conditions. Comments are
specifically requested on this issue.
Permitting the use of PAPRs to supplement existing engineering
controls to protect individual miners under special circumstances as
proposed is consistent with the intent of the Mine Act and is in the
best interest for miner health.

Section 70.213 through 70.214

Use of Administrative Controls

These sections would establish the requirements for using
administrative controls as a supplementary control to maintain the
personal work environment of the affected miners at a safe exposure
level when MSHA has determined that further reduction in respirable
dust concentrations cannot be achieved using all feasible engineering
or environmental controls.
Section 70.213 Administrative Controls; Requirements for Approval
If the operator chooses to use administrative controls as a
supplementary control measure, this proposed section would require the
operator to submit a revision to the plan parameters to the district
manager within five days of receipt of MSHA's written approval in
accordance with proposed Sec. 70.209(b). The proposed revision would
specify the engineering controls that are capable of maintaining the
environment of any occupation under administrative controls and the DO
or another occupation designated by the district manager at or below
the verification limits.
In addition to specifying all feasible engineering controls to be
used, proposed paragraph (a)(2) would require the operator to include a
detailed description of each specific administrative control to be
implemented. Because the effectiveness of administrative controls is
based on adherence to strict time periods, work schedules, and or other
administrative controls, the revision must explain how the operator
would verify compliance with the prescribed administrative control. The
district manager may require the operator to modify the administrative
controls before granting provisional approval of the proposed plan
revision incorporating the use of such measures as a supplementary
control.
Proposed paragraph (b) would require the operator to verify, in
accordance with proposed Sec. 70.206(b) through (e), the adequacy of
the revised plan parameters incorporating the use of administrative
controls within 30 calendar days of obtaining provisional approval from
the district manager. Accordingly, respirable dust samples would be
collected in the environment of (1) The occupation(s) under
administrative controls, (2) the DO, and (3) other occupation(s) that
may be designated by the district manager.
Section 70.214 Administrative Controls; Approval and Conditions for
Continued Use; Revocation of Approval
This proposed section establishes the criteria that the district
manager would use to determine whether to approve the operator's
proposed revision to the plan parameters incorporating the use of
administrative controls as a supplementary control. As previously
discussed under proposed Sec. 70.207, approval of the proposed
revisions would depend on the results of verification sampling and the
operating conditions in effect during the time each sample is
collected. The district manager would approve the revisions if (1) no
valid equivalent concentration measurement exceeds the critical values
listed in Table 70-1 that correspond to the number of shifts sampled,
and (2) the revision incorporates the dust control parameters and
administrative controls that were in effect during verification
sampling. For the district manager to approve the revised plan
parameters for a MMU based on only one shift of sampling, no valid
concentration measurement can exceed 1.71 mg/m3 for
respirable coal mine dust or 87 [mu]g/m3 for respirable
quartz.
Proposed paragraph (b) establishes the requirements for the
continued use of administrative controls as a supplementary control. To
continue to use administrative controls and operate under the same
conditions that were in effect during verification sampling, the
operator would be required to comply with the approved revised plan on
each production shift, and particularly with the prescribed
administrative controls. Since miners must actively comply for
administrative controls to be effective in reducing dust exposure, the
operator must train the affected miners to follow prescribed
administrative controls and require their cooperation for them to be
effective.
In addition, the operator would be required to ensure that no
occupation is exposed to concentrations of respirable dust that exceed
the applicable dust standard. MSHA will evaluate the effectiveness of
the dust control parameters and the operator's performance in complying
with all provisions of the approved plan.
Since the use of administrative controls as a supplementary control
is not intended to be permanent and their use could be permitted only
until feasible engineering controls become available, proposed
paragraph (b)(3) would require the operator to continue to seek and
implement additional improvements when they become available. To ensure
compliance with

[[Page 10822]]

these requirements, MSHA will review the operator's approved plan
parameters, including the operator's compliance history, every 6 months
to determine if the operator is using all feasible engineering controls
and if the plan parameters continue to be suitable to the current
operating conditions. If the district manager determines that other
controls have become available which would be suitable to the
particular MMU, the district manager would notify the operator and the
representative of miners of such findings.
MSHA approval to use administrative controls as a supplementary
control may be revoked if the operator fails to meet the requirements
of proposed paragraphs (b)(1), (2) and (3) of this section. If the
operator's plan provisions are revoked, the operator would be required
to submit a revision to the plan parameters for the affected MMU that
would include a VPL at which compliance with the applicable dust
standard would be achieved.
Section 70.215 Quarterly Evaluation of Approved Plan Parameters
Because conditions in an underground mine are constantly changing,
the effectiveness of previously approved dust control parameters for a
particular MMU may change. Consequently, plan parameters may later be
inadequate in preventing overexposures on individual shifts and
adjustments may be necessary to continually comply with the applicable
dust standard. Therefore, in addition to ensuring compliance with the
plan parameters under existing Sec. 75.362(a)(2), the operator also
has the responsibility to ensure that the plan parameters continue to
be effective in controlling respirable dust as required by Sec.
75.370(a), and to upgrade the plan parameters when deemed appropriate.
This is necessary to prevent overexposures on individual shifts and, in
the long run, the occurrence of coal workers' pneumoconiosis and
silicosis in miners.
The importance of assessing the continued adequacy of plan
parameters and the role of operators in that process was recognized by
the Dust Advisory Committee:

MSHA should develop specific performance requirements for
operator sampling relative to documentation of continued adequacy of
the plan parameters. (MSHA, 1996)

To accomplish this, proposed Sec. 70.215, would require an operator to
implement a 3-month interval (quarterly) sampling program at MMUs where
the continued adequacy of the approved plan parameters is in question
and miners are at risk of being overexposed as indicated by MSHA-
collected respirable dust samples used to audit operator compliance
with applicable standards. Therefore, rather than require all operators
to sample quarterly, the quarterly monitoring requirement is triggered
when airborne dust concentrations, as measured under MSHA's sampling
program, exceed the applicable dust standard. This risk-based approach
is more performance-oriented and minimizes unnecessary sampling. The
purpose of operator quarterly sampling would be to monitor the adequacy
and suitability of the approved dust control parameters under
prevailing conditions.
Since operators have the responsibility for providing a workplace
that is free of excessive dust, all operators are encouraged to design
and implement a monitoring program suitable to their specific mine to
ensure that the applicable dust standard is not exceeded. MSHA believes
that operators have a number of incentives to monitor the quality of
the air in each MMU on a regular basis to ensure they can (1) assess
the effectiveness of their dust control parameters or need for
adjustments to continually comply with the applicable dust standard and
(2) avoid citations and penalties during MSHA sampling inspections.
Under the proposed rule, the sampling process would begin with the
determination by the district manager of the particular MMUs which
would be regularly sampled at the mine. In determining which MMUs at a
mine should be sampled periodically, the district manager would, under
the proposed rule, first review the results of respirable dust samples
after each sampling inspection of a MMU. If a valid equivalent
concentration measurement for any occupation exceeds the applicable
dust standard by at least 0.1 mg/m3, quarterly sampling
would be required.
The proposal also provides for the suspension of quarterly sampling
when all respirable dust samples submitted by the operator in
accordance with this section, together with samples taken by MSHA
during at least four consecutive quarters, demonstrated continuing
compliance with the applicable dust standard. To ensure that the proper
MMUs are exempted from quarterly sampling when miners are no longer at
risk of being overexposed, each operator- and MSHA-collected sample
must be at or below the applicable dust standard.
Under paragraph (a), the operator would begin quarterly sampling
during the next full 3-month period following MSHA notification of the
designation of a MMU for sampling. The proposed rule provides a
schedule for quarterly sampling. For example, during the period January
1 through March 31, operators would be required to sample each
designated MMU in producing status. When there is a change in the
operational status of the particular MMU that affects operator
monitoring, proposed Sec. 70.219(a) requires the operator to report
such status change to the district manager. Suppose, for example, a MMU
has been in nonproducing status for 75 calendar days during the current
quarterly sampling period, the operator would still be expected to
satisfy the sampling requirements because there would be sufficient
time remaining in the current period to sample the required one shift.
Failure to submit the required number of valid respirable dust samples
within a given quarterly period would constitute a violation of this
provision. Operators would be encouraged to conduct the required
sampling at the beginning of each quarterly sampling period. All
samples submitted by the operator would be processed by MSHA.
To provide consistency and uniformity among operator-collected
samples for purposes of monitoring plan effectiveness, the proposed
monitoring program would require the operator to sample selected
occupations in accordance with proposed Sec. 70.206(b), (d) and (e)
for one shift. Also, since the objective of quarterly sampling is to
evaluate the continued adequacy of the approved plan parameters under
the prevailing conditions, each sample must be collected under the
operating conditions specified in proposed Sec. 70.201(e) which
specifies that the amount of material produced must equal or exceed the
VPL, unless sampling in accordance with proposed Sec. 70.220(d). Only
the dust control parameters listed in the approved ventilation plan, at
levels not exceeding 115 percent of the specified quantities, are to be
in place during sampling. As in verification sampling, if the operator
fails to attain the VPL on the shift sampled, all samples for that
shift will be voided by MSHA. However, if any sample, regardless of
production, is found to exceed the applicable dust standard by any
amount, it would be used by MSHA to determine the equivalent
concentration for that occupation. Also, if the MMU being sampled is
authorized to use PAPRs under special circumstances (proposed

[[Page 10823]]

Sec. 70.212) and those circumstances prevent the MMU from achieving
the VPL, all samples for that shift would be used to determine the
equivalent concentration for the affected occupations.
Since these samples are for evaluation purposes, the operator would
not be required to use a control filter in accordance with proposed
Sec. 70.201(d). The district manager may require the operator to
reverify the adequacy of the plan parameters for a particular MMU based
on these results and other compliance data if the data indicates that
the parameters are no longer effective in maintaining compliance. If,
on the other hand, the operator or MSHA is prevented from confirming
the suitability of the approved dust control parameters to the current
operating conditions because of repeated submission of invalid samples,
reverification of the plan parameters would be required by the district
manager.
Under proposed paragraph (c), when a valid equivalent concentration
measurement exceeds the applicable dust standard by at least 0.1 mg/
m3, the operator must make approved respirators available to
the affected miners in accordance with Sec. 70.300, unless the
occupations are under a PAPR protection program. The operator must
determine the cause and correct the identified deficiency to reduce the
concentration of respirable dust to within the applicable dust standard
and avoid future overexposures. This requires the operator to review
the dust control parameters and to determine what factors may have
contributed to the overexposures. As discussed elsewhere in the
preamble, if the sampled occupation is under an approved PAPR program,
each valid concentration measurement would be adjusted in accordance
with Sec. 70.2. The equivalent concentration would be compared to the
applicable dust standard. For example, assume the reported equivalent
concentration of a sample is 2.56 mg/m3 and the MMU is
assigned a protection factor of 4. Then the equivalent concentration
measurement, adjusted for the use of a PAPR, is 0.64 mg/m3
[2.56 mg/m3/4 = 0.64 mg/m3].
Additionally, since the presence of excessive dust poses a
significant health hazard to miners, proposed paragraph (c)(3) would
require excessive dust conditions to be recorded in the same manner,
but with some exceptions, as the hazards recorded under Sec. 75.363(b)
of this title. The record would include: (1) The date the sample was
taken; (2) the location in mine and the occupation where the excessive
dust condition occurred; (3) the equivalent concentration measurement
of each sample collected; (4) the specific action taken to reduce the
concentration of respirable dust to within the applicable dust
standard. MSHA will be providing the operator with a respirable dust
sample data report that contains much of the same information required
under this paragraph. In order to reduce the operator's paperwork
burden, the MSHA respirable dust sample data report could serve as this
record, provided the operator includes the specific corrective action
taken, certifies its accuracy and completeness, and retains the record
for at least 12 months at a surface location as required by Sec.
75.363(c) and (d). The dust record does not need to be countersigned,
provided that the mine official certifying the record is aware of the
monitoring results and directed or supervised the implementation of the
corrective actions. These records provide notice to mine management
that excessive dust conditions are recurring, the locations in the
mine, and the effectiveness of the various corrective actions. For
example, if an excessive dust condition occurs repeatedly and the same
corrective action is taken, the corrective action may not be effective.
Posting the record on the mine bulletin board will alert all affected
miners of the particular dust hazards to which they have been exposed
and the specific corrective action(s) being taken by the operator to
reduce the dust concentration in the work environment to within the
applicable dust standard to prevent similar occurrences in the future.
The requirement to inform miners is necessary to assure miners that the
operator is making efforts to provide a safe and healthful work
environment. This is a new requirement and the Agency solicits comments
on the proposed approach to require that excessive dust conditions and
the corrective action taken be recorded, certified and retained as
currently required for other hazards under Sec. 75.363.
If the results of quarterly sampling indicate that the approved
plan parameters are no longer adequate to control respirable dust under
the prevailing operating conditions, the operator must revise the plan
parameters and submit the proposed revision to the district manager for
review and approval. For example, if any valid equivalent concentration
measurement meets or exceeds the citation threshold value (CTV) listed
in Table 70-2 that corresponds to the applicable dust standard in
effect, the plan parameters would need to be upgraded and verified
under current conditions. Because the results indicate that miners are
being overexposed, MSHA will conduct follow-up sampling whenever an
operator's quarterly sample meets or exceeds the CTV and the plan
parameters are not revised by the operator.
Under proposed paragraph (e), the results of operator quarterly
sampling will not be used to determine compliance with the applicable
dust standard. If any sample result exceeds the CTV, the operator would
not be cited for a violation as would be the case if MSHA sampled. The
operator would, however, be required to take corrective action. Failure
to take such action to reduce the respirable dust concentration within
the applicable dust standard would be citable under this section.
MSHA requests comments on the appropriateness of the criteria used
to trigger operator monitoring of plan effectiveness and proposed
frequency, especially with regard to the 3-month interval, that
maximize the protection of miners' health. Also, whether a more
performance-oriented requirement should be imposed on operators,
requiring them to monitor at the frequency needed to assure, with
reasonable accuracy, the continued adequacy of the approved plan
parameters in preventing overexposures on individual shifts.
Section 70.216 Respirable Dust Samples; Transmission by Operator
MSHA is proposing no substantive changes to existing Sec. 70.210,
except for removing reference to Sec. 70.202 (Certified person;
sampling) from existing paragraph (c) to eliminate repetition since
revised Sec. 70.201 specifies that all sampling required under this
part must be conducted by a certified person, and redesignating it as
Sec. 70.216. Existing paragraph Sec. 70.210(e) would be removed since
all samples submitted by the operator under this part would be
processed by MSHA. The proposed rule, like the existing rule, requires
all respirable dust samples collected in accordance with this part to
be transmitted to MSHA within 24 hours after the end of the sampling
shift in containers provided by the manufacturer of the filter
cassette. The need to verify the adequacy of the dust control
parameters for a particular MMU in the shortest possible time requires
that samples be promptly transmitted to MSHA for analysis.
Each sample transmitted by the operator must be accompanied by a

[[Page 10824]]

properly completed dust data card. All dust data cards submitted must
be signed by a person certified to collect samples and must include
that person's certification number. By signing the card, that person
certifies that the sample was collected in accordance with the
requirements of this part.
To maintain program integrity, all samples collected by an operator
would be considered by this proposed rule to fulfill the sampling
requirements of this part. Samples to be used by operators for other
purposes would have to be identified in writing or by electronic mail
to the district manager, by each filter cassette identification number,
prior to their intended use.
Operators that use PCDMs under proposed Sec. 70.220 are exempt
from the requirements of this section, except when transmitting samples
for quartz analysis required by proposed Sec. 70.220(c).

Information To Be Posted on the Mine Bulletin Board

Section 70.217 Respirable Dust Samples; Report to Operator; and Posting
Under the proposed rule, existing Sec. 70.210 would be revised and
redesignated as Sec. 70.217. It specifies the type of sampling and
other related information the operator would post on the mine bulletin
board. The proposed posting requirements are intended to serve in the
best interest of miners without being overly burdensome to operators.
The continuation of posting requirements is intended to promote miner
awareness of process of verifying the adequacy of the dust control
parameters for each MMU specified in the mine ventilation plan and of
the respirable dust conditions in the mine. This is consistent with the
statutory intent that miners play a role in preventing unhealthy
conditions and practices where they work. This approach is consistent
with the recommendations of the Dust Advisory Committee regarding miner
participation in the sampling process.
Paragraph (a)(1) through (6) of the proposed rule retains the
existing requirement regarding the types of data MSHA would report on
samples submitted by the operator. The results of all MSHA sampling
would be reported to the operator. The data report would include the
identification of the MMU or DA in the mine where each sample was
collected; the equivalent concentration of respirable dust for each
valid sample; the occupation code, where applicable; and the reason for
voiding any sample. In addition to providing data on individual
samples, the Agency would also furnish information on the dust control
parameters that were in effect during MSHA sampling by providing a copy
of completed MSHA Form 2000-86 (Revised), Respirable Dust Sampling and
Monitoring Data.
Paragraph (b)(1) of the proposed rule retains the existing
requirement that the operator post on the mine bulletin board the
respirable dust sample data report provided by MSHA. The operator must
post the end-of-shift exposure information if using a PCDM in
accordance with Sec. 70.220. The results of all respirable dust
samples collected by federal mine personnel that MSHA would provide
under revised paragraph (a) must be posted. Additionally, the operator
would post a copy of MSHA Form 2000-86 for each MMU sampled by federal
mine personnel. This requirement would ensure that miners and their
representative(s) are provided information concerning the quality of
the mine air where they work and the dust control parameters under
which MSHA sampling was conducted.
MSHA recognizes the importance of input from the miners and their
representatives in the plan approval process. To assure miners
understand the verification process, proposed paragraph (b)(3) would
require the posting of all written notifications received from the
district manager pertaining to verifying the adequacy of the dust
control parameters under this part. This includes all correspondence
submitted in accordance with proposed Sec. Sec. 70.209 and 70.212. The
district manager would be available to discuss with the representative
of miners as well as individual miners all aspects of the plan
parameter verification process.
Proposed paragraph (c) specifies the length of time the information
provided under paragraph (b) would be posted on the mine bulletin
board. Results of operator verification sampling and all written
notifications received from the district manager that pertain to the
plan verification procedures could be removed immediately following
notification of approval of the plan parameters for a particular MMU.
Correspondence required under proposed Sec. 70.212(c)(1) regarding the
occurrence of special circumstances requiring the use of PAPRs must
remain posted for the period of time that PAPRs are in use. The
respirable dust sample data report provided by MSHA on operator
sampling in accordance with proposed Sec. 70.215 and MSHA sampling
results, including the information specified in proposed paragraph
(b)(2) of this section, must be posted for at least 31 calendar days
following receipt. If using a PCDM, the end-of-shift exposure data
along with the information specified in paragraph (b)(2) must be posted
for at least 7 calendar days following the end of the sampling shift.
Section 70.218 Violation of Respirable Dust Standard; Issuance of
Citation; Action Required by Operator; and Termination of Citation
Proposed Sec. 70.218 addresses the circumstances under which MSHA
would issue a citation for excessive dust and establishes the specific
actions that an operator would be required to take within the time for
abatement fixed in the notice. It also sets forth the conditions under
which MSHA would terminate such citations.
Under proposed paragraph (a), the operator would be cited for a
violation of either Sec. 70.100(a) and (b), or Sec. 70.101 when a
valid equivalent concentration measurement for any occupation sampled
by MSHA exceeds the citation threshold value (CTV) listed in Table 70-2
that corresponds to the applicable dust standard in effect. As
discussed in section III.A.4. of the preamble, these measurements will
be based on single-shift samples collected with approved sampling
devices that will be operated portal-to-portal. The devices will remain
operational, during the entire shift or for 8 hours, whichever time is
less, as has been the long-standing practice.
The CTVs and an explanation of how they were derived was originally
published in Federal Register notice of February 3, 1998 (63 FR 5687),
entitled ``Coal Mine Respirable Dust Standard Noncompliance
Determinations.'' As explained in that notice and in Appendix C of the
current notice of proposed rulemaking, each CTV was calculated so that
citations would be issued only when a single-shift measurement
demonstrates noncompliance at least at a 95 percent confidence level.
Under this proposed rule, MSHA would issue no more than one citation
based on the result of single shift samples from the same MMU, unless
separate citations are warranted for occupations exposed to different
dust-generating sources. The following examples illustrate how MSHA
would apply the CTVs to make noncompliance determinations. Suppose that
a measurement of 2.41 mg/m3 is obtained for the DO, and
measurements of 2.34, 1.54, 2.00, and 1.56 mg/m3, are
obtained for four other occupations exposed to the same dust-generating
source as the DO during a single shift on a MMU required to comply with
an applicable dust standard of 2.0 mg/m3. Because at

[[Page 10825]]

least one measurement exceeds the 2.33-mg/m3, CTV (the
citation value for a 2.0-mg/m3 standard), a citation would
be issued for exceeding the applicable dust standard on the shift
sampled. Even though two individual measurements (2.41 and 2.34 mg/
m3) exceeded the CTV, one of which is the DO, only one
citation would be issued. The DO would be identified in the narrative
of the citation as the affected working environment, because all
occupations were exposed to the same dust-generating source. Since MSHA
would assume responsibility for all compliance sampling under this
proposed rule, these five occupations would be resampled by federal
mine personnel during abatement sampling to verify that the condition
causing the excessive dust levels has been corrected if the district
manager concluded that a revised plan was not necessary.
Suppose that in the previous example the 2.34-mg/m3
measurement was obtained for a roof bolter, and the MMU was being
ventilated using a double-split ventilation system. This means that the
roof bolter, working on a separate split of air from that of the
continuous miner, is exposed to a different dust generating source than
the DO. Therefore, the roof bolter may not be adequately protected by
dust controls implemented for the DO. Consequently, two citations would
be issued. Since MSHA samples would be used, all dust control
parameters and mining activity would be documented on MSHA Form 2000-
86. This information would be reviewed by MSHA along with the sample
results to determine if the dust control parameters specified in the
approved ventilation plan would need to be upgraded.
MSHA believes that, because of the large ``margin of error''
separating each CTV from the corresponding applicable dust standard,
use of the CTV table would provide ample protection against erroneous
citations, a concern raised by previous commenters. This matter was
fully explored in the analysis published in Appendix C of the February
3, 1998 notice (63 FR 5703-5709). That analysis showed that for
exceptionally well-controlled environments, the probability that any
given citation is erroneous will be substantially less than 5 percent.
The analysis also showed that this probability is even smaller in
environments that are not well controlled. Therefore, any citation
issued under this proposed rule in accordance with the CTV table would
be much more likely the result of excessive dust concentration rather
than measurement error. With regard to the risk of erroneous failures
to cite, MSHA concluded that ``the probability of erroneously failing
to cite a case of noncompliance at a given sampling location is less
than 50 percent when the applicable dust standard is exceeded on a
significant proportion of shifts at that location'' (63 FR 5709).
Furthermore, noncompliance determinations based on the results of
single-shift samples would reduce the chances for failure to cite cases
of noncompliance. According to the inspector sampling inspections of
MMUs conducted between August and December 2001, only 14 MMUs were
found to be in violation of the applicable dust standard. These MMUs
were cited under the more recent enforcement policy of averaging
measurements taken over multiple shifts, compared to 260 MMUs that
would have been citable using single-shift measurements in combination
with the CTV table. This clearly demonstrates that the proposed
enforcement strategy would not compromise miners' health, instead it
would have identified 246 additional instances of overexposure.
Otherwise, these overexposures would continue to go undetected under
the current policy of measurement averaging.
MSHA has also carefully considered suggestions from previous
commenters that the Agency cite for noncompliance whenever any single-
shift measurement exceeded the applicable dust standard as this would
provide greater health protection to the miner. However, MSHA rejected
these suggestions because an enforcement action might not be sustained
at this level of confidence. The likelihood that a particular
measurement exceeds the applicable dust standard, but not the CTV, due
to measurement error, can actually exceed the likelihood that the
measurement exceeds the standard due to excessive dust concentration. A
thorough technical discussion of this issue is provided at 63 FR 5709-
5712 (Appendix D of the Federal Register notice cited above).
MSHA has concluded that using single-shift measurements for
noncompliance determinations in accordance with the CTV table neither
increases nor decreases the applicable dust standard. Operators would
continue to be required to maintain compliance with the applicable dust
standard at all times. Also, the operator's dust control parameters
must be verified as adequate to maintain dust concentrations at or
below the applicable dust standard on all shifts, not merely at or
below the CTV.
As explained in the notice regarding single-shift measurements of
respirable coal mine dust published in today's Federal Register, the
Mine Act requires MSHA to regulate exposures on each shift. Since MSHA
does not track the number of shifts each miner works over a lifetime,
MSHA must, protect miners by limiting their exposure on each shift.
Furthermore, as explained in Parts VI and VII of today's notice,
eliminating overexposures on individual shifts is beneficial to miners'
health. For miners working where there is a pattern of recurrent
overexposures on individual shifts, eliminating such overexposures is
expected over a working lifetime, to significantly reduce the risk of
CWP. Therefore, the Secretary has concluded that equivalent dust
concentrations should be maintained below the applicable dust standard
on each and every shift.
If an operator receives a citation for exceeding the applicable
dust standard, proposed paragraphs (b)(1) through (4) would require the
operator to take specific actions to immediately protect miners and to
prevent them from being overexposed on subsequent shifts within the
time period fixed in the citation. First, the operator would continue
to make available approved respiratory equipment to affected miners in
accordance with existing Sec. 70.300 and encourage their use until the
overexposure condition is corrected, unless the cited occupation is
already under a PAPR protection program. The operator would then review
the dust control parameters in effect to determine the cause of the
excessive dust concentration and correct any deficiencies identified to
reduce the equivalent concentration to within the applicable dust
standard. If the corrective action the operator takes indicates that
the dust control parameters originally approved for the MMU may no
longer be adequate for the current conditions, the operator should
revise the plan parameters.
Since MSHA would be assuming responsibility for all compliance
sampling, proposed paragraph (a)(4) would require the operator to
notify the district manager in writing or by electronic means, of what
those corrective measures are within 24 hours after implementation.
This would enable the district manager to determine whether MSHA should
schedule sampling to assess the adequacy of the operator's corrective
actions or whether to require the operator to initiate verification
sampling. This determination would be based on (1) the review of the
information the operator provides; (2) the latest MSHA inspection
report documenting the measured quantities of the dust control

[[Page 10826]]

parameters that were in use and other conditions that were in effect at
the time of sampling that resulted in MSHA issuing a citation for
excessive dust; and (3) the operator's prior performance in complying
with the plan parameters.
If the district manager concludes that the corrective measures
taken are sufficient to achieve and maintain compliance, MSHA would
conduct sampling to determine if the operator's actions were effective
to gain compliance. For example, if the operator believes that the
overexposure was caused by improperly following work practices, the
proper course of action would be to review these work practices with
the affected miners rather than require the operator to revise the
plan. Since there would be no need to change the plan parameters, MSHA
would initiate abatement sampling in this particular case. Like
compliance sampling, federal mine personnel would sample five different
occupations including the occupation originally cited for the entire
shift or for 8 hours, whichever time is less. However, if this problem
should recur, the district manager would inform the operator that the
plan parameters are no longer adequate to provide the required level of
health protection and require the operator to initiate verification
sampling.
If, on the other hand, the district manager determines that dust
control parameters may not maintain respirable dust levels at or below
the applicable dust standard and requires the operator to upgrade the
dust control portion of the mine ventilation plan, the operator would
be required to initiate the plan verification process under proposed
Sec. 70.206.
Under proposed paragraph (c), an excessive dust citation would be
terminated when the results of all valid respirable dust samples
collected by MSHA were at or below the applicable dust standard. The
subsequent action form would clearly and fully describe the action
taken to abate the violation. If compliance was demonstrated, the
operator may be required to revise the plan parameters depending on the
type of corrective action taken to abate the violation. This would
include, at a minimum, the actual dust control parameters that were in
effect when MSHA sampled the MMU. If MSHA samples indicate continued
noncompliance, then MSHA may proceed to revoke approval of the dust
control provisions of the ventilation plan. The operator may be
required to initiate the verification sampling if the district manager
determines that the dust control parameters originally approved are no
longer adequate to maintain respirable dust levels at or below the
applicable dust standard under current operating conditions at the MMU.
If, instead of MSHA conducting sampling to determine whether the
operator's actions were effective to gain compliance, the operator
initiates verification sampling under proposed Sec. 70.206, MSHA would
terminate a citation for excessive dust after the revised plan
parameters were verified by the operator to be adequate for the current
mining conditions.

Reporting of Changes in Operation Status

Section 70.219 Status Change Reports
The proposed rule would retain the existing provision of Sec.
70.220, which would be redesignated as Sec. 70.119, with some
revision. Not only would the operator continue reporting to the
district manager changes in the operational status of a mine, MMU, or
DA that affect the respirable dust sampling requirements of this part,
but also when such status changes could potentially affect compliance
sampling which will be conducted by MSHA. This would enable MSHA to
carry out its sampling responsibilities more effectively and
efficiently by avoiding unnecessary mine visits. Status changes would
be reported either in writing or by electronic mail within three
working days after the status change occurred.

Use of Personal Continuous Dust Monitors (PCDM) to Monitor Exposure

Section 70.220 Personal Continuous Dust Monitor (PCDM)
MSHA has long recognized that continuous monitoring of the work
environment offers the potential to improve miner health protection.
The current system of monitoring concentrations of respirable dust to
which miners are exposed relies on periodic sampling and on corrective
actions taken after the delay in obtaining the sampling results.
Continuous monitoring, on the other hand, would allow mine operators
and miners to be aware of the actual dust conditions on a real-time
basis. This would provide mine personnel with current information on
the performance and condition of the dust control parameters. Early
indications of deteriorating conditions, when the dust levels approach
the applicable dust standard, would enable mine personnel to take
appropriate corrective measures, thus averting possible overexposure.
The health benefits of continuous monitoring were also recognized by
the Task Group and the Dust Advisory Committee both of which
recommended accelerated development, field testing, and immediate
deployment of such monitors once verified as reliable.
While such a monitor is not yet commercially available, significant
progress has been made to advance the state of personal continuous
monitoring technology, especially since MSHA published its proposed
rule on plan verification on July 7, 2000. According to NIOSH, a one-
piece personal dust monitor (called ``PDM-1'' for short) would be
available for in-mine use by the end of 2003. This device is designed
to provide continuously-measured exposure information in real-time
during the shift, projected end-of-shift average concentration, and the
time-weighted average dust concentration reading within 15 minutes
after the end-of-shift.
Therefore, as recommended by the Dust Advisory Committee and urged
by the mining community, MSHA is proposing a new standard under Sec.
70.220 to encourage deployment of the PDM-1 or other approved PCDMs by
permitting operators to use this technology in conjunction with
engineering and administrative controls as part of a comprehensive dust
control program to prevent overexposures on individual shifts.
Proposed paragraph (b) would permit the operator to use
administrative controls without obtaining approval from the
Administrator for Coal Mine Safety and Health under proposed Sec.
70.209. The operator would be required to include in the proposed plan,
the specific administrative controls to be used, how each would be
employed and by whom, and the method for ensuring that such controls
are complied with on each shift. In addition, the operator would be
required to identify the miners or specific occupations to be monitored
on each shift using PCDMs and to implement procedures to ensure that no
miner will be exposed during any shift to dust concentrations in excess
of the applicable dust standard.
Since the device is designed to display continuous real-time dust
concentrations, the operator would be expected to develop written
procedures for the proper use of this type of dust monitor. Key to the
successful employment of this technology is the proper application of
its capability to supply timely information on dust levels and miner
exposure during the shift. The ability to be aware of the dust levels
to which miners are exposed in real time would require the operator to
develop specific guidelines regarding

[[Page 10827]]

the frequency with which the exposure measurements will be read and the
types of action to be taken and by whom. The operator would need to
specify how and by whom will the end-of-shift measurements be recorded
and certified. The operator should also detail the role of the miner in
this process. To ensure the continued reliability of the information
supplied by the instrument, the operator must follow the calibration
and maintenance procedures prescribed by the manufacturer. MSHA
technical assistance would be available to assist any operator who
elects to use this technology in developing an effective and reliable
exposure monitoring program.
Proposed paragraph (c) would require the operator to demonstrate,
as prescribed by proposed Sec. 70.204, the adequacy of the proposed
plan in controlling respirable dust by monitoring each miner's exposure
under the operating conditions specified in proposed Sec. 70.201(e).
Since the objective is to verify the effectiveness of the operator's
respirable dust control program, the PCDM would remain with a miner
portal-to-portal and be operational for the entire shift or for 12
hours, whichever time is less to reflect maximum length of an extended
shift.
Since the device is not designed to assess the quartz exposure of
individual miners, the operator would be required to collect separate
samples for quartz analysis. Samples would be collected in the same way
as for individual miners assigned to the occupations identified in
proposed Sec. 70.206(a). Additionally, in accordance with proposed
Sec. 70.201(d), the operator would be required to use a control filter
when collecting samples for quartz analysis. As discussed under
proposed Sec. 70.201(d), the weight gain of each exposed filter
cassette will be adjusted by subtracting the weight gain or loss of the
control filter cassette. These samples would be transmitted to MSHA in
accordance with proposed Sec. 70.216. Also, the end-of-shift exposure
information for each miner along with production data must be posted on
the mine bulletin board for 7 calendar days following completion of the
shift.
As previously discussed under proposed Sec. 70.207, approval of
the operator's plan incorporating the use of PCDMs would depend on the
results of verification sampling and the operating conditions in effect
for each shift monitored. The district manager would approve the plan
if (1) no valid equivalent concentration measurement exceeds the
critical values listed in Table 70-1 that correspond to the number of
shifts monitored, and (2) it incorporates the parameters that were in
effect during verification sampling.
When approval is granted by the district manager, the operator
would be required to monitor the exposure of each miner on a MMU on
every shift under the prevailing conditions, unless the operator
demonstrated during verification sampling that the exposure of each
miner working on the same shift is represented by sampling only the DO
and/or another occupation specified in Sec. 70.206(a). If approved by
the district manager, the operator would be permitted to conduct
representative personal monitoring. Each PCDM would be operated portal-
to-portal and remain operational the entire shift or for 12 hours,
whichever time is less.
The end-of-shift exposure measurements would not be used by MSHA to
cite an operator for exceeding the applicable dust standard. Instead,
the operator would be required to take the actions required by proposed
Sec. 70.215(c), (d) and (e) whenever a valid end-of-shift measurement
exceeds the applicable dust standard by at least 0.10 mg/m3.
Violations of either Sec. 70.100(a) or Sec. 70.101 would be cited
when a valid sample taken by MSHA met or exceeded the citation
threshold value (CTV) listed in Table 70-2 that corresponds to the
applicable dust standard in effect. When cited, the operator would be
required to take the actions required by Sec. 70.218(b). The district
manager will consider the citation abated if the operator meets the
requirements of proposed Sec. 70.218(c).
Comments are solicited on the proposed monitoring approach and
other alternative approaches using PCDMs to limit exposure of miners to
respirable coal mine dust. Specifically, under what conditions should
MSHA permit its use as part of the approved ventilation plan without
requiring the adequacy of the operator's proposed exposure control
program to be verified? If implementation of this technology is
permitted as an alternative to plan verification, what specific
provisions should be included in the ventilation plan to ensure that
miners will not be overexposed on any particular shift? Should all
miners be required to wear PCDMs or only specific occupations and, if
so, which occupations? How frequently should PCDMs be used (e.g., every
shift, etc.)? Should the end-of-shift measurements be used by MSHA to
enforce compliance with the applicable dust standard? Is it appropriate
to use PCDMs only in the face areas or in outby areas as well? Is there
an alternative to a continuous monitoring program that could provide
equivalent protection? Should there be an alternative approach tailored
to small mines? If so, what should it consist of (e.g., monitor one
shift each week)?
Since the PCDMs is capable of supplying timely information on dust
levels, how should engineering and administrative decisions be based on
readings of the PDM? For example, should a PCDMs reading trigger an
immediate check of the dust control parameters or adjustments to
operating conditions, such as the amount of air being delivered to the
working faces? Who should be responsible for deciding on the proper
course of action to be taken based on a PCDMs reading (e.g., miner
being monitored, section foreman, etc.)? Who should be empowered to
make the determination to remove an individual so that their end-of-
shift exposure is not above the applicable dust standard?
B. Part 75
Section 75.370 Mine Ventilation Plan; Submission and Approval
This proposed rule would amend Sec. 75.370 by adding a new
paragraph (h) that reflects the proposed change in Sec. 70.2 and
paragraph (d) of Sec. 70.201 of this part. Under proposed paragraph
(h), the operator would be required to record and maintain records of
the total amount of material produced each production shift by each MMU
during the previous six-month period, which would be made available for
inspection by authorized representatives of the Secretary and the
miners' representative. This is the same type of production information
that the operator is currently reporting on the dust data card
accompanying each bimonthly sample and which is subsequently posted by
MSHA on the Internet. Paragraph (h) would not require an operator to
record and maintain other information such as recovery and reject rate,
inherent moisture of the product, sulfur content or other variables
associated with each production level.
These production records are essential to demonstrate the adequacy
of the dust control parameters in controlling respirable dust as
required by Sec. 75.370(a)(1) of this title. The records are needed to
establish the verification production level (VPL), in accordance with
revised Sec. 70.2, under proposed Sec. 75.371(f), and to confirm that
the 30-shift period on which the VPL is based represents typical
production conditions for the MMU. Additionally, MSHA and the miners'
representative need these records to monitor changes in production
levels as it directly impacts the continued effectiveness of the plan's
dust control

[[Page 10828]]

provisions. Finally, because verification and subsequent quarterly
monitoring of the adequacy of plan parameters is conditioned on the
VPL, these records are necessary to determine if the VPL used in
approving the operator's dust control parameters for a particular MMU
continues to reflect typical production levels at the MMU.
The proposed rule would permit production records for each MMU to
be maintained in any form utilized by the operator to measure the total
amount of material produced, provided the method is the same as that
used to establish the VPL under proposed Sec. 75.371(f). For example:
number of loaded shuttle cars, feet of advance, raw tonnage, or number
of longwall passes would each be an acceptable method of recording
production--provided the same method was consistently used.
Section 75.371 Mine Ventilation Plan; Contents
The proposed rule would revise paragraphs (f) and (t). Existing
paragraph (f) would be revised to require the dust control provisions
of the ventilation plan to include any specific work practices used to
minimize the dust exposure of individual miners assigned to specific
occupations, information on the location of the roof bolter(s) during
the mining cycle for each continuous miner section, and the cut
sequence for each longwall mining section. Also, the dust control
provisions of every ventilation plan would be required to include the
length of each normal production shift and the verification production
level (VPL) as determined in accordance with revised Sec. 70.2. This
information would enable MSHA to more effectively assess the
suitability of the operators's proposed plan parameters before
determining whether or not to grant provisional approval. For example,
the dust control parameters may be less protective if verified over an
8-hr shift when the length of the production shift is 9 hours. Also,
since MSHA recognizes the critical role of miners in the implementation
of the plan parameters at each MMU, this is intended to provide more
information to miners concerning the specific conditions under which
the adequacy of the plan parameters for each MMU was demonstrated. With
this information, the miner will be able to bring problems to the
attention of mine management or to request an inspection by MSHA under
Sec. 103(g) of the Act if operating conditions no longer reflect those
in effect during verification sampling and there is concern about the
dust conditions at a particular MMU.
Although a VPL and shift length for each MMU would be included in
the ventilation plan, the operator would not be cited if the total
amount of material produced or the length of the actual production
shift is not as specified in the plan. MSHA considers these to be plan
design criteria, not minimum plan parameters that must be in effect on
every shift. MSHA would expect production on a MMU to exceed the VPL on
about 33 percent of all production shifts. If the district manager
determines that an operator's actual production exceeds the VPL on more
than 33 percent of the production shifts over a six-month period, or
the shift length no longer reflects the conditions under which the
approved plan parameters were originally verified, and operator or MSHA
samples exceed the applicable dust standard, the district manager may
require that the adequacy of the plan parameters be verified under
different operating conditions of production or shift length.
Since MSHA is proposing to revoke existing Sec. Sec. 70.207 and
70.208, which require bimonthly sampling by mine operators, existing
paragraph (t) would be revised to remove the provision that mine
operators identify in the ventilation plan the locations where samples
for designated areas (DA) would be collected, including the specific
location of each sampling requirement, and the reference to Sec.
70.208. However, to ensure that the mine atmosphere where miners
normally work or travel is continuously maintained in compliance,
proposed paragraph (t) would continue to require mine operators to
identify in the mine ventilation plan the location of each DA, defined
in revised Sec. 70.2, and the particular dust control measures that
would be used at the dust generating sources for these locations. These
locations would continue to be sampled by MSHA personnel as discussed
earlier (see Background Section) to monitor operator compliance with
the applicable dust standard and to assess the adequacy of the
operator's dust control measures at these locations.

C. Part 90

To maintain consistency with the proposed revisions to part 70,
subpart A of this proposed rule also contains new definitions of
identical terms. Included are definitions of new terms such as
``approved sampling device,'' ``citation threshold value,''
``equivalent concentration,'' ``MRE,'' and ``quartz.''
Subpart B of the proposed rule would be revised by changing the
procedures for determining the average quartz percentage used to
calculate the applicable dust standard. These are identical to the
procedures proposed under Sec. 70.101. The proposed rule also
clarifies the application of specific transfer and pay-protection
provisions under special circumstances that reflect long-standing MSHA
policy in effect since the rule became effective on December 5, 1980.
The proposed rule substantially revises the existing operator
sampling requirements under Subpart C of part 90. Consistent with the
proposed amendment to part 70, the proposed rule would revoke existing
provisions concerning operator bimonthly and abatement sampling of part
90 miners. Consequently, Sec. Sec. 90.201(d) and 90.208 would be
removed. While MSHA would be assuming responsibility for all
enforcement-based monitoring of part 90 miners in underground coal
mines, operators would continue to play a vital role in assessing the
quality of the mine atmosphere in positions to which new or transferred
miners are assigned to work.
As under existing Sec. 90.207, which has been revised and
redesignated as Sec. 90.204, the operator employing part 90 miners
would be required to collect five valid samples within a prescribed
time period for purposes of verifying the suitability of a new or
transferred part 90 miner's assigned work position. To ensure that the
part 90 miner is not personally overexposed, the duration of sampling
would no longer be limited to 480 minutes, but would be carried out
over the miner's entire work shift, regardless of the number of hours
worked.
Another significant change is how the results of operator-submitted
samples would be analyzed by MSHA and the type of action required based
on those results. MSHA would abandon its long-standing practice of
relying on averaged results to make compliance decisions. Because
averaging can obscure specific instances of overexposures by diluting
sample results taken over multiple shifts, each valid sample would be
compared with the applicable dust standard. Therefore, to be confident
that a part 90 miner is placed in an atmosphere which actually meets
the applicable dust standard, all five valid samples must be at or
below the standard. If the result of any sample exceeds the standard by
at least 0.1 mg/m3, the operator would be required to take
corrective action and take an additional five valid samples for the
affected part 90 miner.
Since the primary purpose for taking these samples is to assess the
suitability of the part 90 miner's working environment, these samples
would not

[[Page 10829]]

be used by MSHA to cite the operator for noncompliance with the
applicable dust standard. As discussed below, only MSHA-collected
samples would be used for that purpose. However, an operator would be
cited for failure to take appropriate corrective action to place the
affected part 90 miner in an atmosphere that meets the applicable dust
standard within the specified time period.
Since MSHA would assume responsibility for compliance and abatement
sampling, the proposed rule sets forth new procedures for determining
noncompliance with the applicable dust standard; the specific actions
that an operator would be required to take within the time for
abatement fixed in a citation; and the conditions under which MSHA
would terminate a citation for a violation of the standard. Under the
proposed rule, citations for violations of Sec. Sec. 90.100 or 90.101
would be issued only when a valid single-shift sample demonstrates
noncompliance with at least 95-percent confidence. MSHA would consider
a violation for excessive dust to be abated and terminate the citation
when the result of a valid single-shift sample is at or below the
applicable dust standard.
Although existing subpart D has been revised to reflect MSHA
sampling of part 90 miners, the specific requirements are essentially
the same. It now states that when approving an operator's dust control
plan, the district manager would consider the results of MSHA sampling
for compliance or abatement purposes. It also indicates that MSHA
would, through compliance and abatement sampling, monitor the continued
effectiveness of the operator's dust control measures. Finally,
throughout Part 90, ``shall'' has been replaced by ``must.''
For ease of review, MSHA is republishing the entire regulatory text
of subparts A, B, C and D of Part 90 as it will appear in the Code of
Federal Regulations.

Sections 90.1 through 90.3

Scope, Definitions, and Part 90 Option

Section 90.1 Scope
This section would remain unchanged.
Section 90.2 Definitions
The proposed rule includes definitions virtually identical to
corresponding definitions in proposed Part 70 for terms such as
``approved sampling device,'' ``citation threshold value,''
``equivalent concentration,'' and ``MRE.'' Accordingly, as in Part 70,
some existing definitions of terms such as ``certified person,''
``concentration,'' ``mechanized mining unit,'' and ``respirable dust''
have been modified either to more clearly convey the intended meaning
under the proposed rule, to reflect the conventional definition or to
be consistent with the definition of identical terms in proposed Part
70 of this title. Most of the other definitions remain unchanged under
the proposed rule. No discussion is included below if a definition
would not change under the proposed rule.
Approved Sampling Device
``Approved sampling device'' would mean a sampling device approved
by the Secretary and the Secretary of Health and Human Services under
part 74 (Coal Mine Dust Personal Sampler Units) of this title; or
approved by the Secretary when it has been demonstrated that a
respirable dust concentration measurement can be converted to a
concentration measurement equivalent to that obtained with an approved
sampling device. Under the proposed rule, respirable dust sampling for
Part 90 miners would continue to be collected using sampling devices
approved by NIOSH pursuant to existing 30 CFR part 74. Also, to
accommodate the adoption of advanced sampling technology in the future
such as continuous respirable dust monitors, the proposed rule would
permit the Secretary to approve and use any technologically advanced
sampling devices that should become available in the future but could
not be approved under the regulatory requirements of 30 CFR part 74.
Therefore, under the proposed rule, any newly developed sampling
instrument would be considered an approved device pursuant to this
definition when the Secretary demonstrates that the respirable dust
concentration measured by the new instrument can be converted to a
concentration measurement equivalent to that obtained by a device
approved under 30 CFR part 74 of this title.
Certified Person
The existing definition would be modified by removing references to
existing Sec. Sec. 90.202 and 90.203. The provision requiring the use
of a certified person to conduct sampling as required by this part is
being transferred to revised Sec. 90.201. Existing Sec. 90.203 which
requires approved sampling devices to be maintained and calibrated by a
certified person would be retained and redesignated as Sec. 90.202.
Citation Threshold Value (CTV)
``Citation threshold value'' would mean the lowest acceptable
equivalent dust concentration measurement demonstrating that the
applicable dust standard has been exceeded at a high level of
confidence and at which MSHA would cite an operator for a violation of
Sec. Sec. 90.100 or 90.101 under proposed Sec. 90.207. Since MSHA
would be assuming responsibility for compliance sampling under the
proposed rule or sampling currently being carried out by operators
under existing Sec. 90.208(a), a determination of noncompliance would
be based solely on the results of single shift samples collected by
MSHA in accordance with proposed Sec. 72.500 of this title. Appendix C
explains how each critical value listed in proposed Table 70.2 was
derived. Each CTV is calculated to ensure that citations will be issued
only when a single-shift measurement demonstrates noncompliance with at
least 95 percent confidence.
Concentration
The existing definition would be modified by replacing the term
``substance'' with ``respirable dust'' to more clearly convey the
meaning under the proposed rule.
Equivalent Concentration
``Equivalent concentration'' would mean the concentration of
respirable dust, as measured by an approved sampling device, converted
to an 8-hour equivalent concentration as measured by a Mining Research
Establishment (MRE) sampler. This conversion is accomplished in two
steps. First, the concentration measurement is multiplied by a constant
factor prescribed by the Secretary specifically for the approved
sampling device. The result is then multiplied by t/480, where t is the
sampling time in minutes if longer than eight hours, to make it
equivalent in dosage to the concentration as measured by an MRE sampler
on an 8-hour work shift. Since sampling will be conducted over the
course of the Part 90 miner's entire work shift, which includes travel
to and from the assigned work position, t will also be equal to the
length of the entire work shift of the miner being sampled. If the
length of the Part 90 miner's work shift is eight hours or less, then t
must equal 480 minutes.
The current U.S. coal mine applicable dust standard is based on
epidemiologic studies of British coal miners. In these studies, miners
routinely worked 8-hour shifts, and their respirable dust exposures
were assessed based on 8-

[[Page 10830]]

hour measurements using a sampling device known as the MRE instrument.
Work shifts in U.S. coal mines now frequently exceed eight hours.
According to a recent survey of MSHA District Offices conducted in
August of 2002, approximately 48 percent of underground mines work 9-
hour shifts or longer. Therefore, to provide the intended level of
protection to miners working longer than eight hours, it is necessary
to convert coal mine dust concentration measurements to equivalent 8-
hour values as measured by the MRE instrument.
The first step in the conversion from ``concentration'' to
``equivalent concentration'' is intended to make the measurement
equivalent to the concentration measured by an MRE instrument. This
instrument was designed to selectively collect airborne dust in a way
that would approximate the deposition of inhaled particles in the lung.
Because the MRE instrument was large and cumbersome, other, more
portable samplers were developed for use in U.S. coal mines. Currently
approved sampling devices use a 10-mm nylon cyclone to separate the
respirable fraction of airborne dust, instead of the four horizontal
plates used in the MRE sampler. Such differences in sampler design lead
to systematic differences in the amount of dust collected. Since 1980,
measurements made using the currently approved cyclone-based devices
operating at a flow rate of 2.0 liters per minute (lpm) were multiplied
by the constant factor of 1.38 prescribed by the Secretary for the
approved sampling device used. Application of this factor compensates
for the difference in dust collection characteristics and makes the
measurements equivalent to what would be obtained using an MRE
instrument.
Similarly, the second step in the conversion from ``concentration''
to ``equivalent concentration'' is intended to compensate for
differences between current conditions and conditions under which the
existing applicable dust standard was developed. Specifically, it is
designed to ensure that miners working shifts longer than eight hours
will be afforded the same level of protection as miners working an 8-
hour shift. MSHA developed the existing standard from 8-hour shift
exposure measurements. Therefore, MSHA will adjust the measured
concentration to be equivalent, in its effect on cumulative exposure,
to a concentration over an eight-hour exposure period. This is
accomplished by multiplying the concentration measurement by t/480,
where t is the sampling time (i.e., length of the work shift) in
minutes.
The formula for an equivalent concentration is:
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.004

where t = sampling time in minutes (which will be the Part 90 miner's
entire work shift) and airflow rate = 0.002 m3/min). The
product of t and the airflow rate is the total volume of air from which
dust is accumulated on the filter.
The following example is meant to illustrate the effect of the
second step in the conversion, multiplication by t/480, which adjusts
for the full length of the work shift. In this example, it is assumed
that the first step in the conversion, multiplication by 1.38 for
equivalency with an MRE sampler, has already been performed.
Suppose a Part 90 miner sample is collected over a 9-hour work
shift. Suppose that the amount of dust accumulated during the shift is
0.77 mg. If the concentration were not adjusted to an 8-hour equivalent
concentration, the MRE-equivalent concentration would be calculated as
0.98 mg/m3. Under the definition of ``equivalent
concentration,'' this quantity is then multiplied by 540/480, yielding
an equivalent concentration measurement of 1.10 mg/m3.
This adjustment does not change the daily limit on the accumulated
dose of respirable coal mine dust as intended by the existing exposure
limit for coal mine dust. Since the current limit was based on an
assumption that exposure occurs over an 8-hour shift, it corresponds to
a daily cumulative dose of respirable coal mine dust of 8 x 1.0 = 8 mg-
hr/m3 as measured by the MRE instrument. The proposed
definition of equivalent concentration will maintain this same MRE-
equivalent 8 mg-hr/m3 daily limit, regardless of the length
of the working shift being sampled.
To continue the example, the exposure accumulated during the Part
90 miner's entire work shift is the same, whether over eight hours at
an average of 1.10 mg/m3 or over nine hours at an average of
0.98 mg/m3. In either case, the MRE-equivalent exposure
accumulated during the entire work shift is 8.8 mg-hr/m3,
which exceeds the intended limit of 8 mg-hr/m3. Under the
proposed definition of ``equivalent concentration'' provided here, this
will be reflected by the fact that, when more than 8 mg-hr/
m3 (MRE-equivalent exposure) is accumulated over the course
of the particular shift sampled, the equivalent concentration will
exceed 1.0 mg/m3, regardless of the shift's length.
MSHA originally proposed a different, but mathematically
equivalent, method of adjusting concentrations to an 8-hour equivalent
and solicited comments on the proposed method. The proposed method
would have defined ``concentration'' to mean what is here defined as
``equivalent concentration.'' Instead of making an explicit adjustment
to the concentration, using the factor of t/480 as in the present
definition, the earlier proposed rule would have substituted 480 for
the actual sampling time in the definition of respirable dust
concentration. The proposed definition of ``equivalent concentration''
is meant to both preserve the ordinary definition of ``concentration''
and to clarify the adjustment to an 8-hour equivalent.
MSHA believes that the proposed adjustment to an ``8-hour
equivalent concentration'' is necessary to protect Part 90 miners from
excessive exposures who normally work nontraditional or extended
shifts. For example, a Part 90 miner working for ten hours at an
average concentration of 1.0 mg/m3 will inhale and retain
more respirable coal mine dust as a result of that specific shift than
a miner working for eight hours at the same average concentration. By
comparing the adjusted concentration to the concentration limit
originally intended for Part 90 miners working an 8-hour shift, the
same cumulative exposure limit is applied on individual shifts for all
Part 90 miners.
It should be noted that the ACGIH approach of reducing the
permissible concentration to compensate for the extension of a shift
beyond eight hours is similar in its effect to the approach taken here
of adjusting the equivalent concentration upwards and comparing it to a
fixed limit. MSHA makes similar adjustments for extended work shifts in
the enforcement of exposure limits in metal and nonmetal mines under 30
CFR 56.5001 and 57.5001. Taking into account the reduced recovery time
that results from an extended work shift

[[Page 10831]]

would have led to a numerically greater and more protective adjustment,
but this would also have introduced additional complexities in the
calculation of equivalent concentration measurements. The Secretary
believes that the method chosen strikes a reasonable balance between no
adjustment at all, and a far more complex adjustment that would attempt
to model clearance, deposition, and retention mechanisms.
Mechanized Mining Unit (MMU)
The existing definition would be modified by removing the reference
to Sec. 70.207(e) (Bimonthly sampling; mechanized mining units), which
will be deleted, and replaced with proposed Sec. 70.206(d); and
transfers the requirements for identifying each MMU specified in
existing Sec. Sec. 70.207(f)(1) and (f)(2), to revised Sec. 70.2.
MRE
``MRE'' would mean Mining Research Establishment of the National
Coal Board, London, England. This is a new definition which has been
included to be consistent with revised Sec. 70.2.
Quartz
The existing definition would be modified by specifying the
analytical method that MSHA has been using since 1983 to determine the
quartz content of respirable dust samples. The reason for this
modification is to standardize the analytical procedure, thereby
enabling other certified laboratories to reproduce quartz
determinations made by MSHA. Also, to accommodate the adoption of
improved or other quartz analytical techniques in the future, the
definition of ``quartz'' has been expanded in the proposed rule to
provide MSHA the flexibility to use alternative analytical techniques
once these techniques have been demonstrated to provide quartz
measurements that are equivalent to those obtained under current
analytical method.
Respirable Dust
The existing definition has been modified by transferring the
requirement regarding what constitutes an approved sampling device to
the proposed new definition of the term ``approved sampling device''
above.
Transfer
The existing definition has been modified by clarifying when a
change in work assignment would not constitute a transfer under
proposed Part 90. MSHA recognizes that there may be circumstances which
are beyond the control of the operator, such as equipment malfunction,
that may interrupt work being performed by a Part 90 miner in his or
her regular work assignment, necessitating the assignment of the Part
90 miner to another job temporarily. For example, if the Part 90 miner
is regularly assigned as a shuttle car operator in a MMU and the
continuous mining machine breaks down, that Part 90 miner could be
temporarily assigned to work in a different position and location in
the mine. Consistent with MSHA's longstanding policy, such a change in
duties would not constitute a transfer under Part 90 if the assignment
does not last more than one shift. If such an assignment lasts longer
than one shift, the operator would be required to notify the district
manager in writing. This notice would list the temporary duties and the
reasons for the assignment. Also, to demonstrate compliance with the
applicable dust standard, the operator would be required to collect
five valid samples from the newly assigned work position under proposed
Sec. 90.204(a)(2). The 1.0-mg/m3 standard remains in effect
even if the operator is unable to collect the required number of
samples because of the short duration of the temporary assignment.
Section 90.3 Part 90 Option; Notice of Eligibility; Exercise of Option
This section remains the same, with the exception of paragraphs (d)
and (e) which have been revised to reflect the new address for mailing
of the Exercise of Option Form or written request to re-exercise the
option to work in a low-dust area of the mine.

Sections 90.100 Through 90.104

Dust Standards, Rights of Part 90 Miners

Section 90.100 Respirable Dust Standard When Quartz Is Not Present
MSHA is proposing no substantive changes in existing Sec. 90.100,
except for revising the section heading to correspond with the heading
of proposed Sec. 70.100, which is identical, and removing the
reference to Sec. 90.206 (Approved sampling devices; equivalent
concentrations) and replacing it with Sec. 90.2. The requirements
contained in revised Sec. 90.2 are similar to the standard in existing
Sec. 90.206. The proposed rule retains the applicable dust standard of
1.0 mg/m3.
Section 90.101 Respirable Dust Standard When Quartz Is Present
The proposed rule would revise the section heading to correspond
with the heading of proposed Sec. 70.101, which is identical. MSHA
would retain the existing formula (10 divided by the concentration of
quartz, expressed as a percentage) for reducing the applicable dust
standard below 1.0 mg/m3 in proportion to the percentage of
quartz when the quartz content of respirable dust in the mine
atmosphere exceeds 10 percent, instead of 5 percent as contained in
existing Sec. 90.101. Since the maximum standard for a Part 90 miner
is 1.0 mg/m3, the quartz content must exceed 10 percent to
cause a reduction in the applicable dust standard.
The Agency would change the procedures for determining the average
quartz percentage used to calculate the applicable dust standard. Only
the results of MSHA samples would be used to establish the applicable
dust standard. The quartz results of the three most recent valid MSHA
samples would be averaged and the resultant percentage used to set the
new applicable dust standard. However, if the Part 90 miner is already
assigned to an area of the mine under a reduced standard below 1.0 mg/m
\3\ when these revised procedures become effective, a new applicable
dust standard would be established by averaging the results of the
first two MSHA samples taken after the effective date with the quartz
percentage associated with the applicable dust standard in effect. If
fewer than two MSHA samples are taken, the existing standard would
continue to remain in effect.
Application of the revised procedures will result in the setting of
reduced standards in a timely manner that (1) more accurately represent
the quartz percentage of respirable dust in the environment of the Part
90 miner at the time of sampling; (2) reflect the dynamics of the
mining process and the changing geologic conditions of the mine strata;
and (3) continue to protect Part 90 miners over multiple shifts.
Under the proposed rule, MSHA would also report the quartz
percentage to the nearest tenth of a percent, instead of truncating the
results to the nearest full percentage as has been the longstanding
practice. While this change will have no impact on the setting of
applicable dust standards below 1.0 mg/m3, it will be more
protective for other miners because it permits the setting of reduced
standards at such levels as 1.1 mg/m3, 1.4 mg/m3,
1.6 mg/m3, 1.8 mg/m3, and 1.9 mg/m3.
Setting these particular standards currently is not mathematically
possible using the above formula due to the practice of truncating the
average quartz percentage. Another change involves removing the
reference to Sec. 90.206 (Approved sampling devices; equivalent
concentrations) and replacing it with Sec. 90.2. The requirements
contained in revised Sec. 90.2 are similar to the standard

[[Page 10832]]

in existing Sec. 90.206. Also revised under the proposed rule is the
example illustrating how a reduced standard is established when
respirable dust associated with a Part 90 miner contains more than 10
percent quartz under the proposed revised dust-standard setting
procedures.
Section 90.102 Transfer; Notice
MSHA is proposing no substantive changes in existing Sec. 90.102,
except to clarify in the regulatory text the application of the
transfer provision in paragraph (a) when a Part 90 miner is assigned to
a different shift. To conform with MSHA's long-standing policy, the
proposed rule permits assigning a Part 90 miner to a different shift
under certain circumstances without violating paragraph (a) of Sec.
90.102(a). Unlike the pay protection afforded Part 90 miners by Sec.
90.103(b) which would be applied ``[w]henever a Part 90 miner is
transferred * * *'' (emphasis added), the job and shift protections
provided by existing Sec. 90.102(a) apply ``whenever a Part 90 miner
is transferred in order to meet the respirable applicable dust standard
* * *'' (emphasis added). The intent to limit the scope of job and
shift protections under paragraph (a) of this section and the purpose
of doing so were explained as follows in the preamble to the existing
Part 90 rules:

The operator may transfer a Part 90 miner without regard to
these job and shift limitations if the respirable dust
concentrations in the position of the Part 90 miner complies with
the applicable dust standard, but circumstances require changes in
job assignments at the mine. Reductions in workforce or changes in
operational methods at the mine may be the most likely situations
which would affect job assignments. Any such transferred Part 90
miner would still be protected by all other provisions under this
part. (45 FR 80761)
In instances where operators need to reassign employees to
accommodate unforseen situations and unexpected mine and market
conditions, MSHA believes that some leeway should be provided to
assist operators in placement of a Part 90 miner. (45 FR 80766)

These explanations show that MSHA did not intend the provisions of
existing paragraph (a) to apply when a Part 90 miner is working in a
position that meets the applicable dust standard and, for legitimate
business reasons, the operator assigns the miner to a new job or
shift.\11\ On the other hand, when the reasons for changing a Part 90
miner's shift or job involve maintaining compliance with the applicable
dust standard, then the provisions of paragraph (a) apply and the miner
is entitled to job and shift protections, unless these protections are
waived in accordance with this standard. MSHA will continue to
carefully scrutinize any changes in job or shift assignments for a Part
90 miner to determine whether paragraph (a) of Sec. 90.102 applies
because the change constitutes a transfer to meet the applicable dust
standard and, if not, to determine if the change in the Part 90 miner's
job or shift assignment was due in any part to action which could be
characterized as improper under the Mine Act.
------------------------------------------------------------------------

\11\ As noted above, however, the other protections provided by
Part 90 would apply. For example, on the new shift or in the new job
there could be no reduction in the miner's pay and compliance would
have to be maintained with the applicable dust standard and the
sampling requirements.
------------------------------------------------------------------------

Section 90.103 Compensation
The proposed rule would redesignate existing paragraphs (c) through
(f) as (d) through (g) and add new paragraph (c). Proposed new
paragraph (c) clarifies MSHA's longstanding policy of not applying the
Part 90 miner compensation provisions of existing paragraphs (a) and
(b) of this section in situations where, after initial compliance with
the applicable dust standard by the operator, the Part 90 miner on his
or her own initiative applies for and accepts another job in a work
area with an average respirable dust concentration at or below 1.0 mg/
m3.\12\ Under these circumstances, the miner has not waived Part 90
status.\13\ Therefore, the issue being addressed by proposed paragraph
(c) is how the Part 90 wage provisions of existing paragraphs (a) and
(b), which would be retained under the proposed rule, should be
interpreted when a Part 90 miner initiates and accepts a job change.
For the following reasons, MSHA believes that the compensations
provisions of Part 90 may be read to provide no compensation protection
for a Part 90 miner under these circumstances.
------------------------------------------------------------------------

\12\ At mines where a job bidding procedure is in effect, use of
the bidding procedure is not dispositive of whether a job change is
initiated by the miner. The job bidding procedure is applicable to
all job changes, including operator-initiated changes. Thus, factors
relating to the intent and actions of the miner and the operator
must be evaluated.
\13\ Existing Sec. Sec. 90.104(a)(2) and (3) provide for waiver
of Part 90 miner status when the miner applies for and accepts or
retains a position known by the miner to exceed the applicable dust
standard.
------------------------------------------------------------------------

Existing Sec. 90.103, which would be retained in its entirety
under the proposed rule, protects a miner from any immediate reduction
in hourly wage as a result of exercising the option. Where no transfer
of the miner occurs after the option is exercised, paragraph (a)
prescribes:

The operator must compensate each Part 90 miner at not less than
the regular rate of pay received by that miner immediately before
exercising the option under Sec. 90.3.

Existing Sec. 90.103(b) addresses compensation protection for a
Part 90 miner when there is a transfer of the miner. It prescribes:

Whenever a Part 90 miner is transferred, the operator must
compensate the miner at not less than the regular rate of pay
received by that miner immediately before the transfer.

As defined by proposed Sec. 90.2, a transfer, ``by the operator''
would include, but is not limited to, an operator-initiated job
reassignment in order to meet the applicable dust standard or a
reassignment due to a realignment or reduction in the workforce.
However, a miner-initiated job change does not necessarily constitute a
transfer for purposes of compensation under Sec. 90.103(b).
Accordingly, the compensation provision of Sec. 90.103(b) may be
interpreted as not applicable to a job change initiated by a Part 90
miner.
The above interpretations of Sec. Sec. 90.103(a) and (b) are also
consistent with statutory language. Section 101(a)(7) of the Mine Act
addresses several specific matters relative to mandatory health and
safety standards promulgated by MSHA and in relevant part provides:

* * * Where appropriate, the mandatory standard shall provide that
where a determination is made that a miner may suffer material
impairment of health or functional capacity by reason of exposure to
the hazard covered by such mandatory standard, that miner shall be
removed from such exposure and reassigned. Any miner transferred as
a result of such exposure shall continue to receive compensation for
such work at no less than the regular rate of pay for miners in the
classification such miner held immediately prior to his transfer. *
* * (emphasis supplied)

Thus, section 101(a)(7) supports an interpretation that the
compensation provisions of Sec. Sec. 90.103(a) and (b) do not apply
where a Part 90 miner initiates a job change for reasons of job
preference and that Sec. 90.103(b) is limited to job changes which are
``a result of'' exposure to respirable coal mine dust.
Accordingly when there is a Part 90 miner-initiated job change, the
compensation provisions of Sec. Sec. 90.103(a) and (b) would not be
applicable in the Part 90 miner's new job and the miner would be paid
whatever the new job usually pays. Thus, for example: A miner exercised
the Part 90 option when his or her job paid $10 per hour. If the

[[Continued on page 10833]]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]]

[[pp. 10833-10882]]
Verification of Underground Coal Mine Operators' Dust Control
Plans and Compliance Sampling for Respirable Dust

[[Continued from page 10832]]

[[Page 10833]]

operator keeps the Part 90 miner in the same work position because
compliance with the applicable dust standard is maintained, or if the
operator transfers the miner to a new work position to achieve
compliance, then the Part 90 miner cannot be paid less than the $10 per
hour received immediately before exercising the option. If, then, the
miner was to initiate and accept a change in work assignment to a job
which paid $8.50 per hour, no pay protection would accompany the part
90 miner to the new position and the miner would receive $8.50 per
hour.
The remainder of Part 90 provisions, however, would continue to
apply to the Part 90 miner in the new work position. As noted earlier,
a miner-initiated job change to a position which is at or below the
applicable dust standard for a Part 90 miner does not constitute a
waiver of Part 90 rights. Thus, in the new job the miner retains Part
90 status and all other requirements of Part 90 continue in effect,
including the operator's obligations to continuously maintain the
applicable dust standard and to give MSHA notice whenever the miner's
work assignment changes last longer than one shift.
For purposes of consistency, redesignated paragraphs (e) and (g)
have been revised to read as follows: ``* * * under paragraphs (a), (b)
and (d) * * *'' and ``* * * in paragraphs (a), (b), (d), and (e) * *
*,'' respectively.
Section 90.104 Waiver of Rights; Re-exercise of Option
The proposed rule would retain the existing provisions of Sec.
90.104, with some minor revisions for purposes of simplification. In
paragraph (a)(2), ``exceeds the applicable dust standard'' would
replace the statement beginning with ``* * * has an average respirable
dust concentration * * *'' Paragraph (a)(3) would be revised by
replacing the statement beginning with ``* * * average respirable dust
concentration * * *'' with ``existing work position exceeds the
applicable dust standard.'' Lastly, the section heading for Sec.
90.3(e) has been removed from existing paragraphs (b) and (c).

Sections 90.201 through 90.207

Sampling Procedures

Section 90.201 Sampling; General Requirements
MSHA is proposing to modify the general requirements for operator
sampling of new or transferred Part 90 miners under existing Sec.
90.201. Since MSHA would be responsible for collecting samples to
determine if an operator has abated a noncompliant condition, the
proposed rule would remove existing paragraph (d). The proposed rule
would also revise and redesignate existing paragraphs (b) as (c), (c)
as (f), and (e) as (d), revise paragraph (a), and add new paragraph
(b).
Revised paragraph (a) specifies the purpose of operator sampling
under this proposed rule. While MSHA would be assuming responsibility
for most of the sampling currently being carried out by the operator,
revised paragraph (a) would continue to require operators to conduct
sampling to verify that the working environment of a new or transferred
Part 90 miner complies with Sec. Sec. 90.100 or 90.101 as required by
existing Sec. 90.207, which has been redesignated as Sec. 90.204.
Also, to minimize repetition and maintain consistency with virtually
identical provisions in proposed amendments to Part 70, paragraph (a)
would be modified by removing the reference to Part 74 approval (Coal
Mine Dust Personal Sampler Units), and replacing it with ``approved
sampling device,'' as defined under revised Sec. 90.2.
Proposed new paragraph (b) would retain the requirements in
existing Sec. Sec. 90.202(a) and (b) that sampling required under this
part be conducted by an individual certified by MSHA and the manner by
which a person would be certified. Therefore, existing Sec. 90.202(a),
(b), and (c) would be removed.
Since the objective of operator sampling proposed under this part
is to verify that the assigned position of a new or transferred Part 90
miner complies with the applicable dust standard, the sampling device
would continue to be worn by each Part 90 miner as required by existing
Sec. 90.201(b). However, under redesignated paragraph (c), the
requirement that sampling devices ``remain operational during the
entire shift or for 8 hours, whichever time is less'' would be removed.
Instead, the sampling device would be operated portal-to-portal and be
operational during the Part 90 miner's entire work shift, regardless of
the number of hours worked, to ensure that the sampled Part 90 miner is
not personally overexposed. That is, the sampling device would be
turned ``ON'' when the Part 90 miner enters the mine and remain
operational while traveling to the assigned work position, while
performing normal work duties, and while traveling back to the mine
entrance, at which time the device would be turned ``OFF.'' It should
be pointed out that the duration of MSHA sample collection will
continue to be limited to 480 minutes as has been the longstanding
practice. Simply stated, the sampling device would be operated portal-
to-portal and remain operational during the entire shift or for 8
hours, whichever time is less. The Agency solicits comments on the
duration of MSHA sampling under the proposed rule.
Unless otherwise directed by the district manager, the respirable
dust samples will continue to be collected by placing the sampling
device on the Part 90 miner; on the piece of equipment which the Part
90 miner operates within 36 inches of the normal working position; or
at a location that represents the maximum concentration of dust to
which the Part 90 miner is exposed.
Under redesignated paragraph (f), not only would the operator be
required to submit the date but also the time when sampling required by
this part would begin when requested by the district manager. This is
necessary since operators may choose to sample any shift on the date
provided to MSHA. Knowing the time of the scheduled sampling will
enable MSHA to monitor operator sampling on a case-by-case basis to
verify compliance with both the operating conditions and sampling
requirements of this part.
Finally, the requirement that operators take corrective action
during the time for abatement fixed in a citation for violation of
Sec. Sec. 90.100 or 90.101 specified in existing paragraph (d) of
Sec. 90.201 would be transferred to proposed Sec. 90.207(b)(2). The
requirement that the operator sample the affected Part 90 miner until
five valid samples are taken under existing paragraph (d) would be
removed since MSHA is proposing to revoke operator sampling
requirements under existing Sec. 90.208.
Section 90.202 Approved Sampling Devices; Maintenance and Calibration
In an effort to consolidate the requirements that address
maintenance and calibration procedures of approved sampling devices,
MSHA is proposing in Sec. 90.202(a) through (e) to retain the
requirements in existing Sec. 90.203(a) and (b) and Sec. 90.204(a)
through (e), with minor changes. These standards require the sampling
device be maintained as approved and calibrated only by a certified
person in accordance with MSHA Informational Report IR 1240 (1996). The
process of certifying an individual for maintenance and calibration
would remain unchanged. It would continue to require an individual to
successfully complete the applicable MSHA examination. Scheduling
information for MSHA training courses and examinations would be
available from MSHA District Offices.

[[Page 10834]]

These standards require approved sampling devices to be calibrated
at a flowrate of 2.0 liters of air per minute. They also establish the
flowrate and testing and examination requirements for approved sampling
devices. Careful examination and testing of sampling devices would
continue to be required immediately prior to the start of a shift
during which samples would be collected for purposes of this proposed
rule. This would include testing the battery voltage and examining all
external components of the sampling devices to be used. Any necessary
external maintenance to assure the sampling devices are clean and in
proper working condition should be performed at this time by a
certified person. Temporary certification of persons provided under
existing Sec. 90.203(c) would not be retained under the proposal.
Section 90.203 Approved Sampling Devices; Operation; Air Flowrate
Proposed Sec. Sec. 90.203(a) through (c) retains the operation and
flowrate requirements for approved sampling devices in existing
Sec. Sec. 90.205(a) through (d), with minor changes. Since MSHA has
defined an approved sampling device in revised Sec. 90.2 to mean a
device approved in accordance with part 74 of this title, proposed
paragraph (a) excludes reference to part 74. Similarly, for purposes of
simplification, reference to Sec. 90.202 (Certified person; sampling)
would be removed and, wherever used, it would be replaced by certified
person as defined in revised Sec. 90.2.
MSHA believes that the two on-shift examinations of sampling
devices under proposed paragraphs (b)(1) and (b)(2), which are
identical to the examinations required under existing Sec. 90.205(b)
and (c), continue to be an important part of a reasonable and prudent
sampling program. The first examination would be made by a certified
person during the second hour after the sampling devices are placed in
operation. This examination would assure that each sampling device is
operating properly and at the proper flowrate. If the proper flowrate
is not maintained, necessary adjustments in the flowrate would be made
at this time by the person certified to collect samples. The second
examination would be made during the last hour of operation of the
sampling devices. If the proper flowrate is not maintained, the
certified person is required to make a notation on the dust data card
for that sample stating that the proper flowrate was not maintained.
Because it is unclear where on the dust data card such a notation
should be made, proposed paragraph (c) would require all notations
regarding failure to maintain proper flowrate or other events occurring
during sampling that may impact the validity of the sample to be made
on the back of the dust data card.
Section 90.204 Respirable Dust Sampling
This section, previously titled ``Compliance sampling'' under
existing Sec. 90.207, would be modified under the proposed rule and
redesignated as Sec. 90.204. Since the operator sampling requirement
under existing Sec. 90.208(a) would be revoked, the proposed rule
would remove existing paragraph (b) and redesignate paragraph (a)(3) as
(a)(2). The proposed rule would also add new paragraphs (b) and (c).
Consistent with the proposed operator sampling requirements
contained in revised Part 70, MSHA would also be assuming
responsibility for all sampling for compliance and abatement purposes.
This sampling is currently being carried out by the operator under
existing Sec. Sec. 90.201(d) and 90.208(a). However, the proposed rule
would continue to retain the existing provisions of Sec. 90.207, with
major changes under redesignated Sec. 90.204. The objective of this
provision is to maintain operator responsibility for verifying the
suitability of the atmosphere in the position to which a new or
transferred Part 90 miner would be assigned to work. This would assure
that any new or existing Part 90 miner would be placed in an atmosphere
which meets the applicable dust standard.
Therefore, to determine if a new Part 90 miner is working in an
area of the mine where the dust concentration during each shift does
not exceed 1.0 mg/m\3\, the operator would be required to collect five
valid samples within 15 calendar days after being notified by MSHA that
a Part 90 miner is employed at the mine in accordance with proposed
Sec. 90.201. The operator would also be required to collect five valid
samples under proposed paragraph (a)(2) to verify the suitability of a
work position to which a Part 90 miner was transferred under Sec.
90.102. Valid samples are defined in the proposed rule as respirable
dust samples collected and submitted as required by this part, and not
voided by MSHA. Voided or invalid samples would not satisfy the
sampling requirements and operators would be required to collect and
submit additional samples. In addition, all samples required by this
part would be required to be taken while the Part 90 miner is
performing normal work duties. Failure to take the required number of
valid samples under proposed Sec. 90.204 would constitute a violation.
Consequently, it would be advantageous to collect and submit the
samples required early during the specified 15-day period.
While the proposed rule continues the operator requirement to
collect five valid samples, the results would no longer be averaged to
determine whether the applicable dust standard is being continuously
maintained. Instead, consistent with proposed Sec. 72.500 of this
title, each of the five valid sample will be compared to the applicable
dust standard individually. Under this evaluation procedure, if all
five samples are at or below the applicable dust standard, MSHA is
confident that the Part 90 miner is being placed in an atmosphere which
actually meets the standard. However, if any valid sample exceeds the
applicable dust standard by at least 0.1 mg/m3, the operator
would be required to immediately take corrective action and take an
additional five valid samples from the environment of the affected Part
90 miner within 15 days following receipt of notification from MSHA.
The proposed rule permits the operator to meet the applicable dust
standard in either of two ways: (1) By implementing control measures to
lower the dust concentration in the Part 90 miners's existing assigned
position; or (2) by transferring the Part 90 miner to another area of
the mine that meets the standard.
Since these samples are used to verify the suitability of the
assigned work position, no operator samples will be used to make
determinations as to compliance with the applicable dust standard under
Sec. Sec. 90.100 or 90.101 of this part. Therefore, if any of the
additional samples collected under proposed paragraph (b)(2) of this
section exceed the applicable dust standard by at least 0.1 mg/
m3, the operator would be cited for failure to take
corrective action under proposed paragraph (c) of this section.
Section 90.205 Respirable Dust Samples; Transmission by Operator
MSHA is proposing no substantive changes to existing Sec. 90.209,
except for removing reference to Sec. 90.202 (Certified person;
sampling) from existing paragraph (c) to eliminate repetition since
revised Sec. 90.201 specifies that all sampling required under this
part must be conducted by a certified person, and redesignating it as
Sec. 90.205. Existing paragraph Sec. 90.209(e) would be removed since
all samples submitted by the operator under this part would be
processed by MSHA. The proposed rule, like the existing rule, would
require each Part 90 miner sample collected by

[[Page 10835]]

the operator to be transmitted to MSHA within 24 hours after the end of
the sampling shift in containers provided by the manufacturer of the
filter cassette. The need to verify the suitability of the Part 90
miner's assigned work position in the shortest possible time requires
that samples be sent promptly to MSHA for analysis.
Each transmitted sample must be accompanied by a properly completed
dust data card. All dust data cards submitted must be signed by a
person certified to collect samples and must include that person's
certification number. By signing the card, that person certifies that
the sample was collected in accordance with the requirements of this
part.
To maintain program integrity, all samples transmitted by an
operator would be considered by this proposed rule to fulfill the
sampling requirements of this part. However, if operators wish to
collect samples for other purposes, they would need to notify the
district manager in writing or by electronic means prior to the
intended sampling shift and identify each filter cassette to be used by
its identification number. This prior notification is not required if
non-approved sampling devices and filter cassettes are used by an
operator for non-regulatory purposes.
Section 90.206 Respirable Dust Samples; Report to Operator and Part 90
Miners
Under the proposed rule, reporting provisions of existing Sec.
90.210 would be revised and redesignated as Sec. 90.206. It specifies
the type of sampling data and other related information the operator
would be provided by MSHA on each Part 90 miner sampled by the operator
or by MSHA. The Agency believes that the proposed reporting
requirements are in the best interest of the Part 90 miner. These
provisions promote miner awareness of the respirable dust conditions in
the Part 90 miner's working environment by making available current
information on the results of all sampling-related activities. This is
consistent with the statutory intent that miners play a role in
preventing unhealthy conditions and practices where they work. This
approach is also consistent with the recommendations of the Advisory
Committee regarding miner participation in the sampling process.
In proposed paragraph (a), the phrase ``The Secretary shall provide
the operator'' has been replaced with ``MSHA will provide.'' Paragraphs
(a)(1) through (6) of the proposed rule retains the existing
requirement regarding the types of data MSHA would be reporting on
samples submitted by the operator, except for paragraph (a)(4) which
would be removed since averaging of multiple valid samples would no
longer be permitted under the proposed rule. Also, since MSHA would
undertake sampling for compliance purposes, currently performed by the
operator under existing Sec. 90.208, the results of MSHA samples would
also be reported to the operator. The data report would include the
location within the mine from which each Part 90 miner sample was
collected; the equivalent concentration of respirable dust for each
valid sample; the occupation code, and the reason for voiding any
sample. In addition to providing data on individual samples, under
proposed paragraph (7), the Agency would also furnish information on
the dust control measures that were being used in the work position of
the sampled Part 90 miner by providing a copy of completed MSHA Form
2000-86 (Revised).
Paragraph (b) of the proposed rule retains the existing provision
of requiring the operator to provide a copy of the sample data report
to the affected Part 90 miner but, for privacy reasons, prohibits the
operator from posting the original or a copy of this report on the mine
bulletin report.
Section 90.207 Violation of Respirable Dust Standard; Issuance of
Citation; Action Required by Operator; and Termination of Citation
Proposed Sec. 90.207 is a new requirement that addresses the
circumstances under which MSHA would issue a citation for violation of
the applicable dust standard. It also establishes the specific actions
that an operator would be required to take within the time for
abatement fixed in the citation. This proposed section also sets forth
the conditions under which MSHA would terminate such citations.
Under proposed paragraph (a), the operator would be cited for a
violation of Sec. 90.100 or Sec. 90.101 when the equivalent
concentration of a valid Part 90 miner sample collected by MSHA meets
or exceeds the citation threshold value (CTV) listed in Table 70-2 of
this title that corresponds to the applicable dust standard in effect.
As discussed in section III.A.4. of the preamble, these measurements
will be based on single-shift samples collected with approved sampling
devices that will be operated portal-to-portal. The devices will remain
operational during the entire shift or for 8 hours, whichever time is
less, as has been the long-standing practice.
The CTVs and an explanation of how they were derived was originally
published in Federal Register notice of Feb. 3, 1998 (63 FR 5687),
entitled ``Coal Mine Respirable Dust Standard Noncompliance
Determinations.'' As explained in that notice and in Appendix C of the
current notice of proposed rulemaking, each CTV was calculated so that
citations would be issued only when a single-shift measurement
demonstrates noncompliance at least at a 95 percent confidence level.
The following example illustrates how MSHA would apply the CTVs to
make noncompliance determinations. Suppose that a measurement of 1.27
mg/m\3\ is obtained for a Part 90 miner under a 1.0-mg/m\3\ standard.
Because the measurement meets or exceeds the CTV of 1.26 mg/m\3\ (the
citation value for a 1.0-mg/m\3\ standard), a citation would be issued
for exceeding the applicable dust standard on the shift sampled. The
Part 90 miner's work position would be identified in the narrative of
the citation as the affected working environment.
MSHA believes that, because of the large ``margin of error''
separating each CTV from the corresponding applicable dust standard,
use of the CTV table would provide ample protection against erroneous
citations. This matter was fully explored in the analysis published in
Appendix C of the February 3, 1998 notice (63 FR 5703-5709). That
analysis showed that for exceptionally well-controlled environments,
the probability that any given citation is erroneous will be
substantially less than 5 percent. The analysis also showed that this
probability is even smaller in environments that are not well
controlled. Therefore, citations issued in accordance with the CTV
table would be much more likely the result of an excessive dust
concentration rather than a measurement error. With regard to the risk
of erroneous failures to cite, MSHA concluded that ``the probability of
erroneously failing to cite a case of noncompliance at a given sampling
location is less than 50 percent when the applicable dust standard is
exceeded on a significant proportion of shifts at that location'' (63
FR 5709 above).
MSHA has also concluded that using single-shift measurements for
noncompliance determinations in accordance with the CTV table neither
raises or lowers the applicable dust standard. Operators would continue
to be required under Sec. 90.100 or Sec. 90.101 to continuously
maintain compliance with the applicable dust standard, not merely at or
below the CTV.
As explained in the notice regarding single-shift measurements of
respirable coal mine dust published elsewhere in today's Federal
Register, the Mine Act requires MSHA to regulate exposures on

[[Page 10836]]

each shift individually. Since MSHA does not track the number of shifts
each miner works over a lifetime, MSHA must, as a matter of practical
necessity, protect miners by limiting their exposure on each shift.
Furthermore, as explained in Sections VI and VII of the present notice,
eliminating overexposures on individual shifts is beneficial to miners'
health. For miners working where there is a pattern of recurrent
overexposures on individual shifts, eliminating such overexposures is
expected, over a working lifetime, to significantly reduce the risk of
pneumoconiosis. Therefore, the Secretary has concluded that equivalent
dust concentrations should be maintained at or below the applicable
dust standard on each and every shift.
If an operator is cited for a violation of the applicable dust
standard, proposed paragraphs (b)(1), (b)(2), (b)(2)(i) and (b)(2)(ii)
would require the operator to take specific actions within the time for
abatement fixed in the citation. First, in order to provide immediate
health protection, the operator would be required to make available
approved respiratory equipment to the affected Part 90 miner that
complies with existing Sec. 70.300. The operator would then determine
the cause of the excessive dust concentration and take appropriate
corrective action to gain compliance. As under the current Part 90
rule, the proposed rule would permit the operator to achieve compliance
in either of two ways: (1) By implementing control measures to reduce
the dust levels in the Part 90 miner's work position; or (2) by
transferring the affected Part 90 miner to work in another location at
the mine where the concentration of respirable dust does not exceed the
standard. Any Part 90 miner who is transferred to another position
would continue to remain a Part 90 miner at the new position, even if
the job is at a surface mine.
If the operator chooses to lower dust levels in the Part 90 miner's
assigned work position, proposed paragraph (b)(2)(i) would require the
operator to notify the district manager in writing or by electronic
means within 24 hours after implementing the control measures. Since
MSHA would be assuming responsibility for compliance and abatement
sampling under this proposed rule, this notice would enable MSHA to
schedule and conduct follow-up sampling to determine whether the
operator's corrective action(s) was effective to gain compliance.
The requirement of proposed paragraph (b)(2(i) would not apply if
the corrective action involved transferring the Part 90 miner to
another work position to achieve compliance. Instead, the operator
would be required to comply with Sec. 90.102(c) by giving the district
manager written notice of the transfer and the date on which it is to
be effective before such a transfer would be allowed to occur. This is
necessary so that MSHA could (1) update its computerized management
information system to permit the processing of the five operator
samples taken from the Part 90 miner's new work position as required by
proposed paragraph (b)(3) of this section and (2) schedule and conduct
follow-up sampling for abatement purposes.
After complying with Sec. 90.102(c), the operator would be
required to sample the affected Part 90 miner until five valid samples
were collected and submitted within the abatement period fixed in the
citation. As discussed under proposed Sec. 90.204, the purpose for
taking these samples is to verify the suitability of the particular
working environment in which the Part 90 miner was placed. Therefore,
MSHA does not intend to take enforcement action based on the results of
operator samples, only for failure to take corrective action under
proposed paragraph (b)(2) of this section. Under this proposed rule,
only valid samples collected by MSHA would be used to abate a violation
of Sec. 90.100 or Sec. 90.101.
In order to determine if the operator abated the excessive dust
violation, MSHA would collect one valid sample from the affected Part
90 miner's position while he or she is performing normal work duties.
As discussed under Sec. 90.201, the duration of MSHA sample collection
would continue to be limited to 480 minutes as has been the long-
standing practice. If the MSHA abatement sample exceeds the applicable
dust standard but is less than the appropriate CTV, MSHA may sample
additional shifts to confirm the adequacy of the operator's corrective
action. MSHA would consider a violation of the applicable dust standard
to be abated and terminate the citation when the result of a valid MSHA
sample is at or below the applicable dust standard. The subsequent
action form would clearly and fully describe the action taken to abate
the violation. If the violation was abated by reducing the dust levels
in the Part 90 miner's work position, proposed paragraph (c)(1) would
require the operator to submit a respirable dust control plan to the
district manager for approval in accordance with Sec. 90.300 of this
part, which has been retained under this proposed rule. A dust control
plan would not be required to be submitted if compliance was achieved
by transferring the Part 90 miner to another work position at the mine.
Section 90.208 Status Change Reports
The proposed rule retains the existing provision of Sec. 90.220,
which would be redesignated as Sec. 90.208, with some revision. It
would require the operator to report in writing or by electronic means
any change in status of a Part 90 miner that affects sampling to a
designated MSHA District office within three working days after a
status change has occurred. Knowing the status of every Part 90 miner
will enable the Agency to carry out its sampling and monitoring of
operator sampling activities in the most efficient and responsible
manner. The operator would be in violation of Sec. 90.208 when the
operator fails to comply with the sampling requirements of this part or
MSHA was unable to carry out its sampling of a particular Part 90 miner
for compliance purposes due to the unavailability of the Part 90 miner
that was not reported by the operator as required.

Sections 90.300 and 90.301

Respirable Dust Control Plans

Section 90.300 Respirable Dust Control Plan; Filing Requirements;
Contents
The proposed rule retains the existing provisions of Sec. 90.300,
which sets forth in detail when a dust control plan must be filed and
the information that the operator must include in the plan. Although
the language of part of paragraph (a) of the proposed rule differs from
that of the existing section, the specific requirements are essentially
the same. This change was made in the proposed rule for clarity and
consistency with virtually identical provisions in existing Sec.
71.300 of this title.
If an operator abates the violation by implementing control
measures that lower the dust in the Part 90 miner's work position,
proposed paragraph (a) requires the operator to prepare a respirable
dust control plan applicable to the Part 90 miner in the position
identified in the citation. Each plan must be designed to continuously
maintain the respirable dust level, in the Part 90 miner's assigned
work position, at or below the applicable dust standard. This plan must
be submitted to the district manager for approval within 15 days after
the citation is terminated. A copy of the approved plan must be
provided to the affected Part 90 miner. However, the operator is
prohibited from posting the original or

[[Page 10837]]

a copy of the plan on the mine bulletin board.
If, on the other hand, the operator abates a violation of the
applicable dust standard by transferring the part 90 miner to another
position at the mine, the operator is not required to submit a dust
control plan to the district manager for approval.
As under existing paragraph (b), the operator would be required to
include details on the control measures that were implemented to reduce
the dust and abate the violation, as well as any other provisions
required by the district manager. The plan must also include the
specific time, place and manner that the control measures would be
used. Failure to do so would constitute a violation of this section.
Section 90.301 Respirable Dust Control Plan; Approval by District
Manager; Copy to Part 90 Miner
The proposed rule retains the existing provisions of Sec. 90.301,
which specifies the criteria MSHA would use to approve the operator's
dust control plan. Since MSHA would assume sampling of Part 90 miners
for compliance purposes, the following phrase was inserted towards the
end of paragraph (a): * * * ``the results of MSHA sampling and.'' Also,
the proposed rule would add the word ``continuously'' to paragraph
(a)(1) for consistency with Sec. 90.300(a), and replace the phrase
``MSHA may take respirable dust samples to determine whether'' in
paragraph (b) with ``MSHA will monitor the continued effectiveness of''
to reflect MSHA's assumption of sampling for compliance purposes.

V. Health Effects

A. Introduction

For as long as miners have taken coal from the ground, many have
suffered respiratory problems due to their occupational exposures to
respirable coal mine dust. Long-term retention of coal mine dust in the
lung causes chronic lung diseases including coal workers'
pneumoconiosis (CWP), silicosis, and chronic obstructive pulmonary
disease (COPD) (e.g., chronic bronchitis, emphysema, and airways
obstruction). Coal workers' pneumoconiosis occurs in two stages: simple
and complicated pneumoconiosis. Simple CWP is categorized into three
levels of severity: 1, 2, and 3. Miners with simple CWP, especially the
more advanced categories, have a substantially increased risk of
developing complicated pneumoconiosis (more typically known as
progressive massive fibrosis (PMF)). Progressive massive fibrosis can
cause significant loss of lung function and give rise to respiratory
symptoms (e.g., breathlessness, wheezing), and lead to disability and
premature mortality. Overall, coal miners are at risk of increased
morbidity and premature mortality arising from all of the chronic
diseases associated with coal mine dust exposure.
Elimination or reduction of coal mine dust exposure is the only
effective way to prevent or minimize occupational lung disease among
coal miners. However, routine screening affords the potential to
prevent further development of disease among those, who despite dust
control measures, still develop CWP. Pursuant to 42 CFR part 37, the
National Institute for Occupational Safety and Health (NIOSH) operates
a program for underground coal miners designed to detect early CWP.
This screening program for CWP is termed the Coal Workers' X-ray
Surveillance Program (CWXSP).
In 1998, MSHA estimated that there were approximately 45,000
underground coal miners and 39,000 surface coal miners (Mattos, 1999).
A small percentage of the mining involved anthracite coal, the highest
rank coal, while most involved bituminous coal which is a medium rank
coal.
There are complementary data sources, described below, which
provide estimates of the prevalence of occupational respiratory disease
among coal miners. Together these data demonstrate the progress over
the last thirty years in the reduction of occupational respiratory
disease among coal miners, as well as the need for further action to
reduce occupational lung disease.
In accordance with 30 CFR part 50, both surface and underground
coal mine operators must report any known cases of occupational
illnesses to MSHA. Under this requirement, mine operators reported 224
cases of coal workers' pneumoconiosis in 1998 (Mattos, 1999). Of these,
138 cases occurred among coal miners who worked underground, while the
remaining 86 cases occurred among surface coal miners (Mattos, 1999).
There were also 14 cases of silicosis, eight in underground mines,
reported to MSHA in 1998 in accordance with 30 CFR part 50 (Mattos,
1999).
In the 1990s, MSHA conducted a one-time medical screening and
surveillance program in various regions of the country. This program
was designed to help more coal miners, especially surface coal miners,
learn whether or not they had CWP, and to provide a more accurate
estimate of the prevalence of simple CWP and PMF among these coal
miners. Through this special program, MSHA tried to minimize obstacles
that may prevent some miners from participating in respiratory
diagnostic procedures. Nine geographical groups of miners were
encouraged to participate in this x-ray program that was independent of
the CWXSP (MSHA, Internal Chart, 1999). The study groups included eight
active surface coal mining communities in Pennsylvania, Kentucky and
West Virginia, as well as Poteau, Oklahoma and Gillette, Wyoming. A
ninth group included underground miners in Kentucky. The process was
designed to encourage miner participation by providing for a greater
degree of anonymity than may be available under the NIOSH x-ray
program. Across the eight surface groups surveyed, the prevalence rate
of CWP among participants was 5.6% (130/2,305). The CWP prevalence rate
among the participating underground Kentucky miners was 9.2% (37/404).
Due to the different outreach initiatives number and type of
participants in these various subgroups, relative to the population of
today's coal miners, these data may not be representative of the
overall prevalence of CWP among today's coal miners.
The Secretary of Labor's Advisory Committee on the Elimination of
Pneumoconiosis Among Coal Workers (Dust Advisory Committee, 1996)
recommended that the CWXSP for pneumoconiosis include surface coal
miners and independent contractors and that it increase underground
coal miners' participation to at least 85 percent. In response, MSHA
and NIOSH implemented the Miners' Choice Health Screening Program
(Miners' Choice) in October 1999. The Miners' Choice program and Coal
Workers' X-Ray Surveillance Program (CWXSP) identify cases of simple
and complicated pneumoconiosis, including coal workers' pneumoconiosis
and silicosis--hereafter referred to as ``CWP.'' All of the Miners''
Choice x-rays were processed using the same procedures and criteria
used in the CWXSP in accordance with the requirements of 42 CFR part
37.
MSHA and NIOSH are conducting preliminary analyses of the first
three years of the Miners' Choice program. These data and analyses are
being handled, conducted, and reported pursuant to the DOL's and DHHS's
respective Information Quality

[[Page 10838]]

Guidelines.\14\ Preliminary analyses of these data are expected in
Spring 2003. The analyses will be made available to commenters through
the MSHA and NIOSH Web sites, http://www.msha.gov and http://
www.cdc.gov/niosh/homepage.html respectively.

---------------------------------------------------------------------------

\14\ Specifically, the information is maintained in a
confidential manner, all methodologies for data processing are
transparent, and all available records were included. This
information is reliable and accurate, and is presented in a clear
and objective manner, as required by the Department of Labor's
Information Quality Guidelines and the Department of Health and
Human Services' Guidelines for Ensuring the Quality of Information
Disseminated to the Public.
---------------------------------------------------------------------------

As of the end of fiscal year 2002, more than 19,500 active coal
miners from 20 states voluntarily participated in Miners' Choice. The
overall CWP prevalence rate for radiographic categories of simple CWP
categories 1, 2, 3, and PMF combined was 2.8% (546/19,517) among miners
examined in Miners' Choice during the 2000-2002 period. This is similar
to the CWP prevalence rate of 2.25% for initial participants in the
Miners' Choice Program reported in the 2000 NPRM (65 FR 42100). Among
Miners' Choice participants, the CWP prevalence rate was higher among
underground coal miners at 3.8% (356/9,265), than it was for surface
coal miners, 1.8% (188/10,184). The CWP prevalence rate for independent
contractors was 2.9% (2/68). These findings show that CWP continues to
occur among coal miners working under the current program to control
respirable coal mine dust, including quartz.
Coal miners with simple CWP, particularly the advanced categories,
are much more likely to develop life-threatening complicated CWP (i.e.,
progressive massive fibrosis, or PMF), than those with category 0 (ILO
profusion categories of 0/0 or 0/1) (Cochrane, 1962; Hurley et al.,
1987; Hurley and Jacobsen, 1986; Hurley and Maclaren, 1987; Jacobsen,
et al., 1971; McLintock, et al., 1971; and Morfeld, et al., 1992). In
addition, epidemiological studies have shown that even among miners
with category 0, those with a CWP profusion category suggesting
pneumoconiosis (i.e., 0/1) are at increased risk of developing PMF
compared to miners with a CWP profusion category of 0/0 (Hodous and
Attfield, 1990 and McLintock, et al., 1971).
Several studies provide consistent information relevant to this
issue. In a study of miners who participated in round six (1990-1995)
of the Coal Workers' X-Ray Surveillance Program (CWXSP), Althouse et
al. (1998) found an average prevalence rate of 2.2% for simple CWP
category 1 and higher among the 8,210 miners who reported beginning
work in underground coal mines in 1973 or later. Miners who reported
other prior dusty work were excluded from the analysis. Althouse et al.
(1998) also report an overall decline in the CWP prevalence rates
between 1970 and 1995. While this result is encouraging, it also
demonstrates that pneumoconiosis is still occurring among miners who
have worked only under the current applicable dust standard, and for
less than a full working lifetime. The Althouse et al. (1998) study did
not include estimates of exposure concentration, but the prevalence
rates were shown to increase with tenure in mining (up to 22 years). In
an earlier study, NIOSH compared the observed prevalences of CWP among
miners who participated in rounds 3 and 4 of the CWXSP with the
predicted prevalences from the epidemiological study by Attfield and
Morring (1992b) (NIOSH 1995, Appendix L). That analysis included coal
miners in the CWXSP who had started work between 1969 and 1986 and who
had worked 10 or more years; exposure concentrations were estimated at
or below the current standard. NIOSH found that the observed and
predicted prevalences were similar, thus supporting the validity of the
predictions from that epidemiological study. The findings from the
Attfield and Morring (1992b) study are consistent with the findings
from other epidemiological studies, including Attfield and Seixas
(1995). Comparing the effect of miners' exposures received either
before or after 1970, Attfield and Seixas (1995) found that exposure
during both time periods contributed to the development of
pneumoconiosis.
In addition, the epidemiological studies are relevant to predicting
the risks of occupational respiratory diseases among miners working
today because the cumulative exposures of miners working at the current
standard of 2.0 mg/m3 for a full 45-year working lifetime
are well within the range of the data examined in these studies
(Attfield and Seixas, 1995; Attfield and Morring 1992a,b; Attfield and
Hodous, 1992; Seixas et al. 1992, 1993). Thus, risk estimates based on
these studies do not require extrapolation beyond the range of the
data. These epidemiological studies included quantitative estimates of
miners' exposures to respirable coal mine dust and found statistically
significant relationships between cumulative exposure and prevalence of
pneumoconiosis or COPD. Despite several differences in the surveillance
and epidemiological studies (e.g., exposure estimation and tenure, x-
ray readers, miner participation rates, and mines), the observed
prevalence rates from the surveillance studies confirm the predicted
prevalences from the epidemiological studies.
The Mine Act of 1977 states:

``* * * in promulgating mandatory [health]
standards which must
adequately assure on the basis of the best available evidence that
no miner will suffer material impairment of health or functional
capacity even if such miner has regular exposure to the hazards
dealt with by such standards for the period of his working life.''
Mine Act 101(a)(6)(A).

Findings from the CWXSP indicate an overall decline in the prevalence
of CWP from 11% in the 1970s to 2.8% in the sixth round of CWXSP (1992-
1996) (NIOSH, Work-Related Lung Disease Surveillance Report, Table 2-
11, 1999). Even so, Miners' Choice, CWXSP, and MSHA's one-time medical
surveillance programs in the 1990s consistently show prevalence of CWP
to be at levels that cause concern. If patterns of overexposure to
respirable coal mine dust remain unchanged for these coal miners, the
prevalence of CWP would continue to increase, as their cumulative
exposure to respirable coal mine dust increases over their coal mining
careers.
Both MSHA and NIOSH (Re-opening notice for the Determination of
Respirable Coal Mine Dust published elsewhere in today's Federal
Register; Criteria Document, 1995) find the current program for
preventing overexposures to respirable coal mine dust is not sufficient
to adequately prevent overexposures to respirable coal mine dust and
protect the health of the coal miners.

B. Hazard Identification

1. Agent: Coal
Coal is a fossil fuel derived from partial degradation of
vegetation. Through its combustion, energy is produced which makes coal
a valuable global commodity. It has been estimated that over one-third
of the world uses energy provided by coal (Manahan, 1994).
Approximately 1,800 underground and surface coal mines are in operation
in the United States annually producing slightly over a billion short
tons of coal (Mattos, 1999).
Coal may be classified on the basis of its type, grade, and rank.
The type of coal is based upon the plant material (e.g., lignin,
cellulose) from which it originated. The grade of coal refers to its
chemical purity. Although coal is largely carbon, it may also contain
other elements such as hydrogen, oxygen,

[[Page 10839]]

nitrogen, and sulfur. ``Hard'' coal refers to coal with a higher carbon
content (i.e., 90-95%) than ``soft'' coal (i.e., 65-75%). Coal rank
relates to geologic age, indexed by its fixed carbon content, down to
65%, and then by its heating value. Volatile matter varies inversely
with the fixed carbon value. The most commonly described coal ranks
include lignite (low rank), bituminous coal (medium rank), and
anthracite (high rank) (Manahan, 1994).
2. Physical State: Coal Mine Dust
Aerosols are a suspension of solid or liquid particles in air
(Mercer, 1973); they may be dusts which are solid particles suspended
in the air. Coal dust may be freshly generated or may be re-suspended
from surfaces on which it is deposited in mines. As discussed below,
coal mine dust may be inhaled by miners, depending upon the particle
size.
Coal mine dust is a heterogenous mixture, signifying that all coal
particles do not have the same chemical composition. The particles are
influenced by the type, grade, and rank of coal from which they were
generated (Manahan, 1994). Irrespective of differences in coal
characteristics, these dusts are water-insoluble, which is important
biologically and physiologically. Unlike soluble dusts which may
readily pass into the respiratory system and be cleared via the
circulatory system, insoluble dusts may remain in the lungs for
prolonged periods of time. Thus, a variety of cellular responses may
result that could eventually lead to lung disease.
3. Biological Respirable Coal Mine Dust
The principal route of occupational exposure to respirable coal
mine dust occurs via inhalation. As a miner breathes, coal mine dust
enters the nose and/or mouth and may pass into the mid airways (e.g.,
bronchi, terminal bronchioles) and lower airways (e.g., respiratory
bronchioles, alveolar ducts).
Coal mine dust has a size distribution that is estimated to range
between 1 and 100 micrometers ([mu]m) (1 [mu]m = 10-6 m)
(Silverman, et al., 1971). The size of coal particles is critical in
determining the level of the respiratory tract at which deposition and
retention occur (American Conference of Governmental Industrial
Hygienists, 1999; American Industrial Hygiene Association, 1997).
Particles that are greater than 10 [mu]m are largely filtered in
the nasal passages. However, it has long been known that some particles
greater than 10 [mu]m in size, can be inhaled, and that some of these
particles can reach the alveoli of the lungs (Lippman and Albert,
1969). According to the British National Coal Board, ``particles as
large as 20 microns (i.e., micrometers ([mu]m)) mean diameter may be
deposited, although most `lung dust' lies in the range below 10 microns
diameters'' (Goddard, et al., 1973). Particles less than 10 [mu]m in
size easily move throughout the respiratory tract. As particle size
decreases from 10 to 5 [mu]m, however, there is greater penetration
into the mid and lower regions of the lung. Particles that are
approximately 1-2 [mu]m are the most likely to be deposited in the lung
(American Conference of Governmental Industrial Hygienists, 1999;
Mercer, 1973). During mouth breathing, there may be a slight upward
shift in the particle deposition curve such that 2-3 [mu]m-sized
particles are the most likely to be deposited in the respiratory tract
(Heyder, et al., 1986). Irrespective of nasal or mouth breathing, the
potential respiratory tract penetration of particles less than 10 [mu]m
in size is important because particles in the respirable size range
deposit in the deep lung where clearance is much slower.
For the purposes of this rule, ``respirable dust'' is defined as
dust collected with a sampling device approved by the Secretary of
Labor and the Secretary of the Department of Health and Human Services
(DHHS) in accordance with 30 CFR Part 74 (Coal Mine Dust Personal
Sampler Units). In practice, the coal mine dust personal sampler unit
has been used in the U.S. The particles collected with an approved
sampler approximate that portion of the dust which may be deposited in
the lung (West, 1990; 1992). It does not, however, indicate pulmonary
retention (i.e., those particles remaining in the lung). For those
particles that are deposited in the lung, clearance mechanisms normally
operate to assist in their removal. For example, within the thoracic
(tracheal-bronchial) region of the lung, cilia (i.e., hairlike
projections) line the airways and are covered by a thin layer of mucus.
They assist in particle clearance by beating rhythmically to project
particles toward the throat where they may be swallowed, coughed,
sneezed, or expectorated. This rhythmic beating action is effective in
removing particles fairly quickly (i.e., hours or days). Within the
alveolar region of the lung, particles may be engulfed by pulmonary
macrophages. These large ``wandering cells'' may remove particles via
the blood or lymphatics. This process, unlike the movement of the cilia
is much slower (i.e., months or years). Thus, some particles,
particularly those that are insoluble, may remain in the alveolar
region for long periods of time, despite the fact that pulmonary
clearance is not impaired. It is the pulmonary retention of coal mine
dust which may be the impetus for respiratory disease.
It is also important to note that silica may be present in the coal
seam, within dirt bands in the coal seam, and in rock above and below
coal seams. Of the silica found in coal mines, quartz is the form which
is found. Thus, quartz may become airborne during coal removal
operations (Manahan, 1994). Miners may inhale dust that is a mixture of
quartz and coal. MSHA is concerned with the inhalation of quartz since
it may be deposited in the lungs of miners and produce silicosis. This
is a restrictive lung disease which is characterized by a stiffening of
the lungs (West, 1990; 1992). Silicosis has been seen in coal miners
(e.g., surface miners, drillers, roofbolters) (Balaan, et al, 1993).
Silicosis may develop acutely (i.e., 6 months to 2 years) following
intense exposure to high levels of respirable crystalline quartz.
Silicosis has also been observed in coal miners following chronic
exposure (i.e., 15 years or more), but may be accelerated (i.e., 7-10
years) in some cases (Balaan, et al, 1993). Silicosis is irreversible
and may lead to other illnesses and premature mortality. People with
silicosis have increased risk of pulmonary tuberculosis infection and
an increased risk of lung cancer (Althouse, et al., 1995; International
Agency for Research on Cancer, 1997). MSHA's current standard of 2.0
mg/m3 for respirable coal dust requires that quartz levels
in the respirable coal mine dust be 5% or lower. Otherwise, the 2.0 mg/
m3 respirable coal dust exposure limit does not apply and
must be adjusted downward for percentage of quartz. If respirable coal
mine dust contains more than 5% quartz, then the following formula is
applied (30 CFR 70.101; 30 CFR 71.101).
Respirable dust standard (mg/m3)= {(10)/(% Quartz){time}
The intent of this formula, as prescribed by the Secretary of
Health, Education, and Welfare in 1971, whenever the respirable coal
mine dust in the mine atmosphere of the active workings contains more
than five percent quartz, is to maintain miner exposures to quartz
below 0.1 mg/m3 (100 [mu]g/m3).\15\
------------------------------------------------------------------------

\15\ The applicable dust standard for intake air in Sec.
70.100(b) and for miners who have exercised rights under Part 90
regulations in Sec. 90.100 is 1.0 mg/m3. Those standards
are also lowered if the quartz content of the respirable coal mine
dust exceeds 5 percent. However, no effect occurs until the quartz
content exceeds 10 percent.

------------------------------------------------------------------------

[[Page 10840]]

C. Health-Related Effects of Respirable Coal Mine Dust

1. Description of Major Health Effects
Consistently, epidemiological studies have demonstrated miners to
be at risk of developing respiratory symptoms, a loss of lung function,
and lung disease as a consequence of occupational exposure to
respirable coal mine dust. As noted previously, risk factors include
type(s) of dust, dust concentration, duration of exposure, age of the
miner (often measured as age at time of medical examination), and coal
rank.
a. Simple Coal Workers' Pneumoconiosis (Simple CWP) and Progressive
Massive Fibrosis (PMF)
In earlier stages of pneumoconiosis the term, ``simple coal
workers' pneumoconiosis'' (simple CWP), has been used, while in more
advanced stages, the terms ``complicated CWP'' and PMF have been used
interchangeably. Simple CWP and PMF involve the lung parenchyma and are
produced by deposition and retention of respirable coal dust in the
lung.
To determine if a miner has simple CWP or PMF, chest x-rays are
taken and classified by a certified radiologist or reader. Opacities
(both irregular and rounded) are identified on chest films and then
classified using a scale of 0 through 3 (e.g., simple CWP category 1),
where higher category values indicate increasing concentration of
opacities. In some instances, two category values may be given. For
example, simple CWP category 2/3 signifies that the reader decided the
film was category 2, but suspected that it might have been category 3.
The International Labour Office (ILO) has provided a full description
of the criteria for these classifications (ILO, 1980).
Studies have shown that the prevalences of both small rounded and
small irregular opacities increase with increasing coal mine dust
exposure (Amandus et al., 1976; Cockcroft et al., 1983; Collins et al.,
1988). Miners with small opacities (rounded and/or irregular) on their
chest x-rays were more likely to report chronic cough and phlegm, and
breathlessness, than miners without small opacities (category 0/0)
(Collins et al., 1988). This effect was more common among miners with
predominately small rounded opacities (Collins et al., 1988; Rae et
al., 1971). Small irregular opacities have been associated with
impaired lung function (Amandus et al., 1976; Cockcroft et al.,
1982b,c; Collins et al., 1988). The pattern of lung function impairment
reported by Collins et al. (1988) was consistent with that typically
associated with dust exposure in coal miners, and was distinctly
different from the pattern observed among smokers.
Because simple CWP represents an early stage of a progressive
disease, miners who have had a chest x-ray classified as ILO category 1
or greater are more likely than those with a clear x-ray (category 0)
to progress to the more severe stages of the disease, including the
complicated form, PMF (categories A, B, or C) (Cochrane, 1962;
Jacobsen, et al., 1971; McLintock, et al., 1971; Morfeld et al., 1992;
Balaan, et al., 1993). In addition, miners with simple CWP were found
to have an increased risk of dying from pneumoconiosis (as the
underlying or a contributing cause on the death certificate), and this
risk tended to increase with increasing radiographic category (Kuempel
et al., 1995).
Progressive massive fibrosis (PMF) is associated with decreased
lung function and increased premature mortality (Rasmussen, et al.,
1968; Atuhaire, et al., 1985; Miller and Jacobsen, 1985; Attfield and
Wagner, 1992). Progressive massive fibrosis is also associated with
increases in respiratory symptoms such as chest tightness, cough, and
shortness of breath. Miners with PMF also have an increased risk of
acquiring infections and pulmonary tuberculosis (Petsonk and Attfield,
1994; Yi and Zhang, 1996). Finally, miners with PMF have an increased
risk of right-side heart failure (i.e., cor pulmonale) (Cotes and
Steel, 1987).
b. Other Health Effects
During a medical examination, a miner may be questioned by his/her
physician about symptoms such as cough, phlegm production, chest
tightness, shortness of breath, and wheezing. Occupational physicians
may also conduct pulmonary function tests using spirometry or
plethysmography. Pulmonary performance may be assessed via repeated
measurements of lung volumes and capacities, such as the forced
expiratory volume in one second (FEV1), vital capacity (VC), forced
vital capacity (FVC), residual volume (RV), and total lung capacity
(TLC) (West, 1990; 1992). Changes in lung volumes and capacities may
indicate a loss of the integrity of the lung (i.e., respiratory
system). More importantly, they can provide information for diagnosis
of diseases affecting the airways and/or elasticity of the lung (i.e.,
obstructive vs. restrictive lung disease)(West, 1990; 1992).
The term, chronic obstructive pulmonary disease (COPD), refers to
three disease processes that are often difficult to properly diagnose
and differentiate: Chronic bronchitis, emphysema, and asthma (Coggon
and Taylor, 1998; Garshick, et al., 1996; West, 1990; 1992). As
indicated by several studies, the exposure of miners to respirable coal
mine dust places them at increased risk of developing COPD.
Furthermore, COPD may occur in miners with or without the presence of
simple CWP or PMF.
COPD is characterized by airflow limitations, and thus there is a
loss of pulmonary function. As in simple CWP or PMF, a miner with COPD
may have a variety of respiratory symptoms (e.g., shortness of breath,
cough, sputum production, and wheezing) and may be at increased risk of
acquiring infections. COPD is associated with increased premature
mortality (Hansen, et al., 1999; Meijers, et al., 1997).
Briefly, in chronic bronchitis and in asthma, there is excess
mucous secretion in the mid to lower airways (West, 1990; 1992). In
contrast, emphysema is characterized by dilatation (enlargement) of
alveoli that are distal to the terminal bronchioles, which leads to
poor gas exchange (i.e., poor transfer of oxygen and carbon dioxide).
Additionally, there is a breakdown of the interstitium between the
alveoli. These pathological changes may be confirmed upon autopsy. With
asthma, the airflow limitations may be partially or completely
reversible, while they are only partially reversible with chronic
bronchitis and emphysema.
The Mine Safety and Health Administration (MSHA) and the NIOSH
recognize that respiratory symptoms, loss of lung function, and COPD
may impair the ability of a miner to perform his/her job and may
diminish his/her quality of life (65 FR 49215). Additionally, miners
having such health effects are at increased risk of morbidity (e.g.,
from cardio-pulmonary disease, infections) and premature mortality.
2. Toxicological Literature
To better understand the human health effects of exposure to
respirable coal mine dust and to more fully characterize the associated
risks, it is important to consider data that have been obtained in
animal based toxicological studies. To date, sub-acute studies (a study
with a duration of 30 days, or less, in which multiple exposures of the
same agent are given) and chronic studies (a study with a duration of
more than 3-months, in which multiple exposures of same agent are
given) attempted to mimic miners'

[[Page 10841]]

exposures. Inhalation was generally the route of exposure, although
several studies have also employed instillation techniques (i.e., a
method which places a known quantity of dust into the trachea or
bronchi).
Most recent toxicological studies have been short-term studies,
largely focusing on ``lung overload'' (Sipes, 1996; Oberdorster, 1995;
Morrow, 1988, 1992; Witschi, 1990), species-dependent lung responses
(Nikula, et al., 1997a,b; Mauderly, 1996; Lewis, et al., 1989; Moorman,
et al., 1975), and particle size-dependent lung inflammation (Soutar,
et al., 1997). The data have shown that pulmonary clearance of
particles may become impaired, potentially leading to inflammatory and
other cellular responses in the lung. Although overloading has not been
demonstrated in humans, the finding of reduced lung clearance among
retired U.S. coal miners (Freedman and Robinson, 1988) is consistent
with this possibility.
The data from Moorman, et al. (1975), Lewis, et al. (1989), and
Nikula, et al. (1997a,b) are noteworthy for several reasons. First,
these groups of investigators conducted chronic inhalation toxicity
studies (i.e., chronic bioassays). This is important since miners'
exposures also occur via inhalation, and over a working lifetime.
Secondly, the investigators used an exposure concentration of 2.0 mg/
m3 in their bioassays. As noted above, this is the current
MSHA standard for respirable coal mine dust. Thirdly, the exposures
involved nonhuman primates, whose responses are thought to closely
mimic those of man. Some of the key findings of these studies included:
deposition of coal dust in the animals' lungs, retention of coal dust
in alveolar tissue, altered lung defense mechanisms, reduced pulmonary
airflows, and hyperinflation of the lungs. One of the shortcomings of
these studies is that complete dose-response relationships were not
developed. However, at higher exposure concentrations, greater effects
may be expected which is a basic tenet of toxicology. Thus, at exposure
concentrations above 2.0 mg/m3, MSHA and NIOSH believe that
more severe obstructive lung disease may occur (65 FR 42078).
3. Epidemiological Literature
Epidemiological studies have consistently demonstrated the serious
health effects of exposure to high levels of respirable coal mine dust
(i.e., above 2.0 mg/m3) over a working lifetime. Table V-2
lists epidemiological studies since 1986 whose results will be
discussed on the basis of the type of observed health effect. Studies
completed even earlier including the early work of Cochrane (1962),
McLintock, et al. (1971), and Jacobsen, et al. (1971) demonstrated the
adverse health effects (e.g., simple CWP, PMF) of respirable coal mine
dust in British coal miners.
Both early and recent studies have shown that the lung is the major
target organ (i.e., organ in which toxic effects occur) when exposure
to respirable coal mine dust occurs. As seen in Table V-2, numerous
studies of miners have been conducted. Recent U.S. studies were
conducted using data from one or more of the first four rounds of the
National Study of Coal Workers' Pneumoconiosis (NSCWP), and have
provided extensive data on miners' health. Many of these studies
demonstrated that miners are at increased risk of multiple, concurrent
respiratory ailments (Attfield and Seixas, 1995; Kuempel, et al., 1997;
Meijers, et al., 1997; Seixas, et al., 1992) .

Table V-2.--Respirable Coal Mine Dust Epidemiological Studies, by
Reported Outcomes from 1986 to Present
------------------------------------------------------------------------
Studies Reported outcomes
------------------------------------------------------------------------
Meijers, et al., 1997............ PMF, SCWP, COPD, LLF
Bourgkard, et al., 1998.......... PMF, SCWP, LLF, RS
Kuempel, et al., 1997*...........
Maclaren, et al., 1989...........
Kuempel, et al., 1995*........... PMF, SCWP, COPD
Love, et al., 1997............... PMF, SCWP, LLF
Love, et al., 1992...............
Althouse, et al., 1998*.......... PMF, SCWP
Attfield and Morring,1992b*......
Attfield and Seixas, 1995*.......
Goodwin and Attfield, 1998*......
Hodous and Attfield, 1990*.......
Hurley and Jacobsen, 1986........
Hurley and Maclaren, 1987; 1988
Hurley, et al., 1987.............
Morfeld, et al., 1997............
Starzynski, et al., 1996.........
Yi and Zhang, 1996...............
Collins, et al., 1988............ SCWP, COPD, LLF, RS
Morfeld, et al., 1997............ SCWP
Cockcroft and Andersson, 1987.... SCWP, COPD, LLF
Wang, et al., 1997...............
Leigh, et al., 1994.............. COPD, LLF, RS
Marine, et al., 1988.............
Seixas, et al., 1993.............
Soutar and Hurley, 1986..........
Attfield and Hodous, 1992*....... LLF, RS
Carta, et al., 1996..............
Henneberger and Attfield,1997*...
Henneberger and Attfield,1996*...
Lewis, et al., 1996..............
Seixas, et al., 1992*............

[[Page 10842]]

Hansen, et al.,.................. 1999 LLF
Weiss, et al., 1995..............
------------------------------------------------------------------------
COPD: Chronic obstructive pulmonary disease.
SCWP: Simple coal workers' pneumoconiosis.
LLF: Loss of lung function.
PMF: Progressive massive fibrosis.
RS: Respiratory symptoms.
* Studies of U.S. Miners Who Participated in the National Study of Coal
Workers' Pneumoconiosis (NSCWP).

a. Simple Coal Workers' Pneumoconiosis (Simple CWP) and Progressive
Massive Fibrosis (PMF)
Studies following Cochrane (1962) and McLintock et al. (1971) have
confirmed that the risk of PMF increases with increasing category of
simple CWP (Hurley and Jacobsen, 1986; Hurley, et al., 1987; Hurley and
Maclaren, 1988; Hodous and Attfield, 1990). However, the risk of PMF
was greater than previously predicted among miners with simple CWP
category 1 or without simple CWP (i.e., category 0) (Hurley, et al.,
1987). The risk of PMF increased with increasing cumulative exposure,
regardless of the initial category of simple CWP (Hurley, et al.,
1987), indicating that reducing dust exposures is a more effective
means of reducing the risk of PMF than reliance on detection of simple
CWP.
Attfield and Seixas (1995) have demonstrated a relationship between
cumulative exposure to respirable coal mine dust and predicted
prevalence of pneumoconiosis (i.e., simple CWP, PMF). Two strengths of
this study include the quantitative description of exposure-response
among both miners and ex-miners (who had worked approximately 13-40
years in mining) and the fact that these data represent recent
conditions experienced by miners in the U.S. They studied a group of
approximately 3,194 men who worked in underground bituminous coal
mines. The U.S. miners and ex-miners had participated in Round 1 (1970-
1972) or Round 2 (1972-1975) of the NSCWP and were examined again in
Round 4 (1985-1988). The study population excludes 86 miners for whom
there was missing exposure data or unreadable x-rays. Chest x-rays were
read to determine the number of cases of simple CWP and PMF. Attfield
and Sexias (1995) used two or three B readers to identify the profusion
of radiographic opacities based on the ILO classification scheme. The
most inclusive category defined in their paper was CPW 1+ which
includes simple CWP categories 1, 2, and 3, as well as PMF. Dust
exposure estimates were generated from measurements of dust
concentrations as well as from work history. A logistic (or logit)
regression model was used to estimate prevalence of simple CWP and PMF.
In this statistical analysis, proportions are transformed to natural
logarithmic values, i.e., y = ln [p/(1-p), before a linear model is fit
to the data (Armitage, 1977). The logistic model assumes that the data
have a binomial distribution (e.g., presence or absence of PMF) for a
given set of covariate values (e.g., age, coal rank, dust exposure,
pack-years of smoking). Using logistic modeling, relationships were
developed between cumulative dust exposure and prevalence of simple CWP
(category 1+, category 2+) and PMF. These relationships were the key
strengths of the Attfield and Seixas study and serve as the basis for
the quantitative risk assessment (QRA) of this rule.
The recent paper of Kuempel, et al. (1997) has provided a detailed
discussion and quantitative presentation of excess risks associated
with respirable coal dust exposures. Their study was based upon results
from previous studies of some 9,000 underground coal miners who
participated in the NSCWP (Attfield and Morring, 1992b; Attfield and
Seixas, 1995). Kuempel, et al. estimated excess (exposure-attributable)
prevalence of simple CWP and PMF (i.e., number of cases of disease
present in a population at a specified time, divided by the number of
persons in the population at that specified time). Point estimates of
excess risk of PMF ranged from 1/1000 to 167/1000 among miners exposed
at the current MSHA standard for respirable coal mine dust. These
estimates were based upon dust exposure that occurred over a miner's
working lifetime (e.g., 8 hours per day, 5 days a week, 50 weeks per
year, over a period of 45 years). Actual occupational lifetime exposure
may be more, due to extended work shifts and work weeks. The point
estimates of PMF presented by Kuempel, et al. (1997) were related to
coal rank, where higher estimates (e.g., 167/1000) were obtained for
high-rank coal (anthracite coal) and somewhat lower estimates were
obtained for medium/low rank bituminous coal (e.g., 21/1000). Within
each coal rank, the estimates of simple CWP cases were at least twice
as high as those for PMF (e.g., 167/1000 PMF vs. 380/1000 simple
CWP£=1).
The data of Attfield and Seixas (1995) and Kuempel, et al. (1995;
1997) were consistent with previous data of Attfield and Morring
(1992b) who reported relationships between estimated dust exposure and
predicted prevalence of simple CWP or PMF. They also noted that
exposure-response relationships were steeper for higher ranks of coal
such as anthracite, and concluded that the risks for anthracite miners
appeared to be greater than for miners exposed to lower rank coal dust.
Attfield and Morring (1992b) used similar methods as described above
(i.e., logistic modeling), but included miners from Round 1 of the
NSCWP (1969-1971); thus representing an earlier time point in the NSCWP
when the respirable coal mine dust concentrations were much higher than
they are today.
Recently, Goodwin and Attfield (1998) reported that there were
concerns regarding methodological inconsistencies across surveys given
during the four rounds of the NSCWP. In particular, they noted the
discordance in classification of simple CWP and PMF among readers of
chest films. Despite potential discordance, Goodwin and Attfield (1998)
have confirmed previous findings of a decline in simple CWP prevalence
from 1969 to 1988. Yet, these analyses also demonstrated that simple
CWP has not been eliminated. The Round 4 prevalence rates were 3.9
percent for simple CWP category 1 and higher, and 0.9 percent for
category 2 and higher. This illustrates the need for continued efforts
to reduce dust exposures.
Given the current system for monitoring exposures and identifying
overexposures in the U.S., miners are at increased risk of developing
simple

[[Page 10843]]

CWP and PMF from a working lifetime exposure to respirable coal mine
dust (Althouse et al. 1998, Attfield and Seixas, 1995; Attfield and
Morring, 1992b; Goodwin and Attfield, 1998; Kuempel, et al. 1997,
1995). Whenever overexposures (i.e., excursions above the applicable
dust standard) occur, the long-term mean exposure of miners may be
increased, thereby causing an upward shift on the exposure-response
curve. Such a shift then places these overexposed coal miners at
increased risk of developing and dying prematurely from simple CWP and
PMF.
The Attfield and Seixas epidemiological study (1995) is the most
appropriate to use in estimating the benefit of reduction of
overexposures. The authors applied scientific rigor to the collection,
categorization, and analyses of the radiographic evidence for the group
of 3,194 underground bituminous coal miners who participated in Round
4, 1985-1988, of the National Study of Coal Workers' Pneumoconiosis
(NSCWP). Radiologic evidence was carefully collected and analyzed by
multiple independent, NIOSH certified B readers to identify stages of
simple CWP and PMF. In the targeted population of 5,557 miners, the
participating miners (3,280) were similar to the non-participants
(2,277) with regard to age at the first medical examination and
prevalence of simple CWP category 1 or greater. The non-participants
had worked slightly longer, yet had lower prevalence of simple CWP
category 2 or greater, than the participants. This study describes the
differences among current miners and ex-miners (health-related or job-
related) in the relationships between the estimated cumulative exposure
to respirable coal mine dust and prevalence of simple CWP category 1 or
greater. Such data and relationships were not available in other U.S.
studies and non-U.S. studies.
A potential limitation in the U.S. studies is the possible bias in
the exposure data, which has been the subject of several studies (Boden
and Gold, 1984; Seixas et al., 1991; Attfield and Hearl, 1996). An
advantage of the Attfield and Seixas 1995 study (and the earlier
studies based on the same data set) is that the larger mines included
in these epidemiological studies were shown to have exposure data with
relatively small bias (Attfield and Hearl, 1996). Another limitation in
exposure data used in the U.S. studies is that the airborne dust
concentrations used to estimate individual miners' cumulative exposures
to respirable coal mine dust were based on average concentrations
within job category (these average values were combined with data of
each individual miner's duration employed in a given job). The earlier
U.S. exposure-response studies of miners participating in the first
medical survey of the NSCWP (Attfield and Morring, 1992b; Attfield and
Hodous, 1992; Kuempel, et al., 1995) relied primarily on exposure
measurements from a dust sampling survey during 1968-1969 to estimate
miners' exposures before 1970 (Attfield and Morring, 1992a). An
advantage of the Attfield and Seixas 1995 study is that, in addition to
the pre-1970 exposure estimates, more detailed exposure data were
available to estimate miners' exposures from 1970 to 1987, during which
the mean airborne concentrations were stratified by mine, job, and year
(Seixas, et al., 1991).
The most complete exposure data available are those for coal miners
in the United Kingdom (Hurley, et al., 1987; Hurley and Maclaren, 1987;
Soutar and Hurley, 1986; Marine, et al., 1988; Maclaren, et al., 1989).
These studies include medical examinations and individual estimates of
exposure for more than 50,000 miners for up to 30 years. The U.S.
studies are consistent with these U.K. studies in demonstrating the
risks of developing occupational respiratory diseases from exposure to
respirable coal mine dust. These risks increase with increasing
exposure concentration and duration, and with exposure to dust of
higher ranked coal. The QRA and associated benefits for this rulemaking
were based on the Attfield and Seixas (1995) study because, in addition
to the advantages described above, it best represents the recent
conditions experienced by miners in the U.S. The QRA, Significance of
Risk discussion, and Benefits estimates follow in Sections VI, VII, and
IV (a)(2), respectively. The international studies provide an important
basis for comparison with the U.S. findings, and several of the recent
international studies are described in detail here.
Bourgkard, et al., (1998) conducted a 4-year study of a group of
French coal miners who were employed in underground and surface mines.
The investigators examined the prognostic role of cumulative dust
exposure, smoking patterns, respiratory symptoms, lung CT scans, and
lung function indices for chest x-ray worsening and evolution to simple
CWP and PMF. Bourgkard, et al., (1998), through selection of a younger
worker population (i.e., 35-48 years old at start of study), attempted
to focus on the early stages of simple CWP. In essence, they hoped to
identify those miners who needed to be relocated to less dusty
workplaces or who needed to be clinically monitored. Bourgkard, et al.
(1998) found a significant association between cumulative dust exposure
and what was termed chest x-ray ``worsening'' (i.e., increase in
reader-designated category signifying progression of simple CWP). In
addition, they found that miners with pneumoconiosis, wheezing,
decreased lung function, and high cumulative dust exposure at the first
medical examination were those most likely to show worsening on their
chest x-rays four years later.
Love, et al. (1997, 1992) reported on occupational exposures and
the health of British opencast (i.e., surface or strip) coal miners.
They studied a group of approximately 1,200 miners who were employed at
sites in England, Scotland, and Wales. The mean age of the men was 41;
many had worked in the mining industry since the 1970s. To determine
dust exposure levels, full-shift personal samples were collected. Most
were respirable dust samples which were collected using Casella
cyclones according to the procedures described by the British Health
and Safety Executive (HSE). Thus exposure determinations would be
comparable to exposure determinations obtained in U.S. surface coal
mines since both measure respirable dust according to the British
Medical Research Council (BMRC) criteria.
These investigators found a doubling in the relative risk of
developing profusion of simple CWP category 0/1 for every 10 years of
work in the dustiest jobs in surface mines. These respirable coal dust
exposures were under 1 mg/m\3\. Love, et al. (1992, 1997), like other
investigators, emphasized the need for monitoring and controlling
exposures to respirable coal mine dust, particularly in high risk
operations (e.g., drillers, drivers of bulldozers).
Meijers, et al. (1997) studied Dutch coal miners who were examined
between 1952 and 1963, and who were followed until the end of 1991.
They reported an increased risk of mortality from simple CWP and PMF
among miners who had generally worked underground for 20 or more years.
Their conclusions were based upon dramatic increases in standardized
mortality ratios (SMRs). There were several limitations in this study,
however.
Morfeld, et al. (1997) published a recent paper that investigated
the risk of developing simple CWP in German miners and addressed the
occupational exposure limit for respirable coal dust in Germany. Their
study included

[[Page 10844]]

approximately 5,800 miners who worked underground from the late 1970s
to mid-1980s. Morfeld, et al. observed increases in relative risks
(RRs) of developing early x-ray changes, category 0/1, that were
exposure-dependent. Relative risks (RRs) increased with higher dust
concentrations.
Starzynski, et al. (1996) conducted a mortality study on a group of
11,224 Polish males diagnosed with silicosis, simple CWP, or PMF
between 1970 and 1985. This cohort was subdivided by occupation into
four subcohorts: Coal miners (63%); employees of underground work
enterprises (8%) (i.e.,drift cutting and shaft construction jobs);
metallurgical industry and iron, and nonferrous foundry workers (16%);
and refractory materials, china, ceramics and quarry workers (13%). The
investigators found that coal miners had a slight, statistically
significant excess overall mortality (i.e., all causes) as indicated by
a standardized mortality ratio (SMR) of 105 (with a 95% confidence
interval (C.I.) of 100-110). Also, excess of deaths from diseases of
the respiratory system among coal miners was nearly four times that of
the referent population (SMR of 383 with a 95% C.I. of 345-424). The
study of Starzynski, et al. (1996) agrees with others that there is
premature mortality among coal miners from simple CWP and PMF.
Unfortunately, there is little or no information presented on miner
work history, exposure assessment (e.g., respirable coal mine dust,
silica), and mine environment (e.g., coal rank(s), underground vs.
surface mining).
Yi and Zhang (1996) conducted a study to measure the progression
from simple CWP to PMF or death among a cohort of 2,738 miners with
simple CWP who were employed at the Huai-Bei coal mine in China.
Relative risks (i.e., RRs) were calculated for progression from simple
CWP category 1 to simple CWP category 3 and for progression from simple
CWP category 3 to death. Their results demonstrated that miners with
simple CWP category 1 are at risk of developing simple CWP category 2
and simple CWP category 3 (e.g., RRs of 1.101 and 2.360, respectively).
They also found that miners with PMF had a decreased life expectancy.
Other risk factors for development of PMF included long-term work
underground, and drilling. This study was limited by a lack of exposure
assessment, estimation of miner smoking histories, and use of a
radiological classification system that differs from that of the ILO.
Hurley and Maclaren (1987) studied British coal miners who were
examined between 1953 and 1978, over 5-year intervals. They have shown
that exposure to respirable coal dust increases the risks of developing
simple CWP and of progressing to PMF. As seen in their data analysis,
these responses were dependent upon dust concentration and coal rank.
That is, greater responses were seen at higher dust concentrations and
with higher rank coal (i.e., increasing percent carbon). The
investigators also noted that estimated risks were unaffected by
changes in the proportion of miners with simple CWP who transferred
jobs. The authors concluded that ``limiting exposure to respirable coal
dust is the only reliable way of limiting the risks of radiological
changes to miners.''
b. Other Health Effects
As noted in Table V-2, there were 21 studies in which the loss of
lung function (LLF) was examined in coal miners. Fourteen of these
studies also included an evaluation of respiratory symptoms (RS) in the
miners. There were nine studies describing chronic obstructive
pulmonary disease (COPD) in miners.
Henneberger and Attfield (1997; 1996), Kuempel, et al. (1997),
Seixas, et al. (1993), Attfield and Hodous (1992), and Seixas, et al.
(1992) evaluated data from pulmonary function tests and standardized
questionnaires to miners in the NSCWP. A common finding in their
studies was an increase in respiratory symptoms such as cough,
shortness of breath, and wheezing. The symptoms were dependent upon the
dust concentration to which the miners had been exposed, with more
pronounced symptoms occurring after long-term exposures to higher
exposure levels. These studies also demonstrated that a loss of lung
function occurred among miners.
Attfield and Hodous (1992) studied U.S. miners who had spent 18
years underground (on average) and who participated in Round 1 (1969-
1971) of the NSCWP. They observed that greater reductions in pulmonary
function were associated with exposure to higher ranks of coal (i.e.,
anthracite vs. bituminous vs. lignite). Using linear regression models,
Kuempel et al., (1997) predicted the excess (exposure attributable)
prevalence of lung function decrements among miners with cumulative
exposures to respirable coal mine dust of 2 mg/m\3\ for 45 years (i.e.,
90 mg-yr/m\3\). The excess prevalence estimated were 315 and 139 cases
per thousand for forced expiratory volume in one second
(FEV₁) of <80% and <65% of predicted normal values,
respectively, among never-smoking miners (a sub-group of 977 NSCWP
participants studied in Seixas et al., 1993). Such reductions in
FEV₁ are clinically significant; FEV₁ <80% (of
predicted normal values) is a measure that is used to determine
ventilatory defects (American Thoracic Society, 1991). Three recent
studies found impaired FEV₁ to be a predictor of increased
pre-mature mortality (Weiss, et al., 1995; Meijers, et al., 1997;
Hansen et al., 1999).
Seixas, et al. (1993) conducted an analysis of 977 underground coal
miners who began working in or after 1970 and were participants of both
NSCWP Round 2 (1972-1975) and Round 4 (1985-1988). They found a rapid
loss of lung function in miners and further declines in lung function
with continuing exposure to coal mine dust. Collectively these studies
have shown that the prevalence of decreased lung function was
proportional to cumulative exposure. That is, with exposure to higher
coal dust levels over a working lifetime, there were more miners who
experienced a loss of lung function. Also, the types of respiratory
symptoms and patterns of pulmonary function decrements observed by both
Attfield and Hodous (1992) Seixas, et al. (1992;1993) are
characteristic of COPD.
The U.S. findings on respiratory symptoms and loss of lung function
in miners have agreed with those of previous British studies by Marine,
et al. (1988) and Soutar and Hurley (1986). Marine, et al. (1988)
analyzed data from British coal miners and focused their attention on
respiratory conditions other than simple CWP and PMF. In particular,
they examined the Forced Expiratory Volume in one second
(FEV₁) among smoking and nonsmoking miners and, on the basis
of reported respiratory symptoms, identified those miners with
bronchitis. Using these data, logistic regression models were used to
estimate the prevalence of chronic bronchitis and loss of lung
function. Marine, et al. concluded that both exposure to respirable
coal mine dust and smoking independently cause decrements in lung
function; their contributions to COPD appeared to be additive in coal
miners.
Soutar and Hurley (1986) examined the relationship between dust
exposure and lung function in British coal miners and ex-miners. The
men who were studied were employed in coal mines in the 1950s and were
followed up and examined 22 years later. These miners and ex-miners
were categorized as smokers, ex-smokers, or nonsmokers. The Forced
Expiratory Volume in one second (FEV₁), the Forced Vital
Capacity (FVC), and the FEV₁/FVC ratios decreased in all
study groups and these reductions in lung function were

[[Page 10845]]

inversely proportional to dust exposure. Thus, Soutar and Hurley
concluded that exposure to respirable coal mine dust can cause severe
respiratory impairment, even without the presence of simple CWP or PMF.
They speculated that the pathology of coal dust-induced lung disease
differs from that induced by smoking.
Centrivacinar emphysema in coal miners has been associated with the
amount of dust retained in their lungs at the end of life and with
their dust exposures during life and the years worked underground
(Ruckley et al., 1984; Leigh et al., 1983, 1994). Emphysema in coal
miners has also been associated with pathological measurements of
pneumoconiosis (Cockcroft et al., 1982a), and with lung function
decrements and irregular opacities on chest x-rays (Cockcroft et al.
1982b,c; Cockcroft and Andersson, 1987).
Recent studies from China (Wang, et al., 1997) and the European
community (Bourgkard, et al., 1998; Carta, et al., 1996; Lewis, S., et
al., 1996) have also supported the British and U.S. findings which
demonstrated the correlation between occupational exposure to coal dust
and respiratory symptoms and loss of lung function in miners.
Wang, et al. (1997) examined lung function in underground coal
miners and other workers from several factories in Chongqing, China.
For their study, information was obtained on exposure duration, results
of radiographic tests, and smoking history. Pulmonary function tests
were performed, providing the Forced Expiratory Volume in one second
(FEV₁), the Forced Vital Capacity (FVC), and
FEV₁/FVC data. Additionally, the diffusing capacity for
carbon monoxide (DL_CO) was measured. This is an indicator of
diffusion impairment at the ``blood-gas barrier'' which may occur, for
example, when this barrier becomes thickened (West, 1990; 1992). Wang,
et al. (1997) found that there was impairment of pulmonary function
among the coal miners and they had evidence of obstructive disease.
Like other studies, such effects were observed among coal miners even
in the absence of simple CWP. Pulmonary function was further decreased
when simple CWP was present. This study did not provide exposure
measurements and there was no consideration of exposure-response
relationships. Also, silica exposures and their potential effects were
not examined in the underground coal miners.
As noted above, Bourgkard, et al. (1998) was interested in the
earlier stages of simple CWP (i.e., Categories 0/1 and 1/0) and the
prognostic role of cumulative dust exposure, smoking patterns,
respiratory symptoms, lung CT scans, and lung function indices for
chest x-ray worsening and evolution to simple CWP category 1/1 or
higher. Over a 4-year period, they studied French coal miners who were
employed in underground and surface mines. Bourgkard, et al. (1998)
found that, at the first medical examination, the ratio of the Forced
Expiratory Volume in one second (FEV₁) to the Forced Vital
Capacity (FVC) (i.e., FEV₁/FVC) and other airflows
determined from a forced expiration (West, 1990; 1992) were lower among
miners who later developed simple CWP category 1/1 or higher. These
miners also experienced more wheezing at the first medical examination.
Thus, the results of their study suggested that lung function changes
may serve as an early indicator of miners who are at increased risk of
developing simple CWP and PMF and who should be monitored more closely.
Carta, et al. (1996) have examined the role of dust exposure on the
prevalence of respiratory symptoms and loss of lung function in a group
of young Italian coal miners (i.e., mean age at hire 28.9 years, mean
age at first survey 31.2 years). These miners worked underground and
were exposed to lignite (i.e., low rank coal) which had a 5-7% sulfur
content. They were followed for a period of 11 years, from 1983 and
1993. Carta, et al. (1996) found few abnormalities on miner chest x-
rays taken throughout the 11-year study. However, there was an
increased prevalence of respiratory symptoms and loss of lung function.
This was particularly noteworthy since dust exposures were often below
1.0 mg/m3; the cumulative dust exposure for the whole cohort
was 6.7 mg-yr/m3 after the first survey. Thus, Carta, et al.
(1996) demonstrated that miners experience respiratory effects of
exposure to dust generated from a lower rank coal and at lower
concentrations. They have recommended yearly measurements of lung
function for miners.
Lewis, et al. (1996) studied a group of British miners, many of
whom entered the coal industry in the 1970s. Based upon chest x-rays,
the miners had no evidence of simple CWP or PMF. The objective of this
study was to determine whether coal mining (i.e., exposure to
respirable coal mine dust) is an independent risk factor for impairment
of lung function. Lewis, et al. (1996) found that there was a loss of
lung function in miners (smokers and nonsmokers), particularly among
miners who were under approximately 55 years of age. For miners who
smoked, there was a greater loss of lung function than in nonsmoking
miners with the same level of exposure to respirable coal mine dust.
Above age 55, the loss of lung function was similar for miners and
their controls, although all smokers continued to exhibit a greater
loss of lung function than nonsmokers. Lewis, et al. (1996) concluded
that the deficits in lung function may occur in the absence of simple
CWP and PMF, and independent from the effects of smoking.
There have been two recent mortality studies that have demonstrated
a relationship between exposure to respirable coal mine dust and
development of COPD. This association was reported by Kuempel, et al.
(1995) in the U.S., and by Meijers, et al. (1997) in the Netherlands.
These two groups of investigators have reported that occupationally-
induced COPD (e.g., chronic bronchitis, emphysema) can occur in miners,
with or without the presence of simple CWP or PMF. They also found that
the risk of premature mortality from COPD was elevated among miners and
could be separated from the effects of smoking and age.
Kuempel, et al. (1995) found an increase in relative risk (RR) of
premature mortality from COPD among U.S. coal miners who participated
in the NSCWP from 1969 through 1971. In their data analysis, the
exposure-response relationship was evaluated using the Cox proportional
hazards model. This model assumes that the hazard ratio between
nonexposed and exposed groups does not significantly change with time.
When fitting a curve to the data (e.g., log-linear), cumulative
exposure was expressed as a categorical or continuous variable. Due to
model limitations (e.g., less statistical power, influence of category
scheme, use of lowest exposure group for comparisons vs. use of non-
exposed group), Kuempel, et al., (1995) believed that the exposure data
should be expressed as a continuous variable. If, for example, the
cumulative exposure was 90 mg-yr/m3 (i.e., 2 mg/
m3 for 45 years), then the relative risk of mortality from
chronic bronchitis or emphysema was 7.67. Kuempel, et al. (1995) also
showed that relative risk decreased with lower cumulative exposures
(i.e., below 90 mg-yr/m3) and increased with higher
cumulative exposures (i.e., above 90 mg-yr/m3). Thus, these
investigators demonstrated a statistically significant exposure-
response relationship for COPD.
Meijers, et al. (1997) have shown, among Dutch miners, reductions
in lung volumes and capacities are good predictors of the increased
risk of

[[Page 10846]]

premature mortality from COPD. For example, a diminished forced
expiratory volume in one second (FEV₁) or a diminished ratio
of the FEV₁ to the forced vital capacity \16\ (FVC) (i.e.,
FEV₁/FVC) upon medical examination was associated with a
significantly increased standardized mortality ratio (SMR) for COPD
(322 and 212, respectively). In other words, miners with diminished
lung capacity based on FEV₁ were two to three times more
likely to die prematurely due to COPD than miners who had normal lung
function. In contrast, SMRs for COPD were not significantly increased
in miners with normal lung volumes and capacities. These data support
prior conclusions of Seixas, et al. (1992, 1993) and Attfield and
Hodous (1992) based on morbidity studies.
------------------------------------------------------------------------

\16\ Forced vital capacity (FVC) is the total volume of gas that
can be exhaled with a forced expiration after a full inspiration;
The vital capacity measured with a FVC may be less than that
measured with a slower exhalation (West, 1992).
------------------------------------------------------------------------

VI. Quantitative Risk Assessment

Having reviewed the reported health effects associated with
exposure to respirable coal mine dust, MSHA has evaluated the evidence
to determine whether the current regulatory strategy can be improved.
The criteria for this evaluation are established by section
101(a)(6)(A) (30 U.S.C. 811(a)(6)(A)) of the Mine Act, which states
that:

The Secretary, in promulgating mandatory standards dealing with
toxic materials or harmful physical agents under this subsection,
shall set standards which most adequately assure on the basis of the
best available evidence that no miner will suffer material
impairment of health or functional capacity even if such miner has
regular exposure to the hazards dealt with by such standard for the
period of his working life.

Based on Court interpretations of similar language under the
Occupational Safety and Health Act, there are three questions that must
be addressed: (1) Whether health effects associated with the current
pattern of overexposures on individual shifts constitute a material
impairment to miner health or functional capacity; (2) whether the
current pattern of overexposures on individual shifts places miners at
a significant risk of incurring any of these material impairments; and
(3) whether the proposed rules will substantially reduce those risks.
The statutory criteria for evaluating the health effects evidence
do not require absolute certainty. Under section 101(a)(6)(A) of the
Mine Act, MSHA is required to proceed according to the ``best available
evidence'' (30 U.S.C. 811(a)(6)(A)). Furthermore, the need to evaluate
risk does not mean that an agency is placed into a ``mathematical
straightjacket.'' In Industrial Union Department, AFL-CIO v. American
Petroleum Institute (448 U.S.), otherwise known as the ``Benzene''
decision, the court ruled that:

So long as they are supported by a body of reputable scientific
thought, the Agency is free to use conservative assumptions in
interpreting the data * * * risking error on the side of
overprotection rather than underprotection. (448 U.S. 607, 100 S.Ct
2844 (1980) at 656)

As explained earlier, MSHA's objective in strengthening the
requirements for verifying the effectiveness of dust control plans, and
in enforcing effective plans through the new enforcement policy
proposed, is to ensure that no miner is exposed to an excessive
concentration of respirable dust on any individual shift (i.e., a
concentration in excess of the applicable dust standard). MSHA's
samples, combined with the more frequent bimonthly operator samples
reveal recent overexposures on individual shifts in many mines.
Furthermore, these dust samples demonstrate that, in many mines, dust
concentrations exceed the applicable dust standard on a substantial
percentage of the production shifts. This pattern has persisted for
many years; and, since the existing program permits individual shift
excursions above the applicable dust standard, a similar pattern can be
expected to continue over the working lifetime of affected miners--
unless an effort is made to eliminate excessive exposures on individual
shifts.
In this quantitative risk assessment (QRA), MSHA will demonstrate
that reducing respirable coal mine dust concentrations to no more than
the applicable dust standard on each and every shift would, over a 45-
year occupational lifetime, significantly bring down the cumulative
exposure to respirable coal mine dust, thereby significantly reducing
the risk of both simple CWP and PMF among miners. This reduction in
risk would result from reducing concentrations on just that percentage
of shifts currently showing an excess.
MSHA has estimated health benefits of the two rules based on
eliminating excessive exposures at only those MMUs and roofbolter
designated areas (RB-DAs) currently exhibiting a pattern of recurrent
overexposures on individual shifts. In the previous proposed rule, MSHA
used operator sampling data from the year 1999 to identify and
characterize such MMUs. In the current proposed rule, MSHA has updated
the analysis to 2001, included MSHA DO sampling data in addition to
operator data, and expanded the quantitative analysis to include the
reduction in risk expected for certain miners not previously considered
(i.e., miners working in RB-DAs). As a result, MSHA believes it has now
more comprehensively quantified the reduction in risk expected for the
most highly exposed miners currently subject to recurrent
overexposures.
By ``exhibiting a pattern of recurrent overexposures,'' MSHA means
that, for the same DO or RB-DA, at least two valid MSHA or bimonthly
operator samples have exceeded the applicable dust standard during a
year. MMUs exhibiting such a pattern are highly likely to have
experienced excessive exposures on at least six shifts during the year
under consideration.\17\
------------------------------------------------------------------------

\17\ MSHA estimates a MMU average of 384 production shifts per
year. At MMUs exhibiting a pattern of recurrent overexposures in
2001, valid DO samples were obtained on an average of about 30 of
these 384 production shifts. If dust concentrations on two or more
of the sampled shifts exceed the standard, then it follows, at a 95-
percent confidence level, that the standard is exceeded on at least
six shifts over the full year.
If a different definition of ``exhibiting a recurrent pattern of
overexposures'' had been used in the QRA, the estimate of the
reduction in risk and associated benefits would have been different.
For example, if the criterion were that four or more bimonthly DO
exposure measurements exceeded the applicable dust standard then
overexposures would be expected, with 95% confidence, to occur on at
least 20 shifts in a year of 384 shifts. Using more than two
recorded overexposures as the criterion would arbitrarily reduce the
population for which MSHA is estimating benefits and decrease the
estimated number of prevented cases.
------------------------------------------------------------------------

Based on 2001 MSHA and operator data, there were 716 MMUs (out of
1,256 total) at which dust concentrations for the DO exceeded the
applicable dust standard on at least two of the sampling shifts (MSHA,
datafile: DO--2001.ZIP). MSHA considers these 716 MMUs, representing 57
percent of all MMUs and more than one-half of all underground coal
miners working in production areas, to have exhibited a pattern of
recurrent overexposures. Valid DO samples were collected on a total of
20,905 shifts at these 716 MMUs, and the applicable dust standard was
exceeded on 4,028 of these shifts, or 19.3 percent. For this 19.3
percent, the mean excess above the standard, as measured for the DO
only, was 1.04 mg/m3.
These results are based on a large number of shifts (an average of
nearly 30 at each of the 716 MMUs). Therefore, assuming representative
operating conditions on these shifts, the results can be extrapolated
to all production

[[Page 10847]]

shifts, including those that were not sampled, at these same 716 MMUs.
With 99-percent confidence, the overall percentage of production shifts
on which the DO sample exceeded the standard was between 18.6 percent
and 20.0 percent for 2001. At the same confidence level, again assuming
representative operating conditions, the overall mean excess on
noncompliant shifts at these MMUs was between 0.96 mg/m3 and
1.11 mg/m3. If, as some commenters on the earlier single
sample proposed rule and the Dust Advisory Committee proceedings have
alleged, operators tend to reduce production and/or increase dust
controls on sampled shifts, then the true values could be higher than
even the upper endpoints of these 99-percent confidence intervals.
The available data suggest that, unless changes are made to enforce
the applicable dust standard on every shift, the same general pattern
of overexposures observed in 2001 will persist into the future.\18\
Therefore, MSHA concludes that without the proposed changes:
------------------------------------------------------------------------

\18\ Appendix VI.1 compares the pattern observed in 2001 to that
in earlier years.
------------------------------------------------------------------------

? More than half of all MMUs would continue to have a pattern
of recurrent overexposures on individual shifts;
? At those MMUs with recurrent overexposures, full-shift
average respirable dust concentrations for the DO would continue to
exceed the applicable dust standards on about 20 percent of all
production shifts;
? Among those shifts on which DO exposure exceeds the
applicable dust standards, the mean excess for the DO would continue to
be approximately 1 mg/m\3\.
If all overexposures on individual shifts are eliminated, the
reduction in total respirable coal mine dust inhaled by a miner over a
working lifetime will depend on three factors: (1) The average volume
of air inhaled on each shift that would otherwise have exceeded the
applicable dust standard, (2) the degree of reduction in respirable
dust concentration in the air inhaled on such shifts, and (3) the
number of such shifts per working lifetime. While the inhaled dose (mg)
could not be measured directly, it is biologically and quantitatively
related to the accumulated exposure (i.e., airborne concentration
multiplied by duration, summed across jobs for each miner) used to
predict CWP and PMF prevalences in the Attfield-Seixas models. If a
miner inhales ten cubic meters of air on a shift (U.S. EPA, 1980),
reducing the respirable coal mine dust concentration in that air by
1.04 mg/m\3\ will result in 10.4 mg less dust inhaled on that shift
alone. Assuming the miner works 240 shifts per year, then reducing
inhaled respirable dust by an average of 10.4 mg on 19.3 percent of the
shifts will reduce the total respirable coal mine dust inhaled by 482
mg per year, or nearly 22,000 mg over a 45-year working lifetime:

1.04 mg less respirable coal mine dust per m\3\ of inhaled air
x 10 m\3\ inhaled air per shift
x 46.32 affected shifts (i.e., 19.3% of 240) per work year
x 45 work years per working lifetime
= 21,678 mg less respirable coal mine dust inhaled per working
lifetime.

In Section V, the strengths and weaknesses of various
epidemiological studies were presented, supporting the selection of
Attfield and Seixas (1995) as the study that provides the best
available estimate of material health impairment with respect to CWP.
Two strengths of this study are its quantitative description of
exposure-response among both miners and ex-miners (who had worked as
miners for approximately 13-40 years) and the fact that it reflects
recent conditions experienced by coal miners in the U.S. Using the
exposure-response relationship it is possible to estimate the health
impact of bringing dust concentrations down to or below the applicable
dust standard on every shift. This is the only contemporary
epidemiological study of CWP in U.S. miners providing such a
relationship.
Attfield and Seixas (op cit) used two or three B readers to
identify the profusion of opacities based on the ILO classification
scheme.\19\ The most inclusive category defined in their paper was CWP
1+, which include simple CWP categories 1, 2, and 3, as well as PMF.
The second category CWP 2+, does not include simple CWP, category 1,
but does include the more severe simple CWP categories, 2 and 3, as
well as PMF. The third category used in their report was PMF, denoting
any category (A, B, or C) of large opacities. The authors applied
logistic regression models to the prevalence of CWP 1+, CWP 2+, and PMF
as a function of accumulated coal mine dust exposure calculated for
each miner included in the study. In the absence of data
differentiating the inhalation rates of individual miners, the
accumulated exposures in these models were expressed in units of mg-yr/
m \3\.
------------------------------------------------------------------------

\19\ If three readings were available, the median value was
used. If two readings were available, the higher of the two ILO
categories was recorded. Eighty radiographs were eliminated because
only one reading was available.
------------------------------------------------------------------------

At the MMUs being considered (those exhibiting a pattern of
recurrent overexposures), bringing dust concentrations down to no more
than the applicable dust standard on each and every production shift
would reduce DO exposures on the affected shifts by an average of 1.04
mg/m\3\. Assuming this average reduction applies to only 19.3 percent
of the shifts, the effect would be to reduce cumulative exposure, for
each miner exposed at or above the DO level, by 0.20 mg-yr/m\3\ over
the course of a working year (i.e., 19.3 percent of shifts in one year,
times 1.04 mg/m\3\ per shift). Therefore, over a 45-year working
lifetime, the benefit to each affected miner would, on average, amount
to a reduction in accumulated exposure of approximately 9.0 mg-yr/m\3\
(i.e., 45 years times 0.20 mg-yr/m\3\ per year). If, as some miners
have testified, operator dust samples submitted to MSHA tend to under-
represent the frequency or magnitude (or both) of individual full-shift
excursions above the applicable dust standard, then eliminating such
excursions would provide a lifetime reduction of even greater than 9.0
mg-yr/m\3\ for each affected miner.
The Attfield-Seixas models predict the prevalence of CWP 1+, CWP
2+, and PMF for miners who have accumulated a given amount of exposure,
expressed in units of mg-yr/m\3\, by the time they attain a specified
age. Benefits of reducing cumulative exposure can be estimated by
calculating the difference between predictions with and without the
reduction. For example, suppose a miner at one of the MMUs under
consideration begins work at age 20 and retires at age 65. At these
MMUs, the mean DO concentration reported in 2001 was 1.15 mg/m\3\; so,
after 45 years, a miner exposed at this level can be expected to have
accumulated a total exposure of nearly 52 mg-yr/m\3\ (i.e., 45 yr x
1.15 mg/m\3\). By the year of retirement, such a miner is expected to
accumulate, on average, 9.0 mg-yr/m\3\ less exposure if individual
shift excursions are eliminated. For 65-year-old miners, reducing an
accumulated total dust exposure of 52 mg-yr/m\3\ by 9.0 mg-yr/m\3\
reduces the predicted prevalence of ``CWP 1+'' by more than 16 per
thousand (see the entry for affected DO miners in Table VI-1).\20\
------------------------------------------------------------------------

\20\ The Attfield-Seixas model predicts a higher prevalence of
CWP, and consequently a greater risk reduction (35 per thousand DO
miners at age 65), after 45 years of occupational exposure to coal
mine dust in central Pennsylvania or southeastern West Virginia.
(Attfield and Seixas attribute this effect to the type of coal mined
in those geographic areas). However, few underground coal mines in
central Pennsylvania or southeastern West Virginia are still
operating. In fact, only about 29 of the 716 MMUs exhibiting a
pattern of recurrent overexposures in 2001 were from those areas.
Therefore, the risk assessment presented here, along with projected
benefits of the rule, are based on the lower risks predicted for
miners working outside central Pennsylvania and southeastern West
Virginia.

------------------------------------------------------------------------

[[Page 10848]]

This result, however, applies only to DO miners at age 65. The
Attfield-Seixas models provide different predictions for each year of
age that a miner attains. The predicted benefit turns out to be smaller
for younger miners and larger for older miners. This is partly because
younger miners will have accumulated less exposure reduction as a
result of today's final changes, and partly because the Attfield-Seixas
models depend directly on age as well as on cumulative exposure. The
health effects of recurrent overexposures can occur long after the
overexposures occurred. Even after a miner retires and is no longer
exposed to respirable coal mine dust, the additional risk attributable
to an extra 9.0 mg-year/m\3\, accumulated earlier, continues to
increase with age. Consequently, the benefit to be gained from
eliminating individual shift excursions also continues to increase
after a miner is no longer exposed. For example, assuming no additional
exposure after age 65, the predicted reduction in average prevalence of
CWP 1+ increases from 16.6 per thousand at age 65 to 21.4 per thousand
at age 70. Presumably, the increasingly greater predicted reduction in
risk of disease after age 65 is due to the latent effects of the
reduction in earlier exposure and the progressive nature of CWP.
To quantify benefits expected from eliminating overexposures on
each and every shift, MSHA applied the Attfield-Seixas models to a
hypothetical population of miners who, on average, begin working at age
20 and retire at age 65, assuming different lifetimes.\21\ To show the
range of potential reductions in risk depending on a miner's lifetime,
Table VI-1 presents the risk reductions predicted at three different
attained ages: 65, 73, and 80 years. The projected benefit increases
with attained age. However, MSHA's best estimate of the benefit to
exposed miners is expressed by the reduction in prevalence of disease
predicted at age 73.\22\
------------------------------------------------------------------------

\21\ Appendix VI.2 contains a technical description of the
Attfield-Seixas models and an explanation of how MSHA applied them
to obtain the results shown in Table VI-1. The method used in
applying the models differs slightly from that used in the previous
proposed rule, and Appendix VI.2 also explains this difference. In
addition, an EXCEL workbook entitled ``RiskRdxn.xlw'' showing the
formulas used in the calculations has been placed into the public
record for these proceedings.
\22\ The expected lifetime for all American males, conditional
on their having reached 20 years of age, is 73 years (calculated
from U.S. Census, March 1997, Tables 18 and 119).
------------------------------------------------------------------------

Since not all underground coal miners are overexposed to dust with
the same frequency or at the same level, Table VI-1 shows the risk
reductions projected for three different categories of affected miners:
(1) DO miners, (2) NDO miners who are faceworkers neither classified as
a DO nor subject to a separate applicable dust standard applicable to a
RB-DA, and (3) DA roofbolters. The reduction in risk predicted for each
of these three categories will now be discussed in turn.
(1) DO Miners. As explained earlier, for DO miners the predicted
lifetime exposure reduction accumulates at a rate of 0.20 mg/m\3\ of
reduced exposure per year during the 45 ``working years'' between 20
and 65, reaching a maximum of 9.0 mg-yr/m\3\ upon retirement at age 65.
Between ages 65 and 80, the accumulated reduction in dust exposure
remains at an estimated average of 9.0 mg-yr/m\3\, but (as also
explained previously) the benefit in terms of both simple CWP and PMF
risk continues to increase.
The first row of Table VI-1 presents the reductions in risk
expected among affected DO miners who work at a MMU exhibiting a
pattern of recurrent overexposures. For this group of miners, the
calculation at an average lifetime of 73 years shows that bringing dust
concentrations down to no more than the applicable dust standard on
each shift would:
? Reduce the combined risk of simple CWP and PMF by 24.4
cases per 1000 affected DO miners; \23\
------------------------------------------------------------------------

\23\ ``Affected DO miners'' include all miners who work at MMUs
with a pattern of recurrent overexposures and who are exposed to
dust concentrations similar to the DO over a 45-year working
lifetime.
------------------------------------------------------------------------

? Reduce the combined risk of simple CWP (category 2 and 3)
and PMF by 15.5 cases per 1000 affected DO miners;
? Reduce the risk of PMF by 7.6 cases per 1000 affected DO
miners.
When the dust concentration measured for the DO exceeds the
applicable dust standard, measurements for at least some of the other
miners in the same MMU may also exceed the standard on the same shift,
though usually by a lesser amount. Furthermore, although the DO
represents the occupation most likely to receive the highest exposure,
one or more of these other miners may be exposed to even higher
concentrations than the DO on some shifts. Therefore, the second
category of affected miners addressed in Table VI-1 is the population
of non-DO faceworkers other than those working in roofbolter DAs (who
are addressed as a separate, third category).
(2) NDO Miners. This category covers all faceworkers other than the
DO, except those roofbolters for which a separate DA applicable dust
standard has been established. (Roofbolters not coming under a DA
standard are included in the NDO category). To estimate how NDO miners
(other than those subject to a DA standard) would be affected by the
proposed rules, MSHA examined the results from all valid dust samples
collected by MSHA in underground MMUs during 2001 (MSHA, data file:
Insp2001.zip). Within each MMU, MSHA typically takes one sample on the
DO and, on the same shift, four or more additional samples representing
other occupations. In 2001, there was an average of 1.0 NDO measurement
in excess of the standard on shifts for which the DO measurement
exceeded the standard.\24\ For NDO measurements that exceeded the
standard on the same shift as a DO measurement, the mean excess above
the standard was approximately 0.6 mg/m\3\.\25\
------------------------------------------------------------------------

\24\ With 95-percent confidence, on shifts for which the DO
measurement exceeds the standard, the mean number of other
occupational measurements also exceeding the standard is at least
0.91.
\25\ With 95-percent confidence, the mean excess is at least
0.59 mg/m\3\.
------------------------------------------------------------------------

Combining these results with the 19.3 percent rate of excessive
exposures observed for the DO on individual shifts, it is reasonable to
infer that, at the MMUs under consideration, an average of 1 other
miner, in addition to the 1 classified as DO, is currently overexposed
on at least 19 percent of all production shifts. In 2001, the mean of
the highest dust concentration reported for any non-DO miner on sampled
shifts was 1.08 mg/m\3\. Over the course of each working year, the
reduction in exposure expected for such miners as a result of
implementing the proposed rules is 0.12 mg-yr/m\3\ (i.e., 19.3 percent
of one year, times 0.6 mg/m\3\).
To assess the reduction in risk expected from eliminating all
single-shift exposures for these NDO miners, MSHA again applied the
Attfield and Seixas models to miners who begin working at age 20 and
retire at age 65, assuming lifetimes of 65, 73, and 80 years. This
time, however, the resulting decrease in predicted prevalence was
multiplied by 1.0/6 = 0.167, to reflect the fact that the assumed rate
of overexposure applies, on average, to

[[Page 10849]]

about one-sixth of the faceworkers not classified as the DO.\26\
------------------------------------------------------------------------

\26\ There are an estimated 6 NDO miners for each DO miner, and
an average of 1.0 of these 6 miners is overexposed. This does not
include roofbolters working in designated areas, who are treated as
a separate group in the present analysis.
------------------------------------------------------------------------

The second row of Table VI-1 contains the risk reductions for NDO
miners expected as a result of eliminating all individual shift
overexposures. Over an occupational lifetime, the average reduction in
risk for simple CWP and PMF combined, and for PMF alone, increases with
age. However, the risk reduction at each age is smaller for the
affected NDOs than for the affected DOs. This is expected because the
estimated probability that a NDO (other than a RB-DA) will, under
current conditions, be overexposed on a given shift is only 16.7
percent of the corresponding probability for the DO. For the MMUs under
consideration, the predicted reduction in risk for faceworkers other
than the DO who live an expected lifetime of 73 years is: 2.3 fewer
cases of ``CWP 1+'' per thousand affected NDO miners; 1.5 fewer cases
of ``CWP 2+'' per thousand affected NDO miners; and 0.7 fewer cases of
PMF per thousand affected NDO miners.
(3) Roofbolter DA (RB-DA) Miners. Because roofbolters are often
exposed to higher quartz concentrations than other miners, the
applicable dust standard for them is frequently different from the
standard applicable to other miners working in the same MMU. Therefore,
many roofbolters are classified as working in a ``roofbolter designated
area'' (RB-DA). For purposes of this QRA, such roofbolters were
excluded from the analysis of NDO miners presented above. Based on 2001
MSHA and operator data, 194 out of a total 659 RB-DAs met MSHA's
criterion for exhibiting a pattern of recurrent overexposures--i.e.,
dust concentrations exceeded the applicable dust standard on at least
two of the sampled shifts (MSHA, datafile: RBDA2001.ZIP). Valid RB-DA
samples were collected on a total of 3477 shifts at these 194 RB-DA
MMUs, and the applicable dust standard was exceeded on 837 of these
shifts, or 24.1 percent (95% confidence interval: 22.7 to 25.5). For
this 24.1 percent, the mean excess above the standard, as measured for
the RB-DA only, was 0.72 mg/m\3\ (95-percent confidence interval: 0.64
to 0.80).
At these RB-DAs (i.e., those exhibiting a pattern of recurrent
overexposures), the mean concentration reported in 2001 was 0.94 mg/
m\3\; so, after 45 years, an RB-DA miner can be expected, if there is
no change in current conditions, to have accumulated a total exposure
of more than 42 mg-yr/m\3\. By retirement at age 65, such a miner would
be expected to accumulate, on average, 7.8 mg-yr/m\3\ less exposure if
overexposures on all individual shifts were eliminated. (45 years x
24.1% of 0.72 mg/m\3\). The third row of Table VI-1 shows the estimated
impact of the proposed rules on the risk predicted for RB-DA
roofbolters. At age 73, reducing an accumulated total dust exposure of
42 mg-yr/m\3\ by 7.8 mg-yr/m\3\ reduces the predicted prevalence of
``CWP 1+'' by 19.6 per thousand, of ``CWP 2+'' by 12.1 per thousand,
and of PMF by 6.0 per thousand.

Table VI-1.--By Age, Average Reduction in Cases of Occupational Respiratory Disease Expected To Result From Implementation of Single Sample and Plan
Verification Rules
--------------------------------------------------------------------------------------------------------------------------------------------------------
Reduction in cases of occupational respiratory disease per 1,000 affected miners
-----------------------------------------------------------------------------------------------------------
Simple CWP \a\ (categories 1, 2 or Simple CWP(categories 2 or 3) or PMF
3) or PMF \b\ (``CWP 1+'') PMF (``CWP 2+'') -----------------------------------
Type of miner ------------------------------------------------------------------------ Age
Age Age -----------------------------------
------------------------------------------------------------------------
65 73 80 65 73 80 65 73 80
--------------------------------------------------------------------------------------------------------------------------------------------------------
Affected Designated Occupation Miners \c\ 16.6 24.4 30.6 6.3 15.5 28.0 2.8 7.6 16.1
(DO).......................................
Affected Non-Designated Occupation Miners 1.6 2.3 2.9 0.6 1.5 2.7 0.3 0.7 1.5
\d\ (NDO)..................................
Affected Roof Bolter Designated Areas Miners 13.0 19.6 25.3 4.8 12.1 22.5 2.2 6.0 12.8
\e\ (RB-DA)................................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Simple CWP: simple coal workers' pneumoconiosis.
\b\ PMF: progressive massive fibrosis.
\c\ Affected Designated Occupation (DO) Miners: includes all miners who work at the 57 percent of the Mechanized Mining Units under consideration and
who are exposed to dust concentrations similar to the DO, over a 45-year occupational lifetime. Risk reduction estimates are based on reducing the
mean dust concentration of 1.15 mg/m \3\ (Std. Error = 0.018) observed in 2001 for DOs at the MMUs under consideration.
\d\ Affected Non-Designated Occupation (NDO) Miners: includes all underground faceworkers under consideration who are not classified as the DO or a
``designated area roofbolter.'' Risk reduction estimates are based on reducing the mean dust concentration of 1.08 mg/m \3\ (Std. Error = 0.011)
observed in 2001 for the NDO sample showing the highest dust concentration on a given MSHA sampling day within a MMU.
\e\ Affected Roofbolter Designated Area (RB-DA) Miners: includes all miners working as roofbolters in the 29.4 percent of RB-DAs exhibiting a pattern of
recurrent overexposures. Risk reduction estimates are based on reducing the mean dust concentration of 0.94 mg/m \3\ (Std. Error = 0.025) observed in
2001 for the RB-DAs under consideration.

MSHA acknowledges that the assumptions and data used in this QRA
are subject to various caveats, but the Secretary believes that, on
balance, MSHA's analysis probably underestimates the increased risk of
material impairment attributable to individual shift overexposures
accumulated over an occupational lifetime. Some previous commenters,
however, have disagreed with this assessment or argued that some
aspects of it ``need further consideration.'' The only commenter
offering specific criticisms was the NMA, which submitted a critique by
M.J Nicolich and J.F. Gamble (September, 2000) along with general
comments from Richard Lawson. Nicolich and Gamble brought up four
points that, in the NMA's view, cast doubt on our conclusions. These
four points will be discussed in turn.
(1) According to Nicolich and Gamble, ``[t]he QRA has made some

[[Page 10850]]

assumptions that have led to incorrect estimates of the percent of
miners who would be at reduced risk on the new plan, and have
misrepresented the degree of risk reduction among the miners who would
have reduced risk.'' In support of this position, Nicolich and Gamble
argued that (a) the sample data on which the QRA was based were not
independent and (b) that the distribution of values by which
concentrations exceeded the applicable dust standard was likely to be
skewed and would, therefore, be better represented by its median than
by its mean. They argued, further, that as a consequence of (a), the
estimated ``number of workers that will have reduced risk will likely
be too high and the degree of risk among these fewer workers will be
under-estimated * * *'' and that, as a consequence of (b), ``the degree
of risk reduction among the miners experiencing over-exposure will
likely be too large (because of an overestimate of the intensity of the
exposure of the over-exposed miners).''
Both parts of this argument are flawed. The discussion that
Nicolich and Gamble offer in support of (a) has nothing to do with
independence of sample data and provides no basis for concluding that
MSHA has overestimated the percentage of miners expected to experience
reduced risk if overexposures on individual shift are eliminated. It
should also be noted that this part of their argument involves an
apparent misunderstanding of how MSHA estimated the number of miners
that would be affected by this rule. Contrary to Nicolich and Gamble's
line of reasoning, the estimated percentage of shifts exceeding the
applicable dust standard at MMUs exhibiting a pattern of recurrent
overexposures was not used to estimate the size of the mining
population at risk. It is true that the number of affected miners used
in calculating benefits was estimated from the proportion of MMUs
exhibiting a pattern of recurrent overexposures (see section IX.A.2.
Benefits). However, this estimate would remain the same, regardless of
the overexposure rate observed for MMUs defined as exhibiting a
pattern. It is also true that if a more stringent criterion were used
to define MMUs exhibiting a pattern, then fewer MMUs (and, therefore,
fewer miners) would be included in the benefit estimates. The rule,
however, applies to all MMUs, not just those defined as exhibiting a
pattern of recurrent overexposures for purposes of the QRA. Therefore,
adopting a more stringent criterion for recurrence would simply mean
that additional miners benefitting from the rule would be left out of
the benefit estimates.
Furthermore, the second part of their argument (b) is not relevant
to the calculation of the accumulated effect of individual shift
exposures, as modeled by the Attfield/Seixas model being employed. In
support of their position, Nicolich and Gamble present the example of
nine laborers who earn $10,000 per year and a boss who earns $100,000
per year and point out that the mean income ``is not a good measure of
the `typical value.' '' They then propose (based on no supporting data
other than that of this example) that the median would be a better
measure of the ``typical'' degree by which individual shift
overexposures exceed the applicable dust standard.
Nicolich and Gamble fail to consider that the objective is not to
estimate a ``typical'' degree of excess but, rather, to estimate the
total degree of excess, accumulated over an occupational lifetime. The
variable used in the Attfield/Seixas model is cumulative exposure,
defined by the product of exposure duration and mean ``intensity''
(i.e., dust concentration), not median intensity. In the example of
nine laborers and a boss, the total annual payout is ten times mean
salary, not median salary. Similarly, cumulative exposure is given by
the product of exposure duration and mean intensity regardless of the
shape of the statistical distribution of excess dust concentrations.
Since MSHA's use of the mean value fully accords with the Attfield/
Seixas model employed, the commenters have provided no basis for
concluding that MSHA has overestimated the degree of risk reduction to
be expected among miners experiencing individual shift overexposures.
(2) According to Nicolich and Gamble, ``[t]he Attfield and Seixas
model does not take into account the over-exposures identified by
MSHA.'' Based on this premise, they argue that ``the estimates of
exposure in the model are less than actual exposure and the E-R [i.e.,
exposure-response]
slope is steeper than the actual slope.'' More
specifically, they attempt to show that Attfield and Seixas should have
estimated the mean concentration for face occupations to be 1.57 mg/m
\3\ rather than 1.46 mg/m \3\. From this, they conclude that ``[t]he
toxicity of coal mine dust is therefore over-estimated.''
This argument is based on the false premise that individual shift
overexposures were not included in the data from which the Atffield/
Seixas model was generated. Contrary to Nicolich and Gamble, however,
neither MMUs with a pattern of recurrent overexposures nor individual
shift overexposures per se were excluded from the data used by Attfield
and Seixas. Therefore, contrary to their argument, the existence of
such overexposures does not create a ``bias in exposure estimates''
that ``produces an overestimate in the toxicity of coal mine dust.''
Specifically, the value of 1.46 mg/m\3\ used by Attfield and Seixas to
represent the mean concentration for faceworkers already includes those
measurements exceeding the applicable dust standard. Therefore, the
corresponding value (1.57 mg/m\3\) proposed by Nicolich and Gamble
essentially double-counts those measurements.
(3) According to Nicolich and Gamble, ``[t]here is a background
prevalence of CWP that is not related to coal mine dust exposure'' and
``prevalences that occur at zero exposure should be subtracted from the
observed prevalence.'' Nicolich and Gamble failed to note that
background prevalences have no bearing on the expected reductions in
risk as calculated and presented in this risk assessment. All estimates
of expected risk reduction in this QRA are based on calculating a
difference between two estimated risks: with and without the
elimination of individual shift overexposures accumulated over an
occupational lifetime. Both of these estimated risks include the same
background effect that is not attributable to coal mine dust exposure.
Therefore, any background effect is canceled out when the difference is
calculated. The estimated reduction in risk is, according to the
Attfield/Seixas model, free of any background effect.\27\
------------------------------------------------------------------------

\27\ Although it is canceled by subtraction when estimating the
effect of reducing cumulative exposure, the Attfield/Seixas model
does, in fact, incorporate an age-dependent background effect.
Therefore, since the model allows for a positive response at zero
exposure, the slope of the exposure-response relationship is not
artificially inflated.
------------------------------------------------------------------------

(4) Nicolich and Gamble criticized the use of irregular opacities
as indicating coal workers' pneumoconiosis. However, studies have shown
that the prevalences of both small rounded and small irregular
opacities increase with increasing years worked underground (Amandus et
al., 1976; Cockcroft et al., 1983) and with increasing coal mine dust
exposure (Collins et al., 1988). The relationship between irregular
opacities and coal mine dust exposure has been observed among both
smokers and nonsmokers (Cockcroft et al., 1983). Amandus et al. (1976)
found that smoking, age, and years underground

[[Page 10851]]

were all significant predictors of irregular opacities. Irregular
opacities were most common among miners who were older than 30, had
bronchitis, and smoked, but exposure to coal mine dust was still a
significant factor. Collins et al. (1988) found that the small
irregular opacities were statistically significantly associated with
both dust exposure and age in U.K. coal miners, but did not find a
significant relationship with smoking. The exposure-response
relationship was less steep for small irregular opacities than for
small rounded opacities (Collins et al, 1988). Therefore, the use of
combined opacities rather than rounded opacities only may actually
dampen the exposure-response relationship for pneumoconiosis (e.g., in
Attfield and Seixas, 1995), which is in contrast to the Nicolich and
Gamble comment that the inclusion of irregular opacities would over-
estimate the risk of pneumoconiosis. Nonetheless, the use of combined
opacities is supported by the fact that statistically significant
exposure-response relationships have been observed for both types of
small opacities (rounded and irregular) in coal miners, and both types
have been associated with adverse health effects.
Miners with small rounded opacities on their chest x-rays were more
likely to report symptoms of chronic bronchitis (cough and phlegm) than
were miners without small opacities (category 0/0) (Rae et al., 1971).
In Collins et al. (1988), both small rounded and small irregular
opacities were associated with symptoms of chronic cough and phlegm,
and breathlessness, compared to miners with no opacities observable on
chest x-ray. Small irregular opacities have been associated with
impaired lung function (Amandus et al., 1976; Cockcroft et al.,
1982b,c; Collins et al., 1988). As Nicolich and Gamble state in their
comments, the lung function impairment reported by Collins et al.
(1988) was in addition to that attributable to dust exposure. However,
Collins et al. (1988) found that the observed pattern of lung function
abnormalities was distinctly different from the pattern observed among
smokers. Specifically, the mean FEV1 and mean FVC were significantly
lower among miners with small irregular opacities compared to those
with no observable opacities (i.e., chest x-ray category 0/0), and this
is the pattern of lung function abnormality typically associated with
dust exposure in coal miners (Collins et al., 1988). In contrast,
smokers generally had more severe reductions in FEV1 than in FVC
(resulting in a reduction in the FEV1/FVC ratio). The authors suggest
that the irregular opacities in coal miners may represent damage to the
lungs that causes airways obstruction at different lung locations than
that caused by cigarette smoke. Irregular opacities in coal miners may
have also been associated with emphysema (Cockcroft et al., 1982 b, c).
Because simple CWP represents an early stage of a progressive
disease, miners who have had a chest x-ray classified as ILO category 1
or greater are more likely than those with a clear x-ray (category 0)
to progress to the more severe stages of the disease, including the
complicated form, PMF (categories A, B, or C) (Cochrane 1962; McLintock
et al. 1971; Hurley et al. 1987; Morfeld et al., 1992). PMF has been
associated with impaired lung function, disability, and early death
(Rasmussen et al., 1968; Parkes et al., 1983; Miller and Jacobsen,
1985), and miners with PMF qualify as totally disabled due to
pneumoconiosis under the Department of Labor's Standards for
Determining Coal Miners' Total Disability or Death Due to
Pneumoconiosis under the criteria set forth at (20 CFR 718.304(a)).
Miners with simple CWP were also found to have an increased risk of
dying from pneumoconiosis (as the underlying or a contributing cause on
the death certificate), and this risk tended to increase with
increasing radiographic category (Kuempel et al., 1995). Nicolich and
Gamble are incorrect in stating that an implication of that study is
``no increased mortality associated with exposure''. Instead, Kuempel
et al. (1995) showed a statistically significant exposure-response
relationship for cumulative exposure to respirable coal mine dust and
pneumoconiosis mortality.
After due consideration of the questions posed by Nicolich and
Gamble, we have concluded that the development of CWP, as detected on
chest x-ray as rounded and/or irregular opacities, poses a significant
health risk to miners. Miners who have developed simple CWP have a
materially altered risk status, which is a medically and scientifically
reasonable measure of material impairment. Miners who have a chest x-
ray with small opacities (rounded and/or irregular) are also more
likely to report respiratory symptoms and/or to have lung function
decrements. The use of radiographic evidence of pneumoconiosis
(combined opacities), both by Attfield and Seixas (1995) and in MSHA's
risk assessment, is appropriate for assessing the risk that coal miners
will suffer material impairment of health or functional capacity as a
result of their respirable dust exposures accumulated over a working
lifetime.

Appendix VI.1 DO Overexposure Patterns

In 1998, MSHA attempted to enforce compliance on individual shifts.
Therefore, to compare the 2001 pattern of excess exposures on
individual shifts to that of previous years, MSHA examined the regular
bimonthly DO sample data submitted by mine operators in the 10 years
from 1990 through 1997 and 1999-2000. The same three parameters were
considered as discussed above for 2001: (1) The percentage of MMUs
exhibiting a pattern of recurrent overexposures, as indicated by at
least two of the valid measurements being above the applicable dust
standard in a given year; (2) for those and only those MMUs exhibiting
recurrent overexposures, the overall percentage of production shifts on
which the DO was overexposed, as estimated by the percentage of valid
measurements above the applicable dust standard; and (3) for the MMUs
identified as exhibiting recurrent overexposures, the mean excess above
the applicable dust standard, as calculated for just those valid
measurements that exceeded the applicable dust standard in a given
year.
Although MSHA found minor differences between individual years,
there was no statistically significant upward or downward trend in any
of these three parameters over the 1990-1997 time period (see Table VI-
2). Beginning in 1999, however, there was a significant and persistent
decrease in the average excess above the applicable dust standard
(Parameter #3) for MMUs exhibiting recurrent overexposures.
MSHA attributes this decrease to two important changes in the Agency's
inspection program, beginning near the end of 1998. These changes,
which both resulted in increased MSHA personnel presence, were: (1) An
increase in the frequency of MSHA dust sampling at underground coal
mines; and (2) initiation of monthly spot inspections at mines that
were experiencing difficulty in maintaining consistent compliance with
the applicable dust standard.

[[Page 10852]]

Table VI-2.--Parameters Describing Overexposure to Respirable Coal Mine Dust, Based on Operator DO Samples
----------------------------------------------------------------------------------------------------------------
Parameter #3 (mg/
Parameter Parameter m \3\)
1990-1997 1999-2000 #1 #2 ---------------------------
(Percent) (Percent) 1990-1997 1999-2000
----------------------------------------------------------------------------------------------------------------
Number of Years..................................... 10 10 8 2
-----------------------------------------------------
Median.............................................. 52.6 20.1 1.24 1.00
-----------------------------------------------------
Mean................................................ 51.0 20.5 1.26 1.00
(Std. Error)........................................ (1.36) (0.30) (0.023) 0.07
-----------------------------------------------------
2001................................................ 51.6 20.8 1.08
----------------------------------------------------------------------------------------------------------------
Parameter #1: Percentage of MMUs exhibiting a pattern of recurrent overexposures.
Parameter #2: For those MMUs exhibiting a pattern of recurrent overexposures, the percentage of
production shifts on which the DO was overexposed.
Parameter #3: for those MMUs exhibiting a pattern of recurrent overexposures, the mean excess above the
applicable dust standard among valid DO measurements that exceeded the applicable dust standard.

Appendix VI.2 Application of the Attfield-Seixas Models

Attfield and Seixas (1995) provide separate logistic regression
models for CWP1+, CWP2+, and PMF as a function of cumulative dust
exposure (mg-yr/m3). These models all have the following
form:
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.005

where p is the probability of disease at a specified age and cumulative
exposure. The constant e is the base of the natural logarithms. The
empirically estimated coefficients a₀ (the intercept),
a₁, a₂, and a₃ differ for the three
health effects considered and are presented in Table IV of Attfield and
Seixas (op cit). The values for these coefficients are also shown in
the Excel workbook (RiskRdxn.xlw) MSHA has placed into the public
record as part of these proceedings. The coefficient (a₃) of
``rank'' refers to an additional effect of cumulative exposure to coal
mine dust in central Pennsylvania or southeastern West Virginia, which
the authors attribute to the rank of the coal mined in those areas.
Since few mines in those areas are currently operating, MSHA did not
employ this additional effect in its application of the Attfield-Seixas
models (i.e., MSHA assumed that the value of the indicator variable for
``rank'' is zero).
From equation 1, assuming exposure outside central Pennsylvania and
southeastern West Virginia, it follows that the prevalence of disease,
assuming continued exposure at current levels and approximate linearity
of the exposure effect, is (per thousand miners):
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.006

Similarly, the prevalence of disease, assuming reduced cumulative
exposure attributable to implementation of the proposed rules is (per
thousand miners):
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.007

Note that the ``reduced mean annual exposure'' is the current mean
annual exposure (based on 2001 data) reduced by eliminating
overexposures on just that percentage of shifts for which overexposures
have been shown to currently occur. MSHA then estimated the impact of
eliminating all overexposures on individual shifts by calculating (for
ages 65, 73, and 80) the differences:
[GRAPHIC]
[TIFF OMITTED]
TP06MR03.008

It is these differences that are presented in Table VI-1. The
calculations for each specific entry are detailed in the EXCEL
workbook, RiskRdxn.xlw, which has been placed into the public
record.\28\
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\28\ The method used here provides an approximation of the
expected risk reduction ([Delta]), assuming approximate linearity of
the exposure-response relationship over the exposure range of
interest. This differs from the method used in the previous proposed
rule, where lower bounds on the risk reduction were calculated. The
calculations in the previous proposed rule defined
[Delta]' = P _y',-P_x',
where y' = y/x and x' = e a₀+a₁x age
The previous method results in lower values than those shown in
Table VI-1. For example, for ``CWP 1+'' among affected DO miners at
age 73, applying the previous method to 2001 operator and MSHA data
would have resulted in a calculated risk reduction of 16.3 per
thousand instead of the 24.4 per thousand presented in Table VI-1.
MSHA believes the method used in the current proposed rule more
accurately represents the reduction in risk that can be expected if
all individual shift overexposures are eliminated.

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[[Page 10853]]

VII. Significance of Risk

The proposed single sample and plan verification rules prevent
respirable coal mine dust overexposures by identifying them and then
requiring corrective actions. As discussed in the Health Effects
Section, CWP is a progressive disease that develops after many years of
cumulative exposure to respirable coal mine dust, which may include
quartz, and is associated with material impairment of health and pre-
mature death (see Health Effects Section). The joint promulgation of
the proposed single sample and plan verification rules would
significantly reduce the risk of development of CWP over an
occupational lifetime. The best available data were used to conduct the
QRA.
(A) Through the ``Benzene decision,'' the U.S. Supreme Court
provided further guidance on determining and interpreting the
significance of risks.

It is the Agency's responsibility to determine, in the first
instance, what it considered to be a ``significant'' risk. Some
risks are plainly unacceptable. If, for example, the odds are one in
a billion that a person will die from cancer by taking a drink of
chlorinated water, the risk clearly could not be considered
significant. On the other hand, if the odds are one in a thousand
that regular inhalation of gasoline vapors that are 2% benzene will
be fatal, a reasonable person might well consider the risk
significant and take appropriate steps to decrease or eliminate it.
Although the Agency has no duty to calculate the exact probability
of harm, it does have an obligation to find that a significant risk
is present before it can characterize a place of employment as
`unsafe' (448 U.S. at 655).

The industry recognizes the health significance of maintaining
exposures at or below the applicable dust standard. For example, at the
August 16, 2000 public hearing, the National Mining Association's
representative Mr. Watzman, stated ``* * * (MSHA,) we don't want to see
any miner overexposed. Our objective has been and will always be to
maintain dust levels below the applicable dust standard.'' The United
Mine Workers of America's written comments echoed the importance of
reducing overexposures, ``Miners'' exposure to unhealthy levels of coal
mine dust leads to the disabling and life shortening ``black lung''
disease [CWP].''
The best estimates of reduction in risk for all categories of CWP,
for miners who live to age 73, after a 45-year occupational exposure to
respirable coal mine dust were: 2.3 per 1,000 affected non-designated
occupation miners; 19.6 per 1,000 affected roofbolter designated areas
miners; and, 24.4 per thousand affected designated occupation miners.
These estimates quantitatively demonstrate MSHA's policy determination
that there would be a significant reduction in risk of CWP as a
consequence of the promulgation of these proposed rules.
(B) There are many elements that compile a QRA. For each element of
a QRA, there may be multiple assumptions (e.g., values of variables and
sources of data) that could be applied. Various assumptions will differ
in the extent to which they are less or more likely to occur (i.e., be
representative). Assumptions may also have relative degrees of impact
on the risk estimate, either increasing or decreasing it. To the extent
that miners experience conditions that differ from the assumptions in
the QRA, their risk of developing CWP will consequently be higher or
lower. A ``conservative'' assumption in the QRA is one that results in
a higher estimate of risk than a less ``conservative'' assumption
would. Estimated benefits (i.e., the number of prevented cases of the
outcome of concern, e.g., CWP) are greater under QRA assumptions that
are ``conservative'' in this sense.\29\
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\29\ For example, in a hypothetical QRA there is a reduction in
risk estimate for CWP of 2.4 per 1,000 affected miners, based on a
relatively conservative assumption for a particular element (holding
all other assumptions constant). A reduction in the risk estimate
for CWP based on an equally likely although less conservative
assumption is 1.0 per 1,000 affected miners, holding all other
assumptions constant. Assuming that the population of affected
miners is 20,000. The more conservative assumption would result in
an estimated 48 (2.4/1,000 * 20,000) prevented cases of CWP compared
to the less conservative assumption's 20 prevented cases of CWP.
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The discussion below identifies various elements of the QRA and how
th