Assigned Protection Factors

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

[Federal Register: June 6, 2003 (Volume 68, Number 109)]
[Proposed Rules]
[Page 34035-34119]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06jn03-31]

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DEPARTMENT OF LABOR
Occupational Safety and Health Administration
29 CFR Parts 1910, 1915, and 1926
[Docket No. H049C]
RIN 1218-AA05

AGENCY: Occupational Safety and Health Administration (OSHA),
Department of Labor.
ACTION: Proposed rule; request for comments and scheduling of informal
public hearings.

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SUMMARY: OSHA is proposing to revise its existing Respiratory
Protection Standard to add definitions and specific requirements for
assigned protection factors (APFs) and maximum use concentrations
(MUCs). The proposed revisions also would supersede the respirator
selection provisions of existing substance-specific standards with
these new APFs (except the APFs for the 1,3-Butadiene Standard).
The Agency developed the proposed APFs after thoroughly reviewing
the available literature, including chamber simulation studies and
workplace protection factor studies. The proposed APFs would provide
employers with critical information to use when selecting respirators
for employees exposed to atmospheric contaminants found in general
industry, construction, shipyard, longshoring, and marine terminal
workplaces. Proper respirator selection using APFs is an important
component of an effective respirator protection program. Accordingly,
OSHA has made a preliminary conclusion that the proposed APFs are
necessary to protect employees who use respirators against atmospheric
contaminants.

DATES: Written comments. The Agency invites interested parties to
submit written comments regarding the proposed rule, including comments
to the information-collection determination under the Supplementary
Information section of this Federal Register notice, by mail,
facsimile, or electronically. You must send all comments, whether
submitted by mail, facsimile, or electronically through OSHA's Web
site, by September 4, 2003.
Informal public hearings. The Agency plans to hold an informal
public hearing in Washington, DC in late summer or early fall of 2003.
OSHA expects the DC hearing to last from 9:30 a.m. to 5:30 p.m. on the
first day, and from 8:30 a.m. to 5:30 p.m. on subsequent days; however,
the exact daily schedule is at the discretion of the presiding
administrative law judge. If an additional hearing is held, the Agency
will announce the date, time, and location of this hearing later in the
subsequent Federal Register notice.
Notice of intention to appear to provide testimony at the informal
public hearing. Interested parties who intend to present testimony at
the informal public hearing in Washington, DC, must notify OSHA of
their intention to do so no later than September 4, 2003.
Hearing testimony and documentary evidence. Interested parties who
will be requesting more than 10 minutes to present their testimony, or
who will be submitting documentary evidence at the hearing, must
provide the Agency with copies of their full testimony and all
documentary evidence they plan to present by September 4, 2003.

ADDRESSES: Written comments. You may submit three copies of written
comments to the Docket Office, Docket No. H049C, Technical Data Center,
Room N-2625, OSHA, U.S. Department of Labor, 200 Constitution Ave.,
NW., Washington, DC 20210; telephone (202) 693-2350. If your written
comments are 10 pages or fewer, you may fax them to the OSHA Docket
Office, telephone number (202) 693-1648. You do not have to send OSHA a
hard copy of your faxed comments. You may submit comments
electronically through OSHA's Home page at http://ecomments.osha.gov/.
If you would like to submit additional studies or journal
articles, you must submit three copies of them to the OSHA Docket Office
at the address above. These materials must clearly identify your
electronic comments by name, date, subject, and docket number so we can
attach them to your comments.
Informal public hearings. The informal public hearing to be held in
Washington, DC will be located in the Auditorium on the plaza level of
the Frances Perkins Building, U.S. Department of Labor, 200
Constitution Ave., NW., Washington, DC.
Notice of intention to appear to provide testimony at the informal
public hearing. Notices of intention to appear at the informal public
hearing should be submitted in triplicate to the Docket Office, Docket
No. H049C, Room N-2625, OSHA, U.S. Department of Labor, 200
Constitution Avenue, NW., Washington, DC 20210. Notices may also be
faxed to the Docket Office at (202) 693-1648 or submitted
electronically at http://ecomments.osha.gov. OSHA Docket Office
and Department of Labor hours of operation are 8:15 a.m. to 4:45 p.m.
Hearing testimony and documentary evidence. Interested parties who
will be requesting more than 10 minutes to present their testimony, or
who will be submitting documentary evidence at the informal public
hearing must mail three copies of the testimony and the documentary
evidence to the Docket Office, Docket No. H049C, Room N-2625, OSHA,
U.S. Department of Labor, 200 Constitution Avenue, NW., Washington DC
20210. Additional information for submitting testimony and evidence is
found under SUPPLEMENTARY INFORMATION.

FOR FURTHER INFORMATION CONTACT: For technical inquiries, contact Mr.
John E. Steelnack, Directorate of Standards and Guidance, Room N-3718,
OSHA, U.S. Department of Labor, 200 Constitution Ave., NW., Washington,
DC 20210; telephone (202) 693-2289 or fax (202) 693-1678. For hearing
information contact Ms. Veneta Chatmon, OSHA Office of Information,
Docket No. H-49C, Room N-3649, U.S. Department of Labor, 200
Constitution Ave., NW., Washington, DC 20210 (telephone (202) 693-
1999). For additional copies of this Federal Register notice, contact
the Office of Publications, Room N-3103, OSHA, U.S. Department of
Labor, 200 Constitution Ave., NW., Washington, DC 20210 (telephone
(202) 693-1888). Electronic copies of this Federal Register notice, as
well as news releases and other relevant documents, are available at
OSHA's Home page at http://www.osha.gov.

SUPPLEMENTARY INFORMATION:

OMB Review Under the Paperwork Reduction Act

After a thorough analysis of the proposed provisions, OSHA believes
that these provisions would not add to the existing collection-of-
information (i.e., paperwork) requirements regarding respirator
selection. OSHA determined that its existing Respiratory Protection
Standard at 29 CFR 1910.134 has two provisions that involve APFs and
also impose paperwork requirements on employers. These provisions
require employers to: Include respirator selection in their written
respiratory protection program (29 CFR 1910.134(c)(1)(i)); and inform
employees regarding proper respirator selection (29 CFR 1910.(k)(ii)).
The information on respirator selection addressed by these two
provisions must include a brief discussion of the purpose of APFs, and
how to use them in selecting a respirator that affords an employee
protection from airborne contaminants. The burden imposed by this
requirement remains the same

[[Page 34037]]

whether employers currently use the APFs published in the 1987 NIOSH
RDL or the ANSI Z88.2-1992 Respiratory Protection Standard, or
implement the APFs proposed in this rulemaking. Therefore, the proposed
use of APFs in the context of these two existing respirator-selection
provisions does not require an additional paperwork-burden
determination because OSHA already accounted for this burden under its
existing Respiratory Protection Standard (see 63 FR 1152-1154; OMB
Control Number 1218-0099).
Both OSHA's existing Respiratory Protection Standard and the
proposed APF provisions require employers to use APFs as part of the
respirator-selection process. This process includes obtaining
information about the workplace exposure level to an airborne
contaminant, identifying the exposure limit (e.g., permissible exposure
limit) for the contaminant, using this information to calculate the
required level of protection (i.e., the APF), and referring to an APF
table to determine which respirator to select. Admittedly, this process
involves the collection and use of information, but it does not require
employers to inform others, either orally or in writing, about the
process they use to select respirators for individual employees, or the
outcomes of this process; by not requiring employers to communicate
this information to others, OSHA removed this process from the ambit of
the Paperwork Reduction Act of 1995 (PRA-95) (44 U.S.C. 3506(c)(2)(A)).
In the alternative, even if PRA-95 applies, the proposal involves the
same information-collection and -use requirements with regard to APFs
as the existing standard (see paragraphs (d)(1) and (d)(3)(i) of 29 CFR
1910.134, and the rationale for the existing APF requirements in the
preamble to the final Respiratory Protection Standard, 63 FR 1163 and
1203-1204); accordingly, the paperwork burden imposed by the proposal
would be equivalent to the burden already imposed under the existing
standard.
Interested parties who want to comment on OSHA's determination that
the proposed provisions contain no additional paperwork burden compared
to the existing paperwork requirements must send their written comments
to the Office of Information and Regulatory Affairs, Attn: OMB Desk
Officer for OSHA, Office of Management and Budget, Room 10235, 725 17th
Street NW., Washington, DC 20503. The Agency also encourages commenters
to submit their comments on this paperwork determination to OSHA along
with their other comments.

Federalism

The Agency reviewed the proposed APF provisions according to the
most recent Executive Order on Federalism (Executive Order 13132, 64 FR
43225, August 10, 1999). This Executive Order requires that federal
agencies, to the extent possible, refrain from limiting state policy
options, consult with states before taking actions that restrict their
policy options, and take such actions only when clear constitutional
authority exists and the problem is of national scope. The Executive
Order allows federal agencies to preempt state law only with the
expressed consent of Congress; in such cases, federal agencies must
limit preemption of state law to the extent possible.
Under section 18 of the Occupational Safety and Health Act (the
``Act'' or ``OSH Act''), Congress expressly provides OSHA with
authority to preempt state occupational safety and health standards to
the extent that the Agency promulgates a federal standard under section
6 of the Act. Accordingly, section 18 of the Act authorizes the Agency
to preempt state promulgation and enforcement of requirements dealing
with occupational safety and health issues covered by OSHA standards
unless the state has an OSHA-approved occupational safety and health
plan (i.e., is a state-plan state) [see Gade v. National Solid Wastes
Management Association, 112 S. Ct. 2374 (1992)]. Therefore, with
respect to states that do not have OSHA-approved plans, the Agency
concludes that this proposal conforms to the preemption provisions of
the Act. Additionally, section 18 of the Act prohibits states without
approved plans from issuing citations for violations of OSHA standards;
the Agency finds that the proposed rulemaking does not expand this
limitation.
OSHA asserts that it has authority under Executive Order 13132 to
propose APF requirements because the problems addressed by these
requirements are national in scope. As noted in section VI (``Summary
of the Preliminary Economic Analysis and Initial Regulatory Flexibility
Analysis'') of this preamble, hundreds of thousands of employers must
select appropriate respirators for millions of employees. These
employees are exposed to many different types and levels of airborne
contaminants found in general industry, construction, shipyard,
longshoring, and marine terminal workplaces. Accordingly, the proposed
requirements would provide employers in every state with critical
information to use when selecting respirators to protect their
employees from the risks of exposure to airborne contaminants. However,
while OSHA drafted the proposed APF and MUC requirements to protect
employees in every state, section 18(c)(2) of the Act permits state-
plan states to develop their own requirements to deal with any special
workplace problems or conditions, provided these requirements are at
least as effective as the final requirements that result from this
proposal.

State Plans

The 26 states and territories with their own OSHA-approved
occupational safety and health plans must adopt comparable provisions
within six months after the Agency publishes the final APF and MUC
requirements. These states and territories are: Alaska, Arizona,
California, Hawaii, Indiana, Iowa, Kentucky, Maryland, Michigan,
Minnesota, Nevada, New Mexico, North Carolina, Oregon, Puerto Rico,
South Carolina, Tennessee, Utah, Vermont, Virginia, Virgin Islands,
Washington, and Wyoming. Connecticut, New Jersey and New York have OSHA
approved State Plans that apply to state and local government employees
only. Until a state-plan state promulgates its own comparable
provisions, Federal OSHA will provide the state with interim
enforcement assistance, as appropriate.

Unfunded Mandates

The Agency reviewed the proposed APF and MUC provisions according
to the Unfunded Mandates Reform Act of 1995 (UMRA) (2 U.S.C. 1501 et
seq.) and Executive Order 12875. As discussed in section VI (``Summary
of the Preliminary Economic Analysis and Initial Regulatory Flexibility
Analysis'') of this preamble, OSHA estimates that compliance with this
proposal would require private-sector employers to expend about $4.5
million each year. However, while this proposal establishes a federal
mandate in the private sector, it is not a significant regulatory
action within the meaning of section 202 of the UMRA (2 U.S.C. 1532).
OSHA standards do not apply to state and local governments, except
in states that have voluntarily elected to adopt an OSHA-approved state
occupational safety and health plan. Consequently, the proposed
provisions do not meet the definition of a ``Federal intergovernmental
mandate'' [see section 421(5) of the UMRA (2 U.S.C. 658(5)]. Therefore,
based on a review of the rulemaking record to date, the Agency believes
that few, if any, of the affected employers are state, local, and
tribal governments. Therefore, the

[[Page 34038]]

proposed APF requirements do not impose unfunded mandates on state,
local, and tribal governments.

Protecting Children From Environmental Health and Safety Risks

Executive Order 13045 requires that Federal agencies submitting
covered regulatory actions to OMB's Office of Information and
Regulatory Affairs (OIRA) for review pursuant to Executive Order 12866
must provide OIRA with (1) an evaluation of the environmental health or
safety effects that the planned regulation may have on children, and
(2) an explanation of why the planned regulation is preferable to other
potentially effective and reasonably feasible alternatives considered
by the agency. Executive Order 13045 defines ``covered regulatory
actions'' as rules that may (1) be economically significant under
Executive Order 12866 (i.e., a rulemaking that has an annual affect on
the economy of $100 million or more, or would adversely affect in a
material way the economy, a sector of the economy, productivity,
competition, jobs, the environment, public health or safety, or state,
local, or tribal governments or communities), and (2) concern an
environmental health risk or safety risk that an agency has reason to
believe may disproportionately affect children. In this context, the
term ``environmental health risks and safety risks'' means risks to
health or safety that are attributable to products or substances that
children are likely to come in contact with or ingest (e.g., through
air, food, water, soil, product use).
The proposed provisions are not economically significant under
Executive Order 12866 (see section VI (``Summary of the Preliminary
Economic Analysis and Initial Regulatory Flexibility Analysis'') of
this preamble). In addition, after reviewing the proposed APF
provisions, OSHA has determined that these provisions do not impose
environmental health or safety risks to children as set forth in
Executive Order 13045. The proposed provisions would require employers
to use APFs in selecting proper respirators for employee use, with the
objective of limiting employee exposures to airborne contaminants. To
the best of OSHA's knowledge, no employees under 18 years of age work
under conditions that require respirator use. However, if such
conditions exist, children who use respirators selected according to
these proposed provisions would receive adequate protection from the
airborne contaminants. In this regard, the Agency is requesting public
comment on whether employees under the age of 18 years use respirators,
and, if they do, the extent to which the respirators provide them with
adequate protection. Based on this discussion, OSHA believes that the
APF and MUC requirements proposed in this rulemaking do not constitute
a covered regulatory action as defined by Executive Order 13045.

Applicability of Existing Consensus Standards

Section 6(b)(8) of the OSH Act requires OSHA to explain ``why a
rule promulgated by the Secretary differs substantially from an
existing national consensus standard,'' by publishing ``a statement of
the reasons why the rule as adopted will better effectuate the purposes
of the Act than the national consensus standard.'' [see 29 U.S.C.
655(b)(8)]. Accordingly, the Agency compared the proposed APF
requirements with the APF provisions of ANSI Z88.2-1992 (``Respiratory
Protection''). This consensus standard, published by the American
National Standards Institute in 1992, is the only publicly available
consensus standard that includes APFs. In most instances, the APFs
being proposed by the Agency are identical to ANSI's APFs, however,
some differences exist. Where OSHA has proposed an APF that differs
from ANSI's, the Summary and Explanation provides the basis for that
decision.

Environmental Impact Assessment

The Agency reviewed the proposed provisions according to the
National Environmental Policy Act (NEPA) of 1969 (42 U.S.C. 4321 et
seq.), the regulations of the Council of Environmental Quality (40 CFR
part 1500), and the Department of Labor's NEPA procedures (29 CFR part
11). OSHA estimates that this proposed rule would have a direct impact
on a relatively small number of respirator users and, in so doing ,
merely alter the type of respirator they are using. The Agency does not
anticipate that this will significantly alter solid waste patterns,
water quality, or ambient air quality. As a result of this review, OSHA
concludes that the proposed provisions would have no significant
environmental impact.

I. General

Table of Contents

The following Table of Contents identifies the major preamble
sections of this proposal and the order in which they are presented:

Introductory Material
Notice and Comment
Dates for Hearings
Supplementary Information
OMB Review Under the Paperwork Reduction Act
Federalism
State Plans
Unfunded Mandates
Protecting Children from Environmental Health and Safety Risks
Applicability of Existing Consensus Standards
Environmental Impact Assessment
I. General
Table of contents
Glossary
II. Pertinent Legal Authority
III. Events Leading to the Proposed Standard
A. Regulatory History
B. Need for Assigned Protection Factors
C. Review of the Proposed Standard by the Advisory Committee for
Construction Safety and Health (ACCSH)
IV. Methodology for Developing Assigned Protection Factors
A. Dr. Nicas' Proposal and Response from Commenters
B. Analyses of WPF Studies
C. Analyses of SWPF Studies
D. OSHA's Overall Summary Conclusions
E. Summaries of Studies
V. Health Effects
VI. Summary of the Preliminary Economic Analysis and Initial
Regulatory Flexibility Screening Analysis
VII. Summary and Explanation of the Proposed Standard
A. Revisions to the Respiratory Protection Standard
B. Superseding the Respirator Selection Provisions of Substance-
Specific Standards in Parts 1910, 1915, and 1926
VIII. Issues
IX. Public Participation--Comments and Hearings
X. Proposed Amendments to Standards

Glossary

This glossary specifies the terms represented by acronyms, and
provides definitions of other terms, used frequently in this proposal.
This glossary does not change the legal requirements as proposed in
this notice of proposed rulemaking, nor is it intended to propose new
regulatory requirements or definitions. It is presented simply to
assist the reader.
A. Acronyms
ACGIH: American Conference of Governmental Industrial Hygienists.
AIHA: American Industrial Hygiene Association.
ANSI: American National Standards Institute.
APF: Assigned Protection Factor (see definition in proposed regulatory
text).
DOP: Dioctylphthalate (an aerosolized agent used for quantitative fit
testing).
DFM: Dust/Fume/Mist filter.
EPF: Effective Protection Factor (see definition below under
``Protection factor study'').
HEPA: High efficiency particulate air [filter]
(see definition below).
IDLH: Immediately dangerous to life or health (see definition below).

[[Page 34039]]

LANL: Los Alamos National Laboratory.
LLNL: Lawrence Livermore National Laboratory.
MSHA: Mine Safety and Health Administration.
MUC: Maximum Use Concentration (see definition in proposed regulatory
text).
NIOSH: National Institute for Occupational Safety and Health.
NRC: Nuclear Regulatory Commission.
OSHA: Occupational Health and Safety Administration.
PAPR: Powered air-purifying respirator (see definition below).
PEL: Permissible Exposure Limit (an occupational exposure level
specified by OSHA).
PPF: Program Protection Factor (see definition below under ``Protection
factor study'').
QLFT: Qualitative fit test (see definition below).
QNFT: Quantitative fit test (see definition below).
RDL: Respirator Decision Logic (respirator selection guidance developed
by NIOSH that contains a set of respirator protection factors).
REL: Recommended Exposure Limit (an occupational exposure level
recommended by NIOSH).
SAR: Supplied-air respirator (see definition below).
SCBA: Self-contained breathing apparatus (see definition below).
WPF: Workplace Protection Factor (see definition below under
``Protection factor study'').
TLV: Threshold Limit Value (an occupational exposure level recommended
by ACGIH).
SWPF: Simulated Workplace Protection Factor (see definition below under
``Protection factor study'').
B. Definitions
Terms followed by an asterisk (*) refer to definitions that can be
found in paragraph (b) (``Definitions'') of OSHA's Respiratory
Protection Standard (29 CFR 1910.134).
Air-purifying respirator*: A respirator with an air-purifying
filter, cartridge, or canister that removes specific air contaminants
by passing ambient air through the air-purifying element.
Atmosphere-supplying respirator*: A respirator that supplies the
respirator user with breathing air from a source independent of the
ambient atmosphere, and includes SARs and SCBA units.
Canister or cartridge*: A container with a filter, sorbent, or
catalyst, or combination of these items, which removes specific
contaminants from the air passed through the container.
Continuous flow respirator : An atmosphere-supplying respirator
that provides a continuous flow of breathable air to the respirator
facepiece.
Demand respirator*: An atmosphere-supplying respirator that admits
breathing air to the facepiece only when a negative pressure is created
inside the facepiece by inhalation.
Filter or air-purifying element*: A component used in respirators
to remove solid or liquid aerosols from the inspired air.
Filtering facepiece (or dust mask)*: A negative pressure
particulate respirator with a filter as an integral part of the
facepiece or with the entire facepiece composed of the filtering
medium.
Fit factor*: A quantitative estimate of the fit of a particular
respirator to a specific individual, and typically estimates the ratio
of the concentration of a substance in ambient air to its concentration
inside the respirator when worn.
Fit test*: The use of a protocol to qualitatively or quantitatively
evaluate the fit of a respirator on an individual.
Helmet*: A rigid respiratory inlet covering that also provides head
protection against impact and penetration.
High-efficiency particulate air filter*: A filter that is at least
99.97% efficient in removing monodisperse particles of 0.3 micrometers
in diameter. The equivalent NIOSH 42 CFR 84 particulate filters are the
N100, R100, and P100 filters.
Hood*: A respiratory inlet covering that completely covers the head
and neck and may also cover portions of the shoulders and torso.
Immediately dangerous to life or health*: An atmosphere that poses
an immediate threat to life, would cause irreversible adverse health
effects, or would impair an individual's ability to escape from a
dangerous atmosphere.
Loose-fitting facepiece*: A respiratory inlet covering that is
designed to form a partial seal with the face.
Negative pressure respirator (tight-fitting)*: A respirator in
which the air pressure inside the facepiece is negative during
inhalation with respect to the ambient air pressure outside the
respirator.
Positive pressure respirator*: A respirator in which the pressure
inside the respiratory inlet covering exceeds the ambient air pressure
outside the respirator.
Powered air-purifying respirator*: An air-purifying respirator that
uses a blower to force the ambient air through air-purifying elements
to the inlet covering.
Pressure demand respirator*: A positive pressure atmosphere-
supplying respirator that admits breathing air to the facepiece when
the positive pressure is reduced inside the facepiece by inhalation.
Protection factor study: A study that determines the protection
provided by a respirator during use. This determination is generally
accomplished by measuring the ratio of the concentration of an agent
(e.g., hazardous substance) outside the respirator (Co) to the agent's
concentration inside the respirator (Ci) (i.e., Co/Ci). Therefore, as
the ratio between Co and Ci increases, the protection factor increases,
indicating an increase in the level of protection provided to employees
by the respirator. Four types of protection factor studies are:
Effective Protection Factor (EPF) study--a study, conducted in the
workplace, that measures the protection provided by a properly
selected, fit-tested, and functioning respirator when used
intermittently for only some fraction of the total workplace exposure
time (i.e., sampling is conducted during periods when respirators are
worn and not worn). EPFs are not directly comparable to WPF values
because the determinations include both the time spent in contaminated
atmospheres with and without respiratory protection; therefore, EPFs
tend to understate the protection that would be obtained if the
respirator were being worn at all times.
Program Protection Factor (PPF) study--a study that estimates the
protection provided by a respirator within a specific respirator
program. Like the EPF, it is focused not only on the respirator's
performance, but also the effectiveness of the complete respirator
program. PPFs are affected by all factors of the program, including
respirator selection and maintenance, user training and motivation,
work activities, and program administration.
Workplace Protection Factor (WPF) study--a study, conducted under
actual conditions of use in the workplace, that measures the protection
provided by a properly selected, fit-tested, and functioning
respirator, when the respirator is correctly worn and used as part of a
comprehensive respirator program. Measurements of Co and Ci are
obtained only while the respirator is being worn during performance of
normal work tasks (i.e., samples are not collected when the respirator
is not being worn). As the degree of protection afforded by the
respirator increases, the WPF increases.
Simulated Workplace Protection Factor (SWPF) study--a study,
conducted in a controlled laboratory setting and in which Co and Ci

[[Page 34040]]

sampling is performed while the subject performs a series of set
exercises. The laboratory setting is used to control many of the
variables found in workplace studies, while the exercises simulate the
work activities of respirator users. This type of study is designed to
determine the optimum performance of respirators by reducing the impact
of sources of variability through maintenance of tightly controlled
study conditions.
Qualitative fit test*: A pass/fail fit test to assess the adequacy
of respirator fit that relies on the individual's response to the test
agent.
Quantitative fit test*: An assessment of the adequacy of respirator
fit by numerically measuring the amount of leakage into the respirator.
Self-contained breathing apparatus*: An atmosphere-supplying
respirator for which the breathing air source is designed to be carried
by the user.
Supplied-air respirator (or airline) respirator*: An atmosphere-
supplying respirator for which the source of breathing air is not
designed to be carried by the user.
Tight-fitting facepiece*: A respiratory inlet covering that forms a
complete seal with the face.

II. Pertinent Legal Authority

The purpose of the Occupational Safety and Health Act, 29 U.S.C.
651 et seq. (the ``OSHA Act'' or ``Act'') is to ``assure so far as
possible every working man and woman in the Nation safe and healthful
working conditions and to preserve our human resources.'' [29 U.S.C.
651(b)]. To achieve this goal, Congress authorized the Secretary of
Labor to promulgate and enforce occupational safety and health
standards [see 29 U.S.C. 654(b) (requiring employers to comply with
OSHA standards), 29 U.S.C. 655(a) (authorizing summary adoption of
existing consensus and federal standards within two years of the Act's
enactment), and 29 U.S.C. 655(b) (authorizing promulgation of standards
pursuant to notice and comment)].
A safety or health standard is a standard ``which requires
conditions, or the adoption or use of one or more practices, means,
methods, operations, or processes, reasonably necessary or appropriate
to provide safe or healthful employment or places of employment.'' [29
U.S.C. 652(8)]. A standard is reasonably necessary or appropriate
within the meaning of section 652(8) of the Act when it substantially
reduces or eliminates significant risk, and is technologically and
economically feasible, cost effective, consistent with prior Agency
action or supported by a reasoned justification for departing from
prior Agency action, and supported by substantial evidence; it must
also effectuate the Act's purposes better than any national consensus
standard it supersedes [see International Union, UAW v. OSHA (LOTO II),
37 F.3d 665 (DC Cir. 1994; and 58 FR 16612-16616 (March 30, 1993)].
OSHA has discussed the nature of adverse health effects caused by
exposure to airborne chemical hazards many times in previous rulemaking
activities [see, for example, the preambles to any of OSHA's substance-
specific standards codified in 29 CFR 1910.1001 to 1910.1052]. As
discussed in the Significance of Risk section of the Respiratory
Protection Standard, the health risk presented to workers can be
represented by the risk that a respirator will not be properly selected
or used, which increases the possibility that the user will be
overexposed to a harmful air contaminant. The risks that are addressed
by the Respiratory Protection Standard are not characterized as
illness-specific risks but, instead, relate to a more general
probability that when a respirator provides insufficient protection,
the wearer may be exposed to a level of air contaminant that is
associated with material impairment of the worker's health.
The Agency believes that a standard is technologically feasible
when the protective measures it requires already exist, can be brought
into existence with available technology, or can be created with
technology that can reasonably be expected to be developed [see
American Textile Mfrs. Institute v. OSHA (Cotton Dust), 452 U.S. 490,
513 (1981); American Iron and Steel Institute v. OSHA (Lead II), 939
F.2d 975, 980 (DC Cir. 1991)]. A standard is economically feasible when
industry can absorb or pass on the costs of compliance without
threatening the industry's long-term profitability or competitive
structure [see Cotton Dust, 452 U.S. at 530 n. 55; Lead II, 939 F.2d at
980], and a standard is cost effective when the protective measures it
requires are the least costly of the available alternatives that
achieve the same level of protection [see Cotton Dust, 453 U.S. at 514
n. 32; International Union, UAW v. OSHA (LOTO III), 37 F.3d 665, 668
(DC Cir. 1994)].
All standards must be highly protective [see 58 FR 16612, 16614-15
(March 30, 1993); LOTO III, 37 F.3d at 669]. Accordingly, section
8(g)(2) of the Act authorizes OSHA ``to prescribe such rules and
regulations as [it]
may deem necessary to carry out its
responsibilities under the Act'' [see 29 U.S.C. 657(g)(2)]. However,
health standards must also meet the ``feasibility mandate'' of section
6(b)(5) of the OSH Act, 29 U.S.C. 655(b)(5). Section 6(b)(5) of the Act
requires OSHA to select ``the most protective standard consistent with
feasibility'' needed to reduce significant risk when regulating health
hazards [see Cotton Dust, 452 U.S. at 509]. Section 6(b)(5) also
directs OSHA to base health standards on ``the best available
evidence,'' including research, demonstrations, and experiments [see 29
U.S.C. 655(b)(5)]. In this regard, OSHA must consider ``in addition to
the attainment of the highest degree of health and safety protection *
* * the latest scientific data * * * feasibility and experience gained
under this and other health and safety laws.'' (Id.). Furthermore,
section 6(b)(5) of the Act specifies that standards must ``be expressed
in terms of objective criteria and of the performance desired'' [see 29
U.S.C. 655(b)(7)].
The proposed APF and MUC provisions are integral components of an
effective respiratory protection program. Respiratory protection is a
supplemental method used by employers to protect employees against
airborne contaminants in workplaces where feasible engineering controls
and work practices are not available, have not yet been implemented, or
are not in themselves sufficient to protect employee health. Employers
also use respiratory protection under emergency conditions involving
the accidental release of airborne contaminants. The proposed
amendments to OSHA's Respiratory Protection Standard, and the Agency's
substance-specific standards, would provide employers with critical
information to use when selecting respirators for employees exposed to
airborne contaminants found in general industry, construction,
shipyard, longshoring, and marine terminal workplaces. Since it is
generally recognized that different types of respiratory protective
equipment provide different degrees of protection against hazardous
exposures, proper respirator selection is of critical importance. The
proposed APF and MUC provisions provide additional guidance on the
point at which an increase in the level of respiratory protection is
necessary. The APF and MUC provisions will greatly enhance an
employer's ability to select a respirator that will adequately protect
employees. OSHA believes that in the absence of these proposed
provisions, employers will be less certain about which respirators to
select for adequate employee protection.

[[Page 34041]]

The Agency also developed the proposed provisions to be feasible
and cost effective, and is specifying them in terms of objective
criteria and the level of performance desired. In this regard, section
VI (``Summary of the Preliminary Economic Analysis and Initial
Regulatory Flexibility Analysis'') of this preamble provides the
benefits and costs of this proposal, and describes several other
alternatives as required by section 205 of the UMRA (2 U.S.C. 1535).
Based on this information, OSHA preliminarily concludes that the
proposed APF and MUC provisions constitute the most cost-effective
alternative for meeting its statutory objective of reducing risk of
adverse health effects to the extent feasible.

III. Events Leading to the Proposed Standard

A. Regulatory History

Congress created the Occupational Safety and Health Administration
(OSHA) in 1970, and gave it the responsibility for promulgating
standards to protect the health and safety of American workers. As
directed by the OSH Act, the Agency adopted existing Federal standards
and national consensus standards developed by various organizations
such as the American Conference of Governmental Industrial Hygienists
(ACGIH), the National Fire Protection Association (NFPA), and the
American National Standards Institute (ANSI). The ANSI standard Z88.2-
1969, ``Practices for Respiratory Protection,'' was the basis of the
first six sections (permissible practice, minimal respirator program,
selection of respirators, air quality, use, maintenance and care) of
OSHA's Respiratory Protection Standard (29 CFR 1910.134) adopted in
1971. The seventh section was a direct, complete incorporation of ANSI
Standard K13.1-1969, ``Identification of Gas Mask Canisters.''
The Agency promulgated an initial Respiratory Protection Standard
for the construction industry (29 CFR 1926.103) in April 1971. On
February 9, 1979, OSHA formally applied 29 CFR 1910.134 to the
construction industry (44 FR 8577). Agencies that preceded OSHA
developed the original maritime respiratory protection standards in the
1960s (e.g., section 41 of the Longshore and Harbor Worker Compensation
Act). The section designations adopted by OSHA for these standards, and
their original promulgation dates, are: Shipyards--29 CFR 1915.82,
February 20, 1960 (25 FR 1543); Marine Terminals--29 CFR 1917.82, March
27, 1964 (29 FR 4052); and Longshoring--29 CFR 1918.102, February 20,
1960 (25 FR 1565). OSHA incorporated 29 CFR 1910.134 by reference into
its Marine Terminal standards (Part 1917) on July 5, 1983 (48 FR
30909). The Agency updated and strengthened its Longshoring and Marine
Terminal standards in 1996 and 2000, and these standards now
incorporate 29 CFR 1910.134 by reference.
Under the Respiratory Protection Standard that OSHA initially
adopted, employers needed to follow the guidance of the Z88.2-1969 ANSI
standard to ensure proper selection of respirators. Subsequently, OSHA
published an Advance Notice of Proposed Rulemaking (``ANPR'') to revise
the Respiratory Protection Standard on May 14, 1982 (47 FR 20803). Part
of the impetus for this notice was the Agency's inclusion of new
respirator requirements in the comprehensive substance-specific
standards promulgated under Section (6)(b) of the OSH Act, e.g., fit
testing protocols, respirator selection tables, use of PAPRs, changing
filter elements whenever an employee detected an increase in breathing
resistance, and requirements referring employees with breathing
difficulties to a physician trained in pulmonary medicine, either at
fit testing or during routine respirator use [see, e.g, 29 CFR
1910.1025 (OSHA's Lead Standard)]. The respirator provisions in these
substance-specific standards took into account advances in respirator
technology and changes in related guidance documents that were state-
of-the-art when OSHA published these substance specific standards and,
in particular, recognized that effective respirator use depends on a
comprehensive respiratory protection program that includes use of APFs.
OSHA's 1982 ANPR sought information on the effectiveness of its
current Respiratory Protection Standard, the need to revise this
standard, and suggestions on the nature of the revisions. The 1982 ANPR
referenced the ANSI Z88.2-1980 standard on respiratory protection with
its table of protection factors, the 1976 report by Dr. Ed Hyatt from
the LASL titled ``Respiratory Protection Factors'' (Ex. 2), and the RDL
developed jointly by OSHA and NIOSH, as revised in 1978 (Ex. 9, Docket
No. H049). Questions #2, #3, and #4 in the 1982 ANPR asked for comments
on how OSHA should use protection factors. The Agency received responses
from 81 interested parties. The commenters generally supported revising
OSHA's Respiratory Protection Standard, and provided recommendations
regarding approaches for including a table of protection factors (Ex. 15).
On September 17, 1985, OSHA announced the availability of a
preliminary draft of the proposed Respiratory Protection Standard. This
preproposal draft standard included the public comments received in
response to 1982 ANPR, and OSHA's own analysis of revisions needed in
the Respiratory Protection Standard to account for state-of-the-art
respiratory protection. The Agency received 56 responses from
interested parties (Ex. 36) which OSHA carefully reviewed in developing
the proposal.
On November 15, 1994, OSHA published the proposed rule to revise 29
CFR 1910.134, and provided public notice of an informal public hearing
on the proposal (59 FR 58884). The Agency convened the informal public
hearing on June 6, 1995. On June 15, 1995, as part of the public
hearing, OSHA held a one-day panel discussion by respirator experts of
APFs. Areas discussed included difficulties in measuring performance of
respiratory protection in WPF and SWPF studies, statistical
uncertainties regarding the distribution of data from these studies,
and the problems associated with setting APFs for all respirators that
protect all potential respirator users across a wide variety of
workplaces and exposure conditions.
OSHA reopened the rulemaking record for the revised Respiratory
Protection Standard on November 7, 1995 (60 FR 56127), requesting
comments on a study performed for OSHA by Dr. Mark Nicas titled ``The
Analysis of Workplace Protection Factor Data and Derivation of Assigned
Protection Factors' (Ex. 1-156). That study, which the Agency placed in
the rulemaking docket on September 20, 1995, addressed the use of
statistical modeling for determining respirator APFs. OSHA received 12
comments on the Nicas report. This report, and the comments received in
response to it, convinced OSHA that more information would be necessary
before it could resolve the complex issues regarding how to establish
APFs, including what methodology to use in analyzing existing
protection factor studies (see Section IV below for a more detailed
explanation of the Nicas report and the comments made on it).
OSHA published the final, revised Respiratory Protection Standard,
29 CFR 1910.134, on January 8, 1998 (63 FR 1152). The standard contains
worksite-specific requirements for program administration, procedures
for respirator selection, employee training, fit testing, medical
evaluation, respirator

[[Page 34042]]

use, and other provisions. However, OSHA reserved the sections of the
final standard related to APFs and maximum use concentration (MUC)
pending further rulemaking (see 63 FR 1182 and 1203). The Agency stated
that, until a future rulemaking on APFs is completed:

[Employers must]
take the best available information into
account in selecting respirators. As it did under the previous
[Respiratory Protection]
standard, OSHA itself will continue to
refer to the [APFs in the 1987 NIOSH RDL]
in cases where it has not
made a different determination in a substance specific standard.
(see 63 FR 1163)

The Agency subsequently established a separate docket (i.e., H049C)
for the APF rulemaking. This docket includes copies of material related
to APFs that it previously placed in the docket (H049) for the revised
Respiratory Protection Standard. The APF rulemaking docket also
contains other APF-related materials, studies, and data that OSHA
obtained after it promulgated the final Respiratory Protection Standard
in 1998.
History of Assigned Protection Factors
In 1965, the Bureau of Mines published ``Respirator Approval
Schedule 21B,'' which contained the term ``protection factor'' as part
of its approval process for half-mask respirators (for protection up to
10 times the TLV) and full facepiece respirators (for protection up to
100 times the TLV). The Bureau of Mines based these protection factors
on quantitative fit tests, using dioctyl pthalate (DOP), that were
conducted on six male test subjects performing simulated work
exercises.
The Atomic Energy Commission (AEC) published proposed protection
factors for respirators in 1967, but later withdrew them because
quantitative fit testing studies were available for some, but not all,
types of respirators. To address this shortcoming, the AEC subsequently
sponsored respirator studies at LASL, starting in 1969.
ANSI standard Z88.2-1969, which OSHA adopted by reference in 1971,
did not contain APFs for respirator selection. Nevertheless, this ANSI
standard recommended that ``due consideration be given to potential
inward leakage in selecting devices,'' and contained a list of the
various respirators grouped according to the quantity of leakage into
the facepiece expected during routine use.
In 1972, NIOSH and the Bureau of Mines published new approval
schedules for respiratory protection under 30 CFR Part 11. However,
these new approval schedules did not include fit testing provisions as
part of the respirator certification process.
NIOSH sponsored additional respirator studies at LASL, beginning in
1971, that used quantitative test systems to measure the overall
performance of respirators. Dr. Edwin C. Hyatt of LASL included a table
of protection factors for, single-use dust respirators; quarter-mask,
half-mask, and full facepiece air-purifying respirators; and SCBAs in a
1976 report titled ``Respirator Protection Factors'' (Ex. 2). The
protection factors were based on data from DOP and sodium chloride
quantitative fit test studies performed on these respirators at LASL
between 1970 and 1973. The table also contained recommended protection
factors for respirators that had no performance test data. Dr. Hyatt
based these recommended protection factors on the judgment and
experience of LASL researchers, as well as extrapolations from
available facepiece leakage data for similar respirators. For example,
he assumed that performance data for SCBAs operated in the pressure
demand mode could be used to represent other (non-tested) respirators
that maintain positive pressure in the facepiece, hood, helmet, or suit
during inhalation. In addition, he recommended in his report that NIOSH
continue testing the performance of respirators that lacked adequate
fit test data. Relative to this, staff members at LASL (from 1974 to
1978) used a representative 35-person test panel to conduct
quantitative fit tests on all air-purifying particulate respirators
approved by the Bureau of Mines and NIOSH.
In August 1975, the Joint NIOSH-OSHA Standards Completion Program
published the RDL (Ex. 25-4, Appendix F, Docket No. H049). The RDL
contained a table of protection factors that were based on quantitative
fit testing performed at LASL and elsewhere, as well as the expert
judgment of the RDL authors. The 1978 NIOSH update of the RDL contained
the following protection factors:
5 for single-use respirators;
10 for half-mask respirators with DFM or HEPA filters;
50 for full facepiece air-purifying respirators with HEPA filters
or chemical cartridges;
1,000 for PAPRs with HEPA filters;
1,000 for half-mask SARs operated in the pressure demand mode;
2,000 for full facepiece SARs operated in the pressure demand mode;
and
10,000 for full facepiece SCBAs operated in the pressure demand
mode.
ANSI's respiratory protection Subcommittee decided to revise Z88.2-
1969 in the late 1970s. During its deliberations, the Subcommittee
conducted an extensive discussion regarding the role of respirator
protection factors in an effective respiratory protection program. As a
result, the Subcommittee decided to add an APF table to the revised
standard. In May 1980, ANSI published the revision as Z88.2-1980 (Ex.
10, Docket No. H049) and it contained the first ANSI Z88.2 respiratory
protection factor table. The ANSI Subcommittee based the table on
Hyatt's protection factors, which it updated using results from fit
testing studies performed at LANL and elsewhere since 1973. For
example, the protection factor for full facepiece air-purifying
particulate respirators was 100 when qualitatively fit tested, or 1,000
when equipped with high efficiency filters and quantitatively fit
tested. The table consistently gave higher protection factors to tight-
fitting facepiece respirators when employers performed quantitative fit
testing rather than qualitative fit testing. The ANSI Subcommittee
concluded that PAPRs (with any respiratory inlet covering), atmosphere-
supplied respirators (in continuous flow or pressure demand mode), and
pressure demand SCBAs required no fit testing because they operated in
a positive pressure mode. Accordingly, it gave these respirators high
protection factors, limited only by IDLH values. The Subcommittee
assigned protection factors of 10,000 and over to respirators used in
IDLH atmospheres.
In response to a complaint to NIOSH that the PAPRs used in a plant
did not appear to provide the expected protection factor of 1,000,
Myers and Peach of NIOSH conducted a WPF study during silica bagging
operations. Myers and Peach tested half-mask and full facepiece PAPRs
and found protection factors that ranged from 16 to 215. They published
the results of the study in 1983 (Ex. 1-64-46). The results of this
study led NIOSH and other researchers, as well as respirator
manufacturers, to perform additional WPF studies on PAPRs and other
respirators.
NIOSH revised its RDL in 1987 (Ex. 1-54-437Q). While the revision
retained many of the provisions of the 1978 RDL, it recognized the
problems involved in developing APFs. The 1987 RDL also revised the
APFs for some respirators, based on NIOSH's WPF studies. For example,
the APFs were lowered for the following respirator classes: PAPRs with
a loose-fitting hood or helmet to 25; PAPRs with a tight-fitting
facepiece and a HEPA filter to 50; supplied-air continuous flow hoods
or helmets to 25; and supplied-air continuous flow tight-fitting
facepiece respirators to 50.

[[Page 34043]]

NIOSH stated that it may revise the 1987 RDL if warranted by subsequent
WPF studies.
In August 1992, ANSI again revised its Z88.2 Respiratory Protection
Standard (Ex. 1-50). The ANSI Z88.2-1992 standard contained a revised
APF table, based on the Z88.2 Subcommittee's review of the available
protection factor studies. In a report describing the revised standard
(Ex. 1-64-423), Nelson, Wilmes, and daRoza described the rationale used
by the ANSI Subcommittee in setting APFs:

If WPF studies were available, they formed the basis for the
[APF]
number assigned. If no such studies were available, then
laboratory studies, design analogies, and other information was used
to decide what value to place in the table. In all cases where the
assigned protection factor changed when compared to the 1980
standard, the assigned number is lower in the 1992 standard.

In addition, the 1992 ANSI Z88.2 standard abandoned the 1980
standard's practice of giving increased protection factors to some
respirators if quantitative fit testing was performed.
Tom Nelson, the co-chair of the ANSI Z88.2-1992 Subcommittee,
published a second report, entitled ``The Assigned Protection Factor
According to ANSI'' (Ex. 135), four years after the Z88.2 Subcommittee
completed the revised 1992 standard. In the report, he reviewed the
reasoning used by the ANSI Subcommittee in setting the 1992 ANSI APFs.
He noted that the Z88.2 Subcommittee gave an APF of 10 to all half-mask
air-purifying respirators, including quarter-mask, elastomeric, and
disposable respirators. The Subcommittee also recommended that full
facepiece air-purifying respirators retain an APF of 100 (from the 1980
ANSI standard) because no new data were available to justify another
value. The Z88.2 Subcommittee also reviewed the 1987 NIOSH RDL values,
particularly the RDL's reduction of loose-fitting facepiece and PAPRs
with helmets or hoods to an APF of 25 based on their performance in WPF
studies. For half-mask PAPRs, the ANSI Subcommittee set an APF of 50
based on a WPF study by Lenhart (Ex. 1-64-42). The ANSI Subcommittee
had no WPF data available for full facepiece PAPRs, so it decided to
select an APF of 1,000 to be consistent with the APF for PAPRs with
helmets or hoods. The Subcommittee, in turn, based its APF of 1,000 for
PAPRs with helmets or hoods on design analogies (i.e., same facepiece
designs, operation at the same airflow rates) between these respirators
and airline respirators. Nelson noted that a subsequent WPF report by
Keys (Ex. 1-64-40) on PAPRs with helmets or hoods was consistent with
an APF of 1,000. According to Nelson, the Subcommittee used WPF studies
by Myers (Ex. 1-64-48), Gosselink (Ex. 1-64-23), Myers (Ex. 1-64-47),
and Que Hee and Lawrence (Ex. 1-64-60) to set an APF of 25 for PAPRs
with loose-fitting facepieces. Nelson stated that two WPF studies,
conducted by Gaboury and Burd (Ex. 1-64-24) and Stokes (Ex. 1-64-66)
subsequent to publication of ANSI Z88.2-1992, supported the APF of 25
selected by the Subcommittee for PAPRs with loose-fitting facepieces.
Tom Nelson stated in his report that the ANSI Subcommittee had no
new information on atmosphere-supplying respirators. Therefore, the
APFs for these respirators were based on analogies with other similarly
designed respirators (Ex. 135). The ANSI Subcommittee based the APF of
50 for half-mask continuous flow atmosphere-supplying respirators, and
the APF of 25 for loose-fitting facepiece continuous flow atmosphere-
supplying respirators, on the similarities between these respirators
and PAPRs with the same airflow rates. Nelson noted that the ANSI
Subcommittee set the APF of 1,000 for full facepiece continuous flow
atmosphere-supplying respirators to be consistent with the APF for SARs
with helmets or hoods found in two earlier studies--a WPF study by
Johnson (Ex. 1-64-36) and a SWPF study by Skaggs (Ex. 1-3803). The
Subcommittee used the analogy between PAPRs and continuous flow
supplied-air respirators to select the APF of 50 for half-mask pressure
demand SARs and 1,000 for full facepiece pressure demand SARs. Nelson
stated: ``The committee believed that setting a higher APF because of
the pressure demand feature was not warranted, but rather that the
total airflow was critical.''
Nelson noted in the report that the Subcommittee selected no APF
for SCBAs. In explaining the committee's decision, he stated that ``the
performance of this type of respirator may not be as good as previously
measured in quantitative fit test chambers.'' Nelson also observed that
the ANSI 88.2-1992 standard justified this approach in a footnote to
the APF table. The footnote states:

A limited number of recent simulated workplace studies concluded
that all users may not achieve protection factors of 10,000. Based
on [these]
limited data, a definitive assigned protection factor
could not be listed for positive pressure SCBAs. For emergency
planning purposes where hazardous concentrations can be estimated,
an assigned protection factor of no higher than 10,000 should be
used.

A new ANSI Z88.2 Subcommittee currently is reviewing the ANSI
Z88.2-1992 standard, in accordance with ANSI policy specifying that
each standard receive a periodic review. This review likely will result
in revisions to the Z88.2 APF table based on WPF and SWPF respirator
performance studies conducted since publication of the current standard
in 1992.

B. Need for APFs

The proposed APF definition and regulatory text are important
additions to, and an integral part of, OSHA's Respiratory Protection
Standard because employers need this information to select appropriate
respirators for employee use when engineering and work-practice
controls are insufficient to maintain hazardous substances at safe
levels in the workplace. Employers need the consistent and valid
information contained in the proposed APF provisions to select
respirators for employee protection, based on the type of hazardous
substance and the level of employee exposure to that substance.
As noted in Table I of the proposed regulatory text, the proposed
APFs differ for each class of respirator. In this regard, the proposed
APF for a class of respirators specifies the workplace level of
protection that class of respirator should provide under an effective
respiratory protection program. Therefore, when the concentration of a
hazardous substance in the workplace is less than 10 times the PEL, the
employer must select a respirator from a respirator class with an APF
of at least 10 for use by employees exposed to that substance. However,
when the concentration of the hazardous substance is greater than 10
times the PEL, the employer must select a respirator that has an APF
greater than 10 for this purpose. In addition, employers would derive
MUCs from the APFs proposed for the different respirator classes. These
MUCs determine the maximum atmospheric concentration of toxic gasses
and vapors at which respirators equipped with cartridges and canisters
can be used to protect employees.
In summary, when used in conjunction with the existing provisions
of the Respiratory Protection Standard, especially the respirator
selection requirements specified in paragraph (d), the proposed APF
definition and regulatory text would provide employers with the
information they need to select the appropriate respirators for
reducing employee exposures to hazardous substances to safe levels.
Accordingly, integrating the proposed APF provisions into the
Respiratory Protection Standard will

[[Page 34044]]

ensure that employees receive the optimum level of protection afforded
by that standard.

C. Review of the Proposed Standard by the Advisory Committee for
Construction Safety and Health (ACCSH)

The proposed provisions would replace the existing respirator-
selection requirements specified by the Respiratory Protection Standard
for the construction industry (29 CFR 1926.103). Accordingly, OSHA's
regulation governing the Advisory Committee on Construction Safety and
Health (ACCSH) at 29 CFR 1912.3 requires OSHA to consult with the ACCSH
whenever the Agency proposes a rulemaking that involves the
occupational safety and health of construction employees. On December
5, 2002, OSHA briefed the ACCSH membership on the proposed provisions
and responded to their questions. On March 27, 2003, the APF proposal
was distributed to the ACCSH membership for their review prior to their
next regular meeting on May 22, 2003. OSHA staff discussed the APF
proposal and answered questions from the ACCSH members during their
meeting on May 22, 2003. The ACCSH then recommended that OSHA proceed
with publishing the proposal.

IV. Methodology for Developing Assigned Protection Factors

This section contains an overview of the analyses performed for
OSHA and summaries of the studies used in these analyses. OSHA entered
the complete analyses and studies into Docket H049C as Exhibits 3, 4,
and 5 and Exhibit 1-156 (Dr. Nicas' report). Studies and information
supporting the APF for each class of respirator are discussed in
Section VII of this document. The analyses discussed below assisted
OSHA in determining its proposed approach to deriving APFs. Commenters
expressed appreciation for the approach suggested by Dr. Nicas, but
nearly all did not support implementation of his methods. However, his
recommendations provided guidance to the Agency regarding the types of
studies and data needed for determining APFs. Dr. Brown's complex
statistical analyses demonstrated the widespread variability inherent
in current workplace protection factor studies. However, he found in
his final analysis that the performance of filtering facepiece and
elastomeric half-mask respirators could not be differentiated, thereby
supporting grouping of these two types of respirator under one APF.

A. Dr. Nicas' Proposal and Response From Commenters

During the June 1995 APF hearings, OSHA devoted a full day to a
panel discussion on the uncertainties associated with sample statistics
and their use for deriving APFs. Based on this discussion, OSHA
contracted with Dr. Mark Nicas to develop a statistical method for
deriving APFs. Nicas used two approaches to account for within-wearer
and between-wearer variabilities. For penetration data collected from a
specific cohort of respirator wearers, he used a one-factor lognormal
analysis of variance. He used a two-factor lognormal analysis of
variance to perform a meta-analysis of the data from studies of
different cohorts of respirator wearers. Using these approaches, Nicas
proposed assigning two different protection factors; he recommended one
for chronic toxicants (i.e., substances regulated by an 8-hour PEL),
and the other for acute toxicants (i.e., substances regulated by a
STEL). Nicas also made recommendations regarding sampling data
management and inclusion of studies in statistical analyses of
respirator performance.
OSHA reopened the rulemaking record on November 7, 1995 (60 FR
56127) to request comment on Dr. Nicas' report titled ``The Analysis of
Workplace Protection Factor Data and Derivation of Assigned Protection
Factors'' (Ex. 1-156). OSHA received 12 comments on the report. While
some commenters expressed general support for Nicas' approach (e.g.,
Ex. 1-182-4, American College of Occupational and Environmental
Medicine), others had serious reservations about establishing APFs
using this approach. The issues raised by these commenters are
described below.
1. Lack of Valid and Reliable WPF Data
Two commenters stated that the available WPF data were of
insufficient quality to permit a sophisticated statistical analysis.
The 3M Company (3M) commended OSHA for ``attempting to use science to
evaluate workplace studies for determining Assigned Protection
Factors,'' but stated that insufficient valid data were available for
such an evaluation, and that the data that were available were too
variable (Ex. 1-182-5). In addition, Organization Resource Counselors,
Inc. (ORC) stated: ``The use of existing, often flawed, workplace
protection factor studies, is not a solution to the problem. * * * A
reliance on sophisticated statistics in an attempt to compensate for a
lack of reliable scientific data on respirator performance is both bad
science and bad policy'' (Ex. 1-182-10).
2. Inappropriate Use of ANOVA Model
Three commenters believed that using Nicas' lognormal ANOVA model
to analyze existing data was inappropriate (Exs. 1-174, 1-182-5, 1-182-
1). Two of these commenters advocated using a simple analysis of the
aggregate data instead (Exs. 1-174, 1-182-5). Thomas Nelson (Ex. 1-174)
and 3M (1-182-5) expressed concern that the ANOVA model focuses
primarily on within-wearer and between-wearer variability, while
ignoring the potential variability contributed by other sources such as
work site, respirator model, filter, and contaminant. Nelson stated:
``A simple analysis of the entire data (i.e., geometric mean, estimates
of percentiles and confidence intervals) includes these and other
possible sources of variation and the within-person variability in the
model.'' Two other commenters, Drs. Rappaport and Kupper [contractors
for the Industrial Safety Equipment Association (ISEA)]
believed that
using an ANOVA model provided some benefits; however, they had concerns
regarding the assumption of log-normality of penetration values, the
lack of validation of the model, and errors that appeared in some of
the equations. Therefore, they regarded ``implementation of Dr. Nicas'
ideas as being problematic at this time,'' and encouraged the industry
to develop improved methods and data for deriving APFs (Ex. 1-182-1).
3. ANOVA Model Fails To Account for Differences Between WPF Studies
Five commenters stated that the proposed analysis fails to account
for important differences between studies that could affect WPF values.
Thomas Nelson and 3M believed that the ANOVA model does not account for
other sources of variability (Exs 1-174, 1-182-5). NIOSH stated that
Nicas' report did not address the effect of the test subjects' work
rates and other activities on a respirator's performance (Ex. 1-182-3),
and did not account for employee training and program surveillance (Ex.
1-182-9). The Chemical Manufacturers Association (CMA) also commented
on factors not considered in the Nicas report, ``including differences
in training, experience, work site, work rate and sample collection''
(Ex. 1-182-7). ORC noted: `` The results of a WPF study are based on at
least the following components: quality of the respirator chosen;
quality of the training program; quality of the fit testing and
selection program; nature of the work and ability

[[Page 34045]]

to challenge the fit of a respirator (sedentary versus high exercise
work)'' (Ex. 1-182-10).
4. Using a Conservative Criterion for Setting APFs
Five commenters stated that Nicas' criterion for setting APF values
was overly conservative. The Dow Chemical Company (Dow) stated that the
Nicas approach ``would result in protection factors which are very
conservative'' (Ex. 1-182-2), while 3M believed that OSHA's use of
Nicas's recommendation would result in a major change in the pattern of
respirator use (Ex. 1-182-5). NIOSH commented that the approach may
result in very low APF estimates because of high WPF variability, and
that while the approach would derive more conservative (i.e., more
protective) APFs, its use for ``WPF studies with small sample sizes * *
* could result in APF estimates less than or equal to 1.0 (APF values
less than 1.0 are meaningless)'' (Ex. 1-182-3). Drs. Rappaport and
Kupper stated that only weak precedence existed for Nicas' use of 95th
percentiles to define APFs, and suggested that other percentiles (e.g.,
the 90th percentile) would be more practical to implement (ISEA, Ex. 1-
182-1). Finally, CMA believed that the proposed criterion rated ``all
respirators on the lowest protection achieved by the lowest performing
person'' (Ex. 1-182-7).
5. APFs Based on a Contaminant's Toxicity (Acute Versus Chronic
Toxicants)
Dr. Nicas proposed that two APFs be assigned to a respirator,
depending on its use against either a chronic toxicant or an acute
toxicant. Four commenters remarked on the feasibility and effects of
this approach. NIOSH commented that ``defining acceptable protection
against short-term exposures is very complex * * *.'' (Ex. 1-182-3). 3M
commented that dual APFs would be confusing to the user community and
workers, and would make program management difficult (Ex. 1-182-5). CMA
provided similar comments, and noted that many materials have both
chronic and acute effects (Ex. 1-182-7). ORC believed that:

* * * different APFs for different contaminants or types of
exposure is not appropriate. Occupational exposure standards should
have adequate safety factors which are based on the health outcome
(e.g., irritation, systemic toxicity, carcinogenicity) of exposure.
(Ex. 1-182-10)

While Drs. Rappaport and Kupper stated that Nicas' argument about
respiratory protection for substances with chronic effects was logical,
they regarded the question of how to deal with acutely toxic substances
as unresolved (Ex. 1-182-1).
6. Distribution of Contaminant Concentrations
Two participants believed that it was necessary to incorporate
information on the variability of ambient exposure concentrations, as
well as the maximum anticipated concentration, when discussing
respirator selection. CMA stated that since an employee's exposures
will vary from day to day, employers should select respirators with
maximum use limits well above the mean exposure levels to ensure ``that
there is less than 5% probability of exposures above the maximum use
limit of the respirator'' (Ex. 1-182-7). In a related comment, ORC
stated that many industrial applications typically have exposures only
2-3 times the acceptable exposure limit; therefore, ``selecting a
respirator with an APF of 10 may mean there is only a remote chance of
overexposure to a contaminant due to fit/wear variability'' (Ex. 1-182-
10).
7. Other Concerns With Nicas' Method
The commenters raised several other issues with Dr. Nicas'
methodology. For example, 3M (Ex. 1-182-5) and CMA (Ex. 1-182-7)
believed that the relationship between outside concentration and WPF
(i.e., WPF increases with increasing Co) was poorly understood;
therefore, a sophisticated analysis of the data is questionable. Other
commenters noted errors in the equations of the proposed model (e.g.,
Ex. 1-182-1) and with the distribution of the respirator penetration
values (Ex. 1-182-1).
8. Miscellaneous Comments (e.g., ANSI APFs)
In addition to responding to the Nicas report, a number of
commenters supported using the APFs recommended in the ANSI Z88.2-1992
respiratory protection standard (Exs. 1-182-1, 1-182-2, 1-182-5, 1-182-
7, 1-182-10). These commenters stated that the members of the ANSI
Z88.2 committee were ``respected industrial hygiene and respirator
experts'' (Ex. 1-182-5), that the ANSI Z88.2-1992 APFs were ``the
appropriate values'' (Ex. 1-182-7), and that the ANSI APFs ``have been
through the ANSI peer review process'' (Ex. 1-182-5). In advocating use
of the ANSI APFs, none of the commenters described the process by which
the ANSI Z88.2 committee derived its APFs, or identified the studies
and other information on which that committee relied. Furthermore,
several commenters (Exs. 1-182-7, 1-182-5, 1-182-10, 1-182-6, 1-182-8)
noted that the ANSI Z88.2-1992 standard does not explicitly account for
several factors in assigning APF values to different respirator
classes, or the use of a respirator in different situations, which they
indicated were necessary considerations. Moreover, some commenters
(Exs. 1-182-11,1-182-12) recommended APFs that differ from those
published by the ANSI Z88.2 Committee. Other commenters believed that
it was OSHA's responsibility to show that the commonly used ANSI Z88.2
1992 APFs were erroneous (Ex. 1-182-2), and that the Agency should not
use SWPF studies to derive APFs (Ex. 1-182-5). Several participants at
the hearing for the final Respiratory Protection Standard stated that
OSHA should issue a second NPRM to address the development of APFs
(Exs. 1-182-1, 1-182-5, 1-182-10).
After carefully considering Dr. Nicas' model and the comments
received in response to his report of the model, the Agency concluded
that other possible approaches to deriving APFs should be investigated.
Accordingly, the Agency identified and collected available data for
this purpose. Of particular interest were data that OSHA could use to
discriminate between the performance of different respirator classes.
The Agency gathered information from both published and non-published
papers and reports, and included WPF, SWPF, PPF, and EPF studies;
Health Hazard Evaluations conducted by NIOSH; respirator performance
data from manufacturers, such as SWPF data submitted to OSHA by Bullard
(Ex. 3-8); and other material related to assessing respirator
performance. This information is in Docket H049 as Exhibits 2, 3, and
4.
To assist in evaluating the data, OSHA employed Dr. Kenneth Brown
(a statistician) and several respirator authorities: Mr. Harry
Ettinger, Dr. Gerry Wood of LANL, and Drs. James Johnson, Kenneth
Foote, and Arthur Bierman of LLNL. After the Agency reviewed all of the
studies and information, it decided to attempt to analyze only WPF and
SWPF studies since they address respirator performance exclusively.
OSHA discusses the work and findings of these individuals below.

B. Analyses of WPF Studies

OSHA contracted with Dr. Brown to investigate possible approaches,
other than those approaches proposed by Nicas, to evaluate respirator
performance data from WPF studies. The following discussion is a
general description of the analyses performed by Brown, as well as his
overall

[[Page 34046]]

conclusions. For a detailed explanation of the methodology and
rationale used in the analyses, refer to Brown's reports in the docket
(Exs. 5-1, 5-2).
OSHA reviewed the available WPF studies for possible inclusion in
Brown's analyses. Early in this review process, the Agency decided to
exclude WPF studies with a gas or vapor workplace challenge agent
because: The preponderance of studies were conducted in workplaces with
particulate challenges; gas/vapor studies did not provide any further
insight or clarification regarding sources of variability in WPF
studies (most likely, gas/vapor studies add variability to the data
such as the effects of humidity on sampling media collection and
desorption efficiencies); and pulmonary elimination differs between
gases/vapors and particulates. Therefore, OSHA decided to analyze only
WPF studies using particulate challenge agents. The Agency evaluated
those studies initially selected for further analysis for compliance
with the requirements of OSHA's Respiratory Protection Standard (29 CFR
1910.134), as well as completeness of the data. The Agency compiled a
list of review items to use in evaluating each study (Ex. 5-5).
OSHA then divided the remaining studies into two categories: Half-
mask negative-pressure air-purifying respirators (APRs) and atmosphere-
supplying respirators (PAPRs and SARs). This procedure resulted in 22
APR studies and 16 PAPR/SAR studies for analysis. OSHA placed a list of
these studies, and their respective respirators, in the docket (Ex. 7-
4). Brown subsequently identified 14 APR studies and 13 PAPR/SAR
studies for further analysis (see Exs. 5-1 and 5-2 for more information
on the evaluation criteria).
Brown's analyses divided the respirators used in these studies into
separate respirator classes. The analyses divided APRs into 5 classes,
listed below in Table 1. As this table shows, Brown's analyses
separated filtering facepieces into four classes based on the
characteristics listed under the Description column heading, with the
fifth class comprised of elastomeric facepiece APRs.

Table 1.--Half-Mask APR Classes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Description
-------------------------------------------------------------------
Class Type Adjustable head Exhalation Double shell
straps valve construction Foam ring liner
--------------------------------------------------------------------------------------------------------------------------------------------------------
1............................................... Filtering facepiece............... ............... ............... ............... ...............
2............................................... Filtering facepiece............... X ............... X ...............
3............................................... Filtering facepiece............... X X X ...............
4............................................... Filtering facepiece............... X X X X
5............................................... Elastomeric facepiece.............
--------------------------------------------------------------------------------------------------------------------------------------------------------

In addition, Brown's analyses divided PAPRs into five classes and
SARs into two classes, as shown in Table 2.

TABLE 2.--PAPR and SAR Classes
------------------------------------------------------------------------
Class Type Description
------------------------------------------------------------------------
1.................... PAPR Loose-fitting facepiece.
2.................... PAPR Loose-fitting facepiece
with hood and/or helmet.
3.................... PAPR Hood and/or helmets--not
loose-fitting.
4.................... PAPR Tight-fitting half-mask
facepiece.
5.................... PAPR Tight-fitting full
facepiece.
6.................... SAR Loose-fitting.
7.................... SAR Hood or helmet.
------------------------------------------------------------------------

Later in the analyses, Brown further divided these classes
according to class of respirator, study, and challenge agent (CLSA).
This division resulted in 26 CLSAs for the APRs and 14 CLSAs for the
PAPRs/SARs.
The data from the WPF studies consisted of simultaneous
measurements of the challenge agent concentration inside the respirator
facepiece (i.e., concentration inside or Ci) and outside the respirator
facepiece (i.e., concentration outside or Co) in the ambient workplace
atmosphere. Corresponding Co and Ci measurements can be used to
calculate the workplace protection factor (WPF = Co/Ci) or penetration
of the contaminant into the respirator (PEN = Ci/Co = 1/WPF). The APR
studies had a total of 917 data pairs, while the PAPR/SAR studies
provided 443 data pairs.
1. Half-Mask APRs
In the first phase of his analysis, Brown statistically analyzed
the data for half-mask negative pressure APRs, both filtering facepiece
and elastomeric APRs, using the following three approaches: (1) Pooled
the data within classes, corrected the data for the positive
relationship found between WPF values and increasing Co, and compared
the differences in WPF statistics between classes; (2) conducted an
intra-study analysis of the performance of two different classes of
respirator used against the same contaminant under similar workplace
conditions; and (3) divided the data into class-study-agent
combinations, and evaluated WPF as a function of Co. The following
sections discuss these approaches in detail.
Approach 1. Brown's initial approach was to determine if he could
pool the data within each respirator class and estimate the fifth
percentile WPF for that respirator class; he then tested for
differences in WPFs between the respirator classes. He divided and
analyzed the data by study, treating the data from each study as a
homogeneous sample arising from the same parent distribution. Then he
examined the data in each study for a Co effect, and constructed a
scatterplot of ln(WPF) versus ln(Co) for each respirator class. In
doing so, he treated extreme or poorly fitting data as outliers and
removed them from the analysis. He subsequently derived a linear
regression of ln(WPF) on ln(Co) for each study, and extrapolated from
the observed range to the entire range of Co values in all of the data.
The positive slopes, which he found for most classes, showed that
ln(WPF) increased as ln(Co) increased. In addition, the regression
lines were well mixed, indicating that studies within the same
respirator class varied more than anticipated. This result indicated
that variability occurring within respirator classes could obscure
differences between respirator classes.
These studies collected data over different ranges of Co.
Therefore, to compare the WPFs observed in the studies, Brown corrected
the WPF values for all studies, using a common Co adjustment factor. He
pooled the adjusted WPFs by class, and then plotted the cumulative
distributions to determine if he could identify differences between
respirator classes, despite intra- and inter-study differences. Finding
no differences

[[Page 34047]]

between respirator classes using the Co adjustment factor, he concluded
that:

Observed 5th percentiles for WPFs, and their lower confidence
intervals when adjusted for the Co effect, showed no clear evidence
that any class was preferable to another. In particular, there was
no indication that Class 5 (elastomerics) performed better than four
disposable classes. (Ex. 5-1, p. 8)

The results of these analyses prompted a more detailed examination
of the data. To control for study-related and agent-related factors
that may contribute to variability, Brown performed an intra-study
analysis on two different respirator classes used against the same
workplace challenge agent under similar workplace conditions (Approach
2).
Approach 2. The second approach attempted to determine respirator
performance after controlling for study-to-study and agent-to-agent
sources of variability. Among the half-mask APRs, the chance of
detecting performance differences appeared to be greatest for
comparisons between elastomeric and filtering facepiece respirators. In
implementing this approach, Brown assumed that controlling for study
and agent sources of variability would result in WPF differences
attributable, in large part, to variability in respirator performance.
Four of the studies compared the performance of elastomeric and
filtering facepiece respirators against the same challenge agent in the
same workplace. After reviewing these studies, a study by Meyers and
Zhuang (Ex. 1-64-51) was selected for further analysis because it was
recent, followed a protocol patterned after other published WPF study
protocols, and was well documented. Brown's statistical analyses of
this study (see Ex. 5-1, Appendix C) indicated large sources of
variability within the study, making comparison of the two respirator
classes difficult and tenuous. Based on plots of the data and the
occurrence of several outliers, it appeared that even data on the same
agent, obtained under similar workplace conditions, may not have come
from the same parent distribution. In addition, the variability of WPFs
within the study (regardless of adjustment for the Co effect) was
large. Therefore, the results of this second approach led Brown to
state that, at least in this analysis, ``workplace studies may have too
much intra-study variability for reasonably valid/accurate/reliable
assessments and comparisons of respirator effectiveness.'' (Ex. 5-1, p.
C-17)
Approach 3. Brown began the third statistical approach by dividing
the data into units smaller than respirator class, i.e., units based on
class of respirator, study, and workplace challenge agent (class-study-
agent or CLSA). This procedure resulted in 42 CLSA combinations. After
removing deficient data (e.g., no data on Co), he narrowed the data set
to 26 combinations. Again, he tested the data for each CLSA to
determine if WPF increases with Co and, if so, whether the effect held
for all respirator classes. Data analyses of the 26 CLSAs indicated
that WPF increased with Co; Brown then derived a common estimate
(across all CLSAs) of the Co effect. He subsequently estimated the
means for the CLSAs within each class of respirator, both with and
without adjustment for Co effect. Brown compared the means of these
CLSAs within and between respirator classes. For each respirator class,
he grouped the CLSAs that had no significant difference between their
means into common subclasses, and plotted both the adjusted and non-
adjusted means [i.e., mean of ln(PEN)]
of the subclasses, as well as
their associated confidence intervals. The results of the comparisons
showed that: the estimated means of CLSAs vary so much within a class
that the mean of one CLSA is likely to be a poor predictor of the mean
of another CLSA within the same class; and it was not visually apparent
from the plots that one class of respirator performed better than
another class. In general, the comparison indicated that study
outcomes, even within the same class of respirator, are highly
heterogeneous.
Final analysis. Since the three approaches discussed above could
not distinguish between respirator effectiveness within or across
classes, the data were viewed, as a whole, from the relationship of Ci
and Co. Brown pooled the data for all 26 CLSAs and derived several
functional relationships from the pooled data. This approach showed
that the majority of the observed data pairs achieved a WPF of 10. (See
Ex. 5-1 for more details.)
After performing the above analyses, Brown made a number of
observations and conclusions. He noted that the range of WPF values
within a CLSA was typically wide, and that the observations were highly
variable. In addition, he believed that variability in WPF studies can
affect the accuracy, validity, and reliability of study results, as
well as the ability to compare study results. Brown noted several
possible sources of variability in WPF studies, including: (1) Study
characteristics related to study design, execution, sample analysis,
and data management and reporting; (2) measurements of Ci at different
outside concentrations (Co effect), taken in conjunction with other
poorly described factors (e.g., particle size, temperature, humidity)
that may affect the relationship of Ci and Co; (3) characteristics of
the ambient agent itself (e.g., possible effects of the agent occurring
in a mixture with other agents); and (4) variations in data among
studies related to using different study procedures (e.g., repeated
measurements on the same worker in some studies versus single
measurements on each worker in other studies, random versus non-random
selection of study participants). He also commented that the analyses
assumed that the data were representative of workplace conditions;
however, the data may not represent either current or future workplaces
in which employees use respirators. Finally, Brown observed that
studies with high Ci values, relative to Co, may have influenced his
findings. He believed that these studies should be closely reviewed
because some study weakness, unrelated to respirator performance, could
be the reason for the high Ci values.
Brown also made some general observations about WPF studies. First,
he believed that the role of WPF studies in assessing and comparing
respirator effectiveness, and influencing APFs, should be reevaluated.
He believed that a more refined instrument that is amenable to
experimental design and control, such as chamber studies, is better
suited for providing information during determination of assigned
protection factors. Brown noted that the use of high concentrations of
a challenge agent in chamber studies may minimize the uncertainty of
extrapolating test results obtained at low outside concentrations to
levels well above the observed range. Therefore, WPF studies would
serve as a counterpart to chamber studies, i.e., WPF studies would
provide data on the respirator during actual use in the workplace, and
identify workplace conditions in which a respirator may perform poorly.
To improve comparability of results, he advocated using uniform
procedures to: select the challenge agent; collect samples; record the
data; and measure and interpret Ci and Co (Ex. 5-1, pp. 42-44).
Overall, the analyses led Brown to several conclusions. First,
workplace studies have limitations for comparing respirator performance
because of uncontrolled sources of variability. Support for this
conclusion comes from the wide confidence intervals for the means of
the CLSAs, and the wide range of those confidence intervals within the
same respirator class. Second, Brown believed that the WPF has limits
as a

[[Page 34048]]

measure of respirator effectiveness because, in general, it tends to
increase as Co increases. This relationship complicates comparisons of
WPF values measured at different Co levels. Third, he found no clear
evidence that one class of respirator is better than any other class,
particularly between elastomeric half-mask and filtering facepiece
respirators. In addition, the differing results between CLSAs within
the same class of respirators indicated that the outcome of one CLSA
may be a poor predictor for another CLSA in the same class.
2. PAPRs and SARs
Dr. Brown analyzed 13 studies to evaluate and compare the
effectiveness of PAPRs and SARs. Ten of the studies were conducted with
PAPRs, and three with SARs. Brown's analyses divided these ``high-
performance'' respirators into seven classes (i.e., five types of PAPR
and two types of SAR) based on their design features (see Table 2),
with subsequent separation of these respirator classes into 14 CLSAs.
Brown used the CLSAs to determine whether any differences in
respirator effectiveness existed among the respirator classes. He
analyzed the data for trends of WPFs, either upward or downward, as Co
increases, and for homogeneity. Brown plotted all of the data, fitted
lines to these plots, made comparisons of study results within each
respirator class, and developed functions from the fitted lines. (For
additional details on these statistical analyses and the data plots,
see Ex. 5-2.)
On reviewing the data plots, Brown concluded that the data were
consistent with a linear relationship between ln(Ci) and ln(Co). Also,
the presence of outliers and/or an imbalanced distribution of the
observations influenced the results. He recommended further
investigation of the outliers, particularly those with unusually high
Ci values, to determine if they resulted from characteristics of the
respirator or other variables. He also recommended studying the
imbalanced distributions to determine if they represented individual
study biases caused, for example, by collecting data at different work
sites or on different work shifts. Finally, Brown noted that the robust
least trimmed squares line may be useful for estimating the
relationship between ln(Ci) and ln(Co).
Fifth percentiles are commonly used as a benchmark for respirator
performance. Brown's analyses showed that fifth percentile estimates
differed considerably within respirator classes that contained more
than one CLSA. The range of the fifth percentile estimates was 28-389
for the five CLSAs in Class 2, 17-107 for the two CLSAs in Class 4, 29-
1779 for two CLSAs in Class 5, and 74-188 for the two CLSAs in Class 7.
The fifth percentile estimates in Classes 3 and 6 were large, while the
fifth percentile estimates were small in Classes 1, 4, and 7. Brown
believed that, while some of these differences may be attributed to a
real difference in respirator performance between classes, the sample
sizes were too small and/or the sampling variability too large to
obtain reliable estimates at low percentile levels. He noted that the
fifth percentile estimates were variable, and were not predictable from
one CLSA to another CLSA within the same respirator class. Thus, he
concluded that the fifth percentile estimates of WPFs have limited
utility for setting assigned protection factors. Table 3 lists the
descriptive statistics for WPFs, for each class-study-agent
combination.

Table 3.--Descriptive Statistics for WPF, by Class, Study Agent
--------------------------------------------------------------------------------------------------------------------------------------------------------
CL1.26.Cd CL2.22.Pb CL2.23.Pb CL2.24.Si CL2.3.BAP CL2.5.Asb CL3.27.EBZ
--------------------------------------------------------------------------------------------------------------------------------------------------------
Curve Label........................... 1 2a 2b 2c 2d No curves 3
Median................................ 2,972.97 127.88 155.29 3,553.72 1,788.32 156.00 11,935.87
Range................................. 25,186.05 1,040.75 6,131.76 95,518.07 8,203.89 537.00 4,746,673.83
Minimum............................... 53.70 22.58 28.24 36.31 371.49 66.00 1,152.26
Maximum............................... 25,239.75 1,063.33 6,160.00 95,554.38 8,575.38 603.00 4,747,826.09
No. Observations (N).................. 33 46 43 59 20 7 58
5th Percentile........................ 280.25 27.82 35.03 92.07 388.70 70.50 1,797.79
10th Percentile....................... 581.87 53.04 43.08 267.60 407.51 75.00 2,365.29
Reject Lognormality?.................. No No No No No No Yes
Geometric Mean........................ 2,523.49 126.85 184.69 2,765.75 1,408.10 151.95 15,623.81
Geometric Stan. Dev................... 3.56 2.28 3.21 6.33 2.50 2.54 5.56
---------------------------------------
CL4.21.Si CL4.6.Pb CL5.18.Pb CL5.21.Si CL6.19.Si CL7.25.Sr CL7.28.Si
---------------------------------------
Curve Label........................... 4a 4b 5 No curves 6 7a 7b
Median................................ 48.67 438.60 7,948.14 85.44 9,178.81 3,827.16 2,480.55
Range................................. 176.27 2,310.33 73,081.90 189.92 34,735.48 87,137.82 33,384.67
Minimum............................... 16.40 23.00 579.04 24.75 668.34 41.67 43.33
Maximum............................... 192.67 2,333.33 73,660.94 214.67 35,403.82 87,179.49 33,428.00
No. Observations (N).................. 7 25 53 4 15 21 52
5th Percentile........................ 17.20 107.06 1,779.12 29.10 1,407.60 74.07 188.14
10th Percentile....................... 18.00 160.95 2,300.18 33.50 2,229.66 79.37 383.47
Reject Lognormality?.................. No No No N too small No No No
Geometric Mean........................ 49.20 400.34 8,319.09 76.10 7,389.62 2,315.04 2,066.00
Geometric Stan. Dev................... 23.60 2.81 3.03 25.60 2.92 9.99 4.02
--------------------------------------------------------------------------------------------------------------------------------------------------------

The objective of the review of these 13 WPF studies was to see what
can be learned about the performance of each respirator class, and its
relative effectiveness, based on the data for Co and Ci. He also
attempted to determine how Ci changes as Co changes, and what factors
affected this relationship.
Brown found too much unexplained variability between study
outcomes, even within the same respirator class and within similar
ranges of Co, to make valid and reliable comparisons. He noted that
study outcomes for the same class of respirator may differ
significantly, which raised concerns about interpreting the outcome for
a class from a single study. More specifically, he questioned whether
the results from one study would be similar

[[Page 34049]]

to another study. He concluded that it is not possible to know to what
extent the outcome of a study is attributable to characteristics of the
respirator used.
Brown believed that the variability identified in this analysis was
probably due to uncontrolled parameters in the workplace test
situations, such as aerosol particle size distributions and densities,
and work activities. Based on the data from these studies, he found
that WPF tends to increase as Co increases (equivalently, penetration,
or PEN., tends to decrease). He believed that the probability of a Co
dependence for WPFs seemed to be established by his analyses.

C. Analyses of SWPF Studies

1. Bullard Models 77 and 88, Clemco Apollo Models 20 and 60, and 3M
Whitecap II
In the mid-1980s, SWPF studies provided OSHA with information on
the effects of temperature, relative humidity, airflow, and facial hair
on respirator performance (LANL, 1988; Ex. 1-64-101, LLNL, 1986; Ex. 1-
64-94). More recent SWPF studies provided additional information on the
performance of the following abrasive blasting respirators: the Bullard
Models 77 and 88 (Ex. 3-8-3), the Clemco Apollo Models 20 and 60 (Ex.
3-7-3), and the 3M Whitecap II (Ex. 3-9-2).
OSHA contracted with Mr. Harry Ettinger to review and comment on
the study principles and protocols described in the five reports
(Bullard, Clemco, 3M Whitecap, the LLNL study, and the LANL study). His
report (Ex. 3-3) contained the following observations and conclusions.
Mr. Ettinger noted that while the reports do not satisfy the
typical criteria for defining peer-reviewed publications, this was not
a serious problem because the studies were conducted in national
laboratories by knowledgeable and experienced investigators.
Furthermore, the review procedures generally used by these national
laboratories most likely provide a sufficient peer-review process. He
noted that none of the reports provided sufficient detail to permit a
statistical re-analysis of the data by OSHA. In addition, he observed
that the studies of the Bullard, Clemco, and 3M respirators reported
considerably higher fit factors than the 1986 and 1988 national
laboratory studies. However, he believed that it was not appropriate to
compare the results of recent studies with the older studies, but he
noted that older respirators may not perform as well as newer designs.
Mr. Ettinger also noted that the tests of the Bullard, Clemco, and
3M respirators satisfied the established criteria of fit factors that
exhibited only brief negative pressure spikes. He believed these
results indicated that if these devices are used and maintained
properly, they appear to have fit factors of at least 20,000. He
believed that, using a safety factor of 20, a protection factor of
1,000 is attainable, assuming that the testing protocol is adequate.
Ettinger stated that he could not define clearly a relationship
between the older and more recent study results. For example, he
suggested that the additional exercises in the more recent study (ORC,
2001; Ex. 3-4-2) did not adequately represent normal or extreme work
situations. Ettinger cautioned against assuming that all blasting
helmets would achieve the high fit factors measured in the recent
studies because performance is device specific, and indicated that
older respirator designs may need to be reevaluated. Furthermore, he
believed that quality control, human factors, minimum flow rate, and
the sturdiness of respirator construction are important variables that
should be evaluated in the testing protocol.
2. NIOSH N95 Study
In 1999, NIOSH conducted a chamber study of 21 N95 respirators (20
filtering facepiece, and 1 elastomeric, respirators) and statistically
analyzed the respirators' performance (Ex. 4-14). At the request of
OSHA, Drs. Johnson, Foote, and Bierman of LLNL undertook a review of
this study to assist the Agency in evaluating APFs of half-mask
respirators (Ex. 3-2). OSHA provided the raw data files from the study
to LLNL for independent evaluation.
The NIOSH investigators used ambient (i.e., room) aerosol as the
challenge agent, and a PortaCount to measure respirator penetration.
Use of ambient aerosol does not require aerosol generation equipment,
thereby circumventing use of a possibly hazardous chemical. However, if
this technique generates a low ambient particle concentration it is
difficult to detect the reduced number of particles that penetrate the
respirator; this effect results in an artificially low protection
factor. In addition, an ambient aerosol that is varying in
concentration during testing can cause error in the penetration
measurements. Study participants can also produce aerosols ranging from
0.1 to 3 particles/cc through their breathing (i.e., ``breathing''
background). Whenever the amount of challenge agent that penetrates the
respirator is low (i.e., on the order of particles/cc or less), the
PortaCount cannot distinguish between particles in the breathing
background and the challenge aerosol penetrating the respirator. The
LLNL researchers believed that the breathing background can limit fit
factor measurements to 1,000 and less when the challenge concentration
is below 2,000 particles/cc (Ex. 4-15). They concluded that challenge
aerosol concentrations can be better controlled in chamber studies than
under this protocol.
When calculating faceseal leakage, the NIOSH authors assumed that
all study participants have the same constant volumetric flow rate
through the respirator. Using a filtration model developed by Rubow
(Ex. 3-7-3), the LLNL reviewers determined media penetration that was
approximately 5% less than the media penetration calculated by the
NIOSH authors using the constant flow rate assumption. Since the method
used by the NIOSH authors results in only a 5% error, and gives a
conservative estimate of the filter penetration, the LLNL reviewers
believed that the constant flow rate assumption is reasonable. The LLNL
reviewers also discussed other considerations, including fluctuations
in peak flows under various exercise conditions, and the correction
factor for filter media penetration used by the NIOSH authors.
Investigating the possible effect of breathing background on the
PortaCount fit factor measurement, the LLNL reviewers applied an
estimated worst-case scenario to the data. The scenario consisted of
the following two assumptions: (1) A challenge aerosol concentration of
3,000 particles/cc, and (2) a breathing background of 5 particles/cc.
Applying these assumptions to the NIOSH data, the LLNL reviewers
recalculated total penetrations, and adjusted the results for breathing
background. They found that, when compared to the NIOSH results, 14 of
the 21 respirators had more tests passing the 0.01 penetration criteria
than before. The LLNL reviewers also calculated the 50th and 95th
percentiles for the penetration data, both with and without applying
the breathing background assumption. In view of their results, they
believed that the original NIOSH analysis and findings result in a
conservative estimate of the respirators' performance.
The LLNL reviewers also used the NIOSH raw data to reproduce
values, geometric standard deviations, and the 95th percentile for
total penetration, filter penetration, and face seal leakage. They then
compared these results to total penetration and face seal leakage
penetrations summarized in the NIOSH study (Exs. 4-1, Table 2; 4-14,
Table I).

[[Page 34050]]

The few discrepancies were small, and could be attributed, for example,
to rounding off values. The 95th percentiles in the NIOSH study were
based on a formula using the geometric mean and geometric standard
deviation, and assumed that the distribution was log normal. For
comparison, the reviewers calculated the 50th and 95th percentiles
based on the raw data alone (i.e., assuming no distribution). Using
this approach, the LLNL reviewers noted that, for many respirator
models, the 50th percentile differed markedly from the geometric mean.
They also saw differences between the 95th percentile calculated using
a log normal distribution and the corresponding percentile determined
directly from the data. LLNL reviewers stated that the NIOSH study
demonstrated the advantages of SWPF studies for half-mask respirators.
Their results confirm the quality of this important SWPF study of
filtering facepiece and elastomeric half-mask respirators.
3. ORC Study of PAPRs and SARs
In 1997, ORC and a group of its member companies sponsored a study
of 11 powered air-purifying and supplied-air respirators (PAPRs and
SARs) to evaluate the protection that these respirators afforded to
workers in the pharmaceutical industry. The study, ``Simulated
Workplace Protection Factor Study of Powered Air Purifying and Supplied
Air Respirators' (Ex. 3-4-1) was completed in 1998 by researchers at
LLNL. OSHA requested Dr. Gerry Wood of LANL to evaluate ORC's LLNL
study. He evaluated the study using the data received from ORC, as well
as information on the study published in the American Industrial
Hygiene Association Journal (Exs. 3-1, 3-4-2).
The raw data files from the study consisted of instantaneous (0.1
second) photometer aerosol measurements obtained before, during, and
after 12 exercise periods (including four periods of normal breathing)
performed by each study participant. The instantaneous penetration
results for the 144 tests were plotted against time. Wood examined
patterns of aerosol penetration into the respirator that occurred
throughout testing, noting that certain exercises often exhibited
penetration spikes. He found that running in place produced the most
penetration spikes. However, he also noted other respirator/subject
combinations result in spikes. Wood indicated that such non-random
distributions of readings was not surprising, as different movements
during an exercise should affect instantaneous penetrations
differently.
Wood calculated 95% confidence limits for the average and maximum
penetration values during each exercise. In doing so, he assumed that
pre-test and post-test background, and chamber aerosol measurements
were distributed normally, since no movement variables were present. He
then calculated aerosol penetration. Wood found that the photometer
reading averages and standard deviations that he analyzed for all 144
data sets were in agreement with the LLNL figures, and that rounding
off figures accounted for any minor differences in average penetrations
that he calculated.
In summary, Dr. Wood believed that the quality of the data,
experimental protocol, measurements and data, and calculations applied
to the data in the ORC-LLNL study were excellent. He agreed with the
authors' conclusions that SWPF studies are useful for comparing
respirators, and that the study protocol was reproducible.

D. OSHA's Overall Summary Conclusions

Prior to this current rulemaking, OSHA explored several procedures
to evaluate and compare respirator performance across models, studies,
agents, and testing protocols. The Agency thoroughly reviewed the
available data on respirator performance to determine the current
concepts, and possible methodologies, for deriving APFs. To evaluate
the data, OSHA had to make several decisions.
For example, while OSHA was aware that particle size can affect
concentration values, the Agency was unable to quantify this factor
based on available information. Consequently, OSHA did not attempt to
adjust for differences in particle size in the analyses. Furthermore,
the Agency had to decide how to address sampling results that were
below the limit of detection (LOD). Accordingly, whenever sampling
results were below the limit of detection, OSHA set the Ci at a
percentage of the LOD reported in the study. When the study reported
extremely low Ci results as a percentage of the LOD, the Agency used
the values provided by the authors.
OSHA was concerned that the analyses be those best able to account
for parameter uncertainty, and be a measure of respirator effectiveness
that is valid over a plausible range of concentrations for each of the
agents against which the respirator is to be used. As discussed above,
the Agency contracted with Drs. Nicas and Brown to independently
evaluate the raw WPF data. As a result of these analyses, OSHA
preliminarily agrees with Drs. Rappaport and Kupper, who indicated
that, while some modeling may be useful, concerns remain regarding the
lack of model validation (Ex. 1-182-1). Furthermore, OSHA finds merit
in Thomas Nelson's comment that a simple analysis of the entire data
may sufficiently cover the relevant sources of variation in these data
(Ex. 1-174). Databases of the information used by the Agency in its
analyses have been placed in the docket for review by interested
parties (Exs. 5-3, 5-4, 5-5).
The Agency also recognizes that WPF and SWPF studies have their
strengths and weaknesses. SWPF studies can control for a number of
variables, thus providing less variable results across respirators
classes than WPF studies. Also, SWPF studies can test respirators
safely at the limits of their effectiveness. However, WPF studies
evaluate respirators during use in the workplace. Therefore, the Agency
believes that WPF or SWPF studies provide complementary information.
OSHA developed the proposed APFs using a multi-faceted approach.
The Agency reviewed the various analyses of respirator authorities,
available WPF and SWPF studies, and other APF literature. For example,
OSHA reviewed Brown's analyses and noted no difference in performance
between filtering facepiece and elastomeric half-mask APRs, and that
few data pairs from the combined data sets analysis failed to achieve a
WPF of 10. In addition, the data from WPF and SWPF studies, as well as
a qualitative review of the available APF literature, supported an APF
of 10 for all half-mask APRs. Therefore, OSHA is proposing an APF of 10
for half-mask APRs. The Agency used a similar approach in developing
the remaining proposed APFs.
In conclusion, the APFs proposed by OSHA in this rulemaking
represent the Agency's evaluation of all the available data and
research literature; i.e., a composite evaluation of all the relevant
quantitative and qualitative information. The Agency seeks comment on
this approach, as well as the proposed APFs developed using this
approach.

E. Summaries of Studies

Researchers often determine the protection afforded by a respirator
by conducting Workplace Protection Factor (WPF) studies and Simulated
Workplace Protection Factor (SWPF) studies. A WPF study measures the
effectiveness of respirators under workplace conditions. Workers
participating in a WPF study wear respirators while performing their
usual job tasks. The WPF is a measure of the reduction in exposure
achieved while using respiratory protection and

[[Page 34051]]

is the ratio of the concentration of the contaminant found in the
workplace air to the concentration found inside the respirator
facepiece. Similarly, a SWPF study measures the ratio of a
contaminant's concentration both outside and inside the facepiece.
However, researchers obtain these measurements in test chambers, which
allows them to control some important variables (e.g., outside
concentration of the challenge agent). Rather than performing the
actual job tasks found in a particular work setting, the study
participants perform a series of exercises in the test chamber that
simulate the actions of workers in general.
In developing the proposed APFs listed in Table 1 of the proposed
amendments to the standards (Section XII). OSHA reviewed data from
properly conducted WPF studies and SWPF studies. In addition, the
Agency reviewed published APF tables. These data formed the basis for
OSHA's proposed APFs. OSHA also reviewed other types of studies, such
as Effective Protection Factors (EPF) and Program Protection Factor
(PPF) studies, along with respirator performance studies that lacked
raw data. A review of those studies can be found in the Docket (Exs. 3-
10, 3-11). However, EPF and PPF studies account for aspects of
respirator use other than effectiveness of the respirator while it is
being worn, while studies that lack raw data give little information
for in-depth statistical analysis. Therefore, OSHA relied on WPF and
SWPF studies, since they attempt to account for actual use conditions
and focus on the performance characteristics of the respirator only.
1. WPF Studies--Filtering Facepiece and Elastomeric Half-Mask
Respirators
Study 1B. C.E. Coulton, H.E. Mullins, and J.O. Bidwell gave a
presentation at the May 1994 American Industrial Hygiene Conference and
Exposition (AIHCE) on worker protection afforded by the same respirator
in two different environments and against two different contaminants
(Ex. 1-64-13). At the first site, the authors determined exposure to
cadmium dust for 18 workers in a plastic colorant manufacturing
facility. They determined exposure to lead fume for 18 workers during
ship breaking and recycling at the second site. At the colorant
facility, cadmium-containing pigments were weighed, mixed with plastic
resin, and fed into extruders for production of concentrated colorant.
Samples were obtained from workers in the weighing, mixing, and
extruding areas. Workers at the ship breaking facility used torches to
cut an aircraft carrier into large sections that were then cut into
smaller pieces on shore. Burners and firemen, on the ship and on shore,
were sampled for lead. Work rate at the colorant facility was judged to
be low, while the work rate of the ship breaking workers was assessed
as being moderate. The respirator used in the study was a 3M 6000
series elastomeric half-mask equipped with either 3M 2040 or 3M 2047
HEPA filters (the 2047 HEPA filter has some activated charcoal for
removal of nuisance levels of organic vapors). Employees normally wore
the study respirator and were provided with training in its proper
donning, fitting, and operation. In addition, the employees had to pass
a saccharin qualitative fit test prior to study participation; they
also had to be clean-shaven. The study was explained to the
participants and they were observed on a one-on-one basis throughout
the sampling periods.
The inside-the-facepiece sampling train consisted of a 25 mm three-
piece cassette with a 0.8 micron pore size mixed cellulose ester
filter. Respirators were probed with a Liu probe inserted opposite the
mouth and projecting one cm into the facepiece. The sampling cassette
was attached directly to the probe, and a cassette heater was utilized
to prevent condensation of moisture from exhaled breath. Outside-the-
facepiece samples used a 25 mm three-piece cassette with a 0.8 micron
pore size mixed cellulose ester filter. The outside sample cassette was
also connected to a Liu probe, and this combination was attached in the
worker's breathing zone. Inside samples and outside samples were
collected at a flow rate of 2 Lpm. Respirators were donned and doffed,
and sampling trains started and stopped, in a clean area. Field blanks
were used for contamination evaluation. Particle size distribution was
ascertained with a six-stage single-jet cascade impactor that sampled
all day at 1 Lpm.
Samples were analyzed by inductively coupled plasma (ICP)
spectroscopy. For both cadmium and lead, the authors presented the
range of outside concentrations, inside concentrations, and the
associated geometric means and standard deviations. Three sets of WPFs
were determined for cadmium and lead, based on three different methods
for reporting inside samples that were below the limit of detection
(LOD) (i.e., calculating WPF using 70% of the LOD; calculating WPF
using the LOD; or eliminating these samples from the WPF calculation
database). No field blank adjustments were made (i.e., no cadmium or
lead detected), and no mention is made of adjusting the data for
pulmonary retention of particles. In addition, samples were invalidated
as a result of equipment and procedural problems, and if the outside
filter weights were less than 100 times the limit of detection (or 101
times the field blank value). The authors reported a mean WPF of 353,
with a fifth percentile of 34, for the cadmium samples, and a mean WPF
of 135, with a fifth percentile of 15, for the lead fume samples. The
authors noted a sizable difference in WPFs for cadmium and lead (using
the same respirator), and discussed a number of possible reasons for
the difference (e.g., differences in particle size, work environment,
work rate). The authors concluded that the ANSI Z88.2-1992 recommended
APF of 10 for half-facepieces was appropriate.
Study 1C. In a poster presentation at the 1992 AIHCE, C.E. Coulton
and H.E. Mullins provided results of a study of several contaminants
(Ex. 1-146). Exposure to iron (Fe), manganese (Mn), titanium(Ti), and
zinc (Zn) were determined for shipyard workers involved with welding
and grinding. The respirators studied were 3M 9920 and 3M 9925 dust/
fume/mist disposable respirators.
At the Agency's request, 3M provided the raw data from the study,
but the information provided had no discussion of sampling or
analytical methodologies. However, in a brief abstract, the authors
mention using blank samples and observing participants during sampling
(in the context of discarding particular sample sets). Outside- and
inside-the-facepiece concentrations, and associated WPFs, were provided
for the four analytes: Fe (31 data sets), Mn (32 data sets), Ti (28
data sets), and Zn (32 data sets). Calculated WPFs ranged as follows:
24 to 1010 for Fe, 10.21 to 715 for Mn, 50.38 to 2545 for Ti, and 27.41
to 854.89 for Zn. Tom Nelson (Ex. 135) calculated a geometric mean (GM)
of 147, a geometric standard deviation (GSD) of 2.5, and a best
estimate fifth percentile of 33 for the 32 sample sets he used in
evaluating this study. The information he provided contained no
additional discussion of the results or study conclusions.
Study 1D. Workplace performance of an elastomeric half-mask against
exposure to lead was reported in 1984 by S.W. Dixon and T.J. Nelson for
11 workers in an unidentified work environment (Ex. 1-64-19). The
participants' work rate was judged to be moderate to heavy. Workers
viewed a training program and selected from three mask sizes of a
Survivair 2000 elastomeric half-mask respirator,

[[Page 34052]]

equipped with organic vapor/high-efficiency particulate filters.
Participants were qualitatively fit tested with isoamyl acetate. Prior
to participation, employees were quantitatively fit tested with a
Dynatec/Frontier FE250A portable unit while wearing the Survivair with
high-efficiency filters and performing six ANSI-recommended exercises.
In addition, paired (before and after) quantitative fit tests were
performed for about half of the WPF determinations to ascertain if
quantitative fit tests can predict WPFs. Participants were instructed
not to break the faceseal during sampling, and were observed throughout
the sampling period.
Samples were collected on 25 mm 0.8 micron pore size polycarbonate
filters, for 30 to 120 minutes (a complete job cycle) at a flow rate of
2 Lpm. Sampling trains were calibrated before and after each day's
sampling, and respirators were disassembled, cleaned, and reassembled
at the end of each day. The authors do not provide a more detailed
discussion of the inside or outside sampling trains (e.g., type of
respirator probe, placement of outside sampling apparatus). Particle
size analysis was performed using light microscopy and scanning
electron microscopy.
Proton induced x-ray emission analysis (PIXEA) was used to analyze
the samples. This method's limit of detection was 2 nanograms per
sample. The authors provide an approximate particle aerodynamic
diameter based on the particle size analyses. Inside-the-facepiece
results were corrected for losses caused by the sample probe but were
not corrected for lung deposition (which the authors believed caused
only a small bias). Thirty-seven WPFs were determined; however, the
individual data sets (i.e., inside concentration, outside
concentration, and associated WPF) were not provided. During the study,
some participants were observed to break the faceseal to talk. The
authors provide an overall range of WPFs achieved, GM, and GSD, for
undisturbed facepiece samples and pooled disturbed and undisturbed
facepiece samples. The authors reported a GM WPF of 3,400, and a best
estimate of the fifth percentile of 390 when the facepiece was not
disturbed, and a GM WPF of 2,400, and a best estimate of the fifth
percentile of 160 when the facepiece was disturbed. The authors also
found no correlation (at the 5% level) between WPF and outside
concentration, or the relationship between WPF and quantitative fit
factors for predicting workplace protection. The authors also estimated
the program protection factor based on historical measures of air lead
concentrations versus blood lead levels (a table and graph of this data
was provided). They concluded that the half-mask respirator they tested
provided WPFs that exceeded an APF of 10, and provided program
protection factors (PPFs) that exceeded 10.
Study 2. Workplace protection against exposure to asbestos fibers
(chrysotile and amosite) was reported at the 1985 AIHCE by T.J. Nelson
and S.W. Dixon for 17 workers who removed asbestos-containing materials
at two sites (Ex. 1-64-54). Six of these workers were removing asbestos
fireproofing from a ceiling at the first site, while eleven workers at
the second site were removing asbestos-containing pipe insulation. The
participants' work rate was judged to be moderate, site temperatures
ranged from 65-85 degrees Fahrenheit, and humidity was very high.
The following six brands of half-mask respirators were studied: 3M
8710 disposable dust/mist respirator; 3M 9910 disposable dust/mist
respirator; American Optical R1050 disposable dust/mist respirator;
Survivair 2000 elastomeric respirator with high-efficiency filters or
DFM filters; MSA Comfo II elastomeric respirator with high-efficiency
filters or DFM filters; and a North 7000 elastomeric respirator with
high-efficiency filters. Participants were trained in respirator use by
the investigators and were qualitatively fit tested using the saccharin
fit test. Supplemental data indicate that participants wore one or more
respirator brands. No mention is made of respirator donning and doffing
procedures, or starting sampling trains in a clean area; however, the
sampling procedures state pumps were stopped and cassettes removed in a
dust-free area. Participants were observed by the researchers
throughout the sampling period.
The inside-the-facepiece sampling train was a 25 mm closed-face
three-piece cassette with a \1/2\-inch extender, containing a 0.8
micron pore size mixed cellulose ester filter. The cassette was
attached directly to a tapered probe inserted into the respirator
midway between the nose and mouth. In-mask samples were collected at a
flow rate of 2.0 Lpm. The outside-the-facepiece sampling cassettes and
probes were identical to the inside-the-facepiece sampling train and
were fastened to the lapel of the subject. Outside samples were
gathered at 0.5 to 1.0 Lpm. Sampling times ranged from 30 to 120
minutes, and the pumps were calibrated before and after each sampling
period. The authors investigated uniform deposition of asbestos fibers
across the filters; they noticed a slight trend for heavier deposition
at the filter center using both methods. They also computed the
precision of sample gathering using open- versus closed-face cassettes
and found no difference between the methods.
Asbestos analysis was based on NIOSH method P&CAM 239 and NIOSH
method 7400 (i.e., the filter mounting and ``A'' counting rules). To
increase analytical sensitivity, the methodology was modified by
counting fibers in a minimum of 500 fields per inside-the-facepiece
filter when less than 100 fibers were counted. The actual number of
fibers counted in each sample was used to compute the airborne
concentration. In addition, one microscopist performed all fiber
counting. The distributions of fiber length and diameter were
determined by transmission electron microscopy using lapel sample
filters. The GM and GSD values for the fiber length, fiber diameter,
and equivalent aerodynamic diameter at each worksite and the combined
data from both sites were reported, but the values for fiber density
and the length-diameter correlation coefficient were not provided. A
total of 84 pairs of inside and outside fiber concentrations, and
corresponding WPFs, were provided by participant, respirator brand, and
sampling period in supplemental data tables. However, the authors
considered seven WPF values measured for the American Optical
respirator as suspect because the inside-the-facepiece filter samples
contained glass fibers, originating from the respirator's filter
matrix. These glass fibers have the same appearance as asbestos fibers
under light microscopy. The authors did not adjust measured values for
field blank values (i.e., blanks were below the limit of
quantification) or fiber retention in the respiratory tract (i.e., the
authors believed that pulmonary fiber retention resulted in only a
slight change in concentration inside the facepiece).
The 3M 8710 results showed a GM WPF of 310, a GSD of 5.3, and a
best estimate of the fifth percentile of 20. The 3M 9910 had a GM WPF
of 580, a GSD of 4.2, and a best estimate of the fifth percentile of
55. The AO R1050 had a GM WPF of 52, a GSD of 4.2, and a best estimate
of the fifth percentile of 5. The Survivair 2000 or MSA Comfo II
equipped with DFM filters had a GM WPF of 240, a GSD of 6.3, and a best
estimate of the fifth percentile of 12. With high-efficiency filters,
the GM WPF was 94, the GSD was 3, and the best estimate of the fifth
percentile was 16. For the North 7700 equipped with high-efficiency
filters, the GM WPF was

[[Page 34053]]

250, the GSD was 6.9, and the best estimate of the fifth percentile was
11.
Since the WPFs for respirators equipped with DFM and high-
efficiency filters were similar, and were well below the protection
expected if filter efficiency alone was the determining performance
factor, the authors concluded that ``* * * filter efficiency was not as
significant a factor in determining the relative workplace performance
against asbestos as the face fit''. The authors also noted comparable
performance between disposable and elastomeric respirators. With regard
to this, the authors noted that perspiration and wetting solutions led
to the elastomeric facepieces slipping on the participants' faces,
something that was not noted with the fibrous disposable respirators.
The authors postulate that the effect of this slippage could be a
reason why the two types of respirators had similar performance.
Study 3. In 1993, A. Gaboury and D.H. Burd performed a WPF study by
measuring exposure to benzo(a)pyrene [B(a)P]
on particles among 22
workers in a primary aluminum smelter (Ex. 1-64-24). The participants
were rack raisers, stud pullers, and rod raisers on anode crews. The
following three brands of elastomeric half-mask respirator devices were
studied: Willson, Survivair, and American Optical. (Note: Respirator
model numbers were not provided) The respirators were equipped with
combination organic vapor/acid gas cartridges and DFM pre-filters, with
the exception that dust/mist pre-filters were used on the American
Optical respirator. The study also examined the performance of a
powered air-purifying respirator (PAPR), but only the negative-
pressure, air-purifying half-mask respirator data are presented here
(the PAPR results are discussed below). The participants had used
respirators for several years, had been previously trained in the use
of the particular respirator under study, and had used it for more than
six months. All participants in half-mask respirators were clean-shaven
and were quantitatively fit tested using the TSI Portacount. The
minimum acceptable fit factor was 100. Industrial hygiene technologists
assisted participants with donning and doffing respirators, cleaned and
maintained the respirators at the end of each work cycle, and observed
participants on a one-to-one basis throughout the sampling period.
Participants were directed not to tamper with the respirator or
sampling equipment. Due to the high heat in the work area, the employer
required that employees rest in a cool environment for one-half hour
during each hour.
The inside-the-facepiece sampling train consisted of a closed-face
three-piece cassette with a 25 mm organic binder free glass fiber
filter, backed with a cellulose ester pad. The sampling cassettes were
connected to a tapered Liu probe inserted into the respirator between
the nose and mouth. The outside-the-facepiece sampling train was
identical to the inside-the-facepiece sampling train; however, no
mention is made of connecting the cassette to a Liu probe. All filters
were pre-calcined at 400 degrees Centigrade for 24 hours. Both inside
and outside samples were collected at a flow rate of 2 Lpm for
approximately 300 minutes, or one-half of the 10-hour work shift.
Respirators and sampling trains were worn and operated until the
employee entered the rest area; they were donned and started prior to
leaving the rest area for the next work cycle. Sampling cassettes were
plugged when not in use and the respirators were cleaned after each
work cycle. Field blanks were used to identify possible contamination
due to handling. Sampling train airflow rates were checked at the
beginning, middle (i.e., after lunch), and end of the work day; on
changing the cassettes; and when a problem was suspected. Sampling
occurred over a five-day period. Only stud pullers and rod raisers used
the elastomeric half-mask respirators.
B(a)P analysis followed the Alcan Method #1223-84. The
ambient B(a)P particle size distribution was determined by collecting
four samples, as close as possible to the workers, using an 8-stage
Anderson cascade impactor (Model 296). Impactor samples were collected
for two to five hours at a flow rate of 2 Lpm. The average percent of
B(a)P mass (across four samples) per impactor stage (defined by an
aerodynamic diameter cut point, in micrometers) was reported. About 93%
of the B(a)P mass was associated with particles having diameters of
less than 9.8 micrometers. A total of 18 pairs of inside and outside
sample concentrations, with associated WPFs, were provided by brand of
respirator and job category, but were not linked to specific
participants. Overall GM, GSD, and 95% confidence interval on the mean
were also provided for the inside and outside concentrations and WPF,
along with an overall fifth percentile WPF. The authors stated that
some employees participated more than once during the study. No mention
is made of adjusting inside-the-facepiece concentrations for particle
retention in the respiratory tract. The half-masks had WPF ranging from
13 to 410, with a GM of 47. The two-sided 95% confidence intervals were
30 and 74 for the dual cartridge respirators. The fifth percentile was
9. The authors found no significant relationship between B(a)P
concentrations inside and outside the facepiece. Also, while the data
were limited, the authors believed no correlation existed between WPF
and quantitative fit factor. The authors concluded that the fifth
percentile for the half-masks they tested were in agreement with the
APF of 10 recommended by the NIOSH RDL.
Study 6. S.W. Lenhart and D.L. Campbell reported in 1984 on a WPF
study in which they measured protection against exposure to particulate
lead (Pb) for 25 primary lead smelter workers; seven of whom worked in
the sinter plant and eighteen of whom were in the blast furnace area
(Ex. 1-64-42). The predominant aerosol forms of lead were dust in the
sinter plant and fume in the blast furnace. In both areas, lead
comprised about 50% of the total aerosol particulate with composition
of the remaining 50% being unknown. All participants wore an MSA
elastomeric half-mask with high-efficiency filters. (Note: No
respirator model number was provided) The study also examined the
performance of an MSA PAPR, but only data for the negative-pressure,
air-purifying half-mask respirator are presented here (the PAPR results
are discussed below). The employees routinely used respirators;
however, no mention is made of them with respirator training.
Participants were quantitatively fit tested using an unspecified
method, and had to achieve the employer's required fit factor of 250.
Workers were instructed not to remove or manipulate the respirator
during sampling, and were observed by the researchers throughout the
sampling period.
The inside-the-facepiece sampler consisted of a closed-face 37 mm
cassette containing an AA filter and AP10 support pad. This cassette
was connected to a tapered Liu probe that was inserted into the
respirator between the nose and upper lip. In-mask samples were
collected at 2 Lpm. The outside-the-facepiece sampling train was a
closed-face 37 mm cassette containing an AA filter and AP 10 support
pad; no tapered Liu probe was used. The outside sample cassette was
attached to the worker's lapel. Outside samples were gathered at 2 Lpm.
The authors collected samples for as much of each 8-hr work shift as
possible. Respirators and sampling trains were donned and doffed, and
samplers were started and stopped, in a lead-free area. Respirator
facepieces were wiped clean inside

[[Page 34054]]

prior to donning after each break and cleaned and sanitized after each
shift. One WPF was measured for each employee. The ambient particle
size distribution was determined using 19 Marple cascade impactor
samples (11 in the sinter plant; 8 in the blast furnace area).
Lead analysis was by flame atomic absorption spectroscopy according
to NIOSH Method S-341. Inside-the-facepiece samples that contained less
than l0ug of lead were reanalyzed by graphite furnace atomic absorption
(limit of detection = 0.2 [mu]g). The ranges for the mass median
aerodynamic diameters (in micrometers) and for the GSD values were
reported. A total of 25 pairs of inside and outside half-mask values,
and the corresponding WPFs, were provided by employee, job title, and
job location. An overall GM and GSD of the WPFs, and various percentile
WPFs, were provided. When samples contained lead below the level of
detection, the authors reported concentration values ``* * * determined
from the least amount of lead detectable by the analytical method and
the sampled volume of air.''
In-mask values were not adjusted for particle retention in the
respiratory tract (the authors imply retention probably had a non-
significant effect on results, but could result in overestimated WPFs).
No mention is made of the investigators using field blanks. They
reported that approximately 98% of the WPFs would be expected to be at
or above 10, 90% above 30, and 75% would be expected to be above 100.
They concluded that an APF of 10 was appropriate for the half-mask
negative pressure air-purifying respirator evaluated in this study. The
authors also discussed two proportional methods of defining an APF.
Study 7. W.R. Meyers and Z. Zhuang conducted a 3-part workplace
protection factor study in three different work environments. In
addition to presenting the study findings, the authors also discuss
their rationale for selecting exposure agents, study facilities, and
workers; study procedures followed at the sites; and analytical
methods. W.R. Meyers and Z. Zhuang in January, 1993 (Ex. 1-64-51) and
W.R. Meyers, Z. Zhuang, and T.J. Nelson in 1996 (Ex. 3-12) reported on
the first part of the study in which the authors determined protection
against exposure to particulate lead (Pb), zinc (Zn), and total
airborne mass (TAM) for 25 workers, on day and evening shifts, in three
brass foundries (3, 9, and 13 participants, respectively). (Note: The
reports mention 26 participants, but data were presented for only 25
participants.) Four brands of half-mask devices were studied: 3M 9920
disposable DFM respirator; American Optical 5-Star elastomeric
respirator with DFM filters (R56A); MSA Comfo II elastomeric respirator
with DFM filters (Type S); and Scott Model 65 elastomeric respirator
with DFM filters (642-F).
Participants were selected from volunteers who normally wore
respirators, were clean-shaven, and passed a fit test. Their work rate
was subjectively determined by observing their work activities.
Respirators were worn for the usual period. For the elastomeric half-
mask respirators, the participants were quantitatively fit tested using
a TSI Portacount; a fit factor of 100 or more constituted a pass.
Disposable respirators were fit tested using the saccharin qualitative
fit test. The investigators trained the participants in the proper
donning and adjustment of the respirators, and instructed them not to
remove or lift the respirator from their face in the work area.
Readjustment of the respirator had to be accomplished by sliding the
facepiece on their face. Workers were observed throughout the sampling
period. Each participant wore two or more respirator brands, and one
WPF was measured per employee for each brand worn.
The inside-the-facepiece sampling train was a 25 mm closed-face
cassette attached directly to a flared mouth probe, inserted into the
respirator opposite the mouth. The cassette contained a 0.5 micron pore
size polyethylene filter and polypropylene backup pad. A 4.5 mm ring
under the filter restricted airflow to an 18 mm circle in the center of
the filter to keep deposition in an area that could be entirely covered
by the proton beam used for sample analysis. A heating bonnet was slid
over the outside of the cassette to minimize condensation of moisture
from exhaled breath. Sampled air was then drawn through a moisture trap
using a personal sampling pump operating at 2 Lpm. The outside-the-
facepiece sampling train was a 10 mm nylon cyclone attached to 25 mm
closed-face cassette (the cassette was not connected to a flared mouth
probe). The cassette contained a 0.5 micron pore size polyethylene
filter and polypropylene backup pad. A 4.5 mm ring under the filter
restricted airflow to an 18 mm circle in the center of the filter. This
sampling train was attached in the lapel area and samples were
collected at a flow rate of 1.7 Lpm.
Two separate samples were gathered during the shift, one during the
first half and another during the second half. Individual WPFs were
based on monitoring times of approximately one to four hours.
Respirators were donned and doffed, and sampling trains were started
and stopped, in a clean area. Elastomeric facepieces were cleaned and
inspected at the end of each shift, but were not wiped out during the
shift unless such wiping was a standard practice before the study (the
authors noted that most of the time workers did not wipe out
facepieces). Air-purifying filters (cartridges) and disposable
respirators were changed at the end of each shift unless the employer's
policy dictated more frequent changing. In addition, the mouth of the
in-mask probe was plugged whenever the respirator was not being worn.
Working (field) blanks and manufacturer's (media) blanks were used to
determine possible contamination of filters due to handling or
manufacturing. The investigators also washed the interior of the
sampling cassettes to ascertain retention of sample particles on the
cassette wall. The ambient particle size distribution was determined by
PIXE 8-stage cascade impactor samples at several work locations in each
foundry. These area samples were collected at roughly mid-chest to
shoulder level of workers for approximately 1 hour, to prevent impactor
overloading.
All samples were analyzed by proton induced X-ray emission analysis
(PIXEA). The mass distribution of Pb, Zn, and TAM by particle
aerodynamic diameter was graphically presented for all cascade impactor
samples. Across the three foundries, 66 pairs of inside-the-facepiece
and outside-the-facepiece concentrations, and the corresponding WPFs,
were provided by job task, employee, brand of respirator, and analyte
(Pb, Zn, and TAM). The authors did not adjust measured values for
particle retention on sampling cassette walls since these losses
appeared to be random, independent of collected mass, and of a
negligible amount. No mention is made of correcting measured in-mask
values for pulmonary particle retention. A foundry-specific average of
the field blank loadings was used as a correction factor for estimating
background and handling contamination for each foundry. Outside-the-
facepiece samples were collected as respirable particulate, thereby
providing respirable mass levels, while in-mask samples were collected
as total particulate mass. The authors initially assumed that particles
larger than 10 microns did not penetrate respirator faceseals; however,
this was found to be incorrect after analyzing in-mask particle size.
Therefore, to avoid comparison of dissimilar measurements, the
investigators used particle size data

[[Page 34055]]

obtained by ambient sampling to convert the respirable mass levels to
total mass levels (using Chimera/TSI Disfit software). The reported
levels represent these total mass values, and form the basis of the
reported WPF values. The authors also provide data and discussion on a
number of sampling analyses, including GM concentration of analyte by
job task, GM concentration of analyte for in-mask and ambient
concentrations, particle size distribution by job category, GM WPF
estimates by job category, GM WPF by respirator type, within shift
sampling variation, and variation between foundries. For the pooled
data from the three foundries, the 3M 9920 filtering facepiece had a
50% WPF of 108, a GSD of 5.2, and a fifth percentile estimate of 7. The
AO half-mask had a 50% WPF estimate of 98, a geometric standard
deviation (GSD) of 5.8, and a fifth percentile WPF of 5. The MSA Comfo
II half-mask had a 50% WPF of 163, a GSD of 3.1, and a fifth percentile
WPF of 26. The Scott half-mask had a 50% WPF of 94, a GSD of 4.8, and a
fifth percentile WPF of 7. For all respirators a 50% WPF of 114, a GSD
of 4.6, and a fifth percentile estimate of 9 was reported. The authors
concluded that ``* * * dust-fume-mist (DFM) half-facepiece respirators,
when conscientiously used, worn, and maintained, provided effective
worker protection.''
Study 8. W.R. Meyers and Z. Zhuang in January, 1993 (Ex. 1-64-51)
and W.R. Myers, Z. Zhuang, and T.J. Nelson in 1996 (Ex. 3-12) reported
on the second part of the three-part study, which evaluated protection
against exposure to particulate iron (Fe) for 16 workers in the sinter
plant and basic oxygen process (BOP) facility of a steel manufacturing
plant. In addition, exposure to particulate calcium (Ca) in the BOP
facility was determined for one worker. The five brands of half-mask
respirators studied were: 3M 8710 disposable dust/mist respirator;
Gerson 1710 disposable dust/mist respirator; American Optical 5-Star
elastomeric respirator with dust/mist filters (R30); MSA Comfo II
elastomeric respirator with dust/mist filters (Type F); and Scott,
Model 65 elastomeric respirator with dust/mist filters (642-D).
In general, each participant wore two or more brands, and one WPF
was measured per employee per brand worn. One employee had one WPF
determined for only one respirator brand. For the elastomeric half-mask
respirators, the participants were quantitatively fit tested. A fit
factor of 100 or more constituted a pass. Disposable respirators were
fit tested using the saccharin qualitative fit test. The overall study
and sampling protocols were discussed by the authors in the foundry
portion of the investigation (see Study 7 discussion above). While not
specifically discussed, it is assumed that the same sampling parameters
used in the foundry study were in place during this particular study,
unless the authors stated otherwise. These assumptions include:
composition of the sampling trains was unchanged; individual WPFs were
based on monitoring times of one to four hours; elastomeric facepieces
were cleaned and inspected at the end of each shift but the insides
were not wiped during the shift such wiping was the employer's standard
practice before the study; air-purifying filter cartridges and
disposable respirators were changed at the end of each shift unless the
employer's policy dictated more frequent changing; and the in-mask
probe mouth was plugged whenever the respirator was not being worn. In
addition, it is assumed that the participants were clean shaven,
normally used respirators, were trained in the proper donning and
adjustment of the respirators, were instructed not to remove or lift
the respirator from their face in the work area, and were observed
throughout the sampling period.
The inside-the-facepiece sampling train was a closed-face 25 mm
cassette containing a 0.5 micron pore size polyethylene filter and
polypropylene backup pad. A reducing ring under the filter restricted
airflow to an 18 mm circle in the center of the filter to aid in PIXE
analysis. A heating bonnet was slid over the outside of the cassette to
minimize condensation of moisture from exhaled breath. This cassette
was attached directly to a flared mouth probe, inserted into the
respirator opposite the mouth. Sampled air was drawn through a moisture
trap using a personal sampling pump operating at 1.5 Lpm. The outside-
the-facepiece sampling train was a closed-face 25 mm cassette
containing a 0.5 micron pore size polyethylene filter and polypropylene
backup pad. A reducing ring under the filter restricted airflow to an
18 mm circle in the center of the filter. The cassette was not
connected to a flared mouth probe. This sampling train was attached in
the lapel area and samples were collected at a flow rate of 1.5 Lpm.
(Note: Unlike the foundry portion of the study, outside samples were
collected as total mass rather than respirable mass samples.) Sampling
pump flows were calibrated before and after each sampling period and
pumps were monitored at approximately 15-20 minute intervals.
Respirators were donned and doffed, and sampling trains were started
and stopped, in a clean area. New cassettes were used for each sampling
period. Working (i.e., field) blanks and manufacturer's (media) blanks
were used to determine possible contamination of filters due to
handling or manufacturing. The investigators also washed the interior
of the sampling cassettes to determine retention of sample particles on
the cassette wall. The ambient particle size distribution was
determined by PIXE cascade impactor samples. Personal impactor samples,
rather than area samples, were collected at the steel mill sites (see
foundry sampling procedures discussed above in Study 7).
Analysis for Fe and Ca on inside-the-facepiece filters was by
proton induced X-ray emission analysis (PIXEA). Due to filter
overloading, analysis for Fe and Ca on outside-the-facepiece filters
was by atomic absorption spectroscopy. The mass distribution of Fe by
particle aerodynamic diameter was tabulated for all cascade impactor
samples. A total of 54 individual pairs of inside- and outside-the-
facepiece concentrations, and the corresponding WPFs, were provided by
shift and date, job category, employee, and brand of respirator. For 16
workers, the WPFs reported were based on the Fe data, while Ca data
were used to calculate the WPF for one worker (flux unloader) in the
BOP facility. Based on analytical information, the authors did not
adjust measured values for particle retention on the walls of the
sampling cassette. No mention is made of adjusting inside-the-facepiece
values for particle retention in the respiratory tract. The average
field blank mass loading was used as a correction factor for estimating
background contamination. The 3M 8710 had a reported GM WPF of 377, a
GSD of 3.7, and a fifth percentile WPF of 44. The Gerson 1710 had a
reported GM WPF of 123, a GSD of 2.7, and a fifth percentile WPF of 24.
The American Optical elastomeric half-mask had a reported GM WPF of
280, a GSD of 2.7, and a fifth percentile WPF of 56. The MSA Comfo II
had a reported GM WPF of 427, a GSD of 4.3, and a fifth percentile WPF
of 39. The Scott elastomeric half-mask had a reported GM WPF of 252, a
GSD of 2.9, and a fifth percentile WPF of 45. The authors concluded
that ``The 5th percentiles for the WPF distributions for each
respirator or pooled data were greater than 20.''
The authors also provided data and discussion on a number of
sampling analyses, including GM concentration of analyte and GM WPF by
job task, GM concentration of Fe inside the facepiece

[[Page 34056]]

and ambient and GM WPF by respirator brand, and particle size
distribution by job category. The authors stated that ``* * * half-
facepiece respirators (maximum use concentration 10 times the PEL) were
a suitable selection for the tasks included in this study.''
Study 9. In January 1993, W.R. Meyers and Z. Zhuang reported on the
third part of their investigation, in which they determined protection
against exposure to particulate titanium (Ti), chromium (Cr), strontium
(Sr) and total ambient mass (TAM) for 22 workers who spray painted
aircraft on day, evening, and night shifts (Ex. 1-64-52). The three
brands of half-mask elastomeric respirators studied were the: American
Optical 5-Star, MSA Comfo II, and Scott Model 65. All respirators were
equipped with combination high-efficiency filter/organic vapor
cartridges.
Twelve participants each wore two brands of respirator with a WPF
determined for each brand worn; nine participants wore one brand of
respirator and had one WPF determined; and one employee had one WPF
determined for one respirator brand and two WPFs determined for another
brand. The participants were quantitatively fit tested and a fit factor
of 100 or more constituted a pass. The overall study and sampling
protocol was discussed by the authors in the foundry portion of the
studies, summarized in Study 7 above (Ex. 1-64-51). While not
specifically discussed, it is assumed that the same sampling parameters
were in place during this particular study as in the foundry study,
unless the authors stated otherwise. These assumptions include:
composition of the sampling trains was unchanged; individual WPFs were
based on monitoring times of one to four hours; elastomeric facepieces
were cleaned and inspected at the end of each shift but were not the
inside was not wiped during the shift, unless such wiping was the
employer's standard practice before the study; filters and disposable
respirators were changed at the end of each shift unless the employer's
policy dictated more frequent changing; and the mouth of the in-mask
probe was plugged whenever the respirator was not being worn. In
addition, it is assumed that the participants were clean-shaven,
normally used respirators, were trained in the proper donning and
adjustment of the respirators, were instructed not to remove or lift
the respirator from their face in the work area, and were observed by
the researchers throughout the sampling period.
The inside-the-facepiece sampling train was a closed-face 25 mm
cassette containing a 0.5 micron pore size polyethylene filter and
polypropylene backup pad. A reducing ring under the filter restricted
airflow to an 18 mm circle in the center of the filter to aid in sample
analysis. A heating bonnet was slid over the outside of the cassette to
minimize condensation of moisture from exhaled breath. This cassette
was attached directly to a flared mouth probe, inserted into the
respirator opposite the mouth. Sampled air was then drawn through a
moisture trap using a personal sampling pump operating at approximately
2 Lpm. The outside-the-facepiece sampling train was a closed-face 25 mm
cassette containing a 0.5 micron pore size polyethylene filter and
polypropylene backup pad. A reducing ring under the filter restricted
airflow to an 18 mm circle in the center of the filter. The cassette
was not connected to a flared mouth probe. This sampling train was
attached in the lapel area, and samples were collected at a flow rate
of 1 Lpm. (Note: Unlike the foundry portion of the study, outside
samples were collected as total mass rather than respirable mass
samples.) Sampling pump flows were calibrated before and after each
sampling period and pumps were monitored at approximately 15-20 minute
intervals. Respirators were donned and doffed, and sampling trains were
started and stopped, in a clean area. New cassettes were used for each
sampling period. Working (i.e., field) blanks and manufacturer's
(media) blanks were used to determine possible contamination of filters
due to handling or manufacturing. The investigators did not wash the
interior of the sampling cassettes to determine retention of particles
on the cassette wall, since a simple alcohol wash would not have
removed dried paint spray. Ambient particle size distributions were not
characterized.
Analysis of all filters was by proton induced X-ray emission
analysis (PIXEA). The average field blank mass loading was used as a
correction factor for estimating background contamination. The authors
did not mention adjusting inside-the-facepiece measured values for
particle retention in the respiratory tract. A total of 36 individual
pairs of inside-the-facepiece and outside-the-facepiece concentrations
of each analyte (total airborne mass, titanium, chromium, strontium)
were provided by shift and date, painting location on the plane (i.e.,
top, side, or underside of the aircraft), employee, brand of
respirator, and paint type (i.e., top coat, primer). A total of 36 WPFs
were reported by shift, task location on the plane, employee, and
respirator brand; of the original 38 data sets, two sets were
eliminated as outliers. For primer spraying, the reported WPFs were
based on Cr data, while WPFs for spraying topcoat were based on Ti
data. WPFs were not calculated for total airborne mass. The authors
also provided data and discussion on a number of sampling analyses,
including GM concentration of analyte (TAM, Ti, Cr) for both in-mask
and ambient measurements by task location on the plane; GM WPF as a
function of painting location on plane and paint type, and respirator
brand; and GM WPF by respirator brand. The fifth percentile estimates
for all WPF data were reported to be much greater than 10. The authors
concluded that these half-facepiece elastomeric respirators, when
properly worn and used in conjunction with existing controls provided
effective worker protection.
Study 13. G. Wallis, R. Menke, and C. Chelton reported in 1993 on a
WPF study in which they evaluated exposure to manganese dioxide dust
for an unknown number of participants in several alkaline battery
manufacturing plants (number of plants not provided) (Ex. 1-64-70). All
participants wore the disposable 3M 8710 dust/mist respirator and
performed their normal work activities. The participants were not
trained by the investigators, but had been previously trained and
routinely used respirators. It was not stated whether the participants
had ever been fit tested for the 3M 8710 respirators. Prior to
sampling, the participants washed their faces and were taken to a clean
area, where the study was explained. The participants were observed
throughout the sampling period.
The inside-the-facepiece sampling train was a closed-face 37 mm
cassette containing a 0.8 micron pore size mixed cellulose ester
filter. The cassette was connected to a tapered Liu probe (made of
nylon) which was inserted into the respirator midway between the nose
and mouth. The outside-the-facepiece sampling train was a closed-face
37 mm cassette containing a 0.8 micron pore size mixed cellulose ester
filter. The outside sampling cassette was attached to the employee's
lapel. No mention is made of connection of the outside cassette to a
tapered Liu probe. Inside- and outside-the-facepiece samples were
collected at an airflow rate of 1.5 Lpm for 30 to 40 minutes. The
authors chose a short sampling interval to prevent resistance across
the inside-the-facepiece sampling filter due to a buildup of moisture
from exhaled breath. Sampling pump flows were

[[Page 34057]]

calibrated before, and rechecked after, each sampling period.
Respirators were donned and doffed, and the sampling trains started
(and assumed stopped), in the clean area. Field blanks were used to
identify possible contamination of filters due to handling. The number
of sample pairs collected per subject was not specified. The ambient
manganese particle size distribution was determined by 6-stage Marple
Cascade impactor equipped with an inlet cowl to prevent debris from
entering the impactor. Samples were collected for several hours at a
flow rate of 2 Lpm, and flows were calibrated before and after each
sampling interval. Four samples were gathered: One in the powder drop
area (Plant A) and three at the bag slitting operations (one in Plant
A, two in Plant B).
Samples were analyzed for Mn by atomic absorption (AA) spectroscopy
according to NIOSH Method 7300. The mass distribution of Mn by particle
aerodynamic diameter was tabulated for all cascade impactor samples.
Less than 30% of the mass was associated with respirable particles. A
total of 70 individual pairs of inside-the-facepiece and outside-the-
facepiece concentrations, and the corresponding WPFs, were provided by
job activity (but not by employee or plant). No mention is made of
adjusting measured values for particle retention in the respiratory
tract or results of field blank analysis. A GM of 50 and a GSD of 3.5
was reported for all the WPF values measured. A calculated fifth
percentile protection factor of 7.5 was also reported. The authors
reported that their data indicated a systematic dependence of WPF on
the concentration outside the respirator. In their discussion of this
observation, the investigators refer to three possible causes presented
by authors of other studies: Program protection factors tend to be low
in low exposure settings since the workers, aware of the low exposure,
exercise less care; low outside concentrations result in inside-the-
facepiece concentrations so small that reliable quantification is
difficult; and filter efficiency increases with loading, and low
concentrations do not adequately load the filter. The authors discuss
these causes relative to their study results, and postulate that
another cause may be particle size selectivity (i.e., smaller particles
have a higher probability of entering the respirator). They conclude
that it is important to characterize respirator performance in the
environment where the respirator will be used.
Study 14. At the 1990 AIHCE, C.E. Colton, A.R. Johnston, H.E.
Mullins, C.R. Rhoe, and W.R. Meyers presented a WPF study in which they
measured protection against exposure to aluminum dust for five
participants working as carbon changers in an aluminum smelter (Ex. 1-
64-15). All participants wore the disposable 3M 9906 dust/mist
respirator. The investigators trained the participants in donning the
respirator and the participants were qualitatively fit tested, although
the fit test method was not described. The total number of samples
collected per employee was not specified, although it is stated that
the five employees were sampled daily for five days. Participants were
observed throughout the sampling period.
The inside-the-facepiece sampling train was a closed-face 25 mm
cassette containing a 0.8 micron pore size polycarbonate filter. The
cassette was connected to a tapered Liu probe, inserted into the
facepiece in an unspecified location. In-mask samples were collected at
an airflow rate of 2.0 Lpm. The outside-the-facepiece sampling train
was a closed-face 25 mm cassette containing a 0.8 micron pore size
polycarbonate filter. Outside samples were gathered as respirable dust
samples with the cassette being connected downstream from a cyclone
apparatus. Sampling airflow rate was 1.7 Lpm. Sampler airflow rates
were calibrated before and after each sample period. No mention is made
of donning and doffing procedures. Field blanks were used to identify
possible filter contamination caused by handling. The ambient aluminum
particle size distribution was determined through 12 area samples
(unspecified locations) collected by Marple personal cascade impactors.
In addition, particulates that passed a cyclone selector were sized by
optical microscopy.
Aluminum was determined by proton induced x-ray emission analysis
(PIXEA). The mass distribution of aluminum by particle diameter and
percent penetration to the collector was graphically presented. Final
calculations used only those outside filter weights that were greater
that 11 times the detection limit. A total of 24 time-weighted-average
(TWA) inside-the-facepiece and outside-the-facepiece concentrations,
with corresponding TWA WPFs, are provided in supplemental data (Ex. 1-
146). The sample pairs are not linked to specific participants. No
mention is made of adjusting sample results for particle retention in
the respiratory tract. The mean blank value was zero, so no adjustment
to measured values was made. The authors reported a GM of 27, a GSD of
1.5, and a fifth percentile of 13 for the 23 sample sets used. The
report concluded that the respirator provided reliable WPFs of 10.
Cumulative probability of achieving a particular WPF, and the effect of
filter weight on WPF, were also graphically presented. The authors
stated that the WPFs represented conservative estimates of protection
since outside concentrations were measured as respirable dust. In the
summary of this study (Ex. 1-146), submitted to OSHA along with the raw
sampling data, the authors recommended that the study not be used to
assess the ultimate APF for this class of respirator since they felt
that the real WPF of the respirator was significantly underestimated.
Study 15. C.E. Colton, H.E. Mullins, and C.R. Rhoe presented a WPF
study at the 1990 AIHCE in which they determined exposure to
particulate Pb and Zn for 17 participants working in core making, mold
making, pouring, and cleaning areas of a brass foundry (Ex. 1-64-16).
All participants wore the disposable 3M 9970 high-efficiency
respirator. The investigators trained the participants in the proper
donning and fitting of the respirator, and participants were fit tested
using the saccharin qualitative fit test method described in Appendix D
of OSHA's Lead Standard (29 CFR 1910.1025). Sampling took place over
five days.
The inside-the-facepiece sampling train was a 25 mm three-piece
cassette containing a 0.8 micron pore size polycarbonate filter (open-
versus closed-face was not specified). The cassette was directly
connected to a tapered nylon Liu probe, inserted into the facepiece
midway between the nose and mouth. The inside-the-facepiece samples
were collected at a flow rate of 2.0 Lpm. The outside-the-facepiece
sampling train was a 25 mm three-piece cassette containing a 0.8 micron
pore size polycarbonate filter. Outside samples were gathered as
respirable dust samples, with the cassette being connected downstream
from a 10 mm nylon cyclone. Samples were collected at a flow rate of
1.7 Lpm, and sampling pumps were calibrated before and after each
sample. The authors do not mention using of field or manufacturer's
blanks, respirator donning and doffing procedures, or methods of
starting and stopping sampling trains in a clean area. The ambient Pb
and Zn particle size distributions were determined by an unspecified
number of Marple personal cascade impactor (Model 2401) samples.
Pb and Zn were determined by proton-induced x-ray emission analysis
(PIXEA). The particle size data were not presented; however, the report
stated that the Pb and Zn aerosols were present as both dust and fume.
The range of

[[Page 34058]]

outside-the-facepiece and inside-the-facepiece concentrations for Pb
and Zn were provided. For the purpose of WPF calculation, inside-the-
facepiece samples with non-detected concentrations were treated as
containing analyte at the detection limit (This situation only arose
with lead, not zinc). For the 62 sample sets taken for lead, the GM WPF
was 415, the GSD was 4.4, and the fifth percentile WPF was 36. For
zinc, the GM WPF was 681, the GSD was 5.6, and the fifth percentile WPF
was 40. The authors believe they handled their results conservatively
since outside concentrations were collected as respirable particulate,
rather than total mass, and inside-the-facepiece samples with non-
detected concentrations were given values of the analytical detection
limit when calculating WPF. In the study summary, the authors concluded
that when the respirator is properly selected, fit tested, and used,
their results supported its use for concentrations up to 10 times the
PEL.
Study 16. A.R. Johnston and H.E. Mullins reported at the 1987 AIHCE
on a WPF study in which they measured exposure to particulate aluminum
(Al), titanium (Ti) and silicon (Si) for three participants working in
the polishing and grinding area of an aircraft components manufacturing
facility (Exs. 1-64-34, 1-146, 1-133). Although WPFs were also measured
for two other participants, one in the blasting area and one in the
coating area, no data were presented for these employees. All
participants wore the disposable 3M 8715 dust/mist respirator. Prior to
testing, the investigators trained the participants in the proper
fitting of the respirator, fit tested the employees using the OSHA Lead
Standard's saccharin qualitative fit test method, and explained the
study to them. Participants had previously worn respirators, but on an
``as needed'' or elective basis only. Employees were observed one-on-
one throughout the sampling period. The number of WPFs measured per
subject was not specified, although it appears that about six WPFs were
measured per subject.
The inside-the-facepiece sampling train was a closed 25 mm three-
piece cassette containing a polycarbonate filter. The cassette was
connected to a tapered nylon Liu probe that was inserted into the
facepiece at an unspecified location. Inside-the-facepiece samples were
collected at a flow rate between 1.5 and 2 Lpm. The outside-the-
facepiece sampling train was a closed 25 mm three-piece cassette
containing a polycarbonate filter. The cassette was connected
downstream from a tapered Liu probe. Outside samples were collected at
a flow rate between 1.5 and 2 Lpm. Sampling times ranged from 35 to 235
minutes. Sampling pumps were calibrated three times a day--at the
beginning of the shift, lunch, and the end of the shift. Sampling
equipment was removed for breaks, which occurred multiple times in some
instances. While no mention is made of using a clean area to don and
doff respirators, and start and stop sampling trains, the authors noted
that cassettes had to be removed in the work area. Field blanks were
used to identify possible filter contamination due to handling. The
ambient particle size distribution was not characterized.
Samples were analyzed by proton induced x-ray emission analysis
(PIXEA). Sample results were adjusted for field blank values, but no
mention was made of adjustments for particle retention in the
respiratory tract. The authors rejected sample sets in which: the
outside filter weight was less than 11 times the mean blank value; the
inside filter weight was non-detectable, or less than the mean field
blank value; or the measured WPF was determined to be an outlier (i.e.,
too far above or below the geometric mean WPF using 5% confidence
intervals). A total of 38 sample sets were accepted for Al (10), Ti
(14), and Si (14). Pairs of inside-the-facepiece and outside-the-
facepiece concentrations, and the corresponding WPFs, are provided in
supplemental data (Exs. 1-146, 1-133), but were not linked to specific
participants. Also, a table of GM WPF, GSD, and fifth percentile WPF,
by analyte, was presented. The authors calculated WPF values for the 10
sample sets of Al, reporting a GM of 145, a GSD of 2.3, and a fifth
percentile of 32. For the 14 sample sets measured for Ti, the GM was
59, the GSD was 1.7, and the fifth percentile was 24. For Si, using 14
sample sets, the GM was 172, the GSD was 3.1, and the fifth percentile
was 24. The authors concluded that their study supports using this
respirator for concentrations up to 10 times the PEL. In addition, the
authors noted a positive correlation between filter weight and WPF. Two
explanations put forth for this effect were that respirators work
better with higher dust loadings, and that WPF measurements are more
accurate at higher dust loadings. The authors favored the latter
explanation, and believed that to assess true respirator performance
capabilities, testing should be conducted at or near the respirator's
APF, or a filter weight versus protection factor curve should be
defined for predicting performance at higher concentrations. In a
summary of this study submitted to OSHA (Ex. 1-146) the authors stated
that:

* * * the mass outside the respirator was very low. For this
reason, the ability of the respirator to provide protection was not
challenged. Therefore, this study should not be used for direct
comparison to others in assigning protection factors as they are
artificially low.

The authors also discussed sampling and analytical considerations
for WPF studies, such as calibration reliability, sample cassette
integrity, analytical sensitivity, and sample handling procedures.
2. WPF Study--Full Facepiece APR
Study 2A. C.E. Colton, A.R. Johnston, H.E. Mullins and C.R. Rhoe of
the 3M Occupational Health and Environmental Safety Division in
May,1989 gave a presentation at the AIHCE on their WPF study (Ex.1-64-
14) performed with full facepiece air-purifying respirators worn in a
secondary lead smelter. Air sampling for lead was conducted over 5 days
in four areas of the plant; the blast furnace, reverberatory furnace,
casting, and warehouse areas.
The respirator evaluated was the 3M 7800 Easi-Air full facepiece
respirator used with 3M 7255 high efficiency filters. The respirator
was equipped with a nosecup inside the facepiece. The sampling probe
was inserted into the respirator in place of the speaking diaphragm to
assure a gas tight seal and consistent probe location close to the
breathing zone of the wearer. The respirators were equipped with
sampling probes using a design by Dr. Ben Liu to minimize particle
entry losses. Both the inside and outside sampling trains used the Liu
designed probe for consistency.
Thirteen workers who normally wore full facepiece respirators in
the plant qualified to participate in the study. They were trained in
proper respirator use, the procedures to be followed for the study, and
how to don and fit the 3M respirator. Quantitative fit testing was
performed using the Portacount QNFT instrument and fit test operators
followed the OSHA Lead standard exercise protocol for fit testing. The
workers were fit tested wearing their normally required personal
protective equipment (PPE), and care was taken to assure that this
additional PPE did not interfere with facepiece fit. The criterion the
authors used for passing the QNFT was a minimum fit factor of 500; 10
times the assigned protection factor of 50 given in the lead standard
for a full facepiece negative pressure respirator. The 13 qualified
workers were measured for face length and width, and

[[Page 34059]]

all the workers except 1 were in Grids 1-4 of the Los Alamos Test
Panel. The one remaining worker's his face was wider than those
accommodated by the Los Alamos Test Panel.
Samples were analyzed by proton induced x-ray emission analysis
(PIXEA) for lead. The authors reported that for PIXEA the sensitivity
is good, typically 10 nanograms per sample. Area samples for particle
size analysis were also collected, using Marple cascade impactors, in
the reverberatory furnace, casting, and warehouse areas. Three particle
size ranges were found; less than 1 [mu]m (15% of the total aerosol),
between 1 to 10 [mu]m (20% of the total aerosol), and greater that 10
[mu]m (65% of the total aerosol). The particle size distribution showed
that both lead dust and lead fume were present.
The authors had pre-established that if the outside filter weights
were less than 51 times the field blank value, the sample set would be
rejected. The authors stated, ``You need at least this much
differential between inside and outside samples if you want to prove or
disprove that a respirator provides a PF of 50.'' None of the workplace
samples were rejected for being less than 51x the field blank value.
However, several sample sets were rejected for other reasons such as
the inside sample coming loose from the probe, sample pump failure,
etc. Field blanks were used, and were handled the same as other
samples. Detectable amounts of lead were found on the field blanks. The
mean value of the field blanks was used to correct the sample values by
subtracting the mean field blank value from the inside and outside
sample weights. WPFs were calculated by dividing the outside
concentration (C_o) by its corresponding inside concentration
(C_i), and checked for outliers. The authors reported that
for the 20 samples collected the geometric mean WPF was 3929 and the
GSD was 9.6, and the 5th percentile WPF estimate was 95. The outside
concentrations ranged from 150 to 8380 [mu]g/m\3\, and the inside
concentrations ranged from 0.03 [mu]g/m\3\ to 3.0 [mu]g/m\3\. Sampling
periods ranged from 30 minutes to 3 hours. The workers were under
constant observation to ensure proper respirator use and wear and to
ensure sample validity.
The authors looked at subsets of the data using multiples of the
field blank mean values ranging from 1,000 times the field blank to
25,000 times the field blank value. The authors found a strong
correlation between filter weight and workplace protection factor when
they looked at the log of the mean filter weight and the log of the
mean WPF. The authors stated that the data appeared to be close to the
plateau region. The authors also stated that the quantitative fit
factors measured during worker fit testing did not correlate with the
WPFs measured in this study.
The authors concluded that `` * * * the results of this study
indicate that this full facepiece respirator with high efficiency
filters reliably provides workplace protection factors in excess of 50
against lead dust and fume aerosol.'' The authors stated that they
would expect 95% of the workplace protection factors to be above 95.
They also stated that ``The ANSI Z88.2 proposed Standard for Practices
for Respiratory Protection has assigned a protection factor of 100 to
this type respirator. These data support that recommendation.''
3. WPF Studies--Powered Air-Purifying and Supplied-Air Respirators
Half-Mask PAPRs
Study 21. In 1983, W.R. Meyers and M.J. Peach of NIOSH reported
half and full facepiece PAPR performance measurements for four workers
during bagging of micro-crystalline silica (Si) in a silica processing
plant (Ex. 1-64-46). The study examined several aspects of the
respirator's performance. Prior to the workplace evaluation, dioctyl
phthalate (DOP) was used to determine filter efficiency. A 4-hour Si
dust chamber study was performed by mounting the PAPR on an
anthropomorphic head, simulating worker breathing, and gathering
inside- and outside-the-facepiece silica samples. Workers were provided
with an unspecified brand of PAPR, with either a tight-fitting half-
mask or full facepiece, and equipped with high-efficiency filters. Both
styles of facepiece were made of natural rubber and had two exhalation
valves. The sealing edge of the facepiece was either an internal roll
(half-mask) or a flat edge with an inner flap (full facepiece). The
filters were located downstream of the respirator's blower unit.
The PAPRs used in the study were identical to those already being
used by the employees; the authors did not mention training the
participants in proper use of the respirator. Respirators were placed
on and removed from the participants by the investigators, as needed
(e.g., start of shift, lunch break, personal breaks, end of shift).
Donning and doffing the respirator, and sampling train starting and
stopping, occurred in a clean area. Samplers were started after the
PAPR was donned and turned on, and were stopped before the PAPR was
turned off for doffing. Facepiece interiors were examined for dust
contamination after each removal (gross contamination was not
observed), and the facepieces were cleaned by the investigators after
each shift. In addition, each PAPR's volumetric air output (with the
facepiece removed) was measured with a dry gas meter. Filters and
batteries were changed according to the manufacturer's instructions.
While no mention is made of fit testing the participants, the
investigators instructed them not to manipulate, lift, or remove the
facepiece during sampling. Participants were observed 100% of the time
during donning and doffing, and about 80% of the time at their
workstations. The authors used field blanks to assess contamination
caused by handling.
The sampling train for the inside-the-facepiece samples consisted
of a 37 mm two-piece cassette containing a 5 micron pore size FWS-B
polyvinyl chloride filter. The cassette was attached directly to a
modified Luer adaptor sampling probe, inserted into the facepiece
between the nose and upper lip of the employee. The flow rate of the
pump was 1.5 Lpm. The outside-the-facepiece samples were collected with
a 37 mm two-piece cassette and a 5 micron pore size FWS-B polyvinyl
chloride filter. The sampling airflow rate was 1.5 Lpm, and the
cassette was attached to the subject's lapel. Outside samples were
collected as total dust since previous sampling revealed 70% or more of
the dust particles to be 10 microns or less in size (i.e., respirable).
Sample times ranged from 84 to 320 minutes, with cassettes being
changed during the employees' lunch break. Overall PAPR performance
(leakage) was determined by replacing the facepiece of two respirators
with an air-filtering head containing a pre-weighed 76 mm glass fiber
filter. The respirators were mounted in a free-standing stationary
position, and run for 6-7 hours (with a battery change at 4 hours). The
air output was measured, the filter weighed, and the ambient Si
concentration estimated. Area samples were collected to determine
particle size. An Anderson impactor was placed 4-8 feet from the
participants and collected samples for about 3 hours at a flow rate of
1 cfm.
Samples were analyzed for free Si according to NIOSH P&CAM 259
(i.e., gravimetric weight and x-ray powder diffraction for Si). Results
were corrected for the average blank filter weight gain, but not for
pulmonary retention (which the authors believed was negligible). Ten
individual inside- and outside-the-facepiece concentrations, with
associated WPFs, are tabulated by sample period, worker,

[[Page 34060]]

type of facepiece, and sample time. The study reported that the half-
mask PAPR did not provide the protection factor of 1,000 previously
expected; instead, the protection factors ranging from 16 to 193. The
authors also provided results for DOP filter penetration, aerodynamic
mass median particle size and GSD, x-ray powder diffraction tests, and
free-standing PAPR leakage measurements. The researchers discussed
several parameters that could have affected results, including poor
respirator use practices of the participants (which the authors
believed they controlled and maintained at a minimal level); inside-
the-facepiece sampling flow rate (which the authors believed was not a
major source of error); and inherent PAPR leakage (however, the free
standing PAPR results indicated minimal leakage). Also discussed as
reasons for the low protection factors were possible leakage of Si past
the blower housing grommet when employees bumped the PAPR during work
(the effect of this was unknown) and leakage from inadequate facepiece
fit (which the authors considered could be significant at moderate to
heavy work rates).
Study 6. S.W. Lenhart and D.L. Campbell of NIOSH reported in 1984
on a WPF study in which they measured protection against exposure to
particulate lead (Pb) for 25 primary lead smelter workers; 7 of the
employees worked in the sinter plant, and 18 worked in the blast
furnace area (Ex. 1-64-42). The predominant aerosol forms of Pb were
dust in the sinter plant and fume in the blast furnace. In both areas,
Pb comprised about 50% of the total aerosol particulate, with
composition of the remaining 50% of particulates being unknown. All
participants wore an MSA half-mask PAPR with high-efficiency filters
(the authors provided no respirator model number in the report). The
study also examined the performance of an MSA negative-pressure air-
purifying respirator, which is discussed above in the half-mask air-
purifying respirator study summaries. The participants routinely used
respirators, but the investigators do not mention respirator training
for the employees. The participants were not normally fit tested with
the half-mask PAPR facepiece; however, for this study, they had to
achieve a fit factor of at least 250 while wearing a negative pressure
air-purifying respirator with the same half facepiece as the PAPR.
Employees were instructed not to remove or manipulate the respirator
during sampling, and were observed throughout the sampling period.
The inside-the-facepiece sampler consisted of a closed-face 37 mm
cassette containing an AA filter and AP10 support pad. This cassette
was connected to a tapered Liu probe that was inserted into the
respirator between the nose and upper lip. In-mask samples were
collected at 2 Lpm. The outside-the-facepiece sampling train was a
closed-face 37 mm cassette containing an AA filter and AP 10 support
pad (with no tapered Liu probe used). The outside sample cassette was
attached to the worker's lapel. Outside samples were gathered at 2 Lpm.
Samples were collected for ``as much of the 8-hr work shift as
possible.'' Respirators and sampling trains were donned and doffed, and
started and stopped, in a lead-free area. The inside of the respirator
facepieces were wiped clean prior to donning after each break, and were
cleaned and sanitized after each shift. The PAPR batteries were
replaced after four hours of use (i.e., according to manufacturer's
instructions). Battery voltage was checked, and airflow rates were
verified to exceed 15 Lpm before use. One WPF was measured for each
participant. The ambient particle size distribution was determined by
19 Marple cascade impactor samples (11 in the sinter plant; 8 in the
blast furnace area).
Analysis of Pb was by flame atomic absorption spectroscopy
according to NIOSH Method S-341. Inside-the-facepiece samples that
contained less than 10 [mu]g of lead were reanalyzed by graphite
furnace atomic absorption (limit of detection = 0.2 [mu]g). The report
provided ranges of the mass median aerodynamic diameters (in
micrometers), as well as the GSD values. The authors provided a total
of 25 pairs of inside- and outside-the-facepiece concentrations, and
the corresponding WPFs, by employee, job title, and job location, as
well as the overall GM and GSD of the PAPR WPFs and several percentile
values. For samples containing Pb below the level of detection, the
authors determined concentration values ``* * * from the least amount
of lead detectable by the analytical method and the sampled volume of
air.'' In-mask measured values were not adjusted for particle retention
in the respiratory tract (the authors imply that retention had a non-
significant effect on the results, but could cause WPF to be
overestimated). No mention is made of using field blanks. Two
approaches to defining an assigned protection factor (APF) were also
discussed. These approaches are: Defining the APF in terms of a
specific proportion of WPFs expected to exceed the APF, and defining
the APF ``in terms of a one-sided lower tolerance limit above which we
may predict with a specific confidence level that 95% of the workplace
protection factors lie.''
The WPF for the PAPR had a GM of 380 and a GSD of 2.6, and the
individual WPFs ranged from 23 to 1,600. Approximately 98% of the WPFs
for the half-mask PAPR were above 50, 90% above 110, 75% above 200, 40%
above 500, and only 25% above 1,000. The authors concluded that an APF
of 50 was appropriate for the PAPR they tested, and that an APF of 500
was inappropriately high for the half-mask PAPR. A protection factor
not in excess of 50 was recommended for half-mask PAPRs. The authors
noted that the WPFs may be too high because the workers did not
routinely undergo a quantitative fit test screen with negative pressure
respirators before receiving their PAPR.
4. WPF Studies--Full Facepiece PAPRs
Study 21. W.R. Myers and M.J. Peach of NIOSH reported in 1983 on
the performance of an unspecified brand of PAPR equipped with a tight-
fitting elastomeric full facepiece and HEPA filters; four employees
used the respirator in a silica bagging operation (A detailed
description of the work setting, sampling methodology, and study
protocol for this study is presented in the discussion of Study 21 in
the section on half-mask PAPRs above) (Ex. 1-64-46). The full facepiece
PAPR had a sealing edge consisting of a flat edge with an inner flap.
The participants routinely used this PAPR and, therefore, the
investigators did not train them in its use. Fit testing was not
performed.
The investigators calculated WPFs for only three of the four
employees because the sample for the fourth employee had an inside-the-
facepiece concentration less than the limit of detection, making it
unsuitable for WPF determination. The samples were evaluated for
crystalline Si by x-ray diffraction. The full facepiece WPFs ranged
from 25 to 215, which are low for a PAPR. In this regard, the authors
reported that the employees routinely bumped and rubbed the belt-
mounted motor blower housing and filter assembly during the bagging
operation. They believed such action may have caused movement between
the neck of the filter and the blower housing grommet; thereby
resulting in the seal failing and allowing unfiltered air to bypass the
filter. They reported some evidence to support this conclusion, but
could not determine the contribution of this problem to the overall
leakage into the facepiece. Although the blowers were checked to ensure
each PAPR

[[Page 34061]]

delivered a minimum 115 Lpm (4 cfm) airflow to the facepiece, the
authors concluded that ``* * * migration of contaminant into the
facepiece of the PAPR system could be a significant source of leakage
when the respirator is exposed to the wide ranging conditions that
exist in the work environment.'' While the WPFs measured in this study
were well below the level expected of a PAPR, the authors stated that
these results ``* * * represent a more accurate measure of the level of
worker protection that can be expected from this type of PAPR system.''
Study 18. At the 1990 AIHCE, C.E. Colton and H.E. Mullins presented
a WPF study in which they assessed protection against exposure to lead
fume and dust for 20 employees working in the blast furnace,
reverberatory furnace, casting, and baghouse areas of a secondary lead
smelter (Ex. 1-64-12). The employees were provided with a 3M Whitecap
PAPR with a high-efficiency filter (TC-21C-456). The investigators
trained the employees in the proper donning, fitting, and operation of
the respirators. Using a TSI Portacount, the investigators conducted
fit testing while the participants performed the exercise sequence
contained in Appendix D of OSHA's Lead Standard; the required fit
factor was 500. Participants were observed continuously throughout the
sampling.
The inside-the-facepiece sampling train consisted of a 25 mm three-
piece cassette containing a 0.8 micron pore size polycarbonate filter.
The authors mounted the sampling cassette directly to an ABS Liu probe
and inserted the probe into the facepiece in place of the speaking
diaphragm. The outside-the-facepiece sampling train was a 25 mm three-
piece cassette containing a 0.8 micron pore size polycarbonate filter.
The authors did not mention attaching the outside cassette to a probe
or the location of the sampling cassette on the employee. Airflow rates
of the sampling pumps were calibrated in-line before and after each
sampling interval, but no sampling airflow rate was provided. Sampling
was conducted for as much of the 8-hour shift as possible, with
sampling intervals ranging from 1 to 4 hours. Field blanks were used,
and area samples for particle size analysis were gathered with a Marple
personal cascade impactor (Model 2401).
Sample and field blank analyses were performed using proton induced
x-ray emission (PIXE) analysis. Particle size analysis by inductively-
coupled plasma--mass spectrometry indicated particles in the dust and
fume range. While the range of inside- and outside-the-facepiece
concentrations were presented, individual inside and outside
concentrations or results by employee or job classification were not
provided. Similarly, the report presented an overall GM WPF, GSD, and
fifth percentile WPF, but not individual WPFs. Of the 55 sample
measurements, 34 of the inside-the-facepiece results were below the
analytical limit of detection. In these instances, the authors used a
conservative WPF calculation by setting the values at the limit of
detection. No lead was detectable on the field blanks so no adjustments
were made to sample weights. The authors do not mention adjusting
inside-the-facepiece values for pulmonary particle retention. Final
calculations used only those sample pairs with outside sample weights
greater than 1,000 times the detection limit. The authors believed this
procedure was necessary to determine that the respirator was capable of
providing a protection factor of 1,000. The authors also analyzed the
data for outliers (at the 99% confidence level). The overall data
analysis resulted in a GM WPF of 8,843, a GSD 3.2, and a fifth
percentile WPF of 1,335. The authors concluded that the data supported
ANSI's proposed APF of 1,000 for full facepiece PAPRs. They also
recommended that fit testing be performed on all tight-fitting
respirators.
5. WPF Study--Helmet/Hood PAPRs
Study 27. At the 1990 AIHCE, D.R. Keys, H.P. Guy, and M. Axon
reported on a 3-month WPF study in which they evaluated exposure to
estradiol benzoate (a steroid) for an unspecified number of workers in
a pharmaceutical facility (Ex. 64-40). They included three loose-
fitting hood/helmet type PAPRs in the study: Racal Breathe Easy 10,
Bullard Quantum, and 3M Whitecap II. All three PAPRs had double-bibbed
capes, were equipped with HEPA filters, and did not have lift-up
visors. A Tyvek hood was part of the Racal and Bullard PAPRs while the
3M had a hard helmet. PAPRs were previously used at the facility, so
workers were already properly trained in their use and were familiar
with wearing them. The investigators observed the participants
continuously, one-on-one, during sampling. While the authors used field
blanks, they did not mention determining particle size or using a clean
area for donning and doffing or for starting and stopping the sampling
train.
The inside- and outside-the-facepiece sampling trains consisted of
a 37 mm two-piece cassette with a glass fiber filter, attached to a
nylon Liu probe. Location of the inside-the-facepiece probe was not
specified. Samples were gathered for \1/2\-3 hours at a flow rate of
2.5-3.5 Lpm. Pumps were calibrated in-line before and after each
sampling period.
The authors used radioimmunoassay (RIA), a very sensitive
analytical technique, to analyze inside-the-facepiece samples, and HPLC
to analyze outside samples; they rejected inside samples with weights
below the limit of quantification. Also, the investigators rinsed the
outside sample probes with methanol and analyzed the rinsate by HPLC to
determine sample loss due to probe use. The authors did not provide any
further analytical information.
Sixty valid sample sets were obtained from the study. Results were
not adjusted for blank value (i.e., all blank values were below 1
nanogram per filter) or probe loss (i.e., the GM of 1% was not
statistically significant). Individual inside and outside
concentrations or WPFs were not reported. Instead, the authors
presented the range of inside- and outside-the-facepiece
concentrations. They determined an overall fifth percentile WPF for
each respirator, along with the number of samples, the minimum and
maximum WPF achieved, a GM WPF, and the GSD. In addition, the authors
determined the percentage of WPFs that fell in selected ranges (e.g.,
<1,000, 1,000-10,000) for each PAPR, and they briefly discussed the
correlation between WPF and outside concentration (i.e., they found WPF
to be independent of outside filter loading in this study). The Racal
Breathe Easy 10, with 29 sample pairs, had a GM WPF of 11,137, a GSD of
3.9, and a fifth percentile WPF of 1,197. The Bullard Quantum, with 9
sample pairs, had a GM WPF of 9,574, a GSD of 3.1, and a fifth
percentile WPF of 1,470. The 3M Whitecap II helmet, with 22 sample
pairs, had a GM WPF of 42,260, a GSD of 9.8, and a fifth percentile WPF
of 997. The authors stated that they obtained WPFs above 10,000 for the
three PAPRs at least 44% of the time, and that the three respirators
provided WPFs above 1,000 throughout the study. The authors concluded
that the results of their study agreed with the then-proposed ANSI
Z88.2-1992 APF of 1,000 for PAPRs with hoods or helmets.
6. WPF Studies--Loose-Fitting Helmet/Hood PAPRs & Loose-Fitting
Facepiece PAPRs
Study 23. W.R. Meyers, M.J. Peach, K. Cutright, and W. Iskander
reported in 1984 on a study in which they examined lead (Pb) exposure
of 12 workers in a secondary lead smelter (Ex. 1-64-47). The job
classifications studied were furnace operator, helper,

[[Page 34062]]

and pig caster. They selected two employees from each classification on
two shifts. The PAPRs used in the study were the 3M W-344 and the Racal
AH3; each employee wore both respirators twice. Pre-shift quantitative
fit testing was performed each day. The investigators trained the
participants, but did not describe the training; they monitored the
employees continuously during sampling.
The authors referred to a companion paper for a description of the
sampling protocol used in this study; therefore, they provided no
information is provided on sampling or analytical methodologies in this
report. Eight impactor samples were collected at each work activity to
determine particle size distribution. Samples were collected for the
full shift, but the investigators did not provide specific sampling
times. The authors also provided the range of inside-the-facepiece
concentrations, with associated GM and GSD, for both brands of
respirator; they measured these concentrations with the PAPRs placed on
manikins which were located at the worksites where employees in the
three job classifications worked.
For each respirator, the study provided 24 individual inside- and
outside-the-facepiece (front and rear) concentrations, along with
associated WPFs and each employee's fit factor. It also provided the
overall GM, GSD, and 95% confidence level on the mean for the inside-
the-facepiece concentrations, WPFs, and fit factors. The authors
tabulated the data by day, shift and work activity. For both
respirators, two samples were discarded due to sampling pump failure,
giving 22 usable measurements for each respirator. The WPFs measured on
the Racal AH3 ranged from 42 to 2,323, with a GM of 205 and a GSD of
2.83. The 3M W-344 had WPFs that ranged from 28 to 5,500, with a GM of
165 and a GSD of 3.57. The two-sided 95% confidence limits around the
mean of the WPFs were 128 and 325 for the Racal AH3, and 94 and 292 for
the 3M W-344. The authors provided a detailed discussion of their
statistical analyses of the data; they also discussed several potential
sources of variation in the workplace performance of PAPRs, including:
a possible relationship between fit factor and WPF; a possible
relationship between fit factor and inside-the-facepiece concentration;
day of the week; shift; leakage into the facepiece due to ambient air
currents; and worker activity. The only sources found to be potentially
significant were leakage into the facepiece due to ambient air currents
and worker activity. The authors stated that ``* * * using the pooled
3M and Racal WPF data and a probability of 0.95 the assigned protection
factor calculated by this method for these PAPRs would be 26.'' They
recommended a reduction in the RDL's APF of 1,000 for loose-fitting
PAPRs with helmets and HEPA filters.
Study 5. W.H. Albrecht, G.R. Carter, D.W. Gosselink, H.E. Mullins,
and D.P. Wilmes reported at the 1986 AIHCE on a study they conducted
that evaluated protection against exposure to asbestos fibers for 12
workers who manufactured asbestos-containing brake shoes for trucks
(Ex. 1-64-23). The employees performed six operations at the facility:
mixing brake shoe components, weighing mixed formulation, pre-forming
molding press charges, molding the shoe, grinding the brake shoe
surface, and drilling shoe mounting holes. The investigators sampled at
each operation. The PAPR studied was the 3M Airhat with high-efficiency
(HEPA) filters. The participants and supervisory staff were shown an
audio slide presentation explaining how to fit respirators and the
procedures for saccharin fit testing; they then received the saccharin
qualitative fit test (since the authors do not specifically mention fit
testing the PAPR, it is assumed that only the half-mask respirators
studied were fit tested). Fit testing was not conducted prior to each
study test. The PAPR was fitted and worn according to the
manufacturer's instructions. Each employee was observed on a one-on-one
basis during testing to assure that they properly donned and used the
respirator and that sampling train integrity was maintained.
The inside-the-facepiece sampling train was a closed-face filter
cassette connected to a tapered Liu probe, inserted into the respirator
between the nose and mouth. The outside-the-facepiece sampling train
was a closed-face filter cassette connected to a Liu probe attached in
the employee's lapel area; the authors do not mention cassette size.
Samples were collected for 30 minutes, but other sampling times were
occasionally used; sampling pump flow rates were 2 Lpm (inside-the-
facepiece) and 0.5 Lpm (outside-the-facepiece). The report does not
mention modifying the inside-the-facepiece probe location (midway
between the nose and mouth) or the sampling flow rate for the PAPR
versus that used for the half-mask respirators studied.
Sampling trains were calibrated before the shift, at lunch, and at
the end of the shift; average airflow rate was used to calculate
sampled air volume. The investigators did not mention determining the
PAPR's airflow rate.
Asbestos analysis was based on NIOSH method 7400, with 500 fields
counted per inside sample filter and 100 fields counted per outside
sample filter. The distributions of fiber length and fiber diameter
were not characterized. The authors stated that blanks were submitted
for fiber counting; however, no further mention is made of the blank
results or how they were addressed. None of the PAPR samples were
comparison counted by Phase Contrast Microscopy (PCM) and Scanning
Electron Microscopy (SCM). A total of seven PAPR WPFs were reported (5
employees). Individual pairs of inside and outside concentration values
were not provided. Individual WPFs were reported for each of the seven
sampling intervals, but were not linked to specific participants or
jobs. The authors provided an overall GM, GSD, and fifth percentile for
the Airhat PAPR; a range of asbestos concentrations and the associated
GM and GSD were also reported by job. An inside-the-facepiece fiber
count of 1,000 was used in calculating the WPF when the sampling result
was at or below the limit of detection (i.e., 1,000 fibers per filter).
The investigators did not mention adjusting inside-the-facepiece values
for fiber retention in the respiratory tract. In addition, the authors
determined that sampling results were not affected, at the 95%
confidence level, by sampling flow rate or open-versus closed-face
sampling cassette. The mean breathing zone concentration of asbestos
for the Airhat PAPR was 4.14 fibers/cc, with a mean breathing zone
concentration range of 1.23 to 8.05 fibers/cc. The authors reported a
GM WPF for the PAPR of 199, with a GSD of 2.36 and a fifth percentile
of 42. Five employees tested the PAPR, resulting in a total of nine
sample sets, including two unusable sets of data. The authors noted
that respirators that had the highest GM and fifth percentile WPFs
(i.e., the 3M Airhat and 3M 9920 DFM respirators) were also tested at
higher breathing zone fiber concentrations. They believed that this
factor probably led to these respirators' increased performance
measurements.
Study 22. In 1986, W.R. Meyers, M.J. Peach, K. Cutright, and W.
Iskander reported on a study in which they evaluated exposure to lead
(Pb) dust and mist for 12 workers on two lead acid plate production
lines of a battery manufacturer (Ex. 1-64-48). They sampled the pasting
operator and two slitter operators on each line for two different
shifts. The respirators studied were the Racal Airstream AH5 and the 3M
W-3316, equipped with a helmet, visor enclosure, and dust/mist filters.
Participants were clean-shaven, and

[[Page 34063]]

each employee wore both types of respirator twice. The AH5 provided a
seal between the employee's face and the face shield by using two
flexible face seals; air was exhausted at the chin. The size of the
faceseal (i.e., large or small) was selected based on the appearance of
best fit and wearer comfort. The 3M's soft flexible face seal gave a
loose-fitting seal between the face and face shield, with air exhausted
at the temples. Prior to field testing, randomly-selected filters
underwent silica dust penetration testing. The investigators put on and
removed the respirators from the employees in a clean area, except when
the employees took personal breaks (in which case, the employees donned
and doffed the respirator in the work area). Employees were not fit
tested, but were instructed in the proper use of the PAPR and directed
not to remove the helmet, lift the face shield, or tamper with the
sampling equipment without notifying the investigators. The
investigators continuously monitored donning and doffing and work
activities. Respirator helmets and visors were cleaned between each
use, and volumetric air output was periodically checked (usually at the
beginning of the shift, lunch, and shift's end). The authors replaced
the batteries according to manufacturer's instructions, and when low
airflow occurred. They also installed new filters at the beginning of
each shift. The investigators started the sampling pumps after the
employees donned the respirators and the PAPR blower was functioning;
they stopped the pumps before turning off the PAPR blower.
Sampling trains were identical and consisted of a closed-face 37 mm
two-piece cassette, containing a 0.45 micron pore size cellulose ester
filter and back-up pad. Inside-the-facepiece sample cassettes were
attached directly to a modified Luer adapter sampling probe, inserted
through the face shield about one to two inches in front of the
employee's mouth. Outside-the-facepiece sample cassettes were located
at the front lower right side of the facepiece, away from the PAPR's
exhaust airflow; they located a second cassette located the employee
near the PAPR's filter, to determine the filter's contaminant
challenge. All samples were collected as total dust at a flow rate of
approximately 2 Lpm over the full shift (The report did not provide
actual sample times). Sampling pumps were calibrated in the laboratory,
and the flow rates confirmed at the worksite. Performance of the PAPR
filtration system was checked by placing operating respirators on
manikins (without simulated breathing), located about 4 feet from the
subjects. Two filter blanks were used for each shift. Particle size
distribution was determined through using a Marple cascade impactor
operating at a flow rate of 3 Lpm.
Inside-the-facepiece samples were analyzed by graphite furnace
using a modified NIOSH P&CAM 214 method, with perchloric acid in the
wet ashing step. Outside-the-facepiece samples were analyzed by atomic
absorption spectroscopy (NIOSH Method S-341 with the perchloric acid
wet ashing step modification). Forty-seven individual inside- and
outside-the-facepiece (i.e., front and rear) time-weighted-average
(TWA) measurements, with associated TWA WPFs, were provided (AH5 = 24;
W-316 = 23). These results were tabulated by day, shift, and work
activity. Overall GM and GSD were also given for the concentration
measurements and WPFs. All blanks were below the analytical limit of
detection; the authors did not mention adjustments for pulmonary
retention. Particle size (large) and stationary manikin filter
efficiency (98%-99.9%) were briefly discussed. The WPFs for the Racal
AH 5 ranged from 23 to 1,063, with a GM of 120 and a GSD of 2.64. The
WPFs for the 3M W-316 ranged from 31 to 392, with a GM of 135 and a GSD
of 1.89. Since the authors found no statistical difference between the
performance of the respirators, they pooled the data for both
respirators; they then graphically plotted the percent of WPFs less
than specific values. The pooled data for the two PAPRs resulted in a
distribution with a GM of 127 and a GSD of 2.28. The authors stated
that, at a 0.95 probability level, this class of PAPRs would receive an
assigned protection factor of 25. The authors also stated that the
results ``* * * strongly suggest that the respirator user community not
view current generation powered air-purifying respirators equipped with
helmets as positive pressure respiratory devices.''
Study 3. A. Gaboury and D.H. Burd (Ex. 1-64-24) and A. Gaboury,
D.H. Burd, and R.S. Friar (Ex. 1-64-348) reported in 1993 on the WPF
study they performed in a primary aluminum smelter. Exposure to
benzo(a)pyrene [B(a)P]
on particles was measured for 22 employees who
worked as rack raisers, stud pullers, and rod raisers on anode crews.
The employees used a Racal Breathe-Easy 1 (BE1/AP3), a loose-fitting
helmeted PAPR. The PAPR came equipped with one-piece non-woven flame-
retardant face seals, visor locking clips, and combination organic
vapor and HEPA filters. (The authors also tested the performance of
several negative-pressure, air-purifying half-mask respirators; see
Study 7 above). The employees previously received training on this
PAPR, and used it for more than six months prior to the study. Forty
percent of the employees had beards (i.e., more than two weeks growth),
but the investigators did not find a significant difference between
bearded and non-bearded participants. No fit testing was performed on
the employees, but previous quantitative fit testing showed fit factors
``greater than 1000 in all cases.'' Industrial hygiene technologists
assisted participants with donning and doffing respirators, cleaned and
maintained the respirators at the end of each work cycle, and observed
participants on a one-to-one basis throughout the sampling period. The
investigators directed the employees not to tamper with the respirator
or sampling equipment. Due to high heat levels in the work area, the
employer required employees to rest in a cool environment for one-half
hour during each work hour.
The inside-the-facepiece sampling train consisted of a closed-face
three-piece cassette with a 25 mm organic-binder-free glass fiber
filter, backed with a cellulose ester pad. Inside sampling cassettes
were connected to a tapered Liu probe, which was inserted through the
PAPR's visor and into the employee's breathing zone. The outside-the-
facepiece sampling train was identical to the above; however, the
investigators did not mention connecting the cassette to a Liu probe.
The outside cassette was mounted on a bracket at the top of the visor.
All filters were pre-calcined at 400 degrees Centigrade for 24 hours.
Both inside and outside samples were collected at a flow rate of 2 Lpm
for approximately 300 minutes, or one-half of the 10-hour work shift.
Respirators and sampling trains were worn and operated until the
employee entered the rest area; they donned and turned on the
respirators prior to leaving the rest area for the next work cycle. The
authors plugged the sampling cassettes when not in use, and cleaned the
respirators after each work cycle. Field blanks were used to identify
contamination due to handling. Sampling train airflow rates were
checked at the beginning, middle (i.e., after lunch), and end of the
work day; upon changing cassettes; and when a problem was suspected.
PAPR turbo-unit flow rate was checked every two hours to assure flow
was greater than six cubic feet per minute (cfm). Sampling occurred
over a five-day period.

[[Page 34064]]

B(a)P analysis followed Alcan Method #1223-84. The ambient
B(a)P particle size distribution was determined by collecting four
samples, as close as possible to the workers, using an 8-stage Anderson
cascade impactor (Model 296). Impactor samples were collected for two
to five hours at a flow rate of 2 Lpm. The average percent of B(a)P
mass (across four samples) per impactor stage (defined by an
aerodynamic diameter cut point, in micrometers) was reported. About 93%
of the B(a)P mass was associated with particles having diameters of
<=9.8 micrometers. A total of 20 pairs of inside and outside sample
concentrations, with associated WPFs, were provided by job category
(but not for individual employees), and whether the employee had a
beard. An overall GM, GSD, and 95% confidence interval on the mean were
also provided for the inside and outside concentrations and WPFs, along
with an overall fifth percentile WPF. The authors stated that some
employees participated more than once during the study. They did not
mention adjusting inside-the-facepiece values for particle retention in
the respiratory tract. The authors found no significant relationship
between B(a)P concentrations inside and outside of the facepiece, but
they did find a correlation between WPF and outside B(a)P
concentrations. The authors stated that, while the data were limited,
they recommended testing PAPRs at relatively high concentrations to
obtain an accurate measure of their performance. The inside B(a)P
concentration ranged from 0.006 to 0.072 [mu]g/m3, with a GM
of 0.012 [mu]g/m3. The outside B(a)P concentration ranged
from 246 to 111.48 [mu]g/m3 with a GM of 16.73 [mu]g/
m3. WPFs ranged from 371 to 8658, with a GM of 1,414. The
two-sided 95% confidence interval limits around the overall GM WPF were
918 and 2,173; the fifth percentile was 275. The authors cautioned that
these results WPFs achieved under conditions of good worker compliance
and tight administrative control; however, without these conditions,
WPFs may be less because: close surveillance of workers is not usually
performed; cleaning during rest periods is not done prior to returning
to the workplace; visor locking clips are not routinely used; and no
respirator is used 100% of the time while in the workplace.
Study 26. At the 2001 AIHCE, D.V. Collia, et al. presented a study
on the workplace performance of a PAPR against exposure to cadmium (Cd)
for seven workers, over three days, in a nickel-cadmium battery
manufacturing facility (Ex. 3-5). The respirator studied was the 3M
Breathe-Easy 12 (BE-12), a loose-fitting facepiece PAPR equipped with
high-efficiency filters; the employees were using this PAPR prior to
the study. During a preliminary visit, the investigators discussed the
study with the union, management and workers. The authors also
evaluated the worksite and took area samples to identify areas with the
highest exposures. Prior to sampling, they informed the employees about
their role in the study, as well as the study's purpose and procedures.
The investigators continuously observed the employees during sampling,
and used field blanks to identify contamination from handling. The
study contained no additional information on sampling protocols (e.g.,
donning and doffing procedures).
Inside-the-facepiece samples were gathered using 25 mm three-piece
cassettes containing an unspecified membrane filter and a porous
plastic back-up pad. A nylon Liu probe was used, and the samplers were
positioned directly across from the midline between the employee's nose
and mouth. Outside-the-facepiece samples used 25 mm three-piece
cassettes containing an unspecified membrane filter, backed with a
cellulose pad. Outside samples were positioned close to the employee's
breathing zone (the investigators provided no further details). All
samples were collected at 2 Lpm for approximately one and one-half
hours (range: 67-156 minutes).
Inside-the-facepiece samples and blanks were analyzed by flame
atomic absorption spectroscopy and heated graphite furnace atomizer
(AAS-HGA). Analysis of outside-the-facepiece samples was by AAS. The
analytical methodology used OSHA's method for Cd in workplace
atmospheres (OSHA ID-189). The authors provided the mean mass for
inside and outside blanks, but made no mention of data adjustments for
blanks or pulmonary retention. They also reported minimum and maximum
concentrations of inside- and outside-the-facepiece samples for each
employee. Supplemental data contained 41 individual measurements of
inside and outside concentrations, tabulated by employee, job area,
sample period and set, sample time, pump flow rate, and sampled air
volume.
WPFs were calculated for 33 of the sample sets (8 of the 41 inside-
the-facepiece samples had no detectable Cd). The calculated GM WPFs
ranged from 1,460 to 9,440. The fifth percentile WPF was calculated in
three different ways: the traditional approach yielded a fifth
percentile WPF of 315; an analysis of variance (ANOVA) model, yielded a
fifth percentile of 280; and the Monte Carlo simulation model approach
resulted in a fifth percentile of 220 when the non-detected inside
values had a value of 0.002, a fifth percentile of 303 with the non-
detected values excluded, and a fifth percentile of 103 with Employee C
excluded. The authors concluded that the BE-12 PAPR provided a level of
protection consistent with an APF of 25.
Study 24. D.W. Stokes, A.R. Johnston, and H.E. Mullins determined
exposure to silica (Si) dust for five workers in a roofing granule
production plant (Ex. 1-64-66). The participants were involved in
cleanup of silica dust byproduct by sweeping, brushing walls, and
shoveling. The respirator studied was the 3M Airhat, a loose-fitting
PAPR with helmet, equipped with dust/mist or high-efficiency filters,
and worn with and without a Tyvek shroud. The investigators assisted
the participants were assisted with donning the sampling equipment;
however, they did not mention training the employees. They observed the
employees during sampling, and used field blanks to determine the
effects of handling on sample contamination. They did not mention
determining the particle size of the contaminant.
Inside-the-facepiece samples were collected through a Liu probe
inserted into the faceshield (they did not provide the probe's specific
location). A 25 mm cassette containing a 0.8 micron pore size
polycarbonate filter was used, and sampling airflow rate was 1.5 Lpm.
Outside-the-facepiece samples were gathered as both total and
respirable dust. Respirable dust samples were collected at 1.8 Lpm
using a 37 mm 0.8 micron pore size polycarbonate filter placed in a
cyclone that attached to the employee's lapel. Total dust samples also
used a 37 mm 0.8 micron pore size polycarbonate filter. Sampling
airflow rate was 2 Lpm, with the sampling cassette attached to the
employee's lapel. The investigators calibrated the sampling pumps each
day, and checked proper airflow rate three times throughout the day.
They collected samples over a four-day period, with sampling times
ranging from 30 minutes to 1 hour. At the beginning and end of each
sample, the authors confirmed that each PAPR's airflow rate was in
excess of 6 cfm.
The authors used proton induced x-ray emission (PIXE) to analyze
the samples. They adjusted the inside- and outside-the-facepiece
concentrations by subtracting the mean blank value, but did not mention
adjustments for pulmonary retention of particles. They also did not
provide individual inside-

[[Page 34065]]

and outside-the-facepiece concentrations and WPFs. They presented
results in two tables showing respirable dust samples with values 25
times the mean blank level, and total dust samples with values 100
times the mean blank level. The investigators provided tables reporting
sample size and overall GM, GSD, and fifth percentile WPF by type of
filter (i.e., dust/mist, HEPA) and the presence or absence of a shroud
(i.e., dust/mist with shroud, dust/mist without shroud). Using the
respirable dust samples that were 25 times the mean blank value, the
authors combined the sampling results of the PAPR with dust/mist
filters (i.e., with and without a shroud) and found an overall GM WPF
of 2,480 and a fifth percentile of 95. The combined respirable dust
results of the HEPA-filtered PAPR gave an overall GM WPF of 5,730 and a
fifth percentile of 762.

Atmosphere-Supplying (Supplied-Air) Respirators

Atmosphere-supplying respirators, also referred to as supplied-air
respirators (SARs) or airline respirators, operate in one of three
modes: Demand, continuous flow, and pressure demand. Demand and
pressure demand respirators can be equipped with half or full
facepieces. Continuous flow respirators can also be equipped with a
helmet, hood, or loose-fitting facepiece.
7. WPF Studies--Loose-Fitting Atmosphere-Supplying Respirators With
Hood or Helmet
Study 28. A.R. Johnston, et al. in 1987 conducted a WPF study
evaluating exposure to silica (Si) among four shipyard workers who wore
a 3M Whitecap II loose-fitting, continuous flow SAR with hood/helmet
while sandblasting paint from the flat top of a barge (Ex. 1-64-36).
The respirator was comprised of a W-8100 abrasive blasting helmet, a W-
5114 breathing tube, a W-2862 air / temperature control valve, 50 feet
of W-9435 air hose, and a W-8054 extended length shroud. To permit
evaluation of the respirator at its low and high range of airflow
rates, air pressure was maintained at 60 or 80 psi, resulting in an in-
helmet airflow rate of either 6.4 or 14.4 cfm. The investigators
informed the employees of the purpose and protocols of the study, and
instructed them in the proper donning and use of the respirator. They
also directed the employees not to adjust or remove the respirator
after sampling began. Sampling trains were connected and disconnected
in a clean area when possible. Sampling pumps were started after
confirming proper operation and donning of the respirator, as well as
airflow rate into the helmet. Pumps were stopped before the helmet was
disconnected from the air supply and removed. The authors maintained
continuous one-on-one observation of the employees during sampling, and
used several field blanks during each day of sampling.
The authors collected inside-the facepiece samples on 25 mm
cassettes containing 0.8 micron pore size polycarbonate membrane
filters. They attached the cassettes directly to a Liu probe inserted
through the center of the faceshield, about midway between the nose and
mouth; the probe extended about 3 mm into the helmet. The flowrate for
the inside samples was approximately 2 Lpm. The authors collected
outside-the-facepiece samples as both total and respirable dust, using
a 37 mm cassette with a 0.8 micron pore size polycarbonate membrane
filter. They used a Bendix or SKC cyclone, operating at 1.7 Lpm airflow
rate, to gather the respirable dust samples and obtained total dust
samples at flow rates ranging between 0.5 and 2 Lpm. Both outside-the-
facepiece sample cassettes were located on the employee's lapel. The
investigators calibrated the sampling pumps at least three times a day,
and sampling periods ranged from 10 to 60 minutes to prevent filter
overloading.
The authors analyzed all samples using PIXE. They found Si on all
18 blanks. Of 68 initial sample sets, they discarded 16 (11 due to test
malfunctions and 5 due to outside loadings less than 10 times the mean
blank level and inside loadings at or below the blank level). They
corrected the remaining 52 sample sets for blank value, and then
tabulated by inside and outside filter weights, inside and outside
sample volume, and associated WPFs. Since nearly all of the dust was of
respirable size, the authors did not report results for the total dust
samples. Comparing the sampling results with the mean blank levels, the
investigators stated that the analytical confidence limits of the data
were poor, with only 11 samples being better than plus or minus 25%.
The authors considered samples with inside concentrations greater than
1,000 times the mean field blank to be an accurate indicator of the
respirator's performance capability; seventeen sample sets met this
criteria, but they removed two samples WPF calculation database as
outliers. For the remaining 15 samples, the GM WPF was 4,076, the GSD
was 2.3, and the fifth percentile WPF was 1,038.
The authors concluded that WPFs generated from sample sets with
light outside dust loadings significantly underestimated respirator
performance; higher outside sample loadings appeared to be less
influenced by non-respirator variables. The investigators judged WPF
estimates derived from data subsets with higher outside filter loadings
as providing a better indication of respirator performance capability.
The authors also discussed an apparent correlation between WPFs and
outside filter loadings (i.e., a higher loading equaled higher a WPF
until reaching a plateau about 600 times the mean blank value);
however, the correlation between WPFs and outside concentrations was
not statistically significant. In addition, the effect of higher versus
lower helmet airflow rate on sample results and WPFs was not
significant. They also discussed the daily and overall WPFs achieved
when using time-weighted-averages for the calculations. They concluded
that their data supported the ANSI Z88.2 proposed APF of 1,000 for
loose-fitting SARs with hoods or helmets.
Study 20. At the 1989 AIHCE, A.R. Johnston, C.E. Colton, D.W.
Stokes, H.E. Mullins, and C.R. Rhoe presented a WPF study on a 3M W-
8000 Whitecap II SAR with a helmet, and equipped with a breathing tube
(W-5114), a compressed air hose (W-9435), and either a vortex cooling
assembly (W-2862) or air regulating valve (W-2907) (Ex. 1-64-37). They
evaluated exposure to iron (Fe) dust and silicon (Si) dust for six
workers involved in grinding iron parts at a foundry. Air supply
pressure was 60 psi with the vortex cooler or 25 psi with the
regulating valve, thereby maintaining a helmet airflow rate of 6.7 cfm
throughout the test. They did not mention employee selection
procedures, previous use of respiratory protection, provision of
training, or respirator donning and doffing procedures. They verified
air supply pressure; valve settings; and integrity of the respirator,
connections, and sampling train before starting the sampling pumps.
They stopped the samplers before disconnecting the respirator from the
air supply; they then took the participants to a clean area to remove
the sampling cassette. The investigators observed the employees on a
one-on-one basis during sampling, and used field blanks to evaluate
possible contamination due to sample handling.
The inside-the-facepiece sampling train consisted of a 25 mm
cassette containing a 0.8 micron pore size polycarbonate filter. The
authors attached the cassette to a Liu probe installed into the
faceshield approximately midway between the nose and mouth; it extended
a few millimeters into the helmet. They

[[Page 34066]]

collected inside-the-facepiece samples at an airflow rate of 2 Lpm. The
outside-the-facepiece sampling train also used 25 mm cassettes
containing 0.8 micron pore size polycarbonate filters. The
investigators collected outside samples as respirable dust using a MSA
or Bendix cyclone operating at an airflow rate of 1.7 Lpm; however,
they did not mention the location of the outside sample cassette. They
collected area samples for particle size analysis using cellulose
acetate filters and a personal sampling pump operating at 2 Lpm. They
calibrated the sampling pumps at least three times a day, but did not
mention specific calibration times.
The authors analyzed the samples for Fe and Si using proton induced
x-ray emission (PIXE) analysis. Having detected Fe and Si on the field
blanks, they used the mean blank value to correct inside- and outside-
the-facepiece sample weights. They used optical microscopy to determine
mean particle size range from 6 area samples. The investigators
presented no data for individual inside- and outside-the-facepiece
concentrations, and associated WPFs; however, they did provide the
range of outside sampling measurements, and the overall average outside
concentration, for both analytes. While they presented the range of
inside-the-facepiece concentrations, they did not report the average
inside concentrations. Outside samples averaged 1,500 [mu]g/
m3 for iron dust, and ranged from less than 100 to 2,800
[mu]g/m3. Outside samples for silicon averaged about 1,000
[mu]g/m3, with a range from less than 100 to 1,500 [mu]g/
m3. Inside concentrations were at or near the detection
limits for both elements. For the 39 samples with values greater than
25 times the field blank, the authors reported a GM WPF of 273, a GSD
of 5.7, and a fifth percentile of 39. For samples with outside filter
weights greater than 750 times the field blank, they reported a GM WPF
of 1,012, a GSD of 2.6, and a fifth percentile of 199. The
investigators found a significant correlation between mean filter
weights and WPFs; this correlation did not plateau at higher filter
loadings. The authors stated that their measurements never reached a
level at which the protection factors were independent of the outside
filter weight. They concluded that the relatively low sample loadings
resulted in WPFs that significantly underestimated the respirator's
performance. They stated that, in the case of SARs, the researchers:

* * * should attempt to target outside loadings of at least 1000
times the anticipated analytical detection limit. If we do not, the
data we get is likely to reflect limitations of our sampling and
analysis procedures, rather than the respirators we are testing.

Study 19. At the 1993 AIHCE, C.E. Colton, H.E. Mullins, and J.O.
Bidwell of 3M presented a WPF study on the 3M Snapcap W-3256 airline
respirator (TC 19C-70) with a loose-fitting hood, fitted with a W-3258
hard hat, W-5114 breathing tube, W-2862 vortex tube air regulating
valve, and 50-100 feet of W-9435 compressed-air hose (Ex. 1-64-17).
They measured exposure to silica (Si) for four workers involved in
furnace teardown at a foundry. The respirators were operated at an air
pressure of 75 psi, with the participants were permitted to regulate
the airflow rate to a comfortable level. The authors later determined
that this level was 8-9 cfm. The job task consisted of using pneumatic
chippers to remove the furnace wall and bottom. Pieces of wall and
bottom either fell into or were shoveled into a barrel for removal. The
employees then vacuumed of the furnace bottom. The job consumed most of
the eight-hour shift. Since the furnace was warm and the work was
physical, the employees worked in pairs for about one hour before
switching with other employees; therefore, sampling times varied over
the two separate days of the study. Participants normally wore air-line
respirators. The investigators informed them of the study's purpose,
procedures, and their role, and provided them with instruction on the
proper donning, fitting, and operation of the respirator; however, the
authors did not mention fit testing the participants. The investigators
observed the employees on a one-on-one basis during sampling. The
employees donned and doffed the respirators and sampling trains in a
clean area, and the investigators checked the integrity of the
respirator and sampling train before the respirator was connected to
the air supply. The authors started the sampling pump after connecting
the respirator to the air line, and stopped the pump before
disconnecting the respirator from the air supply. They used field
blanks to evaluate the possibility of contamination from handling the
samples.
Inside- and outside-the-facepiece samples were collected in 25 mm
three-piece cassettes containing 0.8 micron pore size polycarbonate
filters and porous plastic back-up pads. Inside-the-facepiece cassettes
were attached to the inside of the hood, directly across from the
employee's mouth, with the cassette pointed toward the employee. A
nylon Liu probe was attached to the inside cassette, and a sample line
ran through the elasticized inner shroud and out to the sampling pump;
the inside sampling flow rate was 2 Lpm. Outside-the-facepiece samples
were collected as respirable dust through use of a 10 mm nylon cyclone;
the outside sampling flow rate was 1.7 Lpm. The authors do not mention
the location of the outside sampling cassettes, or what method they
used to conduct particle size sampling.
The investigators used PIXE to analyze collected samples for Si;
however, overloading of many of the outside-the-facepiece samples
prevented PIXE analysis, requiring analysis of these samples by
Inductively Coupled Plasma (ICP) spectroscopy. The authors made no
field blank adjustments to the measured sample weights (i.e., Si was
not detected on the field blanks). The investigators intended to
invalidate sample pairs with an outside filter weight less than 1,001
times the field blank value, or limit of detection if the field blank
value was zero; all outside sample weights were more that 10,000 times
the detection limit. In addition, they rejected sample pairs with
inside sample weights that were less than the mean blank value. They
did not mention correcting inside-the-facepiece values for pulmonary
retention of particles, or how they managed sample results that were
below the analytical detection limit. Particle size analysis showed the
contaminant to be ``a dust with over 50 percent of the mass greater
than 10 [mu]m.'' The authors established a correlation between the PIXE
and ICP analytical methods by analyzing 37 samples using both methods.
They developed a linear regression equation that permitted PIXE
equivalents to be predicted from the ICP results. They reviewed the WPF
results using: The ICP results for the outside concentrations, and PIXE
results for the inside concentrations; and the regression to predict
PIXE equivalents for the outside concentrations, and PIXE results for
the inside concentrations.
The authors calculated WPFs and checked the resulting values for
outliers at the 99% confidence level. They did not provide individual
inside- and outside-the-facepiece concentrations, but instead reported
an overall range of inside and outside concentrations, along with the
ranges' associated GM and GSD. In addition, the authors did not provide
individual WPF values, but presented calculated WPFs as an overall
fifth percentile WPF, GM, and GSD for each of the 2 days, based on both
methods discussed above (i.e., ICP and PIXE equivalent). They found
that the two methods gave similar results. Using the equivalent PIXE
values (i.e., calculated from ICP values), and the

[[Page 34067]]

PIXE in-facepiece values, the GM WPF was 10,344, the GSD was 2.5, and
the fifth percentile WPF was 2290. The authors stated that the loose-
fitting hood performed differently than a loose-fitting PAPR, and this
difference should be reflected in the APF assigned. In addition, they
briefly discussed a comparison of the study results with the results of
several other PAPR and air-line respirator studies.
Study 25. In 2001, T.J. Nelson, T.H. Wheeler, and T.S. Mustard
published a WPF study of a supplied-air hood (Ex. 3-6). They measured
exposure to strontium (Sr) for 19 painters and helpers involved in
sanding and painting operations on several types of aircraft. They
judged the work rate to be light to moderate. Prior to sampling, they
informed the employees about the study, and instructed them to remain
connected to the air supply during calibration and sampling. The
participants used a 3M H-422 series supplied-air hood, equipped with an
outer bib with an inner shroud and hard hat, H-420 hood, W-3258 hard
hat, W-2878 suspension, 50 feet of W-9435 hose, and either the W-2862
vortex cooling assembly or the W-2863 vortex heating assembly. The
investigators regulated the supply air pressure to between 60 and 80
psi. Employees donned the hoods in the work area, but investigators did
not attach the sampling cassettes until after the employees connected
the hood to the air supply and airflow began. They used field blanks to
identify possible contamination due to handling, storage or shipment.
In addition, they used manufacturer's blanks to detect contamination
from manufacture of the filter, and a system blank to determine if
contamination was present in the air supply.
The investigators collected inside- and outside-the-facepiece
samples using 37 mm or 25 mm three-piece cassettes containing mixed
cellulose ester filters. The first 19 samples (i.e., collected during
sanding) utilized 37 mm cassettes/filters, but half of the outside
samples had no detectable Sr. To increase analytical sensitivity, they
collected the remaining 18 samples with 25 mm cassettes and filters.
Once the employee was connected to the air supply, they attached a
sampling cassette inside the hood at a point midway between the nose
and mouth, and to the side of the face. They then uncapped the cassette
and connected a Liu probe to the cassette inlet. The authors placed the
outside cassette in the lapel area and pointed it forward and down.
They started the sampling pumps simultaneously, and performed in-line
calibration. They collected samples at an airflow rate of 2 Lpm, for a
period consisting of 2 hours for sanding and 90 minutes for painting.
At the end of sampling period, they in-line calibrated the pumps,
stopped the pumps, capped and removed the cassettes, and the employees
disconnected and doffed the hood. They collected the system blank by
mounting a cassette in an operating hood that was located away from the
work area, and sampled air from inside the hood at 2 Lpm for 2 hours
The authors did not mention making a particle size determination.
The investigators analyzed the outside-the-facepiece samples and
one of the manufacturer's blanks using NIOSH Method 7300. They used
PIXE analysis for the inside-the-facepiece samples, field blanks,
system blank, and the other manufacturer's blank. They tabulated the
sampling results by date, activity, employee, sample time, inside and
outside sampled volumes, inside and outside concentrations, and WPF.
The authors reported thirty-one individual inside- and outside-the-
facepiece concentrations. However, the results of the outside samples
obtained during sanding operations were only 30 times greater than the
inside sample values. Therefore, the authors did not consider the data
from the sanding operations to be a very useful indicator of respirator
performance, and they did not calculate WPFs for the initial 19 sanding
samples. Of the remaining 18 painting samples, they calculated WPFs for
only 15 samples, after discarding 3 samples due to sampling errors. The
Sr levels measured outside of the respirator ranged from 340 to 24,529
[mu]g/m3, but the investigators found no detectable amounts
of Sr on any inside-the-facepiece sample. Therefore, the authors could
not directly determine WPFs for the respirator. However, they estimated
WPFs by substituting the limit of detection for the inside
concentration values. This procedure resulted in estimated WPFs that
ranged from more than 920 to 52,000. The authors concluded that their
study was ``* * * consistent with other simulated and WPF studies in
that the ANSI Z88.2 WPF of 1000 is supported.''
8. SWPF Studies--Type CE Abrasive Blasting Respirators
Bullard: 1995 LLNL Evaluation. During the development of the
Interim Final Standard for Lead (Pb) in Construction (1926.25; 1996)
and the Final Respiratory Protection Standard (63 FR 1152; 1998), the
E.D. Bullard Company (Bullard) expressed concern about the APF of 25
for Type CE respirators. The concern was that the interim final lead
rule, as issued, went far beyond the HUD guidelines by assigning a
different and lower protection factor to Type CE respirators than the
HUD guidelines, which incorporated the general industry standard at 29
CFR Sec. 1910.1025. Bullard maintained that its Model 77 and 88
respirators provide much greater protection, and sought to have the APF
for these models elevated to 1,000 in the Lead in Construction
Standard. OSHA agreed to provide Bullard with the relief sought only if
it contracted with an acceptable third party to design, monitor, and
interpret the results of a simulated workplace study of these models
under an appropriate and acceptable test protocol. As a condition for
granting that relief, the study had to demonstrate that the abrasive
blasting respirators achieved, at a minimum, a protection factor rating
of at least 20,000 and maintained positive pressure throughout the
testing.
Bullard contracted with Lawrence Livermore National Laboratory
(LLNL) which designed, conducted, and interpreted the results of the
SWPF study, based on a protocol that was acceptable to OSHA. The LLNL
informal report resulting from the testing indicated (based on
computerized data backed up by strip chart recordings) that the two
Bullard abrasive blast respirators achieved a minimum protection factor
of 40,000 and maintained positive pressure throughout the testing.
Therefore, the SWPF study conducted by LLNL demonstrated that, if
used properly, the Bullard respirators were acceptable for lead
exposures that are less than or equal to 1,000 times the PEL (50,000
[mu]g/m3). In an August 30, 1995 memo to its Regional
Administrators, OSHA recognized that the SWPF study results indicated
that an APF greater than 25 was appropriate for the Bullard Model 77
and Model 88 respirators, and the Agency granted these models an
interim APF of 1,000 when used for lead in construction (Ex. 3-8-4;
memo to RAs dated 8/30/95). However, the memo also noted that the
Agency was aware of other data and at least one field study showing
that in the workplace these respirators may provide considerably less
protection when used in ways that do not conform to the manufacturer's
specifications (e.g., the air supply hose is too long; the hose
diameter is incorrect; the manufacturer's specified air pressure is not
maintained) or that do not comply with the requirements of paragraphs
(b), (d), (e) and (f) of 1910.134 (e.g., the respirator is not
inspected frequently enough for

[[Page 34068]]

possible deterioration). The memo further stated that respirators will
provide less protection than they are capable of, when used improperly
(e.g., donning and doffing the respirators while still in containment;
disconnecting the air hose prior to leaving the exposure area). In
addition, these respirators are used in extreme conditions during
construction activities (e.g., substantial and, sometimes rapid,
deterioration caused by high-speed ``bounceback'' of the abrasive
blasting material; very high levels of exposure). The impact of
``bounceback'' on the integrity of the respirator was not evaluated in
the LLNL SWPF study since the study challenge agent was a liquid, not a
particulate (which is typically the type of contaminant found in
workplaces). Also, because these respirators may, at times, be used
near the limits of their protective capability, workers wearing these
respirators in abrasive blasting operations could receive acute
exposures if the respirators do not perform properly. Therefore,
performance consonant with the elevated APF can only be assured when
the respirators are properly used.
As a result of the above, OSHA adopted a modified enforcement
policy for these two respirators. This policy was limited to the Lead
in Construction Standard (29 CFR 1926.62) and applied only to the
Bullard Models 77 and 88. Also, the interim APF of 1,000 was pending
until a final APF for this class of respirators could be determined
through this rulemaking. Since OSHA believes that proper use of these
respirators is imperative, the policy made it clear that the Agency
would be very strict in assuring that these respirators are used in
accordance with the manufacturer's specifications and the requirements
of 1926.62.
Clemco Apollo Models 20 and 60 and 3M Whitecap II. With the
assistance of the Industrial Safety Equipment Association (ISEA), other
respirator manufacturers of Type-CE, continuous-flow, abrasive blasting
respirators covered by the Lead in Construction Standard were
contacted. By participating in a similar study, these manufacturers
were provided with an equal opportunity to obtain the same relief
afforded to Bullard. The Clemco Apollo Models 20 and 60 and the 3M
Whitecap II were tested under conditions similar to the Bullard Model
77and 88 study. Based on the results of the studies, OSHA granted the
respirators the interim APF of 1,000, and developed the same
enforcement policy for Clemco (Ex. 3-7-4; memo to Regional
Administrators dated 03/31/97) and 3M (Ex. 3-9-3; memo to Regional
Administrators dated 12/08/98). Again, the interim APF was contingent
on the final APF for these respirators being determined through this
rulemaking.
9. SWPF Studies--N95 Air-Purifying Respirators
NIOSH N95 Chamber Studies. In 1999, NIOSH conducted a chamber study
of N95 respirators and statistically analyzed the respirators'
performance (Ex. 4-14). The study involved twenty-five subjects meeting
the criteria of the LANL respirator panel. Twenty-one respirators were
tested and included twenty filtering-facepiece and one elastomeric
half-mask. Each test involved a sequence of six sedentary-type
exercises: Normal breathing, deep breathing, moving the head side to
side, moving the head up and down, reading the rainbow passage out
loud, and normal breathing. Each exercise took about 80 seconds. For
all tests, the subjects donned the respirator and conducted a user seal
check in accordance with the manufacturer's instructions. After each
test, the test operator returned the respirator to its original pre-
test configuration (e.g., strap was loosened). The investigators used a
PortaCount Plus, a condensation nucleus type of particle detector, to
determine the protection factor by measuring both the challenge aerosol
(i.e., ambient aerosol) and the aerosol penetrating the respirator.
The total penetration of an aerosol into a respirator includes the
penetration through the filter media in addition to that resulting from
face seal leakage. To determine face seal leakage, the study authors
subtracted estimated filter media penetration from the total observed
penetration. Filter media penetration was ascertained by separate
testing performed on the filter media after human subject testing.
Testing was conducted at an airflow rate of 31.4 Lpm, as determined
from a volume-weighted average cycle having a peak flow rate of 40 Lpm.
The same penetration for a given media was subtracted from the total
penetration for all subjects using a respirator with that media.
Calculating face seal leakage in this manner assumes all subjects have
the same constant, volumetric flow rate through the respirator. The
authors also summarized total penetration and face seal leakage
penetrations. The 95th percentiles presented by NIOSH were based on a
formula using the geometric mean and geometric standard deviation, and
assumes the distribution to be log normal.
LLNL Study of Four N95 Filtering Facepiece Respirators. At OSHA's
request, researchers at LLNL conducted chamber testing on four of the
same commercial N95 filtering facepiece half-mask respirators used in
the NIOSH study (Ex. 4-14). The four N95 filtering facepieces selected
by OSHA for study were: 3M Model 8210, 3M Model 8511, Wilson Model
9501, and MSA Affinity Ultra (formerly Uvex/Pro Tech Model 4010). Six
subjects (three male, three female) with six different face dimensions
(according to lip length) used each filtering facepiece. These subjects
represented six different boxes on the Los Alamos National Laboratory
half-mask test panel (Boxes 4, 5, 7, 8, 9, and 10). Subjects used the
manufacturer's instructions prior to donning the respirator. Each
subject tested each respirator 4 times, for a total of 16 tests per
subject and 96 tests overall. The investigators probed the respirators
in the area of the nose, using the TSI fit-test probe kit, and measured
penetration values with a TSI PortaCount Model 8020. They used ambient
room aerosol as the challenge atmosphere and monitored it continuously
during testing with a second PortaCount. They used room aerosol at
concentrations greater that 2,000 particles/cc. Subjects removed the
filtering facepiece at the conclusion of each test and, after
approximately 2 minutes, redonned the same unit. The test operator
restored the respirator to pre-test configuration (e.g., straps were
loosened) after each donning. Each test consisted of nine exercises:
normal breathing, deep breathing, side-to-side head movement, up and
down head movement, reading the rainbow passage, normal breathing,
scooping rocks between buckets, stacking 30-pound concrete blocks and
normal breathing. Subjects performed each exercise for 80 seconds, with
a 20-second instrument purge cycle and 60 seconds of data collection
per exercise.
For each model of respirator, the investigators used the size that
showed the least penetration when the subject performed a 60-second
reading of the rainbow passage. This was a change from using the
penetration measured during normal breathing (as done in the original
NIOSH tests), and was chosen because reading is frequently found to be
an exercise that permits high penetration. A 60-second normal breathing
fit test was performed in addition to the reading fit test. Multiple
fit tests (both reading and normal breathing) were performed, if
necessary, to select a model size. Once fitted, each

[[Page 34069]]

subject completed four full nine-exercise tests.
The NIOSH penetration results without fit-testing were compared to
the LLNL test results. In general, the investigators found good
agreement between the two studies, with the range of penetrations being
similar in both studies. However, two differences were noted. For one
model, (referred to by the researchers as Model D), the OSHA/LLNL study
result indicated slightly more penetration than was observed in the
NIOSH study. While the minimum penetration for Model D was 2 in both
studies, the maximum penetration was 460 in the OSHA/LLNL study
compared to 370 in the NIOSH study. However, both studies showed this
respirator to be in the low performance range of penetrations. The
researchers believed that this could be attributed to a poor-fitting
individual that participated in the larger NIOSH study, but whose fit
factor attributes were not represented by any participants in the
smaller OSHA/LLNL study. They also noted that the design features of
Model D, such as its folded shape and the plastic nose clip, may
explain this respirator's poor performance. Furthermore, while this
respirator was available in three sizes, it was very difficult to
determine which size provided the best fit for several of the subjects.
The LLNL penetration result for another respirator, referred to by
the researchers as Model A, was slightly better than the NIOSH result
for the same respirator. The LLNL researchers believed that the lower
penetration they measured for Model A was possibly due to the
difference in model size/fit selection criteria between the NIOSH tests
and the LLNL tests (discussed above). Again, they felt that another
possible reason could have been a poor-fitting individual in the larger
NIOSH study that was not represented by the smaller OSHA/LLNL study.
The LLNL researchers further investigated the apparent difference
between the LLNL and NIOSH results for Model A. They found that
eliminating subjects with poorly-fitting respirators significantly
affects results. For example, a subject was started in the LLNL/OSHA
test but was not tested because the investigators were unable to
maintain a proper fit on the individual when using Model A (i.e., it
fell completely off the nose of the subject upon donning). If tested,
this subject or another less obvious subject who experienced poor fit,
could have skewed the results of the LLNL/OSHA N95 evaluation
significantly. The LLNL researchers believed that this latter analysis
illustrates the potential influence of a single outlier on the overall
results of a study. The advantages of controlled SWPF testing are
apparent in this example.
10. SWPF Studies--PAPRs and SARs
ORC Study on Respirators Used in the Pharmaceutical Industry.
Before the publication of the final respiratory protection standard,
Organization Resources Counselors, Inc. (ORC) raised an issue that had
been the subject of discussions between ORC and OSHA for several years.
In 1997, ORC and a group of its member companies sponsored a study of
certain models of powered air-purifying and supplied-air respirators to
evaluate the ability of these respirators to protect workers from
exposures in the pharmaceutical industries. The study, ``Simulated
Workplace Protection Factor Study of Powered Air Purifying and Supplied
Air Respirators,'' (Ex. 3-4-1) was completed in 1998, and the initial
results, along with detailed experimental data, were presented to OSHA.
The experimental protocol used in the study was developed by the
Organization Resources Counselors' respirator task force, LLNL
investigators, participating respirator manufacturers, and
representatives from NIOSH and OSHA. The study included a simulated
workplace exercise protocol consisting of 12 exercises: normal
breathing, twisting the head from side-to-side, moving the head up and
down, touching toes, raising arms above the head, twisting at the
waist, running in place, normal breathing, hand scooping of pebbles,
normal breathing, building a concrete block wall, and normal breathing.
Two exercises, hand scooping of pebbles and building a concrete block
wall, were included to simulate tasks in the pharmaceutical industry.
Seventeen subjects participated in the evaluation of five powered air-
purifying respirators (PAPRs) and six supplied-air respirators (SARs).
Twelve tests were conducted for each respirator, with the study being
performed in the LLNL respirator test facility.
Input from OSHA resulted in two modifications to the protocol. It
was decided that at least one of the three units for each respirator
model tested would be purchased from the open market with the others
being supplied directly from the manufacturer. A second change resulted
from the Agency's interest in evaluating intra-personal variability in
the performance of respirators. This was accomplished by testing one
PAPR model and one SAR model during six wearings by a single
individual. No significant difference in respirator performance was
noted as a result of these modifications, and the overall results are
presented below.
The results of the ORC study indicated that although simulated
workplace protection factors (SWPFs) greater than one million were
recorded during some of these tests, a reporting limit of 250,000 was
established as the highest value in which reliable facepiece leakage
could be detected (limit of quantification). The median SWPFs for all
respirators, except one SAR, were at or above the reporting limit of
250,000. Lower fifth percentiles were above 100,000, with the exception
of the one SAR. APFs were established for each of the 11 respirators by
dividing the lower 5th percentile by a safety factor of 25. APFs ranged
from 6,000-10,000 for PAPRs (including one loose-fitting PAPR), and
3,000-10,000 for SARs, with the exception of one device. This SAR had
lower 5th percentile of less than 20 and an APF of 1. Results are
presented in the table below.

Table 4.--Summary of Simulated Workplace Protection Factor Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
Device Range of SWPFs Median SWPF 5th percentile SWPF
--------------------------------------------------------------------------------------------------------------------------------------------------------
PAPR 1................................ 140,000-£250,000 £250,000 £250,000
PAPR 2................................ 11,000-£250,000 £250,000 170,000-210,000
PAPR 3................................ 11,000-£250,000 £250,000 £250,000
PAPR 4................................ 94,000-£250,000 £250,000 246,000-£250,000
PAPR 5................................ 240-£250,000 £250,000 150,000-230,000
SAR 1................................. 68,000-£250,000 £250,000 £250,000
SAR 2................................. 13,000-£250,000 £250,000 170,000-220,000
SAR 3................................. 9,700-£250,000 £250,000 86,000-114,000
SAR 4................................. 5,500-£250,000 £250,000 150,000-240,000
SAR 5................................. 5-£250,000 GM=1217 13-18

[[Page 34070]]

SAR 6................................. 160,000-£250,000 £250,000 £250,000
--------------------------------------------------------------------------------------------------------------------------------------------------------

List of Respirators

Powered Air-Purifying Respirators With Hoods/Helmets

(PAPR1) 3M Whitecap helmet with chinstrap with GVP blower (hard plastic
helmet with bib).
(PAPR 2) 3M Snapcap hood with chinstrap with GVP-100 blower (Tyvek hood
with bib).
(PAPR 3) Racal BE-5 (clear PVC hood with bib).
(PAPR 4) Racal BE-10 (Polycoated Tyvek hood with bib and head
suspension).

Loose-Fitting Powered Air-Purifying Respirator

(PAPR 5) Racal BE-12 (Polycoated Tyvek loose-fitting facepiece).

Supplied-Air Respirators

(SAR 1) 3M Whitecap helmet with chinstrap (hard plastic helmet with
bib).
(SAR 2) 3M Snapcap hood with chinstrap (Tyvek hood with bib).
(SAR 3) MSA VERSA-Hood with #5-613-1 direct hose connection for
3/8'' hose system (Tyvek hood).
(SAR 4) North Model 85302 TB (Tyvek hood with ratchet head suspension
and bib).
(SAR 5) North Model 85302 T (Tyvek hood with ratchet head suspension).
(SAR 6) Bullard CC2OTIC with 2ORT suspension and 2ONC chinstrap (Tyvek
hood with bib).

Note: All PAPRs tested with high-efficiency filters.

The study report was finalized in 1999, and ORC requested that OSHA
consider assigning an interim final APF of 1,000 to the study's high-
performing respirator models, with provisions for an APF as high as
5,000 based on programmatic and environmental factors (Ex. 3-4-3, 1999
communication with OSHA). ORC also recommended that, because the
current NIOSH respirator certification procedures are not capable of
distinguishing between high-performing PAPRs and SARs (and that some
respirators may not provide adequate protection), the study methodology
should be the basis for determining APFs for all respiratory protective
equipment regulated by OSHA.
In 2000, ORC renewed its requests. They pointed out that the study
demonstrated that the PAPRs tested, including the loose-fitting
facepiece PAPRs, were capable of achieving protection factors of 6,000
to 10,000 (rather than the APF of 25 assigned by NIOSH and adopted by
OSHA), and that the tested SARs achieved protection factors of 3,000 to
10,000. However, one tested SAR model did not provide a protection
factor of 25, demonstrating to the Agency the importance of testing
specific equipment being considered for an increased APF to assure the
expected protection.
ORC asserted that new APFs for the models tested in the study were
warranted. They believed that the study results justified a re-
evaluation of the methods for assessing the ability of PAPRs and SARs
to provide protection against airborne particulates, and asked OSHA to
issue a directive or similar document assigning an interim APF of 1,000
for the SARs and PAPRs that tested successfully in the study. ORC
believed that SWPF testing of PAPRs and SARs was beneficial, and
strongly supported use of a collaborative approach as was pursued in
developing the study.
OSHA permitted use of an interim APF of 1,000 for 9 of the 11
respirators tested and developed an enforcement policy similar to that
followed for the Bullard, Clemco, and 3M respirators (Ex. 3-4-4; 2002
memo to RAs). Again, the interim APFs are subject to a final APF
determination resulting from this rulemaking. OSHA requests comments on
all aspects of this study.
LLNL/OSHA PAPR Study. OSHA requested that LLNL conduct two
additional PAPR studies using the protocol of the 1995-96 ORC study.
The raw data from the two evaluations were then compared with the ORC
SWPF study data.
A modified SWPF protocol was used to test two additional PAPRs, an
MSA OptimAir and a Neoterik, selected by OSHA. The testing employed the
same exercise protocol as the ORC study; however, only three test
subjects participated in the evaluation. The three test subjects each
performed four separate donnings of each respirator model. The 50th and
95th percentiles of the penetration and protection factors for the two
respirators are shown in Table 5.

Table 5
----------------------------------------------------------------------------------------------------------------
Penetration Protection factor
Respirator model ---------------------------------------------------------------------------------
50th percentile 95th percentile 50th percentile 95th percentile
----------------------------------------------------------------------------------------------------------------
MSA OptimAir.................. 1.67 x 10-6(a)... 4.08 x 10-5..... 250,000(a)...... 24,510
Neoterik...................... 2.74 x 10-5...... 1.43 x 10-3..... 36,563.......... 698
----------------------------------------------------------------------------------------------------------------

For the Neoterik, SWPFs of 100 and somewhat less were observed for
the running in place and the moving bricks (building a concrete block
wall) exercises. The Neoterik demonstrated SWPFs near 1,000 and
somewhat less for the twisting head side to side, moving the head up
and down, and touching toes exercises. For the MSA OptimAir, SWPFs
approaching 100 for the running in place exercise were observed, while
all of the other exercises resulted in SWPFs of 10,000 or greater.
Penetration levels by type of exercise were compared between the OSHA
PAPR analyses and the ORC results. In general, the comparison indicated
that the same exercises triggered increased penetration values. That
is, sources of penetration were ``running-in-place'' (for both
respirators) and ``moving bricks'' (for the Neoterik PAPR).

V. Health Effects

In a number of previous rulemakings, OSHA discussed the serious
health effects caused by exposure to airborne chemical hazards (see,
e.g., Appendix A of the Hazard Communication Standard

[[Page 34071]]

at 29 CFR 1910.1200, and the preambles to any of the Agency's
substance-specific standards codified at 29 CFR 1910.1001 to
1910.1052). When OSHA promulgates a new or revised PEL for a chemical
air contaminant, (e.g., Arsenic, 29 CFR 1910.1018; Asbestos, 29 CFR
1910.1001; Benzene, 29 CFR 1910.1028; Lead, 29 CFR 1910.1025; Ethylene
Oxide, 29 CFR 1910.1047), it determines at what level of exposure to
the contaminant employees develop serious health effects (e.g.,
exposure to the contaminant is life-threatening, causes permanent
damage, or significantly impairs employees' ability to perform their
jobs safely).
As discussed in Section VI, ``Summary of the Final Economic
Analysis,'' of the final Respiratory Protection Standard (63 FR 1171),
OSHA estimated that improvements and clarifications made to the
previous Respiratory Protection Standard would prevent, each year,
between 843 and 9,282 (best estimate, 4,046) work-related injuries and
illnesses, and between 351 and 1,626 (best estimate, 932) work-related
deaths from cancer and chronic diseases such as cardiovascular disease.
To support this estimate, OSHA used its Integrated Management
Information System database to identify several substances that had a
wide range of adverse effects, as well as documented workplace
exposures that exceeded the PELs for these substances. The health
effects associated with exposure to these substances include:
? Sudden death or asphyxiation (e.g., from exposure to carbon
monoxide, carbon dioxide);
? Loss of lung function (e.g., from exposure to wood dust,
welding fumes, manganese fumes, copper fumes, cobalt metal fumes,
silica);
? Central nervous system disturbances (e.g., from exposure to
carbon monoxide, trichloroethylene);
? Cancer (e.g., from exposure to chromic acid, wood dust,
silica); and
? Cardiovascular problems (e.g., from exposure to carbon
monoxide).
Furthermore, most of the airborne contaminants measured as part of
the workplace protection factor studies considered during development
of this proposal cause serious health effects. For example, acute lung,
skin, and eye irritation occur as a result of occupational exposures to
styrene, lead, strontium, benzo(a)pyrene, and silica. Longer-term
exposures to other substances sampled in these studies cause bone and
blood effects (lead particulates), neurological effects (mercury
fumes), chronic lung damage (cotton dust), and cancer (asbestos fibers
and chromium particulates).
The risk that an employee will experience an adverse health outcome
while exposed to a hazardous airborne substance is a function of the
toxicity or hazardous characteristics of the substance, the
concentrations of the substance in the air, the duration of exposure,
the physiology of the employee, and workplace conditions. These factors
combined assist in determination of the type of respirator selected to
reduce an employee's exposure below the PEL for the hazardous
substance. Under many workplace-exposure conditions, prevention of
serious health effects depends substantially on the protection afforded
to employees by a respirator.
Employers need the APFs provided in this proposal to select
appropriate respirators for employee use when engineering and work-
practice controls are insufficient to maintain hazardous substances at
safe levels in the workplace. In this regard, the proposed APFs will
permit employers to select respirators for employee protection based on
the type of hazardous substance and the level of employee exposure to
that substance, among other factors. OSHA strongly believes that proper
respirator selection using the proposed APFs will protect employees
from overexposure to hazardous substances, thus preventing the serious
health effects that result from such overexposure.
While APFs are an important factor in respirator selection,
employers must consider other factors as well. In this regard, simply
applying an APF to the level of an airborne contaminant in a workplace
will not ensure that employees receive adequate protection. Throughout
the preamble of the final Respiratory Protection Standard, OSHA
demonstrated that adequate fit testing, proper respirator use, employee
training, and thorough inspection and maintenance of respirators are
some of the other factors essential to an effective respiratory
protection program. The Agency believes that failure to comply with any
of these program requirements substantially increases the chance that
the respirator selected by the employer will not protect employees
against hazardous air contaminants because of respirator malfunction,
excessive leakage, improper use, or some combination of these problems.
Therefore, employers should expect respirators to provide effective
employee protection against the serious health effects of hazardous
airborne substances only when they use the respirators in the context
of a comprehensive respiratory protection program. If respirators are
to provide employees with at least the minimum level of exposure
protection listed in the proposed APF table, employers must comply with
the other respiratory protection requirements specified under OSHA's
Respiratory Protection Standard at 29 CFR 1910.134.
In this rulemaking, OSHA also is proposing to supersede the
existing APF requirements in its substance-specific standards. By
superceding these requirements, the Agency expects that the benefits
estimated for the proposed APFs under the Respiratory Protection
Standard would be available to employers who must select respirators
for employee use under the substance-specific standards. In addition,
OSHA would be harmonizing the APF requirements in the substance-
specific standards with the APF requirements proposed for its
Respiratory Protection Standard. The Agency believes that harmonization
would reduce confusion among the regulated community and aid in uniform
application of APFs, while maintaining employee protection at levels at
least as protective as the existing APF requirements.

VI. Summary of the Preliminary Economic and Regulatory Flexibility
Screening Analysis

A. Introduction

OSHA's Preliminary Economic and Regulatory Flexibility Screening
Analysis (PERFSA) addresses issues related to the costs, benefits,
technological and economic feasibility, and economic impacts (including
small business impacts) of the Agency's proposed Assigned Protection
Factors (APF) rule. The Agency preliminarily determined that this rule
is not an economically significant rule under Executive Order 12866.
The economic analysis meets the requirements of both Executive Order
12866 and the Regulatory Flexibility Act (RFA; as amended in 1996). The
PERFSA presents OSHA's full economic analysis and methodology. The
Agency entered the complete PERFSA into the docket as Exhibit 6-1. The
remainder of this section summarizes the results of that analysis.
The purpose of this PERFSA is to:
? Identify the establishments and industries potentially
affected by the rule;
? Evaluate the costs employers would incur to meet the
requirements of proposed APF rule;
? Estimate the benefits of the rule;
? Assess the economic feasibility of the rule for affected
industries; and
? Determine the impacts of the rule on small entities and the
need for a Regulatory Flexibility Analysis.

[[Page 34072]]

B. The Rule and Affected Respirator Users

OSHA's proposed APF rule would amend 29 CFR 1910.134(d)(3)(i)(A) of
the Respiratory Protection Standard by specifying a set of APFs for
each class of respirators. These APFs specify the highest multiple of a
contaminant's permissible exposure limit (PEL) at which an employee can
use a respirator safely. The proposed APFs would apply to respirator
use for protection against overexposure to any substance regulated
under 29 CFR 1910.1000. In addition, OSHA rules for specific substances
under subpart Z (regulated under the authority of section 6(b)(5) of
the OSH Act of 1970, 29 U.S.C. 655) specify APFs for respirators used
for protection against these chemicals (hereafter referred to as
section 6(b)(5) substances). The proposed rule would supercede most of
these protection factors, and harmonize APFs for these substances with
those for general respirator use.
OSHA based estimates of the number of employees using respirators
and the corresponding number of respirator-using establishments on the
recent NIOSH-BLS survey of respirator use and practices \1\ (Ex. 6-3).
The NIOSH-BLS survey provides up-to-date use estimates by two-digit
industry sector and respirator type for establishments in which
employees used respirators during the previous 12 months.\2\ As shown
in Table VI-1, an estimated 291,085 establishments reported respirator
use in industries covered by OSHA's proposed regulation. Most of these
establishments (208,528 or 71.6 percent) reported use of filtering
facepieces. Substantial percentages of establishments also reported the
use of half-mask and full facepiece nonpowered air-purifying
respirators (49.0 and 21.4 percent, respectively). A smaller number of
establishments reported use of powered air-purifying respirators
(PAPRs) and supplied-air respirators (SARs). Fifteen percent of
establishments with respirators (43,154) reported using PAPRs and 19
percent (56,022) reported using SARs. Table VI-2 presents estimates of
the number of respirator users by two-digit industry sector. An
estimated 2.3 million employees used filtering facepiece respirators in
the last 12 months, while 1.5 million used half masks, and 0.7 million
used full facepiece nonpowered air-purifying respirators. Fewer
employees reported using PAPRs (0.3 million) and SARs (0.4 million).
The industry-specific estimates show substantial respirator use in
several industries, including the construction sector, several
manufacturing industries (SICs 28, 33, 34, and 37), and Health services
(SIC 80).
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\1\ Preliminary results from the 2001 NIOSH-BLS ``Survey of
Respirator Use and Practices'', in press. NIOSH commissioned the
survey to be conducted by BLS, who also tabulated the data after
completing the survey.
\2\ The survey was conducted between August 2001 and January
2002. It asked: ``During the past 12 months, how many of your
current employees used respirators at your establishment?'' It
excluded voluntary use of respirators from detailed followup
respirator use questions (Ex. 6-3).
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The proposed standard would have different impacts on employers
using respirators to comply with OSHA substance-specific standards than
for employers using respirators for other purposes. Therefore, OSHA
used findings from the NIOSH-BLS survey of establishments that reported
respirator use, by general respirator class, for protection against
specific substances (see Table VI-3). OSHA applied these numbers to all
respirator users and establishments within the industries that make up
each sector to derive substance-specific estimates of respirator use.
For those section 6(b)(5) substances not reported by NIOSH, OSHA used
expert judgments of a consultant with experience in the respirator
industry to estimate the percentage of establishments and employees
that use respirators for protection against these chemicals (Ex. 6-2)
(see Table VI-3).

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C. Compliance Costs

The proposal does not raise issues of technological feasibility
because it requires only that employers use respirators already on the
market. However, costs of the proposed APFs result from requiring some
users to switch to more protective respirators than they currently use.
When the proposed APF is lower than the baseline (current) APF,
respirator users must upgrade to a more protective model. Both the 1992
ANSI Z88.2 Respiratory Protection Standard and the 1987 NIOSH RDL
specify APFs for certain classes of respirators. The Agency assumed
that employers currently use the ANSI or NIOSH APFs, or the APFs in the
OSHA substance-specific standards, as applicable, to select
respirators. While the Agency currently refers to the NIOSH RDL as its
primary reference for APFs, in the absence of an applicable OSHA
standard, this analysis assumes that, in most cases, adhering to the
existing ANSI APFs fulfills employers' legal obligation for proper
respirator selection under the existing Respiratory Protection
Standard. However, in the case of full facepiece negative pressure
respirators, the Agency has established that an APF of 50, as opposed
to ANSI's APF of 100, is currently acceptable. In this regard, all but
one of the substance-specific standards with APFs for full facepiece
negative pressure respirators set an APF of 50. In addition, the
existing respirator rule and its supporting preamble require that
quantitative fit testing of full facepiece negative pressure
respirators must achieve a fit factor of 500 when employees use them in
atmospheres in excess of 10 times the PEL; this requirement assumes a
safety factor of 10. Therefore, based on a fit factor of 500, such
respirators would be safe to wear in atmospheres up to 50 times the
PEL, consistent with similar requirements regarding respirator use
found in existing standards for section 6(b)(5) chemicals.
For each respirator type, OSHA compared the proposed and current
APF requirements, including existing APFs for section 6(b)(5)
substances, and identified an incrementally more protective respirator
model. To be adequate, the more protective respirator must have a
proposed APF greater than the current APF.
1. Number of Users Required To Upgrade Respirator Models
For a given respirator type, the number of users required to shift
to a more protective respirator depends on two factors: The total
number of users of that type, and the percentage of those users for
whom the ambient exposure level is greater than the proposed APF. While
survey data are available to estimate the number of users, virtually no
information is available in the literature that provides a basis for
estimating the percentage of users required to upgrade respirators. The
percentage of workers switching respirators would depend on the profile
or frequency distribution of users' exposure to contaminants relative
to the PEL. For example, the Agency proposed to lower the APF for full
facepiece respirators used to protect against cotton dust from 100 to
50; accordingly, when workers have ambient exposures that are greater
than 50 times the PEL, employers must upgrade the respirator from a
full facepiece negative pressure respirator to a more protective
respirator (e.g., a PAPR).
Because of the absence of data on this issue, OSHA made several
assumptions regarding the requirement to upgrade respirators. First,
OSHA assumed that employers use respirators only when their employees
have exposures above the PEL. Second, OSHA assumed employers use the
most inexpensive respirator permitted. These assumptions most likely
overestimate the cost of compliance because many employers require
their employees to use respirators when OSHA does not require such use,
or they require respirators with higher APFs than OSHA currently
requires. As a result, this analysis assumes shifts in respirators that
employers may have implemented already.
The Agency estimated distributions of exposures above the PELs
based on reports from its Integrated Management Information System
describing workplace monitoring of section 6(b)(5) toxic substances
performed during OSHA health inspections. Of the 9,095 samples reported
above the PELs, 68.0 percent reported exposures between 1 and 5 times
the PEL, 13.1 percent found exposures between 5 and 10 times the PEL,
and 9.5 percent documented exposures between 10 and 25 times the PEL.
Exposures for the remaining 9.4 percent of the samples were greater
than 25 times the PEL. Based on these data, OSHA modeled the current
exposure distribution for each respirator type.
2. Incremental Costs of Upgrading Respirator Models
OSHA also analyzed the costs of upgrading from the current
respirator to a more protective alternative. In doing so, OSHA
estimated the annualized unit costs for each respirator type, including
equipment and accessory costs, and the costs for training and fit
testing. OSHA then calculated the incremental cost for each combination
of upgrades from an existing model to a more protective one, taking
into account the effect of replacement before the end of the
respirator's useful life. These annualized costs range from $49.98 (for
upgrading from a supplied-air, demand mode, full facepiece respirator
to a supplied-air, continuous flow, half-mask respirator) to $963.73
(for upgrading from a nonpowered, air-purifying full facepiece
respirator to a full facepiece PAPR).
In certain instances, workers who use respirators under the
substance-specific standards may have to upgrade to a SAR with an
auxiliary escape SCBA. Several substance-specific standards currently
specify SARs for exposures that exceed 1,000, times the PEL.\3\ OSHA
believes that workers are unlikely to regularly use respirators at such
extreme exposure levels, i.e., they are most likely to use them only in
exceptional, possibly emergency-related situations. Furthermore,
exposures at levels more than 1,000 times the PEL would generally be at
or above levels deemed immediately dangerous to life or health (IDLH),
so employers already are required by the Respiratory Protection
Standard to provide each worker with a respirator that has SCBA
capability. For these reasons, this PERFSA estimated no impacts for
these situations.\4\
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\3\ These standards regulate cotton dust, coke oven emissions,
acrylonitrile, arsenic, DBCP, ethylene oxide, and lead.
\4\ Paragraph (d)(2) of the Respiratory Protection Standard
requires employers to provide either a pressure demand SCBA or a
pressure demand SAR with auxiliary SCBA to any employee who works in
IDLH atmospheres.
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3. Aggregate Compliance Costs
For each respirator type affected by the proposed regulation, OSHA
combined the incremental costs of upgrading to a more protective
respirator, the estimated share of users forecast to upgrade, and the
number of users involved to estimate the compliance costs associated
with each respirator type. Table VI-4 shows estimated compliance costs
for OSHA's proposed APF rule of $4.6 million. The proposed rule would
require 1,918 users of nonpowered air-purifying respirators to upgrade
to some respirator more expensive than they are now using at a cost of
$1.8 million. The Agency estimates that 22,848 PAPR users would upgrade
their respirators at a cost of $2.3 million. A relatively small number
of SAR users (5,110) would upgrade to more expensive respirators at a
cost of

[[Page 34080]]

$0.4 million. Industry-specific compliance costs vary according to the
number of respirator users and the proportion of these users affected
by the proposed rule. Industries with relatively large compliance costs
include SIC 17, Special trade contractors ($0.8 million), and SIC 80,
Health services ($0.8 million). Potentially offsetting these costs are
a limited number of cases where employers would be allowed to shift to
a less expensive respirator.
As discussed previously, however, the Agency believes the actual
costs of the proposal almost certainly are overestimated. The cost
analysis assumes all respirator wearers have levels of exposures that
require the particular respirator they are using. Under this
assumption, OSHA estimates over 15,000 employees would be allowed to
safely shift to a less expensive respirator, which could lead to cost
savings for the employer. Such potential cost savings are not accounted
for in this cost analysis.
In many cases, however, employers use respirators when respirators
are not required by OSHA, or use respirators more protective than
required by OSHA. As a result, OSHA's cost analysis overestimates the
number of employees who are affected by the standard, and therefore
overestimates costs associated with the standard.
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D. Benefits

The benefits that would accrue to respirator users and their
employers take several forms. The proposed standard would benefit
workers by reducing their exposures to respiratory hazards. Improved
respirator selection would augment previous improvements to the
Respiratory Protection Standard, such as better fit-test procedures and
improved training, contributing substantially to greater worker
protection. Estimates of benefits are difficult to calculate because of
uncertainties regarding the existing state of employer respirator-
selection practices and the number of covered work-related illnesses.
At the time of the 1998 revisions to the Respiratory Protection
Standard, the Agency estimated that the standard would avert between
843 and 9,282 work-related injuries and illnesses annually, with a best
estimate (expected value) of 4,046 averted illnesses and injuries
annually (63 FR 1173). In addition, OSHA estimated that the standard
would prevent between 351 and 1,626 deaths annually from cancer and
many other chronic diseases, including cardiovascular disease, with a
best estimate (expected value) of 932 averted deaths from these causes.
The APFs proposed in this rulemaking help ensure these benefits are
achieved, as well as provide an additional degree of protection. The
proposed APFs would reduce employee exposures to several section
6(b)(5) chemicals covered by standards with outdated APF criteria,
thereby reducing exposures to chemicals such as asbestos, lead, cotton
dust, and arsenic.\5\ While the Agency did not quantify these benefits,
it estimates that 29,655 employees would have a higher degree of
respiratory protection under the proposed APF standard. Of these
employees, an estimated 8,384 have exposure to lead, 7,287 to asbestos,
and 3,747 to cotton dust, all substances with substantial health risks.
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\5\ In the 1998 rulemaking revising the Respiratory Protection
Standard, the Final Economic Analysis noted that the standard would
not directly affect the benefits for the estimated 5% of employees
who use respirators under OSHA's substance-specific health standards
(except to the extent that uniformity of provisions improve
compliance). Therefore, the Agency likely over-estimated the
benefits of that rulemaking since the standard did not affect
directly the type of respirator used by those employees (63 FR
1173). Conversely, this proposed rulemaking directly addresses the
APF provisions of the substance-specific standards; therefore, this
proposal would affect directly the respirators used by employees
covered by these standards.
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In addition to health benefits, OSHA believes other benefits would
result from the harmonization of APF specifications, thereby making
compliance with the respirator rule easier for employers. Employers
also would benefit from greater administrative ease in proper
respirator selection. Employers would no longer have to consult several
sources and several OSHA standards to determine the best choice of
respirator, but could make their choices based on a single, easily
found regulation. Some employers who now hire consultants to aid in
choosing the proper respirator should be able to make this choice on
their own with the aid of the proposed rule. In addition to having only
one set of numbers (i.e., APFs) to assist them with respirator
selection for nearly all substances, some employers may be able to
streamline their respirator stock by using one respirator class to meet
their respirator needs instead of several respirator classes. The
increased ease of compliance would also yield additional health
benefits to employees using respirators.
The proposed APFs would clarify when employers can safely place
employees in respirators that impose less stress on the cardiovascular
system (e.g., filtering facepiece respirators). Many of these
alternative respirators may have the additional benefit of being less
expensive to purchase and operate. As previously discussed, OSHA
estimates that over 15,000 employees currently use respirators that
would fall in this group (i.e., shift to a less expensive respirator).

E. Economic Feasibility

OSHA is required to set standards that are feasible. To demonstrate
that a standard is feasible, the courts have held that OSHA must
``construct a reasonable estimate of compliance costs and demonstrate a
reasonable likelihood that these costs will not threaten the existence
or competitive structure of an industry'' (United Steelworkers of
America, AFL-CIO-CLC v. Marshall (the ``Lead'' decision), 647 F2d 1189
(DC Cir. 1980)).
OSHA conducted its analysis of economic feasibility on an
establishment basis. Accordingly, for each affected industry, the
Agency compared estimates of per-establishment annualized compliance
costs with per-establishment estimates of revenues and per-
establishment estimates of profits. It used two worst-case assumptions
regarding the ability of employers to pass the costs of compliance
through to their customers: The no-cost-pass-through assumption, and
the full-cost-pass-through assumption. Based on the results of these
comparisons, which define the universe of potential impacts of the
proposed APFs, OSHA then assessed the proposal's economic feasibility
for all affected establishments, i.e., those covered by the proposal.
The Agency assumed that establishments falling within the scope of
the proposal would have the same average sales and profits as other
establishments in their industries. OSHA believes this assumption is
reasonable because no evidence is available showing that the financial
characteristics of those firms with employees who use respirators are
different from firms that do not use respirators. Absent such evidence,
OSHA relied on the best available financial data (those from the Bureau
of the Census (Ex. 6-4) and Robert Morris Associates (Ex. 6-5)), used a
commonly accepted methodology to calculate industry averages, and based
its analysis of the significance of the projected economic impacts and
the feasibility of compliance on these data.
The analysis of the potential impacts of the proposed APF standard
on before-tax profits and sales shown in Table VI-5 is a ``screening
analysis,'' so called because it simply measures costs as a percentage
of pre-tax profits and sales under the worst-case assumptions discussed
above, but does not predict impacts on these before-tax profits or
sales. OSHA used the screening analysis to determine whether the
compliance costs potentially associated with the proposed standard
could lead to significant impacts on all affected establishments. The
actual impact of the proposal on the profit and sales of establishments
in a specific industry would depend on the price elasticity of demand
for the products or services of these establishments.

[[Page 34084]]

Table VI-5 shows the economic impacts of these costs. For each
industry, OSHA constructed the average compliance cost per affected
establishment and compared it to average revenues and average
profits.\6\ These costs are quite small, i.e., less than 0.005 percent
of revenues; the one major exception is SIC 44 (Water transportation),
for which OSHA estimated the costs impacts to be 0.16 percent of
revenues. When the Agency compared average compliance costs with
profits, the costs also are small, i.e., less than 0.17 percent; again,
the major exception was SIC 44, which had an estimated impact of 2.12
percent of profits.\7\ Based on the data for establishments in all
industries shown in Table VI-5, OSHA concludes that the APF proposal is
economically feasible for the affected establishments.
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\6\ OSHA defines ``affected establishment'' as any facility that
uses respirators, as represented in the NIOSH-BLS survey data.
\7\ For some industries, such as SIC 44, data from the NIOSH-BLS
survey were suppressed due to low response rates. In these cases,
the Agency, for the purposes of assessing economic feasibility,
imputed broader sector-level data from the survey to form an
estimate of respirator use. This procedure may result in
overestimating the impact of the proposal in some industries. See
the full PEA (Ex. 6-1) for further details.
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F. Economic Impacts to Small Entities

OSHA also estimated the economic impacts of the proposed rule on
affected entities with fewer than 20 employees, and for affected small
entities as defined by the Small Business Administration (SBA). Table
VI-6 shows the estimated economic impacts for small entities with fewer
than 20 employees: Average compliance costs by industry are less than
0.005 percent of average revenues, and less than 0.19 percent of
profits, in all industries. Table VI-7 presents the economic impacts
for small entities as a whole, as defined by SBA. For these firms,
average compliance costs are less than 0.005 percent of average
revenues and less than 0.03 percent of average profits. Thus, the
Agency projects no significant impacts from the proposed rule on small
entities.
When costs exceed one percent of revenues or five percent of
profits, OSHA considers the impact on small entities significant for
the purposes of complying with the RFA. For all classes of affected
small entities, the Agency found that the costs were less than one
percent of revenues and five percent of profits. Therefore, OSHA
certifies that this proposed regulation would not have a significant
impact on a substantial number of small entities.

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VII. Summary and Explanation of the Proposed Standard

This section of the preamble provides a summary and explanation of
each proposed revision to OSHA's Respiratory Protection Standard
involving assigned protection factors.

A. Revisions to the Respiratory Protection Standard

This section addresses the revisions proposed for paragraphs (b),
(d)(3)(i)(A), (d)(3)(i)(B), and (n) of OSHA's exiting Respiratory
Protection Standard at 29 CFR 1910.134).
Paragraph (b)--Definitions
Revisions to this paragraph would add two important definitions''--
assigned protection factor'' and ``maximum use concentration''--to
OSHA's Respiratory Protection Standard. The following sections explain
these proposed definitions in detail.
1. Assigned Protection Factor
As part of its 1994 proposed rulemaking for the Respiratory
Protection Standard, OSHA proposed a definition for assigned protection
factors (APFs) that read as follows: ``[T]he number assigned by NIOSH
[the National Institute for Occupational Safety and Health]
to indicate
the capability of a respirator to afford a certain degree of protection
in terms of fit and filter/cartridge penetration'' (59 FR 58938). OSHA
proposed this definition on the assumption that NIOSH would develop
APFs for the various respirator classes, building on the APFs in the
1987 NIOSH Respirator Decision Logic (RDL) (59 FR 58901-58903).
However, NIOSH subsequently decided not to publish a list of APFs as
part of its 42 CFR part 84 Respirator Certification Standards (60 FR
30338), and reserved APFs for a future NIOSH rulemaking.
During his opening statement on June 15, 1995 at an OSHA-sponsored
expert-panel discussion on APFs, Dr. Adam Finkel, then Director of the
Agency's Directorate of Health Standards Programs, noted that OSHA
would explore developing its own list of APFs (H-049, Ex. 707-X). The
Agency then announced in the preamble to the final Respiratory
Protection Standard (63 FR 1182) that it would propose an APF table
``based on a thorough review and analysis of all relevant evidence'' in
a subsequent rulemaking. In the final Respiratory Protection Standard,
OSHA reserved a table for APFs, a paragraph [(d)(3)(i)(A)]
for APF
requirements, and a definition of APF under paragraph (b).
In its 1987 RDL, NIOSH defined APF as ``[t]he minimum anticipated
protection provided by a properly functioning respirator or class of
respirators to a given percentage of properly fitted and trained
users'' (Ex. 1-54-437Q). The American National Standards Institute
(ANSI) developed a definition for APF in its Z88.2-1992 Respiratory
Protection Standard that reads, ``The expected workplace level of
respiratory protection that would be provided by a properly functioning
respirator or class of respirators to properly fitted and trained
users' (Ex. 1-50). The ANSI Z88.2 Subcommittee that developed the 1992
standard used the NIOSH definition of APF as a template for its APF
definition; however, the Z88.2 Subcommittee revised the phrase
``minimum anticipated protection'' in the NIOSH definition to
``expected workplace level of respiratory protection.'' It also dropped
the NIOSH phrase ``to a given percentage'' from its definition.
The phrase ``a given percentage'' implies that some respirator
users will not achieve the full APF under workplace conditions. The
``given percentage'' usually is about five percent, which is a
percentage derived from statistical analyses of workplace protection
factor (WPF) studies. In this regard, five percent represents the fifth
percentile of the geometric distribution of protection factors for
individual participants in a WPF study. Each participant's protection
factor is the concentration of challenge agent outside the respirator
(C_o) divided by the concentration of that agent inside the
participant's respirator (C_i), or C_o/
C_i); therefore, the fifth percentile is the threshold for
specifying the APF for the respirator tested under those workplace
conditions. Using the fifth percentile means that about five percent of
the employees who use the respirator under these workplace conditions
may not achieve the level of protection assigned to the respirator (or
class of respirators). Most WPF studies adopt the fifth-percentile
threshold as the conventional standard, recognizing that about five
percent of respirator users will not attain the APF determined for the
respirator or class of respirators even when they receive proper fit
testing and use the respirator correctly as part of a comprehensive
respiratory protection program. However, ANSI dropped the phrase ``to a
given percentage'' to reduce confusion (i.e., the phrase did not
specify a percentage), and to emphasize the level of protection needed
by the vast majority of employees who use respirators in the workplace.
The Agency's review of the available data on respirator
performance, as well as findings from the personal protective equipment
surveys (Exs. 6-1, 6-2), indicate that the existing definitions of APF
are confusing to the respirator-using public. Accordingly, OSHA
believes that the proposed definition would reduce confusion among
employers and employees regarding APFs, thereby assisting employers in
providing their employees with effective respirator protection
consistent with its Respiratory Protection Standard.
The Agency revised the terms in the ANSI APF definition to improve
clarity. OSHA's proposed definition for APF reads as follows:

Assigned protection factor (APF) means the workplace level of
respiratory protection that a respirator or class of respirators is
expected to provide to employees when the employer implements a
continuing, effective respiratory protection program as specified by
29 CFR 1910.134.

The revisions made to the ANSI APF definition in developing this
proposed APF definition include adding the phrase ``when the employer
implements a continuing, effective respiratory protection program as
specified by 29 CFR 1910.134.'' The Agency added this phrase to
emphasize the requirement that employers must select a respirator in
the context of a comprehensive respiratory protection program.
Accordingly, the APFs in Table I of this proposal do not apply when any
of the program elements required by OSHA's Respiratory Protection
Standard are absent from an employer's respirator program, including
fit testing, maintenance, selection, use, training, and other specified
elements. This wording is necessary because the level of employee
protection afforded by the proposed APFs depends on the other elements
of a comprehensive respiratory protection program being in place
continuously, and operating effectively. Employers and employees cannot
expect to achieve an APF reliably unless employers ensure that their
employees use respirators in accordance with a continuing, effective
respiratory protection program.
The proposed APF definition is an important addition to the
Respiratory Protection Standard because it informs employers how the
APF constrains respirator use. The APF can only be achieved by a
respirator or class of respirators that are functioning properly in
accordance with paragraphs (b) and (j) of the Respiratory Protection
Standard. This means that the respirator must be capable of performing
its

[[Page 34093]]

function of reducing employee exposures to airborne contaminants by
being in correct working order. Accordingly, employers must maintain
the respirator properly, with no defects such as cracked or distorted
facepiece seals, missing exhalation valves, broken straps, or any other
defect that would cause leakage into the respirator or prevent proper
operation. For air-purifying respirators, the filters must be
appropriate for the airborne contaminant, and provide an adequate
service life.
Employers must properly fit and train employees for respirator use,
which addresses the requirements in paragraphs (f) and (k) of the
Respiratory Protection Standard. Therefore, employers must fit
employees with the size and model of respirator they will be using in
the workplace. They must then wear that same size and model of
respirator in the workplace, and follow the training they receive for
performing respirator seal checks, inspections for correct respirator
operation, and proper donning and wearing the respirator.
2. Maximum Use Concentration
Employers use MUCs to select appropriate respirators, especially
for use against organic vapors and gases since the MUC specifies the
maximum atmospheric concentration of a hazardous substance against
which a specific respirator or class of respirators with a known APF
can protect employees who use these respirators. MUCs are a function of
the assigned protection factor (APF) determined for a respirator (or
class of respirators) and the exposure limit of the hazardous
substance.
Ed Hyatt in the 1976 LASL report on Respiratory Protection Factors
(Ex. 2) recounted the early history of maximum use concentration (MUC),
starting with the MUC recommendations of the joint American Industrial
Hygiene Association and American Conference of Governmental Industrial
Hygienists committee in 1961. This committee recommended that, for
highly toxic compounds, full facepiece respirators with high-efficiency
filters should use a maximum limit of 100 x the threshold limit value
(TLV). In 1961, in the United Kingdom, Hyatt noted that Letts
recommended that half-mask dust respirators provided effective
protection against airborne contaminants no greater than 10 x the TLV.
In 1974, NIOSH and OSHA started the Standards Completion Program to
develop standards for substances with existing permissible exposure
limits (PELs). This process resulted in the development of NIOSH
Criteria Documents, each of which provided technical information and
recommendations for specific airborne contaminants. These documents
also recommended MUCs for different types of respirators; NIOSH
obtained the information for these MUCs from various sources, including
NIOSH Current Intelligence Bulletins and recognized industrial hygiene
references. NIOSH later published this information in its Pocket Guide
to Chemical Hazards. Other source documents for MUC definitions and
regulations include the 1987 NIOSH RDL, and the ANSI Z88.2-1980 and
ANSI Z88.2-1992 respiratory protection standards.
OSHA's 1994 proposed Respiratory Protection Standard contained the
following definition for MUC:

Maximum use concentration (MUC) means the maximum concentration
of an air contaminant in which a particular respirator can be used,
based on the respirator's assigned protection factor. The MUC cannot
exceed the use limitations specified on the NIOSH approval label for
the cartridge, canister, or filter. The MUC can be determined by
multiplying the assigned protection factor for the respirator by the
permissible exposure limit for the air contaminant for which the
respirator will be used.

Several commenters to the 1994 proposal recommended alternatives to
this definition. Reynolds Metal Company recommended defining MUC as
``the maximum concentration of an air contaminant in which a particular
respirator can be used, based on the respirator's assigned protection
factor'' (Ex. 1-54-222). The American Petroleum Institute (API) noted
NIOSH developed the term ``MUC,'' and that, to avoid confusion, OSHA
should not use the term (Ex. 1-54-330). API proposed using the term
``assigned use concentration'' to replace ``MUC''; API defined
``assigned use concentration'' as ``the maximum concentration of an air
contaminant in which a particular respirator can be used, based on the
respirator's assigned protection factor'' (Ex. 1-54-330). However, when
the Agency published the final Respiratory Protection Standard in 1998,
it reserved the definition of MUC in paragraph (b) and MUC requirements
in paragraph (d)(3)(i)(B) for future rulemaking.
Employers use MUCs to select appropriate respirators, especially
for use against organic vapors and gases. In this regard, the MUC
specifies the maximum concentration of a toxic vapor or gas at which a
respirator will provide protection to an employee who uses the
respirator. Accordingly, in this proposed rulemaking, OSHA defines MUC
as follows:

Maximum use concentration (MUC) means the maximum atmospheric
concentration of a hazardous substance from which an employee can be
expected to be protected when wearing a respirator, and is
determined by the assigned protection factor of the respirator or
class of respirators and the exposure limit of the hazardous
substance. The MUC usually can be determined mathematically by
multiplying the assigned protection factor specified for a
respirator by the permissible exposure limit, short-term exposure
limit, ceiling limit, peak limit, or any other exposure limit used
for the hazardous substance.

Under this proposed definition, MUC represents the maximum
atmospheric concentration of a hazardous substance against which a
specific respirator or class of respirators with a known APF can
protect employees who use these respirators. Accordingly, MUCs are a
function of the assigned protection factor (APF) determined for a
respirator (or class of respirators) and the exposure limit of the
hazardous substance.
The last sentence in the proposed definition describes this
function in terms of a mathematical calculation, i.e., that employers
can ``usually'' determine the MUC by multiplying the APF for the
respirator by the exposure limit used for the hazardous substance.\8\
The term ``usually'' in this sentence is consistent with paragraph
(d)(3)(i)(B)(2), which is part of the proposed MUC requirements (see
section below titled ``Regulatory Text for Maximum Use
Concentrations.'') This proposed paragraph reads, ``Employers must
comply with the respirator manufacturer's MUC for a hazardous substance
when the manufacturer's MUC is lower than the calculated MUC specified
by this standard.'' Therefore, while employers would use the proposed
calculation to determine most MUCs, they would have to use MUCs
determined by respirator manufacturers when these MUCs are lower than
the MUCs determined using the proposed calculation. As noted below in
the explanation of proposed paragraph (d)(3)(i)(B)(2), OSHA believes
that this requirement would provide employees with a necessary added
measure of protection from hazardous substances in the workplace.
---------------------------------------------------------------------------

\8\ For example, when the hazardous substance is nitrobenzene
(with a PEL of 1 ppm), and the respirator used by employees has an
APF of 10, then the calculated MUC is 10 ppm (i.e., 1ppm x 10).
---------------------------------------------------------------------------

Importantly, the last part of the proposed definition specifies
exposure limits as ``permissible exposure limit (PEL), short-term
exposure limit (STEL),

[[Page 34094]]

ceiling limit (CL), peak limit, or any other exposure limit used for
the hazardous substance.'' The exposure limits are consistent with the
terms used in the Z tables in 29 CFR 1910.1000 and the substance-
specific standards in 29 CFR parts 1910, 1915, and 1926.
The phrase ``any other exposure limit used for the hazardous
substance'' refers to exposure limits other than the exposure limits
specified in the OSHA Z tables or in its substance-specific standards;
employers use the other exposure limits to provide additional
protection to employees or to comply with OSHA's general-duty clause
(Section 5(a)(1) of the OSH Act; 29 U.S.C. 654 where OSHA has no
standard). Employers may adopt such exposure limits from existing
consensus standards (e.g., the ACGIH TLVs), or develop them
specifically for the unique hazardous substances found in their
workplaces.
Paragraph (d)(3)(i)(A)--APF Provisions
1. Introduction
As early as 1976, respirator scientists were classifying
respirators into distinct groups based on the level of protection they
provided. These early respirator classes are similar to the classes now
in use, as well as the classes developed by OSHA for this proposal. In
the following parts of this section, the Agency describes the
historical development of APFs for specific classes of respirators, and
then explains OSHA's proposed APF for each of these respirator classes.
In addition to basing the APFs proposed in this rulemaking on the
studies and previous APF standards described in this section, the
Agency contracted with Dr. Kenneth Brown to conduct statistical
analyses of the original data reported in most of the WPF studies
reported below. Dr. Brown's quantitative analyses justify combining
data for filtering facepiece and elastomeric half-mask respirators in
determining an APF for these two respirator classes, and using a
qualitative analysis of the data for identifying APFs separately for
powered air-purifying respirators, supplied-air respirators, and self-
contained breathing apparatuses. (Note that insufficient WPF data were
available for Brown to include full facepiece air-purifying respirators
in his analyses.) OSHA discusses the procedures and results of these
statistical analyses in section IV of this preamble. The Agency
believes that the APFs developed through the procedures discussed below
are consistent with the results of the analyses performed by Dr. Brown.
2. Half-Mask Air-Purifying Respirators
Historical development of APFs for half-mask air-purifying
respirators. In 1976, Ed Hyatt of LANL tested eight commercially
available Bureau of Mines (the Federal agency then designated to
approve respirators) half-mask respirators (Ex. 2). Based on
quantitative fit testing results obtained from a respirator test
panel,\9\ Hyatt assigned six of these respirators an APF of 10; the
remaining two respirators performed less effectively than the other
six, thereby achieving an APF of less than 10. Hyatt did not use data
from the two poor performing respirators to set the APF of 10 for the
class because, as he stated in his report, ``For practical purposes,
the remaining two models are not available.''
---------------------------------------------------------------------------

\9\ LANL developed a respirator test panel consisting of 25 men
and women selected to have face sizes representing about 95% of the
U.S. working population (Ex. 7, docket H049).
---------------------------------------------------------------------------

In 1980, the ANSI Z88.2 Respiratory Protection Standard (i.e.,
``the 1980 ANSI standard;'' Ex. 10, Docket H049) required fit testing
to identify grossly misfitting half-mask respirators. That standard
assigned an APF of 10 to half-mask air-purifying respirators when
employers performed qualitative fit testing, and an APF as high as 100
when they performed quantitative fit testing (Ex. 10, Table 5, p. 21,
Docket H049). ANSI based the latter APF on the results of studies that
quantitatively fit tested a panel of respirator users, much as Hyatt
did in 1976 (Ex. 2).
NIOSH developed its RDL in 1987 (Ex. 1-54-437Q), which assigned an
APF of 5 to single-use and quarter mask air-purifying respirators, and
an APF of 10 to half-mask respirators, including disposable half-mask
respirators. In developing these APFs, NIOSH used results from
quantitative fit-test studies performed on its own respirator test
panel, several LANL quantitative fit-test studies (including Hyatt's
1976 study), and several WPF studies that it conducted in the early
1980s (Exs. 1-64-42, 1-64-47).
The 1992 Z88.2 ANSI Respiratory Protection Standard (i.e., ``the
1992 ANSI standard''; Ex. 1-50) retained an APF of 10 for half-mask
air-purifying respirators, including quarter masks, disposable half-
masks, and half-masks with elastomeric facepieces. In determining these
APFs, a committee of respirator experts convened by ANSI reviewed and
discussed available APF studies, and then arrived at a final decision
using a consensus process.
The following table summarizes the previous APFs assigned to half-
mask air-purifying respirators, beginning with Hyatt's studies at LLNL
in 1976 through the 1992 ANSI standard.

----------------------------------------------------------------------------------------------------------------
APFs
Half-mask air-purifying -----------------------------------------------------------------------------
respirators 1992 ANSI
LANL (1976) 1980 ANSI standard NIOSH RDL (1987) standard
----------------------------------------------------------------------------------------------------------------
Single use (no longer available) 5 ..................... 5.................... ..............
\1\.
Filtering facepiece............... .............. ..................... 10 (disposable)...... 10
Half-mask (elastomeric)........... 10 10 (with QLFT) 100 10................... 10
max. (with QNFT).
----------------------------------------------------------------------------------------------------------------
\1\ Filtering facepieces replaced single-use respirators.

OSHA's proposed APFs for half-mask air-purifying respirators.
Respirator manufacturers construct elastomeric half-masks using
malleable compounds (e.g., silicon, natural or synthetic rubber) that
readily conform to the respirator user's face, thereby effectively
sealing the inside of the mask against penetration by airborne
hazardous substances. Filtering facepieces also are available in a
variety of designs and materials that affect their fit to a user's
face. For example, the design of the ``fold flat'' filtering facepiece
allows employees to fold them for easy carrying and storage; when
employees need this respirator for protection, they unfold the mask and
place the fabric filter over their mouth and nose and then position the
attached elastic headbands or straps around their head.
Half-mask respirators, including the subclasses of elastomeric and
filtering facepiece respirators, vary widely in

[[Page 34095]]

design and construction; these characteristics could result in
different fitting characteristics which, in turn, can affect the level
of employee protection afforded by the respirators. In this regard, an
important question is whether available WPF and SWPF studies
demonstrate sufficient variability in protection between and among
filtering facepiece and elastomeric respirators to warrant different
APF levels.
OSHA reviewed available WPF and SWPF studies that determined APFs
for separate models of half-mask respirators based on each respirator's
performance. These studies usually determine a protection factor for
each respirator user (e.g., an employee in a WPF study, or a member of
a panel of respirator users in a SWPF study) who participates in the
study, with each of these values expressed as the concentration of
challenge agent outside the respirator (C_o) divided by the
concentration of that agent inside the respirator (C_i),
i.e., C_o/C_i. After collecting these values, a
statistical analysis determines the geometric distribution of the
values; the overall APF for the respirator is the estimated value that
lies at the fifth percentile of the geometric distribution. Listed in
the table below are the WPF studies on filtering facepiece and
elastomeric respirators reviewed by the Agency.

----------------------------------------------------------------------------------------------------------------
Geometric
WPF studies for filtering facepieces (by name of Sample size Geometric mean standard 5th percentile
authors and model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
Cohen (Ex. 1-64-11):
Prototype Mercury (disposable respirator)... 26 28 .............. 5
Albrecht et al. (Ex. 1-64-23):
3M 8710..................................... 13 81 1.99 25
3M 9910..................................... 13 107 2.50 20
3M 9920..................................... 10 223 2.38 45
Nelson and Dixon (Ex 1-64-54):
3M 8710..................................... 18 310 5.3 20
3M 9910..................................... 14 580 4.2 55
AO R1050.................................... 7 52 4.2 5
Reed et al. (Ex. 1-64-61):
3M 9910..................................... 19 18 3.1 3
Johnston and Mullins (Ex. 1-64-34):
3M 8715 (with aluminum particulate)......... 10 145 2.3 32
3M 8715 (with titanium particulate)......... 14 59 1.7 24
3M 8715 (with silicon particulate).......... 14 172 3.1 24
Colton et al. (Ex. 1-64-15):
3M 9906..................................... 23 27 1.5 13
Colton et al. (Ex. 1-64-16):
3M 9970 (with lead particulate)............. 62 415 4.4 36
3M 9970 (with zinc particulate)............. 62 681 5.6 40
Myers and Zhuang (Ex. 1-64-51) (conducted in a
brass foundry):
3M 9920 (with zinc particulate)............. 20 108 5.2 7
Myers and Zhuang (Ex. 3-14) (conducted in a
steel mill):
3M 8710 (with iron particulate)............. 10 377 3.7 44
Gerson 1710 (with iron particulate)......... 11 123 2.7 24
Colton and Mullins (Ex. 1-146):
3M 9920 and 3M 9925......................... 32 147 2.5 33
Wallis et al. (Ex. 1-64-70):
3M 8710..................................... 70 50 3.5 7.5
Lenhart and Decker (Ex. 1-64-56):
3M 9920..................................... 5 .............. .............. 12
3M 9970 (two separate studies).............. 2 .............. .............. 86 and 98
Gaboury and Burd (Ex. 1-64-24):
AO, Willson, Survivair...................... 18 47 2.5 9
Gavin et al. (Ex. 1-64-22):
North 7709 (with OV cartridge).............. 63 75 3.1 11.7
Weber and Mullins (Ex. 3-15):
3M 5000 (with OV cartridge)................. 46 39.7 2.14 11
Myers and Zhuang (Ex. 1-64-51) (conducted in a
brass foundry):
AO 5-Star (with DFM filter)................. 6 98 5.8 5
MSA Combo II (with DFM filter).............. 9 163 3.1 26
Scott 65 (with DFM filter).................. 6 94 4.8 7
Myers and Zhuang (Ex. 3-14) (conducted in a
steel mill):
AO 5-Star (with DM filter).................. 11 280 2.7 56
MSA Combo II (with DM filter)............... 8 427 4.3 39
Scott 65 (with DM filter)................... 11 252 2.9 45
Myers and Zhuang (Ex. 1-64-52) (conducted in a
paint-spraying facility):
AO 5-Star (with HEPA or OV filter).......... 38 2,211 .............. 171
MSA Combo II (with HEPA or OV filter)....... 38 4,580 .............. 437
Scott 65 (with HEPA or OV filter)........... 38 6,630 .............. 1,121
Lenhart and Campbell (Ex. 1-64-42):
MSA Combo (with HEPA filter)................ 25 180 4.1 18
Albrecht et al. (Ex. 1-64-23):
3M Easi-Air 7000 (with HEPA filter)......... 8 56 1.35 31
3M Easi-Air 7000 (with DM filter)........... 6 68 1.66 28
Dixon and Nelson (Ex. 1-64-54):
Survivair 2000 and MSA Combo II (with DFM 17 240 6.3 12
filter)....................................

[[Page 34096]]

Survivair 2000 and MSA Combo II (with HEPA 14 94 3.0 16
filter)....................................
North 7700 (with HEPA filter)............... 14 250 6.9 11
Dixon and Nelson (Ex. 1-64-19):
Survivair 2000 (with HEPA or OV filter)..... 37 3,400 3.8 390
Colton et al. (Ex. 1-64-13):
3M 6000 (with HEPA filter and cadmium 25 333 4.18 32
particulate)...............................
3M 6000 (with HEPA filter and lead fume).... 31 129 3.15 19
Colton and Bidwell (Ex. 4-10-4):
3M 7000 (with 7255 HEPA mechanical filter).. 21 1,006 4.65 80
3M 7000 (with 2040 HEPA electrostatic 22 562 3.5 71
filter)....................................
----------------------------------------------------------------------------------------------------------------

OSHA found only one SWPF study on half-mask air-purifying
respirators. In 1987, Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) of
LANL performed a SWPF study that included laboratory testing of the MSA
Comfo II half-mask air-purifying elastomeric respirator. The geometric
mean fit factors they measured during simulated work exercises ranged
from 800 to 5,700 for this half-mask. These results appear to
complement the WPF results discussed in the following paragraph.
The summary statistics for WPF studies of filtering facepieces and
elastomeric half-masks presented in the previous tables show little
difference between these two major subclasses of half-mask respirators.
Most importantly, the estimated protection factors for these two
subclasses evidence considerable overlap. In addition, both tables show
that many respirators in each class received estimated protection
factors above 10, while a few respirators performed below that level.
Accordingly, the WPF studies overall support assigning an APF of 10 for
this respirator class (i.e., half-masks), which consists of quarter
masks, filtering facepieces, and elastomeric half-mask respirators.
OSHA could find no studies on the performance of quarter masks, but
just as in the 1992 ANSI standard (Ex. 1-50) has included quarter masks
with half-masks.
The statistical analyses of these studies performed by Dr. Kenneth
Brown (see section IV above) corroborate these conclusions. These
analyses could not differentiate between filtering facepieces and
elastomeric half-masks, which justifies combining the study data for
these two subclasses into a single class for a subsequent APF
determination. This determination showed that nearly 96% of the WPF
data in these combined studies were at or above an APF of 10.
3. Full Facepiece Air-Purifying Respirators
Historical development of APFs for full facepiece air-purifying
respirators. In 1976, Ed Hyatt of LANL developed an APF table that
included this respirator class (Ex. 2). In this report, Hyatt used the
results from quantitative fit testing to assess six models of full
facepiece negative pressure air-purifying respirators equipped with
HEPA filters. Five of these respirators achieved a protection factor of
at least 100 for 95% of the respirator users; the sixth respirator
attained this level of protection for 70% of the users. Based on the
results for the sixth respirator, Hyatt recommended an APF of 50 for
the respirator class as a whole.
The 1980 ANSI standard listed an APF of 100 for full facepiece air-
purifying respirators with DFM filters. ANSI increased the APF for this
respirator class from 50 to 100 because the poorly performing
respirator in Hyatt's study was no longer in production. Using the 1976
LANL quantitative fit-testing results, the 1980 ANSI standard increased
this APF to a maximum of 1,000 when the respirator used HEPA filters
and the respirator users received quantitative fit testing.
Based on Hyatt's 1976 data, the 1987 NIOSH RDL recommended that
this respirator class receive an APF of 50 when equipped with a HEPA
filter, and an APF of 10 when using DFM filters. NIOSH developed the
lower APF of 10 for respirators equipped with DFM filters after it
tested the efficiency of these filters. In the absence of workplace
protection factor studies of full facepiece respirators, NIOSH based
these APFs on results from earlier quantitative fit testing performed
by LANL on panels of respirator users.
The 1992 ANSI standard retained the 1980 ANSI standard's APF of 100
for full facepiece air-purifying respirators, but required that
respirator users perform fit testing and achieve a minimum fit factor
of 1,000 prior to using the respirators; in this regard, quantitative
fit testing was necessary because no qualitative fit test could achieve
a fit factor of 1,000. The ANSI standard kept this APF because the ANSI
committee found that no new WPF or SWPF studies had been performed for
this respirator class since it last issued APFs in 1980.
The following table summarizes the previous APFs assigned to full
facepiece air-purifying respirators, beginning with Hyatt's studies at
LLNL in 1976 through the 1992 ANSI standard.

OSHA's proposed APFs for full facepiece air-purifying respirators.
Although the 1992 ANSI standard assigned an APF of 100 to full
facepiece air-purifying respirators, OSHA believes that studies
completed after 1992 indicate that an APF of 100 is too high. Colton,
Johnston, Mullins, and Rhoe (Ex. 1-64-14) assessed the protection
afforded to 13 employees over a four day period by the 3M 7800 full
facepiece air-purifying respirator equipped with a HEPA filter. In this
WPF study, the employees performed their regular tasks in the blast
furnace,

[[Page 34097]]

reverberatory furnace, and casting and warehouse areas of a lead
smelter while the authors sampled lead dust and fumes inside and
outside the respirator. The authors found a fifth percentile protection
factor of 95 for the combined samples, but concluded that the
respirator provided reliable protection at protection factors in excess
of 50.
Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) completed the only
SWPF study on a full facepiece air-purifying respirator at LANL; this
study measured the protection afforded by the MSA Ultra Twin with a
HEPA filter. Ten members of the respirator test panel used the
respirator under varying temperature and humidity conditions in a test
chamber while performing simulated work tasks. The authors reported fit
factors with geometric means ranging from 1,000 to 5,300 for this
respirator. However, 23 of the 60 measurements reported were less than
1,000, 7 were less than 100, and 3 of these measurements were less than
50.
After carefully reviewing these studies, OSHA is proposing an APF
of 50 for full facepiece air-purifying respirators. The proposed APF
agrees with the conclusion of Colton, Johnston, Mullins, and Rhoe (Ex.
1-64-14) that this class of respirators provides reliable protection at
an APF of 50. Additionally, the geometric mean simulated work fit
factors reported by Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) were
low for a SWPF study, and a few of the individual measurements were
below an APF of 50; in the workplace, the fifth percentile APF for this
respirator may fall well below 100. Therefore, in view of the paucity
of data reported for this class of respirators, and the constraints
imposed by the available studies, the Agency is proposing a
conservative APF that it believes would afford employees an adequate
and consistent level of respirator protection in the workplace.
Importantly, an APF of 50 corresponds with the APF assigned to full
facepiece air-purifying respirators by OSHA in its substance specific
standards, and by NIOSH in its 1987 RDL. In determining that an APF of
50 was appropriate for protecting employees against the contaminants
identified in its substance specific standards, the Agency reviewed the
existing scientific and technical information, and carefully considered
comments in the records. OSHA believes that the information now
available does not justify revising the previous APF determined for its
substance specific standards. To ensure that the final APF for this
class of respirators provides employees with appropriate protection,
the Agency requests that commenters submit to the record any additional
WPF and SWPF studies that may be available on full facepiece air-
purifying respirators.
4. Powered Air-Purifying Respirators (PAPRs)
Historical development of APFs for PAPRs. In 1976, Ed Hyatt of LANL
gave PAPRs equipped with high efficiency filters, regardless of
facepiece type, a protection factor of 1,000. In doing so, Hyatt
assumed, based on quantitative fit tests, that both tight-fitting and
loose-fitting facepiece PAPRs would always maintain a positive pressure
inside the facepiece.
The committee responsible for drafting the 1980 ANSI standard
assigned an APF of 3,000 to PAPRs equipped with high efficiency
filters. When the respirators used DFM filters, they received an APF of
100. The ANSI committee did not require fit testing for PAPRs because
it assumed, as did Hyatt, that these respirators would maintain
positive pressure during use.
The 1987 NIOSH RDL assigned an APF of 25 to half-mask PAPRs after
NIOSH reviewed the results of two WPF studies that it conducted on
these respirators (Ex. 1-64-42 and 1-64-46). The RDL also gave loose-
fitting PAPRs with hoods or helmet an APF of 25 based on data from two
studies performed by Myers, Peach, Cutright, and Iskander (Exs. 1-64-47
and 1-64-48). However, the RDL recommended an APF of 50 for other PAPRs
equipped with a tight-fitting facepiece or a hood or helmet, as well as
high efficiency filters or gas-vapor cartridges used in combination
with high efficiency filters.
The committee developing the 1992 ANSI standard updated the APFs
specified in the 1980 ANSI standard. Accordingly, the committee
recommended an APF of 50 for tight-fitting half-mask PAPRs based on the
same WPF studies used by NIOSH in developing the 1987 RDL. Tight-
fitting full facepiece PAPRs received an APF of 100 when equipped with
dust filters (based on performance limitations of the filters), and an
APF of 1,000 when used with HEPA filters. While the ANSI committee
retained an APF of 25 for loose-fitting facepiece PAPRs, including
loose-fitting hoods and helmets, it treated tight-fitting PAPRs with
hoods or helmets much as it did tight-fitting full facepiece PAPRs
(i.e., by assigning them an APF of 100 when used with a dust filter,
and an APF of 1,000 when equipped with a HEPA filter).
The following table summarizes the previous APFs assigned to PAPRs,
beginning with Hyatt's studies at LANL in 1976 through the 1992 ANSI
standard.

----------------------------------------------------------------------------------------------------------------
APFs
Powered air-purifying -------------------------------------------------------------------------------
respirators (PAPRs) LANL
(1976) 1980 ANSI standard NIOSH RDL (1987) 1992 ANSI standard
----------------------------------------------------------------------------------------------------------------
Half-mask....................... 1,000 100 (with DFM filter), 50 (with HEPA 50.
3,000 max. (with HEPA filter).
filters).
Full facepiece.................. 1,000 100 (with DFM filter), 50 (with HEPA 100 (with dust
3,000 max. (with HEPA filter). filter), 1,000
filters). (with HEPA
filter).
Hoods or helmets................ 1,000 100 (with DFM filter), 50 (with HEPA 100 (with dust
3,000 max. (with HEPA filter). filter), 1,000
filters). (with HEPA
filter).
Loose-fitting facepiece......... 1,000 100 (with DFM filter), 25 (with any 25.
3,000 max. (with HEPA filter).
filters).
----------------------------------------------------------------------------------------------------------------

OSHA's proposed APFs for half-mask PAPRs. In 1983, Meyers and Peach
performed a WPF study on tight-fitting half-mask and full facepiece
PAPRs in a silica-bagging operation (Ex. 1-64-46). The geometric mean
protection factors for each of the seven employees who used the half-
mask PAPRs ranged from 19 to 193, with a geometric mean protection
factor of 54 for the entire sample. The authors attributed the poor
performance of the half-mask PAPRs to leakage around the filter
assembly connection where it attached to the PAPR blower housing, as
well as to inadequate facepiece fit.
Lenhart and Campbell of NIOSH in 1984 conducted another WPF study
of tight-fitting half-mask PAPRs used by employees in the sinter plant
and furnace areas of a primary lead smelter

[[Page 34098]]

(Ex. 1-64-42). For the entire sample, the authors reported a geometric
mean protection factor of 380 and a fifth-percentile protection factor
of 58.
Two SWPF studies also evaluated tight-fitting half-mask PAPRs.
Skaggs, Loibl, Carter, and Hyatt (Ex. 1-38-3) used fit testing to
assess the performance of the respirators in a test chamber under
variable temperature and humidity conditions. They found that the
geometric mean protection factor for the entire sample ranged from
14,200 to 20,000. In the second SWPF study, da Roza, Cadena-Fix, and
Kramer tested a panel of respirator users who exercised on a treadmill
at different work rates (Ex. 1-64-94). The geometric mean protection
factor for the entire sample (i.e., combining respirator performance at
all work rates) was 5,000.
The following table provides a summary of the WPF and SWPF studies
for tight-fitting half-mask PAPRs.

----------------------------------------------------------------------------------------------------------------
Geometric
WPF studies for half-mask PAPRs (by name of Sample size Geometric mean standard 5th percentile
authors and type/model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
Lenhart and Campbell (Ex. 1-64-42), MSA......... 25 380 2.6 58
Myers and Peach (Ex. 1-64-46), PAPR 10 54 2.44 ..............
(manufacturer and model not specified).........
----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------
Geometric
SWPF studies for half-mask PAPRs (by name of Sample size Geometric mean standard 5th percentile
authors and type/model of respirator tested) deviation SWPF
----------------------------------------------------------------------------------------------------------------
Skaggs et al. (Ex. 1-38-3), MSA with Comfo II 60 14,200-20,000 .............. ..............
facepiece......................................
da Roza et al. (Ex. 1-64-94), MSA with Comfo \1\ 6 \2\ 5,000 .............. ..............
facepiece......................................
----------------------------------------------------------------------------------------------------------------
\1\ The six respirator users of the test panel exercised on a treadmill.
\2\ The geometric mean is for all exercise rates combined.

In arriving at a proposed APF of 50 for tight-fitting half-mask
PAPRs, OSHA relied to a large extent on the WPF study conducted by
Lenhart and Campbell. This study was well controlled and collected data
under actual workplace conditions; these conditions ensure that the
results are reliable and represent the protection employees likely
would receive under conditions of normal respirator use. The Agency did
not consider the Meyers and Peach WPF study for this purpose because of
problems involving filter assembly leakage and poor facepiece fit
reported by the authors; consequently, the abnormally high levels of
silica measured inside the mask would most likely underestimate the
true protection afforded by the respirator. The two SWPF studies
reported much higher geometric mean protection factors than did the WPF
study performed by Lenhart and Campbell. However, OSHA believes that
the higher protection factors reported for these SWPF studies are
consistent with the proposed APF of 50 based on data obtained for this
respirator class in the Lenhart and Campbell WPF study because SWPF
studies typically report significantly higher protection factors than
WPF studies of the same respirator. In addition, the proposed APF
duplicates the APFs assigned to tight-fitting half-mask respirators by
the 1987 NIOSH RDL and the 1992 ANSI standard, both of which based
their APF determinations on data reported in the existing scientific
literature, as well as the opinions of well known experts on
respiratory protection.
OSHA's proposed APFs for full facepiece PAPRs and PAPRs with hoods
or helmets. Two WPF studies determined protection factors for tight-
fitting full facepiece PAPRs. Myers and Peach conducted the first of
these studies in 1983 (Ex. 1-64-46); OSHA described this study in its
earlier discussion of tight-fitting half-mask PAPRs. As noted in this
discussion, the Agency did not use the results of this study because of
problems involving filter assembly leakage and poor facepiece fit
reported by the authors. The second WPF study, by Colton and Mullins,
reported a geometric mean protection factor of 4,226, and a fifth
percentile protection factor of 728 for employees in a secondary lead
smelter (Ex. 1-64-12). Thirty-four samples in this study had no
detectable lead inside the respirators; therefore, the authors used the
limit of detection for lead as a proxy for the concentration of lead
inside the facepiece. When the authors corrected their data analysis by
including these samples, the geometric mean protection factor increased
to 8,843, and the fifth percentile protection factor rose to 1,335. No
SWPF studies on full facepiece PAPRs were available.
One WPF study and one SWPF study are available for tight-fitting
PAPRs with hoods or helmets. In the WPF study, Keys, Guy, and Axon,
determined the protection afforded to employees in a pharmaceutical
manufacturing plant by three different respirators in this class (Ex.
1-64-40). The fifth percentile protection factors for these respirators
were 997, 1,197, and 1,470. Johnson, Biermann, and Foote of LLNL and
Cohen, Hecker, and Mattheis of the Organization Resources Counselors
(ORC) performed the single SWPF study (referred to here as ``the ORC-
LLNL SWPF Study'') in which they collected 576 test samples from four
different PAPRs with hoods or helmets, and equipped with bibs (Ex. 3-4-
2). The lowest protection factor among the 576 test samples was 11,000;
overall, the 576 test samples had a fifth percentile protection factor
greater than 250,000.
The following tables summarize the WPF studies for tight-fitting
full facepiece PAPRs, and the WPF and SWPF studies involving PAPRs with
hoods or helmets.

----------------------------------------------------------------------------------------------------------------
Geometric
WPF studies for full facepiece PAPRs (by name of Sample size Geometric mean standard 5th percentile
authors and model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
Colton and Mullins (Ex. 1-64-12) 3M W-3205
Whitecap (with 3M 7800 full facepiece and HEPA
filter):
Study 1\1\.................................. 20 4,226 2.9 728

[[Page 34099]]

Study 2..................................... 55 8,843 3.2 1,335
Myers and Peach (Ex. 1-64-46) Full facepiece 10 54 2.44 ..............
PAPR (manufacturer and model not specified)....
----------------------------------------------------------------------------------------------------------------
\1\ Study 1 consisted of 20 samples with C_i values over the detection limit, while Study 2 consisted of 34
samples that had C_i values below the detection limit; for analytic purposes, the investigators assigned these
34 samples a C_i value equal to the detection limit.

----------------------------------------------------------------------------------------------------------------
Geometric
WPF studies for PAPRs with hoods or helmets (by Sample size Geometric mean standard 5th percentile
name of authors and model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
Keys et al. (Ex. 1-64-40):
Racal Breathe Easy 10 (hood, double bib, 29 11,137 3.9 1,197
HEPA filter)...............................
Bullard Quantum (hood, double bib, HEPA 9 9,574 3.1 1,470
filter)....................................
3M Whitecap II (helmet, double bib, HEPA 22 42,260 9.8 997
filter)....................................
----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------
SWPF studies for PAPRs with hoods or helmets (by Geometric median 5th percentile
name of authors and model of respirator tested) Range of SWPFs SWPF SWPF
----------------------------------------------------------------------------------------------------------------
ORC-LLNL SWPF Study (Ex. 3-4):
3M Whitecap (helmet with bib and HEPA filter)... 140,000-£ £250,000 £250,000
250,000
3M Snapcap (Tyvek hood with bib and HEPA filter) 11,000-£ £250,000 £170,000
250,000 -210,000
Racal BE-5 Clear PVC (hood with bib and HEPA 11,000-£ £250,000 £250,000
filter)........................................ 250,000
Racal BE-10 (Tyvek hood with bib and HEPA 94,000-£ £250,000 246,000-£
filter)........................................ 250,000 250,000
----------------------------------------------------------------------------------------------------------------

OSHA is proposing an APF of 1,000 for full facepiece PAPRs and
PAPRs with hoods or helmets. With regard to full facepiece PAPRs, the
corrected fifth percentile protection factor of 1,335 reported by
Colton and Mullins in their WPF study fully supports the proposed APF.
The WPF study of PAPRs with hoods or helmets by Keys, Guy, and Axon
justifies the proposed APF of 1,000 for this respirator class. These
authors reported that the average fifth percentile protection factor
for the three respirators tested in their study was well over 1,000.
Moreover, the ORC-LLNL SWPF Study (Ex. 3-4), in which this class of
respirators received extremely high fifth percentile protection
factors, lends substantial validation to OSHA's proposed APF. In
addition, the proposed APFs for full facepiece PAPRs and PAPRs with
hoods or helmets corresponds with the APFs assigned to these respirator
classes in the 1992 ANSI standard; ANSI made these APF determinations
only after a careful review and discussion of the available research by
a panel of respirator experts. While the proposed APF for these
respirators is much higher than the APF recommended in the 1987 NIOSH
RDL, the Agency believes that the WPF and SWPF studies conducted on
these respirators since publication of the RDL justify the proposed
increase.
Footnote 4 of the proposed APF table states that ``* * * only
helmet/hood respirators that ensure the maintenance of a positive
pressure inside the facepiece during use, consistent with performance
at a level of protection of 1000 or greater, receive an APF of 1,000.''
The footnote continues, ``All other helmet/hood respirators are treated
as loose-fitting facepiece respirators and receive an APF of 25.'' OSHA
is proposing that respirators from this class be able to demonstrate
that they maintain a positive pressure inside the facepiece during use
and achieve a level of protection of 1000 or greater. Available WPF and
SWPF studies have found that some of these respirators were shown to
only achieve protection factors well below 1,000 (Exs. 3-4, 3-5). In
all likelihood, the burden of conducting any testing would fall on
respirator manufacturers, but the employer would be responsible for
selecting a properly tested respirator, thereby assuring employees that
they will receive adequate protection against toxic hazards.
OSHA's proposed APFs for loose-fitting PAPRs. A number of WPF and
SWPF studies are available for loose-fitting facepiece PAPRs. An
important purpose of these studies was to determine if APFs differed
between loose-fitting facepiece PAPRs and PAPRs with tight-fitting
hoods or helmets. The NIOSH WPF study by Myers, Peach, Cutright, and
Iskander (Ex. 1-64-47) was the first to report that loose-fitting
facepiece PAPRs did not perform at an APF of 1,000, the value
determined by Ed Hyatt in 1976 after quantitatively fit testing a panel
of respirator users. A follow-up study by Myers, Peach, Cutright, and
Iskander (Ex. 1-64-48) reported a fifth percentile protection factor of
25 for this respirator class.
A WPF study conducted later by Albrecht, Gosselink, Wilmes, and
Mullins (Ex. 1-64-23) reported a fifth percentile protection factor of
42 for the 3M Airhat, a loose-fitting facepiece PAPR with a helmet.
Stokes, Johnston, and Mullins (Ex. 1-64-66) performed a WPF study in a
roofing granule production plant using the 3M Airhat; they found a
fifth percentile protection factor of 95. However, when employees used
the respirator with a Tyvek shroud, the fifth percentile protection
factor increased to 1,615. Gaboury and Burd (Ex. 1-64-24) reported a
fifth percentile protection factor of 275 in a WPF study in which
employees in an aluminum smelter wore a Racal Breathe Easy loose-
fitting facepiece PAPR with a helmet. Collia, Colton, and Bidwell (Ex.
3-5) found a fifth percentile protection factor of 315 in a WPF study
performed on the 3M Breathe Easy 12 PAPR with a loose-fitting head
cover.
OSHA evaluated three SWPF studies addressing the performance of
loose-fitting facepiece PAPRs with hoods or helmets. Skaggs, Loibl,
Carter, and Hyatt (Ex. 1-38-3) reported geometric mean protection
factors ranging from 1,900 to 5,600 for the 3M Airhat, and from 1,200
to 3,500 for the Racal AH3 PAPR with a loose-fitting helmet. A study by
da Roza, Cadena-Fix, and Kramer (Ex. 1-64-94) found geometric mean
protection factors ranging from 10 to 10,000, and from 100 to 20,000,
for the two loose-fitting facepiece PAPRs with helmets they tested.

[[Page 34100]]

Johnson, Biermann, and Foote of LLNL and Cohen, Hecker, and
Mattheis of ORC (Ex. 3-4) assessed the performance of one loose-fitting
facepiece PAPR with a Tyvek head cover as part of the ORC-LLNL SWPF
Study; the results of this study reported three APFs below 10,000, with
the lowest value being 240. The fifth percentile protection factor for
this respirator ranged from 150,000 to 230,000.
The following tables summarize the WPF and SWPF studies for loose-
fitting facepiece PAPRs with hoods or helmets.

----------------------------------------------------------------------------------------------------------------
WPF studies for loose-fitting facepiece PAPRs Geometric
with hoods or helmets (by name of authors and Sample size Geometric mean standard 5th percentile
model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
Myers et al.(Ex. 1-64-47):
3M W-344 (helmet with HEPA filter)....... 23 165 3.57 26
Racal AH 3 (helmet with HEPA filter)..... 23 205 2.83 26
Albrecht et al. (Ex. 1-64-23) 3M Airhat 7 199 2.36 42
(helmet with HEPA filter)...................
Myers et al. (Ex. 1-64-48):
3M W-316 (helmet with DM filter)......... 22 135 1.89 25
Racal AH 5 (helmet with DM filter)....... 24 120 2.64 25
Gaboury and Burd (Ex. 1-64-24) Racal Breathe 20 1,414 2.51 275
Easy I (helmet with HEPA or OV filter)......
Collia et al. (Ex. 3-5) 3M Breathe Easy 12 41 2,523 .............. 315
(Tyvek head cover with HEPA filter).........
Stokes et al. (Ex. 1-64-66):
3M Airhat (helmet) with:
HEPA filter (total)\1\............... 12 5,370 3.0 762
DM filter (without shroud)........... 27 877 5.2 53
DM filter (with shroud).............. 18 11,792 3.1 1,615
DM filter (total).................... 45 2,480 7.0 95
----------------------------------------------------------------------------------------------------------------
\1\ The total consists of the shroud and no-shroud samples combined.

----------------------------------------------------------------------------------------------------------------
SWPF studies for loose-fitting facepiece
PAPRs with hoods or helmets (by name of Sample size Geometric mean Geometric 5th percentile
authors and model of respirator tested) median SWPF
----------------------------------------------------------------------------------------------------------------
Skaggs et al. (Ex. 1-38-3):
3M Airhat W-344 (helmet)................. 60 1,900-5,600 .............. .................
Racal AH3 Airstream (helmet)............. 60 1,200-3,500 .............. .................
da Roza et al. (Ex. 1-64-94):
3M Airhat W-344 (helmet)................. \1\ 6 10-10,000 .............. .................
Racal Breathe-Easy 1 (helmet)............ 6 100-20,000 .............. .................
ORC-LLNL SWPF Study (Ex. 3-4):
Racal BE-12 (Tyvek head cover)........... 144 240-250,000 250,000 150,000-230,000
----------------------------------------------------------------------------------------------------------------
\1\ Used same panel of six respirator users for both respirators; panel exercised on treadmill at 80% cardiac
capacity.

OSHA is proposing an APF of 25 for loose-fitting PAPRs with hoods
or helmets, which is consistent with both WPF studies conducted by
Myers, Peach, Outright, and Iskander (Ex. 1-64-47 and 1-64-48), as well
as the APFs for this respirator class established by the 1987 NIOSH RDL
and by the 1992 ANSI standard. The extreme variability of the fifth
percentile protection factors in the WPF studies warrants a
conservative approach in proposing an APF for this respirator class. In
this regard, seven of the 11 WPF studies found fifth percentile
protection factors of less than 100, and five of these APFs were below
50. The Agency believes that a proposed APF of 25 would provide
employees who use these respirators with an adequate safety margin in
view of the unreliability of the protection factors found for this
respirator class.
The geometric means reported by Skaggs, Loibl, Carter, and Hyatt
(Ex. 1-38-3) were low for a SWPF study, as were a number of the
geometric means determined by de Rosa, Cadena-Fix, and Kramer (Ex. 1-
64-94) in their SWPF assessments. In the workplace, these low geometric
mean SWPFs likely would translate into fifth percentile WPFs of less
than 50. Therefore, the limited and highly variable data in the SWPF
studies support OSHA's conclusion that a conservative APF of 25 would
afford employees an adequate and consistent level of respirator
protection in the workplace.
5. Supplied-Air Respirators (SARs)
Historical development of APFs for SARs. SARs operate in one of
three modes--demand, continuous flow, or pressure demand. Demand or
pressure demand respirators have either a tight-fitting half-mask or a
tight-fitting full facepiece, while continuous flow respirators have
either a tight-fitting, or a loose-fitting, hood or helmet, or a tight-
fitting half-mask or full facepiece.
In 1976, Ed Hyatt of LANL published the initial protection factors
for SARs (Ex. 2). In making these determinations, Hyatt gave an APF of
10 to half-mask SARs operated in the demand mode, while full facepiece
SARs received an APF of 50 in the demand mode. These APFs are the same
APFs that Hyatt assigned to negative pressure half-masks, and full
facepiece, air-purifying respirators. Hyatt based the APF of 10 for
half-mask SARs operating in the demand mode on LANL studies performed
in 1971 and 1972 on a respirator test panel wearing eight half-mask
air-purifying respirators equipped with HEPA filter. In determining an
APF of 50 for full facepieces, Hyatt relied on LANL studies in which a
respirator test panel consisting of 31 firemen wore full facepiece
SCBAs operating in the demand mode.
Hyatt regarded SARs that operate in a positive pressure mode to be
more protective than SARs used in a negative pressure mode; therefore,
he assigned half-mask and full facepiece SARs that function in the
continuous flow, pressure demand, or other positive pressure modes APFs
of 1,000 and 2,000, respectively; the half-mask respirators received a
lower APF than the full facepiece respirators because

[[Page 34101]]

Hyatt considered a half-mask to be less stable on the face than a full
facepiece. SARs with hoods or helmets operated in continuous flow mode
received an APF of 2,000, consistent with the APF Hyatt gave to full
facepiece SARs operating in the continuous flow or pressure demand
mode.
The 1980 ANSI standard differentiated APFs for some SARs depending
on the type of fit testing performed. Accordingly, half-mask and full
facepiece SARs used in the demand mode received APFs of 10 and 100,
respectively, when qualitatively fit tested. When tested
quantitatively, the APFs for these respirators were the protection
factors achieved during fit testing, with the APF limited to the sub-
IDLH value \10\ of the hazardous substance in the workplace.
---------------------------------------------------------------------------

\10\ The concentration of the hazardous substance just below its
IDLH value.
---------------------------------------------------------------------------

Half-mask or full facepiece SARs that functioned in continuous flow
or pressure demand modes required no fit testing because of their
positive pressure operation; consequently, these respirators received
an APF limited only to the sub-IDLH value of the hazardous substance in
the workplace when used without an auxiliary air supply or escape
bottle (i.e., the ``escape configuration''). When equipped in an escape
configuration, these respirators had a maximum APF of 10,000.
Continuous flow or pressure demand SARs with hoods or helmets also
received a maximum APF of 10,000 when not used in an escape
configuration; however, when operated in a escape configuration, the
maximum APF for these respirators was of 10,000+ (i.e., employees could
use them to escape from IDLH atmospheres).
The 1987 NIOSH RDL recommended APFs of 10, 50, and 1,000,
respectively, for half-mask SARs when operated in demand, continuous
flow, and positive pressure (including pressure demand) modes. All SARs
with hoods or helmets received an APF of 25 when used in the
continuous-flow mode. The RDL assigned full facepiece SARs an APF of 50
when they functioned in the demand or continuous flow mode, an APF of
2,000 when operated in the pressure demand or other positive pressure
mode, and a maximum APF of 10,000 when used in the pressure demand mode
with an auxiliary SCBA.
The 1992 ANSI standard did not set different APFs for the same
class of respirator based on the type of fit testing conducted because
WPF studies performed after publication of the 1980 ANSI standard did
not support this practice. After comparing the operational
characteristics of half-mask and full facepiece SARs to half-mask and
full facepiece air-purifying respirators, the 1992 ANSI standard gave
APFs of 10 and 100, respectively, to half-mask and full facepiece SARs
when operated in the demand mode. Pressure demand and continuous flow
half-mask SARs received an APF of 50, consistent with their operational
similarities with half-mask PAPRs. Full facepiece continuous flow SARs
received an APF of 1,000, determined from their operational analogy to
SARs having tight-fitting hoods or helmets. Based on their operational
similarities to loose-fitting continuous flow PAPRs, the committee
drafting the 1992 ANSI standard gave loose-fitting facepiece SARs
operated in the continuous flow mode an APF of 25.
The following table summarizes the APFs given to the various
classes of SARs (i.e., half-mask, full facepiece, tight-fitting with
hoods or helmets, and loose-fitting facepiece), beginning with Hyatt's
studies at LLNL in 1976 through the 1992 ANSI standard.

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
APFs
SARs ---------------------------------------------------------------------------------------------------------------------------------------
LANL (1976) 1980 ANSI standard NIOSH RDL (1987) 1992 ANSI standard
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Half-mask........................... 10 (demand)................................ 10 (demand; with QLFT) 10 (demand)................................ 10 (demand).
1,000 (continuous flow).................... Same as QNFT factor 50 (continuous flow)....................... 50 (continuous flow).
(demand; sub-IDLH
value max.).
1,000 (pressure demand).................... Sub-IDLH (continuous 1,000 (pressure demand).................... 50 (pressure demand).
flow or pressure
demand; no escape
configuration).
10,000 max. (with
escape configuration).
Full facepiece...................... 50 (demand)................................ 100 (demand; with 50 (demand)................................ 100 (demand).
QLFT).
2,000 (continuous flow).................... Same as QNFT factor 50 (continuous flow)....................... 1,000 (continuous flow).
(demand; sub-IDLH
value max.).
2,000 (pressure demand).................... Sub-IDLH (continuous 2,000 (pressure demand).................... 1,000 (pressure demand).
flow or pressure
demand; no escape
configuration).
10,000 max. (with
escape configuration).
Hood or helmet...................... 2,000 (continuous flow).................... Sub-IDLH (continuous 25 (continuous flow)....................... 1,000 (continuous flow).
flow or pressure
demand; no escape
configuration).
10,000 max. (with
escape configuration).
Loose-fitting facepiece............. ........................................... ...................... 25 (continuous flow)....................... 25 (continuous flow).
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 34102]]

OSHA's proposed APFs for half-mask SARs. No WPF studies were
available for half-mask SARs. Therefore, OSHA is proposing an APF of 10
for this respirator class when used in the demand mode based on their
analogous operational performance with negative pressure half-mask air-
purifying respirators tested during WPF and SWPF studies. In addition,
the Agency proposes to give half-mask SARs that function in the
continuous flow or pressure demand modes an APF of 50, consistent with
the performance of half-mask PAPRs in WPF and SWPF studies (and
operated at the same airflow rates). Additional support for the
proposed APFs comes from the 1992 ANSI standard, which assigned an APF
of 10 to half-mask airline SARs operated in the demand mode, and an APF
of 50 when operated in the continuous flow or pressure demand mode. The
1987 NIOSH RDL also gave half-mask demand SARs an APF of 10, but
recommended an APF of 1,000 for these respirators when functioning in
the pressure demand or other positive pressure modes.
Regarding the recommended APF of 1,000, OSHA preliminarily finds
that these respirators warrant the more conservative APF of 50 because
of the possibility that negative pressure could develop inside the mask
during tasks that stress the facepiece seal; moreover, in the absence
of WPF and SWPF data for these respirators, the Agency believes that a
conservative approach to setting this APF is appropriate.
OSHA's proposed APFs for full facepiece SARs. No WPF or SWPF
studies were available involving tight-fitting full facepiece SARs
operated in the demand mode. Therefore, in the absence any such data,
the Agency is assigning this respirator class an APF of 50 based on the
analogous operational characteristics between these respirators and
negative pressure air-purifying respirators when operated in the demand
mode under WPF conditions. The proposed APF is the same as the APF
recommended for this respirator class by the 1987 NIOSH RDL, and
similar to the APF (i.e., 100) given to these respirators by the 1992
ANSI standard. In choosing an APF of 50 instead of 100 for this class
of respirators, the Agency believes that the paucity of WPF and SWPF
studies warrants taking a conservative approach in this determination.
While no WPF studies for full facepiece SARs operated in the
pressure demand or other positive pressure modes were available, there
was one SWPF study of this respirator class by Skaggs, Loibl, Carter,
and Hyatt (Ex. 1-38-3). The study, performed at LANL, evaluated the
respirators under different temperature and humidity conditions; the
results of the study showed that these respirators had geometric mean
protection factors ranging from 8,500 to 20,000. Therefore, the Agency
is proposing an APF of 1,000 for full facepiece SARs used in the
pressure demand or other positive pressure modes based on their
performance in this study (i.e., that the likelihood is high that the
geometric mean SWPFs would translate to fifth percentile WPF of 1,000.
Further justification for the proposed APF comes from the similarity in
operational characteristics (including the same minimum airflow rates)
between these respirators and tight-fitting full facepiece continuous
flow PAPRs, which are receiving a proposed APF of 1,000 in this
rulemaking. (See the discussion of these PAPRs above).
The proposed APF of 1,000 for full facepiece SARs operated in the
pressure demand or other positive pressure modes also is consistent
with the APFs of 1,000 assigned by the 1992 ANSI standard to these
respirators when used in the continuous flow or pressure demand modes,
and the APF of 2,000 recommended by the 1987 NIOSH RDL for pressure
demand respirators in this class. Although the RDL gave an APF of 50 to
these respirators in a continuous flow mode, the Agency believes that
the SWPF study, as well as the WPF studies performed on analogous
tight-fitting full facepiece continuous flow PAPRs, justify the
proposed APF.
OSHA's proposed APF for SARs with hoods or helmets. The Agency
found a number of WPF studies on these respirators, including one by
Johnston, Stokes, Mullins, and Rhoe (Ex. 1-64-36).
These authors performed a WPF study on the 3M Whitecap continuous
flow abrasive blasting helmet (equipped with an extended length shroud)
used by four shipyard employees while sandblasting a barge. After
performing several data analyses, the authors concluded that outside-
the-respirator samples with filter loadings at least 1,000 times
greater than the mean blank value were most representative of the
respirator's performance. Therefore, OSHA is using only statistics
based on these samples for its APF determinations; these statistics
indicate that the estimated fifth percentile protection factor is 1,038
for these samples.
Johnston, Stokes, Mullins, and Rhoe (Ex. 1-64-37) conducted a
second WPF study on the 3M Whitecap II general purpose SAR with a
helmet. In this study, the authors sampled six employees while they
performed grinding operations in a foundry. The authors stated that
``because of the relatively low sample loadings, the WPF numbers
obtained significantly underestimate the performance capability of the
respirator.'' Therefore, OSHA did not use the WPFs from this study in
developing the proposed APF for this respirator class.
Colton, Mullins, and Bidwell (Ex. 1-64-17) published a WPF study on
foundry employees who used the 3M Snapcap continuous flow SAR with an
abrasive blasting hood while exposed to silica during tear-down
operations. The authors reported a fifth percentile protection factor
over 1,000, which they noted was consistent with the APF of 1,000
assigned to these respirators by the 1992 ANSI standard.
In another WPF study, Nelson, Wheeler, and Mustard (Ex. 3-6)
sampled aircraft assembly employees involved in sanding and primer
spraying operations while using the 3M H-422 continuous flow SAR hood
with both an outer and inner shroud. The authors reported that 14 of
the 31 samples taken during primer spraying operations showed
measurable concentrations of strontium (Sr) outside the facepiece
(C_o), but none of the samples showed any measurable
concentration of Sr inside the facepiece (C_i). Based on
these C_o data, and using the lowest detectable limit for
C_i, the authors concluded that ``the WPFs were greater than
1,200 for all samples with a mass of Sr on the C_o samples
1,000 times the detection limit for the C_i samples.'' They
stated further that their study supports the APF of 1,000 given to
these respirators by the 1992 ANSI standard.
In a WPF study conducted at Avondale shipyard, Kiefer, Trout, and
Wallace (Ex. 2-1) sampled the total particulate exposures (i.e., small
and large particle fractions combined) of employees involved in
abrasive blasting operations while using the Bullard Type 88 CE
(continuous flow) SAR abrasive blasting hood. The authors reported WPFs
ranging from 2,817 to 10,000.
OSHA identified four SWPF studies of this respirator class, all
performed by LLNL or LANL for manufacturers of continuous flow SARs
with abrasive blasting hoods or helmets. The geometric mean protection
factors found for these respirators were 40,000 for the Bullard Model
77 and 88 Type CE (continuous flow) SARs with an abrasive blasting hood
(Ex. 1-157), and 100,000 for the Clemco Apollo 20 and 60 Type CE
(continuous flow) SARs with an abrasive blasting hood (Ex. 3-7-3) and
the 3M Whitecap Model W-8100 Type CE (continuous flow) SAR

[[Page 34103]]

with abrasive blasting helmet (Ex. 3-9-2). Based on the results of
these studies, OSHA granted these respirators an interim APF of 1,000
(Exs. 3-7-4, 3-8-4, 3-9-3).
In the latest SWPF study, Johnson, Biermann, and Foote of LLNL and
Cohen, Hecker, and Mattheis of ORC (Ex. 3-4) tested six models of
continuous flow SARs with hoods or helmets as part of the ORC-LLNL SWPF
Study. Five of these respirators had fifth percentile SWPFs ranging
from 86,000 to over 250,000. However, the fifth percentile SWPFs for
the sixth respirator (the North Model 85302 T) ranged from 13 to 18.
The authors attributed the poor performance of this respirator to the
absence of a ``tuck-in'' bib. When the manufacturer corrected this
design problem by adding a tuck-in bib, the resulting model (designated
the North Model 85302 TB) performed as well as most of the other
respirators tested in the study.
The following tables summarize the WPF and SWPF studies for tight-
fitting SARs with hoods or helmets.

----------------------------------------------------------------------------------------------------------------
Geometric
WPF studies for SARS with hoods or helmets (by Sample size Geometric mean standard 5th percentile
name of authors and model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
Johnston et al. (Ex. 1-64-36) 3M W-8100 Whitecap 15 4,076 2.3 1,038
II (abrasive blasting helmet with extended-
length shroud).................................
Johnston et al. (Ex. 1-64-37):
3M W-8000 Whitecap II (helmet)
Study 1 (using £750 x field 8 1,012 2.6 199
blank with iron dust samples)..........
Study 2 (using £30 x field 8 1,417 3.0 224
blank with silicon dust samples).......
Colton et al. (Ex. 1-64-17), 3M Snapcap W-3256 14 10,344 2.5 2,290
(abrasive blasting hood).......................
Nelson et al. (Ex. 3-6), 3M H-422 (hood)........ 31 .............. .............. £1,0
00
Kiefer et al. (Ex. 2-1), Bullard 88 Type Type CE 11 .............. .............. £1,0
(abrasive blasting hood)....................... 00
----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------
SWPF studies for SARs with hoods or helmets (by name Geometric mean/ 5th percentile
of authors and model of respirator tested) Range of SWPFs median SWPF SWPF
----------------------------------------------------------------------------------------------------------------
Bullard-LLNL (Ex. 1-157) \1\, Bullard 77 and 88 Type .................. £40,000 .................
CE (abrasive blasting helmet)...................... (mean)
Clemco-LANL (Ex. 3-7-3) \2\, Apollo 20 and 60 Type .................. £100,000 .................
CE (abrasive blasting hood)........................ (mean)
3M-LANL (Ex. 3-9-2) \3\, 3M Whitecap Model W-8100 .................. £100,000 .................
Type CE (abrasive blasting helmet)................. (mean)
ORC-LLNL SWPF Study (Ex. 3-4-2):
3M Whitecap SAR (helmet with bib and chinstrap). 68,000-£ £250,000 £250,00
250,000 (median) 0
3M Snapcap (Tyvek hood with bib and chinstrap).. 13,000-£ £250,000 170,000-250,000
250,000 (median)
MSA Versa-hood (Tyvek hood)..................... 9,700-£2 £250,000 86,000-114,000
50,000 (median)
North Model 85302 TB (Tyvek hood with bib)...... 55,000-£ £250,000 150,000-240,000
250,000 (median)
North Model 85302 T (Tyvek hood, no bib)........ 5-£250,0 1,217 (mean) 13-18
00
Bullard CC20TIC (Tyvek hood and bib and 160,000-£ £250,000 £250,00
chinstrap)..................................... 250,000 (median) 0
----------------------------------------------------------------------------------------------------------------
\1\ Collected 288 samples (a panel of 4 respirator users x 12 exercises x 6 helmets).
\2\ Collected 264 samples (a panel of 4 respirator users x 11 exercises x 6 helmets).
\3\ Collected 132 samples (a panel of 4 respirator users x 11 exercises x 3 helmets).

The Agency is proposing an APF of 1,000 for continuous flow SARs
with hoods or helmets based on their performance in the WPF and SWPF
studies. In each of the WPF studies [except the second WPF study by
Johnston, Colton, Stokes, Mullins and Rhoe (Ex. 1-64-37)], these
respirators attained a fifth percentile protection factor over 1,000.
In addition, the large geometric mean protection factors found for
these respirators provide substantial evidence for this proposed APF.
The Agency qualified the proposed APF in footnote 4 of its proposed
APF table. This footnote states that * * * only helmet/hood respirators
that ensure the maintenance of a positive pressure inside the facepiece
during use, consistent with performance at a level of protection of
1000 or greater, receive an APF of 1000.'' and that ``[a]ll other
helmet/hood respirators are treated as loose-fitting facepiece
respirators and receive an APF of 25.'' Under this proposed
requirement, an employer must select for employee use only continuous
flow SARs with hoods or helmets that attained a protection factor of at
least 1,000. While better performance has been associated with certain
designs (e.g., double bibs, neck seals or dams, blouses, higher
airflows), the presence of such design considerations are no guarantee
of superior performance. In order to receive an APF of 1,000, it is
contingent upon the respirator manufacturer to be able to demonstrate
that their particular respirator meets the criteria specified in Table
I of the proposed standard. This level of performance can best be
demonstrated by performing a WPF or SWPF study. OSHA is proposing this
requirement because previous WPF and SWPF testing conducted on these
respirators shows that they do not always result in the requisite
protection factor (Exs. 3-4, 3-5).
Accordingly, researchers have recommended that such testing be
performed to ensure that employees use only respirators from this class
that provide them with the specified level of protection during
exposure to hazardous substances. In this regard, while the respirator
manufacturer most likely would perform the required testing, it would
be incumbent on the employer to ensure that the respirators they
selected for employee use received this testing.
While the 1987 NIOSH RDL recommended an APF of 25 for continuous
flow SARs with hoods or helmets, this recommendation is the result of
combining these respirators into a single class with loose-fitting
facepiece SARs, and giving the entire class the low APF (i.e., 25)
assigned originally to loose-fitting facepiece respirators. However,
the 1992 ANSI standard established a separate class for continuous flow
SARs with hoods or helmets based on analogous operating

[[Page 34104]]

characteristics between these respirators and airline respirators at
the same flow rates, with the new class having an APF of 1,000 (loose-
fitting facepiece SARs continued to receive an APF of 25). Accordingly,
OSHA is proposing in this rulemaking to follow the procedure adopted by
the 1992 ANSI standard and divide the two respirator types into
separate classes, based principally on the WPF and SWPF performance of
the continuous flow SARs with hoods or helmets.
OSHA's proposed APF for loose-fitting facepiece SARs. No WPF or
SWPF studies involving this respirator class were available. Therefore,
using analogous operational characteristics between these respirators
and loose-fitting facepiece PAPRs, OSHA is proposing to assign loose-
fitting facepiece SARs an APF of 25. In this regard, loose-fitting
facepiece SARs, when evaluated under the NIOSH respirator-certification
standards (42 CFR part 84), had the same minimum airflow rates found
for loose-fitting facepiece PAPRs. Additional support for the proposed
APF comes from the 1987 NIOSH RDL and the 1992 ANSI standard, both of
which gave this respirator class an APF of 25.
6. Self-Contained Breathing Apparatuses (SCBAs)
Historical development of APFs for SCBAs. As he did with full
facepiece SARs used in the demand mode, Hyatt in 1976 assigned a
protection factor of 50 to a full facepiece SCBA operated in this mode.
Based on results from a panel of 31 respirator users tested at LANL, he
gave full facepiece SCBAs used in the pressure demand mode an APF of
10,000+ (Ex. 2). The 1980 ANSI standard listed half-mask and full
facepiece SCBAs operated in the demand mode as having APFs of 10 and
100, respectively, when qualitatively fit tested; when quantitatively
fit tested, the APFs for half-mask or full facepiece SCBAs functioning
in the demand mode were the protection factors obtained during fit
testing, with this APF limited to the sub-IDLH value. Full facepiece
SCBAs used in the pressure demand mode received an APF of 10,000+. The
1987 NIOSH RDL recommended that half-mask and full facepiece SCBAs
operated in the demand mode receive APFs of 10 and 50, respectively,
and that the APF for full facepiece SCBAs operated in the pressure
demand or other positive pressure mode be 10,000.
The committee responsible for the 1992 ANSI standard could not
reach a consensus on an APF for full facepiece pressure demand SCBAs.
As noted in footnote 4 of the APF table in this ANSI standard,
available WPF and SWPF studies reported that, in some individual cases,
the respirators did not achieve an APF of 10,000 (Ex. 1-50).
Nevertheless, the committee found that a maximum APF of 10,000 was
appropriate when employers used the respirators for emergency planning
purposes and could estimate levels of hazardous substances in the
workplace.
Two newly developed respirators equipped with hoods, Draeger's Air
Boss Guardian and Survivair's Puma, have operational characteristics
similar to SCBAs. The facepiece of the Draeger respirator consists of a
hood with an inner nose cup and a seal at the neck; an air cylinder
supplies air to the facepiece. NIOSH reviewed this respirator in
accordance with its certification requirements specified at 42 CFR part
84, and in January 2001 certified the respirator as a tight-fitting
full facepiece demand SCBA, with the cylinder having a 30-minute
service life; NIOSH also approved the respirator for use in entering
and escaping from hazardous atmospheres. In a May 16, 2001 letter to
OSHA's Directorate of Compliance Programs (Ex. 7-1), Mr. Richard
Metzler of NIOSH justified the classification of the Draeger respirator
as an SCBA on the basis that the neck seal, which is integral to the
facepiece, forms a gas-tight or dust-tight fit with the face,
consistent with the definition of a tight-fitting facepiece specified
by 42 CFR 84.2(k). This letter also noted that the fit testing
procedures used for full facepiece demand SCBAs apply to the Draeger
SCBA, and that, as a full facepiece demand SCBA, NIOSH recommended that
the respirator receive an APF of 50 in accordance with its 1987 RDL.
NIOSH subsequently reviewed the Survivair Puma respirator, which
has a tight-fitting hood supplied by an air cylinder; and certified the
respirator as a pressure demand SCBA with a tight-fitting facepiece. As
part of the certification process, NIOSH specified that fit testing
required of SCBAs would apply to this respirator. However, Steve
Weinstein of Survivair (Ex. 7-2) stated that the hood totally
encapsulates the respirator user's hair, making quantitative fit
testing (e.g, with a Portacount) impossible; in such cases, the fit
testing instrumentation treats dander and other material shed by the
hair as particulates from outside the respirator, causing the fit
factor to be artificially low. However, qualitative fit testing with
the hood is possible because Survivair provides an adapter and P100
filters for this purpose; such fit testing meets the fit-testing
requirements for tight-fitting SCBAs specified in paragraph (f)(8) of
OSHA's Respiratory Protection Standard.
The table below provides a summary of APFs given to the half-mask
and full facepiece SCBAs from Hyatt's 1976 studies at LLNL to the 1992
ANSI standard.

OSHA's proposed APFs for SCBAs. No WPF or SWPF studies for tight-
fitting half-mask SCBAs and tight-fitting full facepiece SCBAs operated
in the demand mode were available. In the only WPF study conducted on
full

[[Page 34105]]

facepiece positive pressure SCBAs, Campbell, Noonan, Merinar, and
Stobbe of NIOSH assessed the performance of two different models of
full facepiece pressure demand SCBAs that met the NFPA 1981 airflow
requirements for respirators used by firefighters (Ex. 1-64-7). While
the authors could not determine WPFs for these respirators because
contaminant levels measured inside the facepiece were too low, pressure
measurements taken inside the facepiece proved more useful. These
measurements showed that four of the 57 firefighters experienced one or
more negative-pressure incursions inside the facepiece while performing
firefighting tasks. After analyzing the data for these firefighters
using two different methods, the authors estimated that the overall
protection factor exceeded 10,000.
In the first of two SWPF studies performed on full facepiece SCBAs
used in the pressure demand mode, McGee and Oestenstad (Ex. 1-64-86)
determined the protection afforded to members of a respirator test
panel consisting of 23 men wearing the Biopack 60 closed circuit SCBA
(Ex. 1-64-86). Three members of the panel had protection factors of
4,889, 7,038, and 18,900, with the remaining members having protection
factors over 20,000. In the second study, Johnson, da Roza, and
McCormack of LLNL (Ex. 1-64-98) tested the Survivair Mark 2 SCBA that
met NFPA 1981 airflow requirements; during testing, a panel of 27
respirator users exercised on a treadmill at 80% of their cardiac
reserve capacity. Although the authors found negative-pressure
incursions inside the facepiece at high work rates, they concluded that
the respirator ``provided [a minimum]
average fit factor of 10,000 [for
any single subject], with no single subject having a fit factor less
than 5,000 at a high work rate.''
The tables below summarize the results of the WPF and SWPF studies
performed on full facepiece pressure demand SCBAs.

----------------------------------------------------------------------------------------------------------------
WPF studies for tight-fitting full facepiece Geometric
pressure demand SCBAs (by name of authors and Sample size Geometric mean standard 5th percentile
model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
Campbell et al. (Ex. 1-64-7), Unspecified model 57 .............. .............. 10,000
(with NFPA-compliant airflow).................. (estimated)
----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------
SWPF studies for tight-fitting full facepiece Geometric
pressure demand SCBAs (by name of authors and Sample size Geometric mean standard 5th percentile
model of respirator tested) deviation WPF
----------------------------------------------------------------------------------------------------------------
McGee and Oestenstad (Ex. 1-64-86), Biopack 60 23 20,000 .............. ..............
(closed circuit)...............................
Johnson et al. (Ex. 1-64-98), Survivair Mark 2 27 29,000 1.63 ..............
(with NFPA-compliant airflow)..................
----------------------------------------------------------------------------------------------------------------

OSHA is proposing APFs of 10 and 50, respectively, for tight-
fitting half-mask SCBAs and tight-fitting full facepiece SCBAs operated
in the demand mode. In the absence of any WPF and SWPF studies on these
respirators, the Agency derived the proposed APFs based on analogous
operational characteristics between these respirators and half-mask
facepiece and full facepiece air-purifying respirators for which WPF
and SWPF studies (described previously) are available. In addition, the
proposed APFs are consistent with the APFs recommended by the 1987
NIOSH RDL for these respirators. (Note that the 192 ANSI standard did
not assign APFs for these respirator classes.)
For tight-fitting full facepiece SCBAs used in the pressure demand
or other positive pressure modes, OSHA is proposing an APF of 10,000,
which is consistent with the 1987 NIOSH RDL and the 1992 ANSI standard.
Empirical support for the proposed APF comes from the WPF study
conducted by Campbell, Noonan, Merinar, and Stobbe (Ex. 1-64-7). This
study showed that individual protection factors for these respirators,
when operating at NFPA-compliant airflows, far exceed 10,000; however,
four respirator users experienced momentary negative-pressure spikes
inside the facepiece, indicating possible leakage of ambient
contamination into the facepiece, and the breathing zone of the user,
under some workplace conditions.
The two SWPF studies also provide support for the proposed APF,
although several individual protection factors fell below 10,000 in the
two studies, and the Johnson, da Roza, and McCormack study (Ex. 1-64-
98) found negative-pressure incursions inside the facepiece during high
exercise rates. Since the WPF and SWPF studies indicate that these
respirators fail to provide the designated level of protection under
some conditions, OSHA states in footnote 5 of its proposed APF table
that ``[w]hen employers can estimate hazardous concentrations for
emergency planning purposes, they must use a maximum assigned
protection factor no higher than 10,000.'' Therefore, this proposed
provision limits use of tight-fitting full facepiece positive pressure
SCBAs to conditions for which an emergency-response plan exists and the
employer can estimate the concentration of the hazardous substance in
those conditions; in addition, the employer must restrict respirator
use to conditions in which the required level of employee protection is
at or below an APF of 10,000.
In proposing to limit use of tight-fitting full facepiece positive
pressure SCBAs to planned emergency conditions only, OSHA acknowledges
that while these respirators are among the most protective respirators
available, the existing WPF and SWPF data demonstrate that they do not
consistently provide employees with a protection level of 10,000 under
some exposure conditions. Therefore, the Agency is proposing that
employers not use these respirators routinely for protecting employees
against workplace exposures requiring an APF above 1,000, but instead
limit their use to non-routine (i.e., emergency) conditions that
require high levels of respirator protection. In this regard, the
Agency believes that few, if any, routine exposure conditions in the
workplace require protection above an APF of 1,000; consequently, the
proposed restriction would have minimal effect on routine respirator
use.\11\
---------------------------------------------------------------------------

\11\ In preparing the risk analysis for the final Respiratory
Protection Standard, OSHA reviewed data in its Integrated Management
Information System for the years 1992 to 1996 to determine
overexposure rates to the hazardous substances listed in Table Z
(``Limits for air contaminants'') of 29 CFR 1910.1000. The Agency
found that less than 0.01% of the exposures to these substances
exceeded an APF of 1,000.

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

[[Page 34106]]

To use full facepiece positive pressure SCBAs under emergency
exposure conditions, the proposal specifies that employers must develop
an emergency plan (which several substance specific standards already
require), and provide an estimate of the concentration levels likely to
result under the emergency conditions. Emergency plans would limit
employee exposure to the hazardous conditions by informing them in
advance of the specific tasks they are to perform, while estimating
concentration levels of the hazardous substance would increase the
likelihood that their exposures to the substance will remain within the
APF assigned to the respirator. In addition, OSHA's proposal to limit
use of these respirators to emergency conditions is similar to the
restriction placed on them in footnote 4 of the APF table published in
---------------------------------------------------------------------------
the 1992 ANSI standard; this restriction reads, in part:

[A]
definitive assigned protection factor could not be listed
for positive-pressure SCBAs. For emergency planning purposes where
hazardous concentrations can be estimated, an assigned protection
factor of no higher than 10,000 should be used. (Ex. 1-50)

For the class of respirators designated as pressure demand SCBAs with
tight-fitting hoods or helmets, including the Survivair Puma, OSHA is
proposing an APF of 10,000 maximum. The basis for this proposed APF are
the analogous operational characteristics between these respirators and
tight-fitting full facepiece pressure demand SCBAs. Accordingly, the
Agency proposes to limit use of demand SCBAs with tight-fitting hoods
or helmets to emergency planning purposes, similar to the restriction
it is placing on tight-fitting full facepiece pressure demand SCBAs.
Paragraph (d)(3)(i)(B)--MUC Provisions
These proposed requirements consist of four separate paragraphs
[(d)(3)(i)(B)(1) through (d)(3)(i)(B)(4)]. Paragraph (d)(3)(i)(B)(1),
which proposes requirements on the use and application of MUCs, reads,
``The employer must select a respirator for employee use that maintains
the employee's exposure to the hazardous substance, when measured
outside the respirator, at or below the MUC.'' This proposed paragraph
requires employers to select respirators for employee protection that
are appropriate to the ambient levels of the hazardous substance found
in the workplace, i.e., that the ambient level of the hazardous
substance must never exceed the conditions specified by the MUC, which
is the exposure limit specified for the hazardous substance multiplied
by the respirator's APF. Accordingly, the proposed requirement ensures
that employers maintain employees' direct exposure to hazardous
substances (i.e., inside the respirator) within levels specified by
OSHA's Z tables and substance-specific standards, and where OSHA has no
standards, within consensus standards levels. Therefore, this provision
would not only provide employee protection consistent with prevailing
industrial-hygiene practice, but with existing regulatory and statutory
requirements as well.
The single note in the proposed MUC provisions follows paragraph
(d)(3)(i)(B)(1). This note reads that ``MUCs are effective only when
the employer has a continuing, effective respiratory protection program
as specified by 29 CFR 1910.134, including training, fit testing,
maintenance and use requirements.'' This provision implies that MUCs
are dependent on the APFs of the respirators selected by employers to
protect employees against airborne contaminants. In this regard, the
Agency determined the APF for a respirator or class of respirators
based on studies that assessed the respirator under conditions that met
or exceeded the program requirements of its Respiratory Protection
Standard at 29 CFR 1910.134. These studies ensured that the study
participants who used the respirators received thorough respirator
training and fit testing, and used the respirators correctly; also,
employers (or research staff in the case of SWPF studies) maintained
the respirators in proper operating condition. Consequently, the APF
used in calculating a MUC is valid for this purpose only if employers
implement a continuing, effective, and comprehensive respiratory-
protection program as required by OSHA's Respiratory Protection
Standard. When employers do not meet the conditions specified in this
note, they may not use the respirator's APF in determining the MUC.
The next MUC provision, proposed paragraph (d)(3)(i)(B)(2), states
that ``[e]mployers must comply with the respirator manufacturer's MUC
for a hazardous substance when the manufacturer's MUC is lower than the
calculated MUC specified by this standard.'' While OSHA believes that a
MUC calculated according to the proposed MUC definition normally would
provide adequate employee protection, it defers to respirator
manufacturers when they recommend a lower MUC for their respirators
under specific hazardous-substance conditions. Respirator manufacturers
warrant such deference because they are most familiar with the
functional limitations of their respirators when exposed to airborne
concentrations of hazardous substances. Also, manufacturer's may base
their recommended MUCs on unpublished WPF or SWPF studies; such
studies, when conducted properly, would increase the validity of their
recommendations. As with a MUC determined using OSHA's proposed
calculation method, the Agency believes that the protection afforded to
employees by a respirator manufacturer's MUC depends on the employer's
full compliance with the comprehensive respiratory-protection program
specified by OSHA's Respiratory Protection Standard.
The Agency would not defer to respirator manufacturers who
recommend higher MUCs than an employer would obtain using the proposed
calculation method because such results would not be consistent with
the maximum ambient level of a hazardous substance in which employees
can use the respirators, i.e., the maximum ambient level of a hazardous
substance would exceed the level determined from the known exposure
limit for the hazardous substance and the protection of the APFs
determined by this proposed rulemaking. Under these conditions, the
respirator manufacturer would be basing the recommendation on an
invalid application of the known exposure limit or the APF (or both);
therefore, such an invalid application would cause employers to select
respirators that are incapable of protecting employees from the ambient
level of a hazardous substance, resulting in serious health impairments
to their employees.
Paragraph (d)(3)(i)(B)(3) of the proposed MUC provisions states,
``Employers must not apply MUCs to conditions that are immediately
dangerous to life or health (IDLH); instead, they must use respirators
listed for IDLH conditions in paragraph (d)(2) of this standard.''
Accordingly, employers could not use the proposed MUC calculation
method (or a respirator manufacturer's MUC) to select a respirator for
employees who are entering an IDLH atmosphere. OSHA found support for
these proposed requirements in comments cited in the preamble to the
final Respiratory Protection Standard. These comments noted that
employers should not use MUCs to select respirators for employees
exposed to IDLH

[[Page 34107]]

atmospheres (Ex. 1-54-381), or stated that employees should not use
air-purifying respirators, including powered air-purifying respirators,
while exposed to IDLH or oxygen-deficient atmospheres (Ex. 1-54-38);
these commenters believed that the MUCs (and the APFs on which they are
based) would not protect employees under these extremely hazardous
exposure conditions.
For employees exposed to IDLH conditions, employers must select a
respirator according to the requirements specified by paragraph (d)(2)
of OSHA's Respiratory Protection Standard. Paragraph (d)(2) requires
employers to select a full facepiece, pressure demand SCBA certified by
NIOSH to have a service life of at least 30 minutes, or a combination
full facepiece, pressure demand, supplied-air respirator with an
auxiliary self-contained air supply, for IDLH exposures. In the
preamble to the final Respiratory Protection Standard, the Agency
justified selecting these respirators as follows:

In [IDLH]
atmospheres there is no tolerance for respirator
failure. This record supported OSHA's preamble statement that IDLH
atmospheres ``require the most protective types of respirators for
workers.

(59 FR 58896.) Commenters and respirator authorities, including NIOSH,
ANSI, and both labor and management, agree that, for IDLH atmospheres,
the most highly protective respirators, with escape capability, should
be required (63 FR 1201).
The last proposed MUC provision, paragraph (d)(3)(i)(B)(4),
requires that ``[w]hen the calculated MUC exceeds another limiting
factor such as the IDLH level for a hazardous substance, the lower
explosive limit (LEL), or the performance limits of the cartridge or
canister, then employers must set the maximum MUC at that lower
limit.'' As with manufacturers' MUCs, these limiting factors would take
precedence over the calculated MUC when they result in lower employee
exposures to the hazardous substances than the calculated MUC;
consequently, employees would receive increased protection against
these hazardous substances.
This proposed paragraph cites several performance limits (i.e., the
IDLH or LEL for a hazardous substance, or the service life of a
cartridge or canister) as examples of limiting factors. In this regard,
OSHA is including these limiting factors as examples only; other
limiting factors specified in a variety of OSHA standards, or used by
employers to meet their obligation to provide a safe and healthful
workplace, also would be applicable to this proposed requirement. In
addition, commenters cited in the preamble to the final Respiratory
Protection Standard believed that employers should not rely on MUCs
determined using the proposed calculation method to estimate the
service life of cartridges and canisters (Exs. 1-54-153, 1-54-165A, 1-
54-222, 1-54-381).

B. Superseding the Respirator-Selection Provisions of Substance-
Specific Standards in Parts 1910, 1915, and 1926

1. Introduction
The substance-specific standards in 29 CFR parts 1910, 1915, and
1926 specify numerous requirements for regulating employee exposure to
toxic substances, including APFs for respirator selection. Under this
proposed rulemaking, OSHA would revise the provisions in its substance-
specific standards that regulate APFs (except the APF requirements for
the 1,3-Butadiene Standard at 29 CFR 1910.1051). These proposed
revisions would remove the APF tables from these standards, as well as
any references to these tables, and would replace them with a reference
to the APF and MUC provisions specified in proposed paragraphs
(d)(3)(i)(A) and (d)(3)(i)(B) of the Respiratory Protection Standard at
29 CFR 1910.134. The Agency believes that the proposed revisions would
simplify compliance for employers by removing many inconsistencies in
APF requirements across its substance-specific standards; therefore,
the proposed revisions would enhance consolidation and uniformity of
these requirements. Accordingly, the purpose of revising the APF
provisions of OSHA's substance-specific standards is to conform these
standards, to the extent possible, to each other and to general APF and
MUC requirements specified by 29 CFR 1910.134.
The proposed revisions would improve the substance-specific
standards because the Agency developed these proposed APF requirements
after careful review and analysis of the available scientific data and
the most recent consensus standards (i.e., the APF provisions in the
NIOSH RDL and the ANSI Z88.2-1992 respiratory protection standard). In
this regard, the Agency preliminarily finds that the proposed APFs are
a significant improvement over the existing NIOSH and ANSI APFs because
it developed them based on the latest WPF and SWPF studies, and used
advanced statistical methods to identify common and unique variance
among respirator classes. Therefore, the proposed APFs represent the
best data and analytic techniques available, thereby lending a high
degree of reliability and validity to the results. Accordingly, the
proposed APFs will provide employers with confidence that their
employees will receive the level of protection from airborne
contaminants signified by these APFs. In addition, applying the
proposed APFs to the substance-specific standards is consistent with
OSHA's goal of bringing uniformity to its respiratory-protection
requirements. Moreover, protection for workers is increased since the
proposed APFs will provide equivalent or increased protection compared
to the ANSI Z88.2-1992 standard, and incorporates the use of APFs into
the employer's respiratory protection program. The Agency believes that
superseding the APF requirements of its existing substance-specific
standards would result in regulatory consistency, which would improve
employer compliance with these provisions, reduce the compliance burden
on the regulated community, and, consequently, further enhance the
protection afforded to employees who use respirators.
In the final rulemaking for its Respiratory Protection Standard,
OSHA noted that the revised standard was to ``serve as a `building
block' standard with respect to future standards that may contain
respiratory protection requirements.'' (See 63 FR 1265, 1998.) In this
regard, the Agency believes that, to the extent possible, future
substance-specific standards should refer to provisions of the final
Respiratory Protection Standard instead of containing their own
respirator requirements, including the generic APF and MUC provisions
specified in this proposed rulemaking. However, on occasion a
substance-specific standard may have respirator-selection requirements
that supplement or supplant the generic APF and MUC provisions (e.g.,
organic-vapor cartridge and canister procedures, prohibiting use of
filtering facepieces or half-mask respirators) that are necessary for
ensuring adequate employee protection against the toxic substance
regulated by the standard. Accordingly, the Agency is retaining a
number of existing respirator-selection provisions that are unique to
the substance-specific standards; the following paragraphs describe
these provisions, and provide OSHA's rationale for retaining them.

[[Page 34108]]

2. Retaining the Respirator-Selection Provisions of the 1,3-Butadiene
Standard
As noted earlier in this section, OSHA is not proposing to revise
the respirator-selection provisions of the 1,3-Butadiene Standard (``BD
Standard''). Therefore, the APFs located in Table 1 (``Minimum
Requirements for Respiratory Protection for Airborne BD'') of the BD
Standard would remain as currently published in paragraph (h)(3)
(``Respirator selection'') of 29 CFR 1910.1051.
The BD Standard requires that employers use respirators during work
operations when engineering and work-practice controls ``are not yet
sufficient to reduce employee [BD]
exposures to or below the
[permissible exposure limits]'' [see 29 CFR 1910.1051(h)(1)(iii)].
Employers must select these respirators based on the APFs listed in
Table 1 of the BD Standard; in addition, they must equip air-purifying
respirators with organic-vapor cartridges or canisters.
OSHA adopted the APFs in Table 1 from the Respirator Decision Logic
developed by the National Institute for Occupational Safety and Health
(NIOSH), even though a negotiated agreement between manufacturers who
use BD and the unions representing their employees recommended the more
permissive ANSI Z88-1992 APFs.
In the preamble to the final BD Standard, the Agency noted that its
``decision to rely on the more protective NIOSH APFs is based on
evidence showing that organic-vapor cartridges and canisters have
limited capacity for adsorbing BD and may have too short a service life
when used in environments containing greater than 50 ppm BD.'' (See 61
FR 56816.) While developing the final BD Standard, OSHA reviewed the
breakthrough test data that were available for organic-vapor cartridges
and canisters challenged against BD (and summarized in Table X-1 of the
preamble to the final BD Standard; see 61 FR 56817). Based on this
review, the Agency concluded:

Allowing for a reasonable margin of protection, and given that
test data were available only for a few makes of cartridges and
canisters, OSHA believes that air-purifying devices should not be
used for protection against BD present in concentrations greater
than 50 ppm, or 50 times the 1 ppm PEL. Thus, OSHA finds that the
ANSI APFs of 100 for full facepiece, air-purifying respirators and
1,000 for PAPRs equipped with tight-fitting facepieces are
inappropriate for selecting respirators for BD.

In summary, test data cited by the Agency in the final BD Standard
demonstrate short breakthrough times for BD concentrations above 50
ppm. Accordingly, these short breakthrough times justified limiting to
50 ppm the upper limit at which employees can use air-purifying
respirators for protection against BD exposures. From the Agency's
analysis of these data, OSHA also developed change schedules for
cartridges and canisters that are unique for BD exposures (see Table 1
of the BD Standard). Additionally, these conclusions still are likely
to be valid because OSHA reviewed the test data only six years ago
(i.e., 1996). Therefore, the Agency is proposing to retain the
conservative NIOSH APFs as necessary to protect employees from BD
exposures. Nevertheless, OSHA is asking employers and employees who are
subject to the provisions of the existing BD Standard to provide
additional information that supports retaining the existing APFs or
adopting the generic APFs specified under this proposed rulemaking (See
Section VII , Issues, of this preamble).
3. Retaining the Respirator-Selection Provisions in Other Substance-
Specific Standards
While OSHA is proposing to retain the existing BD Standard in its
entirety, it also is proposing to retain a number of respirator-
selection provisions in other substance-specific standards as well. The
respirator-selection requirements proposed for retention often provide
protection against a hazardous characteristic or condition that is
unique to the regulated substance. Additionally, OSHA believes that
retaining these requirements in their present form (except for plain-
language revisions, as appropriate) would not increase existing
employer burden because they already must comply with these
requirements; consequently, retaining these provisions will maintain
the level of respirator protection currently afforded to employees. The
following sections describe the most important provisions that the
Agency is proposing to retain.\12\
---------------------------------------------------------------------------

\12\ Most of the provisions described in these sections are in,
or are footnotes to, the respirator-selection tables proposed for
removal from the substance-specific standards. These sections also
describe several other respirator-selection provisions that are not
part of these tables, but which OSHA is retaining and which may be
of interest to the regulated community. If this proposal does not
specifically identify or describe a respirator-selection provision
for removal or revision, then OSHA is retaining that provision in
its existing form. The Agency believes that retaining these
provisions does not increase the regulatory burden of employers
because they must currently comply with them.
---------------------------------------------------------------------------

? Lines 13-17 \13\ and 21-21 under ``Required apparatus'' in
the undesignated table of 29 CFR 1910.1017 (Vinyl Chloride (VC)
Standard); and footnote 1 to Table 1 of 29 CFR 1910.1028 (Benzene
Standard). These provisions specify a minimum service life for
cartridges and canisters used to protect employees during exposure to
these substances. In the VC Standard, employers must provide organic-
vapor cartridges or canisters with a service life of at least one hour
at VC concentrations up to 10 ppm when using chemical-cartridge
respirators. These cartridges and canisters must have a service life of
at least four hours at VC concentrations up to 25 ppm when using a
canister with a powered air-purifying respirator that has a hood,
helmet, half-mask, or full facepiece; the four-hour service-life
requirement also applies when an employee uses a gas mask, but in this
case, the employee must use a front-or back-mounted canister. According
to the Benzene Standard, employers must ensure that canisters used with
non-powered air-purifying respirators have a minimum service life of
four hours when tested at 150 ppm benzene at a flow rate of 64 liters
per minute (Lpm), a temperature of 25[deg]
C, and a relative humidity
of 85%; testing for canisters used with tight-fitting and loose-fitting
powered air-purifying respirators must be at flow rates of 115 Lpm and
170 Lpm, respectively.
---------------------------------------------------------------------------

\13\ Only lines with written text were counted in determining
the number of lines; blank lines that occurred before a written line
were ignored for counting purposes.
---------------------------------------------------------------------------

The Agency believes that these minimum service-life specifications
ensure that employers use the designated respirators at appropriate
concentration levels of the regulated substances. Accordingly, OSHA is
proposing to retain these specifications to provide employees with a
minimum level of cartridge and canister endurance when they use the
designated respirators at these concentrations. While retaining these
specifications may limit employers' flexibility in adopting change
schedules, the Agency considers this limitation warranted in view of
the properties of the substance that require greater protection or a
higher level of protection for employees. Moreover, retaining these
specifications adds no regulatory burden on employers because they must
use the specifications under the existing standards.
? Paragraphs (h)(3)(ii), and lines 6, 7, 10, and 11 under
``Required respirator'' in Table II of 29 CFR 1910.1018 (Inorganic
Arsenic Standard); lines 1-4

[[Page 34109]]

under ``Respirator type'' in Table 1 of 29 CFR 1910.1028 (Benzene
Standard); line 1 under ``Minimum required respirator'' in Table 1 of
29 CFR 1910.1047 (Ethylene Oxide Standard); lines 1-4 under ``Minimum
respirator required'' in Table 1 of 29 CFR 1910.1048 (Formaldehyde
Standard); and lines 1-3 and 8, and footnote 2, under ``Respirator
type'' in Table 1 of 29 CFR 1910.1050 and 1926.60 (Methylenedianiline
(MDA) Standards).
These paragraphs identify the types of cartridges and canisters
employers must select under specific respirator-use conditions. The
Inorganic Arsenic Standard requires employers to provide employees
with: Air-purifying respirators that have a combination high-efficiency
particulate air (HEPA) filter with an appropriate gas-sorbent cartridge
or canister when their exposure exceeds the permissible exposure level
for inorganic arsenic, and their exposure also exceeds the relevant
limit for other gases; front- or back-mounted gas masks equipped with
HEPA filters and acid-gas canisters or any full facepiece supplied-air
respirators when the inorganic arsenic concentration is at or below 500
[mu]g/m3; and half-mask air-purifying respirators equipped
with HEPA filters and acid-gas cartridges when the inorganic arsenic
concentration is at or below 100 [mu]g/m3. The Benzene
Standard specifies that employers must use an organic-vapor cartridge
or canister with air-purifying respirators, and a chin-style canister
with full facepiece gas masks. The Ethylene Oxide Standard states that
employers are to equip air-purifying, full facepiece respirators with
front- or back-mounted canisters approved for protection against
ethylene oxide, while the same respirators under the Formaldehyde
Standard must use a cartridge or canister approved for protection
against formaldehyde. The MDA Standard requires that employers provide
air-purifying respirators with a combination HEPA filter and organic-
vapor cartridge or canister when MDA is in liquid form or is part of a
heated process.
? Line 1 under ``Required respirator'' in Table 1 of 29 CFR
1910.1001, 1915.1001, and 1926.1101(Asbestos Standards); line 6 under
``Required respirator'' in Table I of 29 CFR 1910.1029 (Coke Oven
Emissions Standard); and line 2 under ``Required respirator'' in Table
I of 29 CFR 1910.1043 (Cotton Dust Standard).
These provisions prohibit the use of disposable respirators
(single-use respirators in the Coke Oven Emissions Standard) to protect
employees against these toxic substances; the Cotton Dust Standard
prohibits their use at exposures greater than five times the
permissible exposure level (PEL). However, the Agency does not define
the terms ``disposable respirator'' or ``single-use respirator'' in any
of its standards, including its Respiratory Protection Standard at 29
CFR 1910.134; therefore, to update these requirements, the Agency is
proposing to replace these terms with ``filtering facepiece,'' which it
defines in paragraph (b) of 29 CFR 1910.134. OSHA believes this
revision will not only make these provisions consistent with its new
Respiratory Protection Standard, but will prevent employers from using
respirators not designed with the high-efficiency particulate filters
necessary to capture respirable asbestos fibers (see 51 FR 22718) and
coke oven emissions (see 41 FR 46773-46774), and, in the case of cotton
dust, to provide protection at exposure levels higher than five times
the PEL (see 50 FR 51153-51154).
? Paragraphs (h)(2)(iv) of 29 CFR 1915.1001 and (h)(3)(iii)
of 29 CFR 1926.1101 (Asbestos Standards) also prohibit employers from
selecting disposable respirators for employees who conduct specific
types of Class II and III asbestos work. Consistent with the
explanation and rationale provided in the previous section, OSHA is
proposing to revise the term ``disposable respirator'' to ``filtering
facepiece'' in these standards. The Agency also is proposing to revise
these paragraphs, as well as paragraph (h)(2)(v) of 29 CFR 1915.1001
and (h)(3)(iv) of 29 CFR 1926.1101 (which address respirator selection
for conducting Class I asbestos work in regulated areas), into plain
language to clarify the multifaceted requirements specified by these
paragraphs. By improving employer understanding of the respirator-
selection requirements, OSHA believes that the revisions proposed for
these paragraphs would enhance employee protection without increasing
employers' regulatory burden.
? Lines 2, 3, and 4 under ``Required respirator'' in Table 1
of 29 CFR 1910.1001, 1915.1001, and 1926.1101(Asbestos Standards);
lines 5-6, 8, and 11 under ``Required respirator'' in Table I , and
lines 6 and 10 under ``Required respirator'' in Table II, of 29 CFR
1910.1018 (Inorganic Arsenic Standard); lines 1, 2, and 3 under
``Required respirator'' in Table II of 29 CFR 1910.1025 (Lead
Standard); lines 1, 3, 5, 6, and 10 under ``Required respirator type''
in Table 2 of 29 CFR 1910.1027 (Cadmium Standard); lines 1, 3, 4, and 5
under ``Required respirator'' in Table I of 29 CFR 1910.1043 (Cotton
Dust Standard); lines 1, 2, 3, and 8 under ``Respirator type'' in Table
1 of 29 CFR 1910.1050 and 1926.60 (Methylenedianiline Standard); lines
1, 3-4, 7, and 8 under ``Required respirator'' in Table 1 of 29 CFR
1926.62 (Lead Standard); and lines 1, 3, 6, 8, and 11 under ``Required
respirator type'' in Table 1 of 29 CFR 1926.1127 (Cadmium Standard).
Under these provisions, employers must equip air-purifying
(including powered air-purifying) respirators with high-efficiency
particulate air (HEPA) filters, high-efficiency and high-efficiency
particulate filters (defined as a filter that is at least 99.97%
efficient against mono-dispersed particles of 0.3 micrometers in
diameter or larger), and particulate filters (for the Cotton Dust
Standard only). While OSHA is proposing to retain these provisions, it
is also proposing to replace the terms ``high-efficiency filters'' and
``high-efficiency particulate filters'' with the term ``HEPA filters.''
These three terms have the same meaning, so use of the term ``HEPA''
would impose no additional burden on employers, nor would it diminish
employee protection. The Agency believes that the usual and customary
practice among employers in the cotton-dust industry is to use HEPA
filters with air-purifying respirators; therefore, employers should
experience no additional burden, and employee protection should remain
at current levels, as a result of this revision. In addition, the
proposed revision would make the filter requirements of the Cotton Dust
Standard consistent with other OSHA substance-specific standards and
with its Respiratory Protection Standard, thereby reducing any
confusion that may exist among the regulated community regarding the
appropriate filter to use with air-purifying respirators.
? Footnote 2 to Table II of 29 CFR 1910.1018 (Inorganic
Arsenic Standard). This provision prohibits the use of half-mask
respirators for protection against arsenic trichloride because it is
rapidly absorbed through the skin. OSHA is retaining this provision to
protect employees from the cumulative toxic effects that result from
skin absorption.
? Footnote 2 to Table II of 29 CFR 1910.1025, and footnote 2
to Table 1 of 29 CFR 1926.62 (Lead Standard). These footnotes specify
that employers must provide employees with full facepiece respirators
when employees experience eye or skin irritation that results from
exposure to lead aerosols at use concentrations. These provisions
prevent serious eye and skin injuries among employees.
? Footnote b to Table 2 of 29 CFR 1910.1027 and footnote b to
Table 1 of

[[Page 34110]]

29 CFR 1926.1127 (Cadmium Standard). These provisions require a full
facepiece respirator when an employee experiences eye irritation,
thereby reducing the risk of eye injury among employees.
? Table 1 of 29 CFR 1910.1047 (Ethylene Oxide (EtO)
Standard). This table lists only full facepiece respirators, or
respirators with hoods or helmets, implying that employers must not
select half-mask respirators for protection against EtO. The preamble
to the final EtO Standard states:

The record reflects that high exposures to EtO have been shown
to cause eye irritation and that such effects may occur at exposures
that may be reached for short periods. Therefore, OSHA has chosen to
retain the requirement for full-facepiece respirators in the final
rule. (49 FR 25781)

Accordingly, in this proposal the Agency is making explicit the
prohibition against the use of half-mask respirators to ensure that
employers select only those respirators (i.e., full facepiece
respirators, and respirators with hoods or helmets) that OSHA found, in
the earlier rulemaking, will provide the requisite level of protection
to their employees.
? Footnote 2 to Table 1 of 29 CFR 1910.1048 (Formaldehyde
Standard). This provision requires that employers who select half-mask
respirators instead of full facepiece respirators for formaldehyde
exposures up to 7.5 ppm provide effective gas-proof goggles for
employees to use in combination with the half-mask respirators.
? Table 2 of 29 CFR 1910.1052 (Methylene Chloride (MC)
Standard). This table lists only full facepiece respirators, or
respirators with hoods or helmets, thereby indicating that employers
are not to select half-mask respirators for protection against MC. In
the preamble to the final MC Standard, the Agency states:

OSHA has determined that this standard is necessary because
exposure to MC places employees at significant risk of developing
exposure-related adverse health effects. These effects include * * *
skin and eye irritation. (62 FR 1572)

Later in the preamble, the Agency states that ``employers are required
to provide employees who are at risk of skin and/or eye contact with MC
with appropriate protective clothing and eye protection.'' (See 62 FR
1589.)
The risk of MC-related skin and eye irritation and the need for
proper skin and eye protection convinced OSHA to limit respirator
selection to full facepiece respirators and respirators with hoods and
helmets in the final MC Standard to ensure that employees' facial skin
and eyes are protected during MC exposure. Here the Agency is directly
prohibiting the selection of half-masks, and explicitly limiting
respirator selection to respirators (i.e., full facepiece respirators,
and respirators with hoods or helmets) that would provide the
appropriate level of protection to employees.
? Lines 10 and 11 under ``Respirator type'' in Table 1 of 29
CFR 1910.1028 (Benzene Standard); lines 6-11 under ``Respirator type''
in Table 1 of 29 CFR 1910.1044 (1,2-dibromo-3-chloropropane Standard);
lines 16 and 17 under ``Respirator type'' in Table I of 29 CFR
1910.1045 (Acrylonitrile Standard); line12 under ``Minimum required
respirator'' in Table 1 of 29 CFR 1910.1047 (Ethylene Oxide Standard);
lines 11-13 under ``Minimum respirator required'' in Table 1 of 29 CFR
1910.1048 (Formaldehyde Standard); lines 8-10 under ``Respirator type''
in Table 1 of 29 CFR 1910.1050 and 1926.60 (Methylenedianiline
Standards); lines 13 and 14 under ``Minimum respirator required'' in
Table 2 of 29 CFR 1910.1052 (Methylene Chloride Standard).
These provisions specify which respirators employers are to use
under emergency-escape conditions. With regard to respirators used for
escape, OSHA adopts the same position it did in the final rulemaking
for the Respiratory Protection Standard. In the final rulemaking for
this standard, the Agency noted the variety of escape respirators
permitted under its substance-specific standards, and found that these
standards addressed hazards associated with many different substances
and escape situations. In support of this conclusion, the Agency cited
the following examples:

[U]nder current 29 CFR 1910.1050, the standard covering exposure
to methylenedianiline (MDA), escape respirators may be any full
facepiece air-purifying respirator equipped with HEPA cartridges, or
any positive pressure or continuous flow self-contained breathing
apparatus with full facepiece or hood; for formaldehyde exposure,
escape respirators may be a full facepiece with chin style, front,
or back-mounted industrial canister approved against formaldehyde
(29 CFR 1910.1048).

(63 FR 1202.) As noted earlier in this section, the adverse physical
effects of specific substances (e.g., skin and eye irritation) often
limit respirator selection; these limitations would apply as well to
the selection of escape respirators. Accordingly, OSHA is retaining the
requirements for escape respirators identified in the existing
substance-specific standards because previous rulemakings identified
these respirators based on the unique characteristics of the regulated
substances, as well as the conditions under which employees must use
escape respirators.
As is required currently, respirators covered by these emergency-
escape provisions must meet the requirements of paragraph (d)(2)(ii) of
OSHA's Respiratory Protection Standard, which specifies that these
respirators must be NIOSH-certified for escape from the atmosphere in
which employees will use them. In addition, employees are to use these
respirators only for escaping from, not entering, IDLH atmospheres. For
entering such atmospheres, paragraph (d)(2)(i) of the Respiratory
Protection Standard requires that employees use only full facepiece,
pressure demand SCBAs certified by NIOSH for a minimum service life of
30 minutes, or full facepiece, pressure demand SARs with an auxiliary
self-contained air supply.
? Paragraphs (g)(2)(ii) of 29 CFR 1910.1001, (h)(2)(iii)(A)
of 29 CFR 1915.1001, and (h)(3)(ii) of 29 CFR 1926.1101 (Asbestos
Standards); (f)(3)(ii) of 29 CFR 1910.1025 (Lead Standard); (f)(3)(ii)
of 29 CFR 1910.1043 (Cotton Dust Standard); and (g)(3)(iii) of 29 CFR
1910.1048 (Formaldehyde Standard).
These paragraphs require employers to upgrade a negative pressure
respirator, or a non-powered air-purifying respirator in the case of
the Cotton Dust Standard, to a tight-fitting powered air-purifying
respirator (PAPR) when the employee chooses to use a tight-fitting
PAPR; for the Formaldehyde Standard, this requirement applies when the
employee has difficulty using a negative pressure respirator and the
tight-fitting PAPR provides the employee with adequate protection
against the airborne contaminant. OSHA is proposing to retain these
requirements because tight-fitting PAPRs increase the protection
provided to employees when the respirator-selection provisions identify
a low-end respirator (i.e., a negative pressure respirator or a non-
powered air-purifying respirator) for use.
? Paragraph (h)(2)(iii)(B) of 29 CFR 1915.1001 (Asbestos
Standard). The Agency also is proposing to retain this paragraph in the
Asbestos Standard for Shipyards, which specifies that employers must
inform employees that they (the employees) may require employers to
provide them with a tight-fitting PAPR instead of a negative pressure
respirator. This requirement provides an extra margin of protection to
employees by ensuring that

[[Page 34111]]

employers take positive action to inform them of their option to
upgrade to a more protective respirator than the one that they would
normally receive for use when exposed to asbestos.
? While the paragraphs described in the previous section
require employers to upgrade employee respirators, every substance-
specific standard has a provision, usually as a footnote to its APF
table, that gives employers discretion to select respirators that
provide employees with more protection from atmospheric contaminants
than the required respirator. Under this proposal, the Agency would
consolidate this discretionary alternative into a generic provision in
proposed paragraph (d)(3)(i)(A) of the Respiratory Protection Standard
(i.e., ``[employees must * * * select a respirator that meets or
exceeds the required level of employee protection'' [emphasis added]).
The Agency concludes that relocating this provision in proposed
paragraph (d)(3)(i)(A) of the Respiratory Protection Standard will
highlight this alternative to employers, and will encourage more of
them to select more protective respirators for their employees than is
now the case.
4. Substantive Revisions to the Respirator-Selection Requirements in
Substance-Specific Standards
OSHA is proposing to revise respirator-selection requirements in
several substance-specific standards that regulate employee exposure to
organic-vapor substances. The following sections describe these
proposed revisions.
? Paragraphs (g)(2) of 29 CFR 1910.1017 (Vinyl Chloride
Standard), (g)(2)(i) of 29 CFR 1910.1028 (Benzene Standard), (h)(2)(i)
of 29 CFR 1910.1045 (Acrylonitrile Standard), and (g)(2)(i) of 29 CFR
1910.1048 (Formaldehyde Standard). These paragraphs exempt employers
from paragraphs (d)(3)(iii)(B)(1) and (B)(2) of OSHA's Respiratory
Protection Standard; the exempted paragraphs consist of respirator-
selection provisions that protect employees against gases and vapors.
Because OSHA would be removing the existing change schedules from these
substance-specific standards under this proposed rulemaking, it becomes
necessary to identify requirements that it believes would provide
employees with at least the same level of protection as the existing
provisions. These requirements are paragraphs (d)(3)(iii)(B)(1) and
(B)(2) of its Respiratory Protection Standard; by removing the current
exemptions, employers would apply paragraphs (d)(3)(iii)(B)(1) and
(B)(2) of the Respiratory Protection Standard to select respirators
that protect employees against the gases and vapors regulated by these
substance-specific standards. In addition, this revision would provide
employers with increased flexibility in selecting respirators without
adding to their compliance burden (i.e., their existing respirator-
selection procedures would be acceptable under this revision). (Note
that the exemption would still remain for the 1,3-Butadiene Standard
because, as noted above, the Agency is retaining the existing
respirator-selection provisions of that standard.)
? Paragraph (g)(2)(ii) of 29 CFR 1910.1048 (Formaldehyde
Standard). This paragraph specifies a change schedule for chemical
cartridges and canisters used for formaldehyde exposures that do not
have an end-of-service life indicator (ESLI) approved by NIOSH. OSHA is
proposing that employers select respirators according to paragraphs
(d)(3)(iii)(B)(1) and (B)(2) of its Respiratory Protection Standard
instead of these requirements.
The paragraphs proposed for removal require employers who use a
change schedule to select a cartridge or canister that has a NIOSH-
approved ESLI, or to use a change schedule for which they must provide
``objective information or data that will ensure that canisters and
cartridges are changed before the end of their service life'' (see
paragraph (d)(3) of OSHA's Respiratory Protection Standard). When they
choose the latter option, this revision would limit the change schedule
to one work shift because of possible vapor migration in the cartridges
and canisters during storage. The Agency believes that this revision
would: Provide employers with flexibility to use other change schedules
when a NIOSH-approved ESLI is not available; not increase the
regulatory burden of employers because the existing change schedule
would remain valid; and ensure that employees receive at least the same
level of protection as they receive with the existing change schedule,
because employers must use a change schedule that they can demonstrate
is safe for this purpose.
5. Use of Plain Language for Proposed Revisions
Whenever possible, OSHA is using plain language in revising the
regulatory text of the substance-specific standards identified in this
proposal. The Agency believes that this approach improves the
comprehensibility and uniformity of the proposed revisions. OSHA
believes that these improvements would enhance employer compliance with
the provisions, thereby increasing the level of protection afforded to
employees.
6. Summary of Superseding Actions
The following table summarizes OSHA's proposed revisions to
existing substance-specific standards. This table lists only those
provisions for which the Agency is proposing substantive revisions
(e.g., proposing to replace existing requirements with new
requirements); it does not list provisions that OSHA is proposing to
retain in their present form (although the Agency is rewriting them in
plain language).

Summary of Superseding Actions for Specific Standards
------------------------------------------------------------------------
Proposed action (29 CFR
Existing section (29 CFR 1910) 1910)
------------------------------------------------------------------------
1001(g)(2)(ii)............................ Revise.
1001(g)(3)................................ Remove Table 1 and revise.
1001(l)(3)(ii)............................ Redesignate Table 2 as Table
1.
1017(g)(3)(i)............................. Remove table and revise.
1017(g)(3)(iii)........................... Remove.
1018 Tables I and II...................... Remove.
1018(h)(3)(i)............................. Revise.
1018(h)(3)(ii)............................ Remove.
1018(h)(3)(iii)........................... 1018(h)(3)(ii).
1025(f)(2)(ii)............................ Remove Table II.
1025(f)(3)(i)............................. Revise.
1027(g)(3)(i)............................. Remove Table 2 and revise.
1028(g)(3)(ii)............................ Remove Table 1.
1028(g)(2)(i)............................. Revise.
1028(g)(3)(i)............................. Revise.
1029(g)(3)................................ Remove Table I and revise.
1043(f)(3)(i)............................. Remove Table I and revise.
1043(f)(3)(ii)............................ Revise.
1044(h)(3)................................ Remove Table I and revise.
1045(h)(2)(i)............................. Revise.
1045(h)(3)................................ Remove Table I and revise.
1047(g)(3)................................ Remove Table I and revise.
1048(g)(2)................................ Revise.
1048(g)(3)................................ Remove Table 1 and revise.
1050(h)(3)(i)............................. Remove Table 1 and revise.
1052(g)(3)................................ Remove Table 2 and revise.
------------------------------------------------------------------------

------------------------------------------------------------------------
Proposed action (29 CFR
Existing section (29 CFR 1915) 1915)
------------------------------------------------------------------------
1001(h)(2)(i) through (h)(2)(v)........... Remove Table 1 and revise.
------------------------------------------------------------------------

[[Page 34112]]

------------------------------------------------------------------------
Proposed action (29 CFR
Existing section (29 CFR 1926) 1926)
------------------------------------------------------------------------
60(i)(3)(i)............................... Remove Table 1 and revise.
62(f)(3)(i)............................... Remove Table 1 and revise.
1101(h)(3)(i) through (h)(3)(iv).......... Remove Table 1 and revise.
1127(g)(3)(i)............................. Remove Table 1 and revise.
------------------------------------------------------------------------

Section XII (``Proposed Amendments to Standards'') of this notice
provides the full regulatory text of the proposed revisions to OSHA's
existing substance-specific standards dealing with respirator
selection. This section describes both substantive revisions proposed
for the existing respirator-selection requirements, as well as
respirator-selection requirements retained in their current form but
rewritten in plain language.

VIII. Issues

OSHA requests the public to comment on, and to provide additional
information regarding, any of the issues listed below. Please provide a
detailed explanation of each response you make.

Developing and Updating APFs

1. Is the method used by OSHA in developing the proposed APFs
appropriate? OSHA used a multi-faceted approach incorporating both
analyses of data collected in WPF and SWPF studies, as well as OSHA's
review of all relevant materials. OSHA requests comment on the
usefulness of this approach to data collection.
2. Are there any additional studies that may be useful in
determining APFs, that have not already been identified by OSHA in
Section IV of this proposal? Please provide these to the Agency.
3. Are statistical analyses, treatments, or approaches, other than
those described in Section IV of the proposal, available for
differentiating between or comparing the highly variable respirator-
performance data?
4. OSHA is aware of discussions within the respirator community
indicating some sentiment for setting APFs for filtering facepiece
respirators at 5, and for setting an APF of 10 for other half-mask air-
purifying respirators. Based upon OSHA's reviews, OSHA cannot
differentiate between the performance of the two types of respirator,
and OSHA finds compelling evidence from the large number of observed
data points (N = 917 Co/Ci pairs) to support proposing an APF of 10 for
both of these classes of respirators. Is there evidence that a
different APF should be provided for these respirator classes?
5. While there are no WPF or SWPF studies for quarter-mask
respirators, the 1976 LANL Respiratory Protection Factor by Hyatt found
protection factors ranging from 5 to 10. Should OSHA continue to
include quarter-masks in the half-mask class, or separate them into a
class of their own with and APF of 5?
6. OSHA is proposing a method by which to separate loose-fitting
facepiece supplied-air and PAPR hood/helmet respirators from the
better-performing hood/helmet respirators. Respirator performance
studies have shown that some PAPR and continuous-flow supplied-air
respirators provide greater protection than others of the same class.
The 1987 NIOSH Respirator Decision Logic gives an APF of 25 for all of
these respirators while ANSI's 1992 respirator standard gives an APF of
25 to loose-fitting facepiece models and an APF of 1000 to hood/helmet
models. OSHA is proposing an APF of 25 except for those models that
ensure the maintenance of a positive pressure inside the facepiece
during use, consistent with a protection factor of 1000 or greater, in
which case those models would receive an APF of 1000. Is this the
appropriate method by which to distinguish high-performing hood/helmet
respirators from others?
7. The assigned protection factor for a full facepiece respirator
in Table 1 of the proposed standard does not currently take into
account the type of particulate filter that is used. An N95 particulate
filter could potentially, under a worst case scenario, have up to 5%
leakage through the filter. This would decrease the APF for a full
facepiece respirator to a maximum of 20 when N95 filters are used.
Should OSHA take into account the limitations of the filter and assign
an APF of 20 for full facepiece respirators when N95 filters are used?
8. Other Federal Agencies, such as the Nuclear Regulatory
Commission (NRC), have set no APF for filtering facepiece air-purifying
respirators (APRs) for use in their particular work environments. In
some cases, such APRs are not allowed to be used at all. In other
settings, e.g., the healthcare industry, some employers rely very
heavily upon such APRs to protect their employees who work with
patients who have infectious airborne illnesses. How should OSHA
incorporate such information, if at all, into an APF requirement for
all industries under OSHA's jurisdiction?
9. Proper facepiece fit is important in achieving the proposed APF
for tight-fitting respirators. Accordingly, the Agency would appreciate
receiving information on current testing and procedures used by
respirator manufacturers to ensure that the facepieces they make will
fit respirator users properly.
10. When a limiting factor such as IDLH, LEL, or the performance
limit specified for a cartridge and canister by the manufacturers are
less than the calculated MUC, proposed paragraph (d)(3)(i)(B)(4)
requires employers to set the MUC at the lower limit. Accordingly, OSHA
is seeking comment on the following questions:
a. What other limiting factors should OSHA include as examples in
this proposed paragraph?
b. Should the Agency specify the LEL or 10% of the LEL as the
limiting factor?
11. Some hazardous substances found in the workplace do not have an
OSHA PEL. However, a number these substances may have an exposure limit
designated by sources other than OSHA (e.g., recommended by the
chemical manufacturer, ACGIH, NIOSH, EPA). Accordingly, the Agency is
asking for comment on the following issues involving MUCs:
a. Should OSHA expand the definition and application of MUC to
hazardous substances that it does not regulate?
b. Should the Agency require employers to determine MUCs for
substances that have no OSHA PEL (i.e., substances not regulated
specifically by OSHA), and to base respirator selection on such a
determination?
c. For hazardous substances that OSHA does regulate, should it
require employers to comply with the MUC values developed by NIOSH when
these values are lower than the calculated MUC values (i.e., MUC = APF
x PEL)?
12. A prevailing view is that exposure to multiple contaminants in
the workplace affect the performance of respirator filters and
cartridges differently than exposure to single contaminants. To assist
it in developing MUCs for single and multiple contaminants, OSHA is
asking the public to address the following issues:
a. What information and data are available that either support or
do not support this view?
b. Should MUCs for contaminant mixtures differ from MUCs for single
mixtures?
13. Section VII proposes to revise most of the respirator-selection
requirements in OSHA's substance-specific standards. Accordingly, the
Agency is asking for comment on the following questions:
a. This proposal excludes the respirator-selection provisions of
the 1,3-Butadiene Standard from any revision. Is this exclusion
warranted?

[[Page 34113]]

b. Special or unique respirator-selection requirements in the
substance-specific standards (e.g., requirements for emergency-escape,
HEPA filters, upgrading respirators at the employee's request, eye
protection) remain largely intact. Should the Agency standardize these
provisions across all of its substance-specific standards, and, if so,
what requirements should it standardize.
14. The Agency has developed its Preliminary Economic Analysis
(PEA) based on survey data indicating what types of respirators
employees are using currently. The Agency does not, however, have data
on the exposure levels as a multiple of the PEL that respirator users
are currently exposed to. For the purposes of this analysis, the Agency
has used its internal Integrated Management and Information System
(IMIS) data to estimate the distribution of exposures as a multiple of
the PEL. The Agency also assumes that employers are currently using the
respirator with the lowest possible costs that can still satisfy
existing guidance on APFs, allowing employees to be exposed up to the
full limit of a currently assigned APF for that class of respirator.
OSHA seeks comment on whether other data sources or methodologies for
making this projection exist.
a. Is it common for employers to put employees in respirators at
the highest exposure levels permitted by the APF range?
b. Are there particular types of respirators that frequently do not
fit this pattern (i.e., are selected for reasons other than having a
high APF or due to a medical reason for a particular employee)?
c. How do employers approach the issue of uncertainty in possible
exposure levels when integrating APFs into their respirator selection?
d. To what extent will having a single OSHA APF table result in
less confusion than the existing multiplicity of APF tables?
e. Do OSHA's cost estimates of using different types of respirators
adequately represent all of the costs associated with each type of
respirator use?
f. Are their any alternative approaches consistent with the OSH Act
that could reduce the burden of this standard on small entities?

IX. Public Participation--Comments and Hearings

OSHA encourages members of the public to participate in this
rulemaking by submitting comments on the proposal, and by providing
oral testimony and documentary evidence at the informal public hearing
that the Agency will convene after the comment period ends. In this
regard, the Agency invites interested parties having knowledge of, or
experience with, APFs and MUCs to participate in this process, and
welcomes any pertinent data and cost information that will provide it
with the best available evidence on which to develop the final
regulatory requirements.
This section describes the procedures the public must use to submit
their comments to the docket in a timely manner, and to schedule an
opportunity to deliver oral testimony and provide documentary evidence
at the informal public hearings. Comments, notices of intention to
appear, hearing testimony, and documentary evidence will be available
for inspection and copying at the OSHA Docket Office. You also should
read the sections above titled DATES and ADDRESSES for additional
information on submitting comments, documents, and requests to the
Agency for consideration in this rulemaking.
Written Comments. OSHA invites interested parties to submit written
data, views, and arguments concerning this proposal. In particular,
OSHA would encourage interested parties to comment on the issues raised
in section VIII (``Issues'') of the preamble. When submitting comments,
parties must follow the procedures specified above in the sections
titled DATES and ADDRESSES. The comments must clearly identify the
provision of the proposal you are addressing, the position taken with
respect to each issue, and the basis for that position. Comments, along
with supporting data and references, received by the end of the
specified comment period will become part of the proceedings record,
and will be available for public inspection and copying at the OSHA
Docket Office.
Informal Public Hearings. Pursuant to section 6(b)(3) of the Act,
members of the public will have an opportunity at an informal public
hearing to provide oral testimony concerning the issues raised in this
proposal. The hearings will commence at 9:30 a.m. on the first day. At
that time, the presiding administrative law judge (ALJ) will resolve
any procedural matters relating to the proceeding. The hearings will
reconvene on subsequent days at 8:30 a.m.
The legislative history of section 6 of the OSH Act, as well as
OSHA's regulation governing public hearings (29 CFR 1911.15), establish
the purpose and procedures of informal public hearings. Although the
presiding officer of such hearings is an ALJ, and questioning by
interested parties is allowed on crucial issues, the proceeding is
informal and legislative in purpose. Therefore, the hearing provides
interested parties with an opportunity to make effective and
expeditious oral presentations in the absence of procedural restraints
or rigid procedures that could impede or protract the rulemaking
process. In addition, the hearing is an informal administrative
proceeding, rather than adjudicative one in which the technical rules
of evidence would apply, because its primary purpose is to gather and
clarify information. The regulations that govern public hearings, and
the pre-hearing guidelines issued for this hearing, will ensure
participants fairness and due process, and also will facilitate the
development of a clear, accurate, and complete record. Accordingly,
application of these rules and guidelines will be such that questions
of relevance, procedure, and participation generally will favor
development of the record.
Conduct of the hearing will conform to the provisions of 29 CFR
part 1911, ``Rules of Procedure for Promulgating, Modifying, or
Revoking Occupational Safety and Health Standards.'' The regulation at
29 CFR 1911.4 ``Additional or Alternative Procedural Requirements,''
specifies that the Assistant Secretary may, on reasonable notice, issue
alternative procedures to expedite proceedings or for other good cause.
Although the ALJs who preside over these hearings make no decision or
recommendation on the merits of OSHA's proposal, they do have the
responsibility and authority to ensure that the hearing progresses at a
reasonable pace and in an orderly manner.
To ensure that interested parties receive a full and fair informal
hearing as specified by 29 CFR part 1911, the ALJ has the authority and
power to: Regulate the course of the proceedings; dispose of procedural
requests, objections, and comparable matters; confine the presentations
to matters pertinent to the issues raised; use appropriate means to
regulate the conduct of the parties who are present at the hearing;
question witnesses, and permit others to question witnesses; and limit
the time for such questioning. At the close of the hearing, the ALJ
will establish a post-hearing comment period for parties who
participated in the hearing. During the first part of this period, the
participants may submit additional data and information to OSHA, while
during the second part of this period, they may submit briefs,
arguments, and summations.
Notice of Intention To Appear To Provide Testimony at the Informal

[[Page 34114]]

Public Hearings. Interested parties who intend to provide oral
testimony at the informal public hearings must file a notice of
intention to appear by using the procedures specified above in the
sections titled DATES and ADDRESSES. This notice must provide the:
Name, address, and telephone number of each individual who will provide
testimony, and their preferred hearing location; capacity (e.g., name
of the establishment/organization the individual is representing; the
individual's occupational title and position) in which each individual
will testify; approximate amount of time required for each individual's
testimony; specific issues each individual will address, including a
brief statement of the position that the individual will take with
respect to each of these issues; and any documentary evidence the
individual will present, including a brief summary of the evidence.
OSHA emphasizes that the hearings are open to the public, and that
interested parties are welcome to attend. However, only a party who
files a proper notice of intention to appear may ask questions and
participate fully in the proceedings. While a party who did not file a
notice of intention to appear may be allowed to testify at the hearing
if time permits, this determination is at the discretion of the
presiding ALJ.
Hearing Testimony and Documentary Evidence. Any party requesting
more than 10 minutes to testify at the informal public hearing, or who
intends to submit documentary evidence at the hearing, must provide the
complete text of the testimony and the documentary evidence as
specified above in the sections titled DATES and ADDRESSES. The Agency
will review each submission and determine if the information it
contains warrants the amount of time requested. If OSHA believes the
requested time is excessive, it will allocate an appropriate amount of
time to the presentation, and will notify the participant of this
action, and the reasons for the action, prior to the hearing. The
Agency may limit to 10 minutes the presentation of any participant who
fails to comply substantially with these procedural requirements; in
such instances, OSHA may request the participant to return for
questioning at a later time.
Certification of the Record and Final Determination After the
Informal Public Hearing. Following the close of the hearing and post-
hearing comment period, the presiding ALJ will certify the record to
the Assistant Secretary of Labor for Occupational Safety and Health;
the record will consist of all of the written comments, oral testimony,
and documentary evidence received during the proceeding. However, the
ALJ does not make or recommend any decisions as to the content of the
final standard. Following certification of the record, OSHA will review
the proposed APF provisions in light of all the evidence received as
part of the record, and then will issue the final APF provisions based
on the entire record.

List of Subjects in 29 CFR Parts 1910, 1915, and 1926

Assigned protection factors, Hazardous substances, Health,
Occupational safety and health, Respirators, Respirator selection.

Authority and Signature

John L. Henshaw, Assistant Secretary of Labor for Occupational
Safety and Health, U.S. Department of Labor, 200 Constitution Ave.,
NW., Washington, DC 20210, directed the preparation of this notice. The
Agency issues the proposed sections under the following authorities:
Sections 4, 6(b), 8(c), and 8(g) of the Occupational Safety and Health
Act of 1970 (29 U.S.C. 653, 655, 657); section 107 of the Contract Work
Hours and Safety Standards Act (the Construction Safety Act) (40 U.S.C.
333); section 41, the Longshore and Harbor Worker's Compensation Act
(33 U.S.C. 941); Secretary of Labor's Order No. 5-2002 (67 FR 65008);
and 29 CFR Part 1911.

Signed at Washington, DC, on May 28, 2003.
John L. Henshaw,
Assistant Secretary of Labor.

X. Proposed Amendments to Standards

OSHA proposes to amend 29 CFR parts 1910, 1915, and 1926 as
follows:

PART 1910--[AMENDED]

Subpart I--[Amended]

1. The authority citation for subpart I of part 1910 is revised to
read as follows:

Authority: Sections 4, 6, and 8 of the Occupational Safety and
Health Act of 1970 (29 U.S.C. 653, 655, and 657); and Secretary of
Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48
FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), or 3-2000 (62 FR
50017).
Sections 1910.132, 1910.134, and 1910.138 or 29 CFR also issued
under 29 CFR part 1911.
Sections 1910.133, 1910.135, and 1910.136 of 29 CFR also issued
under 29 CFR part 1911 and 5 U.S.C. 553.

2. Section 1910.134 is amended as follows:
a. The text of the definitions for ``Assigned protection factor
(APF)'' and ``Maximum use concentration (MUC)'' is added to paragraph
(b);
b. The text of paragraphs (d)(3)(i)(A) and (d)(3)(i)(B) is added;
and
c. Paragraph (n) is revised.
The added and revised text read as follows:

Sec. 1910.134 Respiratory protection.

* * * * *
(b) * * *
Assigned protection factor (APF) means the workplace level of
respiratory protection that a respirator or class of respirators is
expected to provide to employees when the employer implements a
continuing, effective respiratory protection program as specified by 29
CFR 1910.134.
* * * * *
Maximum use concentration (MUC) means the maximum atmospheric
concentration of a hazardous substance from which an employee can be
expected to be protected when wearing a respirator, and is determined
by the assigned protection factor of the respirator or class of
respirators and the exposure limit of the hazardous substance. The MUC
usually can be determined mathematically by multiplying the assigned
protection factor specified for a respirator by the permissible
exposure limit, short term exposure limit, ceiling limit, peak limit,
or any other exposure limit used for the hazardous substance.
* * * * *
(d) * * *
(3) * * *
(i) * * *
(A) Assigned Protection Factors (APFs). Employers must use the
assigned protection factors listed in Table I to select a respirator
that meets or exceeds the required level of employee protection. When
using a combination respirator (e.g., airline respirators with an air-
purifying filter), employers must ensure that the assigned protection
factor is appropriate to the mode of operation in which the respirator
is being used.

Note to paragraph (d)(3)(i)(A): The assigned protection factors
listed in Table I are effective only when the employer has a
continuing, effective respiratory protection program as specified by
29 CFR 1910.134, including training, fit testing, maintenance and
use requirements. These assigned protection factors do not apply to
respirators used solely for escape.

[[Page 34115]]

Table I.--Assigned Protection Factors
----------------------------------------------------------------------------------------------------------------
Loose-fitting
Type of respirator 1 2 Half mask Full facepiece Helmet/hood facepiece
----------------------------------------------------------------------------------------------------------------
1. Air-Purifying Respirator................. 3 10 50 ................ ..............
2. Powered Air-Purifying Respirator (PAPR).. 50 1000 4 1000 25
3. Supplied-Air Respirator (SAR) or Airline
Respirator:
? Demand mode..................... 10 50 ................ ..............
? Continuous-flow mode............ 50 1,000 4 1,000 25
? Pressure-demand or other 50 1,000 ................ ..............
positive-pressure mode.................
4. Self-Contained Breathing Apparatus
(SCBA):
? Demand mode..................... 10 50 50 ..............
? Pressure-demand or other .............. 10,000 10,000 ..............
positive-pressure mode (e.g., open/ 5 (maximum) 5 (maximum)
closed circuit)........................
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ Employers may select respirators assigned for use in higher workplace concentrations of a hazardous
substance for use at lower concentrations of that substance or when required respirator use is independent of
concentration.
\2\ The assigned protection factors in Table I only apply when the employer implements a continuing, effective
respirator program as specified by OSHA's Respiratory Protection Standard at 29 CFR 1910.134, including
training, fit testing, maintenance and use requirements.
\3\ This APF category includes quarter masks, filtering facepieces, and half-masks.
\4\ Previous studies involving Workplace Protection Factor (WPF) and Simulated Workplace Protection Factor
(SWPF) testing on helmet/hood respirators show that some of these respirators do not provide a level of
protection consistent with an APF of 1000. Therefore, only helmet/hood respirators that ensure the maintenance
of a positive pressure inside the facepiece during use, consistent with performance at a level of protection
of 1000 or greater, receive an APF of 1000. All other helmet/hood respirators are treated as loose-fitting
facepiece respirators and receive an APF of 25.
\5\ Although positive pressure SCBAs appear to provide the highest level of respiratory protection, a SWPF study
of SCBA users concluded that all users may not achieve protection factors of 10,000 at high work rates. When
employers can estimate hazardous concentrations for planning purposes, they must use a maximum assigned
protection factor no higher than 10,000.

(B) Maximum Use Concentration (MUC). (1) The employer must select a
respirator for employee use that maintains the employee's exposure to
the hazardous substance, when measured outside the respirator, at or
below the MUC.

Note to paragraph (d)(3)(i)(B)(1): MUCs are effective only when
the employer has a continuing, effective respiratory protection
program as specified by 29 CFR 1910.134, including training, fit
testing, maintenance and use requirements.

(2) Employers must comply with the respirator manufacturer's MUC
for a hazardous substance when the manufacturer's MUC is lower than the
calculated MUC specified by this standard.
(3) Employers must not apply MUCs to conditions that are
immediately dangerous to life or health (IDLH); instead, they must use
respirators listed for IDLH conditions in paragraph (d)(2) of this
standard.
(4) When the calculated MUC exceeds another limiting factor such as
the IDLH level for a hazardous substance, the lower explosive limit
(LEL), or the performance limits of the cartridge or canister, then
employers must set the maximum MUC at that lower limit.
* * * * *
(n) Effective date. Paragraphs (d)(3)(i)(A) and (d)(3)(i)(B) of
this section become effective September 4, 2003.
* * * * *

Subpart Z--[Amended]

3. The general authority citation for subpart Z of part 1910 is
revised to read as follows:

Authority: Sections 4, 6, and 8 of the Occupational Safety and
Health Act of 1970 (29 U.S.C. 653, 655, and 657); Secretary of
Labor's Orders 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR
35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), or 3-2000 (62 FR
50017); and 29 CFR Part 1911.
* * * * *
4. Section 1910.1001 is amended by:
a. Removing Table 1 in paragraph (g)(3);
b. Redesignating Table 2 in paragraph (l)(3)(ii) as Table 1;
c. Removing the reference to ``Table 2'' in paragraph (l)(3)(ii)
and adding ``Table 1'' in its place; and
d. Revising paragraphs (g)(2)(ii) and (g)(3).
The revisions read as follows:

Sec. 1910.1001 Asbestos.

* * * * *
(g) * * *
(2) * * *
(ii) Employers must provide an employee with tight-fitting, powered
air-purifying respirator (PAPR) instead of a negative-pressure
respirator selected according to paragraph (g)(3) of this standard when
the employee chooses to use a PAPR and it provides adequate protection
to the employee.
* * * * *
(3) Respirator selection. Employers must:
(i) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however,
employers must not select or use filtering-facepiece respirators for
protection against asbestos fibers.
(ii) Provide HEPA filters for air-purifying respirators.
* * * * *
5. In Sec. 1910.1017, remove the table in paragraph (g)(3)(i),
remove paragraph (g)(3)(iii), and revise paragraph (g)(3)(i) to read as
follows:

Sec. 1910.1017 Vinyl chloride.

* * * * *
(g) * * *
(3) * * * (i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Provide an organic-vapor cartridge that has a service life of
at least one hour when using a chemical-cartridge respirator at vinyl
chloride concentrations up to 10 ppm.
(C) Select a canister that has a service life of at least four
hours when using a powered air-purifying respirator having a hood,
helmet, or full or half facepiece, or a gas mask with a front- or back-
mounted canister, at vinyl chloride concentrations up to 25 ppm.
* * * * *
6. In Sec. 1910.1018, remove Tables I and II and paragraph
(h)(3)(ii), redesignate paragraph (h)(3)(iii) as paragraph

[[Page 34116]]

(h)(3)(ii), and revise paragraph (h)(3)(i) to read as follows:

Sec. 1910.1018 Inorganic arsenic.

* * * * *
(h) * * *
(3) * * *(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Ensure that employees do not use half-mask respirators for
protection against arsenic trichloride because it is absorbed rapidly
through the skin.
(C) Provide HEPA filters for air-purifying respirators.
(D) Select for employee use:
(1) Air-purifying respirators that have a combination HEPA filter
with an appropriate gas-sorbent cartridge or canister when the
employee's exposure exceeds the permissible exposure level for
inorganic arsenic and the relevant limit for other gases.
(2) Front- or back-mounted gas masks equipped with HEPA filters and
acid-gas canisters or any full-facepiece supplied-air respirators when
the inorganic arsenic concentration is at or below 500 [mu]g/m\3\; and
half-mask air-purifying respirators equipped with HEPA filters and
acid-gas cartridges when the inorganic arsenic concentration is at or
below 100 [mu]g/m\3\.
* * * * *
7. In Sec. 1910.1025, remove Table II in paragraph (f)(2)(ii) and
revise paragraphs (f)(3)(i) and (f)(3)(ii) to read as follows:

Sec. 1910.1025 Lead.

* * * * *
(f) * * *
(3) * * *(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Provide employees with full-facepiece respirators instead of
half-mask respirators for protection against lead aerosols that cause
eye or skin irritation at the use concentrations.
(C) Provide HEPA filters for air-purifying respirators.
(ii) Employers must provide employees with a powered air-purifying
respirator (PAPR) instead of a negative-pressure respirator selected
according to paragraph (f)(3)(i) of this standard when an employee
chooses to use a PAPR and it provides adequate protection to the
employee as specified by paragraph (f)(3)(i) of this standard.
* * * * * .
8. In Sec. 1910.1027, remove Table 2 in paragraph (g)(3)(i) and
revise paragraph (g)(3)(i) to read as follows:

Sec. 1910.1027 Cadmium.

* * * * *
(g) * * *
(3) * * *(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Provide employees with full-facepiece respirators when they
experience eye irritation.
(C) Provide HEPA filters for air-purifying respirators.
* * * * *
9. In Sec. 1910.1028, remove Table 1 in paragraph (g)(3)(ii) and
revise paragraphs (g)(2)(i) and (g)(3)(i) to read as follows:

Sec. 1910.1028 Benzene.

* * * * *
(g) * * *
(2) * * *
(i) Employers must implement a respiratory protection program in
accordance with 29 CFR 1910.134 (b) through (d) (except (d)(1)(iii)),
and (f) through (m).
* * * * *
(3) * * *
(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Provide employees with any organic-vapor gas mask or any self-
contained breathing apparatus with a full facepiece to use for escape.
(C) Use an organic-vapor cartridge or canister air-purifying
respirators, and a chin-style canister with full-facepiece gas masks.
(D) Ensure that canisters used with nonpowered air-purifying
respirators have a minimum service life of four hours when tested at
150 ppm benzene at a flow rate of 64 liters per minute (LPM), a
temperature of 25[deg]
C, and a relative humidity of 85%; for canisters
used with tight-fitting or loose-fitting, powered air-purifying
respirators, the flow rates for testing must be 115 LPM and 170 LPM,
respectively.
* * * * *
10. In Sec. 1910.1029, remove Table I in paragraph (g)(3) and
revise paragraph (g)(3) to read as follows:

Sec. 1910.1029 Coke oven emissions.

* * * * *
(g) * * *
(3) Respirator selection. Employers must select, and provide to
employees, the appropriate respirators specified in paragraph
(d)(3)(i)(A) of 29 CFR 1910.134; however, employers must not select or
use filtering facepieces for protection against coke oven emissions.
* * * * *
11. In Sec. 1910.1043, remove Table I in paragraph (f)(3)(i) and
revise paragraphs (f)(3)(i) and (f)(3)(ii) to read as follows:

Sec. 1910.1043 Cotton dust.

* * * * *
(f) * * *
(3) * * *
(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however,
employers must not select or use filtering facepieces for protection
against cotton dust concentrations greater than five times (5 X) the
PEL.
(B) Provide HEPA filters for air-purifying respirators used at
cotton dust concentrations greater than ten times (10 X) the PEL.
(ii) Employers must provide an employee with a powered air-
purifying respirator (PAPR) instead of a nonpowered air-purifying
respirator selected according to paragraph (f)(3)(i) of this standard
when the employee chooses to use a PAPR and it provides adequate
protection to the employee as specified by paragraph (f)(3)(i) of this
standard.
* * * * *
12. In Sec. 1910.1044, remove Table 1 in paragraph (h)(3) and
revise paragraph (h)(3) to read as follows:

Sec. 1910.1044 1,2-Dibromo-3-chloropropane.

* * * * *
(h) * * *
(3) Respirator selection. Employers must:
(i) Select, and provide to employees, the appropriate atmosphere-
supplying respirator specified in paragraph (d)(3)(i)(A) of 29 CFR
1910.134.
(ii) Provide employees with one of the following respirator options
to use for entry into, or escape from, unknown DBCP concentrations:
(A) A combination respirator that includes a supplied-air
respirator with a full facepiece operated in a pressure-demand or other
positive-pressure or continuous-flow mode, as well as an auxiliary
self-contained breathing apparatus (SCBA) operated in a pressure-demand
or positive-pressure mode.
(B) An SCBA with a full facepiece operated in a pressure-demand or
other positive-pressure mode.
* * * * *
13. In Sec. 1910.1045, remove Table I in paragraph (h)(3) and
revise paragraphs (h)(2)(i) and (h)(3) to read as follows:

[[Page 34117]]

Sec. 1910.1045 Acrylonitrile.

* * * * *
(h) * * *
(2) * * *
(i) Employers must implement a respiratory protection program in
accordance with 29 CFR 1910.134 (b) through (d) (except (d)(1)(iii)),
and (f) through (m).
* * * * *
(3) Respirator selection. Employers must:
(i) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(ii) For escape, provide employees with any organic-vapor
respirator or any self-contained breathing apparatus permitted for use
under paragraph (h)(3)(i) of this standard.
* * * * *
14. In Sec. 1910.1047, remove Table 1 in paragraph (g)(3) and
revise paragraph (g)(3) to read as follows:

Sec. 1910.1047 Ethylene oxide.

* * * * *
(g) * * *
(3) Respirator selection. Employers must:
(i) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however,
employers must not select or use half-masks of any type because EtO may
cause eye irritation or injury.
(ii) Equip each air-purifying, full facepiece respirator with a
front- or back-mounted canister approved for protection against
ethylene oxide.
(iii) For escape, provide employees with any respirator permitted
for use under paragraph (g)(3)(i) of this standard.
* * * * *
15. In Sec. 1910.1048, remove Table 1 in paragraph (g)(3)(i) and
revise paragraphs (g)(2) and (g)(3) to read as follows:

Sec. 1910.1048 Formaldehyde.

* * * * *
(g) * * *
(2) Respirator programs. (i) Employers must implement a respiratory
protection program in accordance with 29 CFR 1910.134 (b) through (d)
(except (d)(1)(iii)), and (f) through (m).
(ii) If employees use air-purifying respirators with chemical
cartridges or canisters that do not contain end-of-service-life
indicators approved by the National Institute for Occupational Safety
and Health, employers must replace these cartridges or canisters as
specified by paragraphs (d)(3)(iii)(B)(1) and (B)(2) of 29 CFR
1910.134, or at the end of the workshift, whichever condition occurs
first.
(3) Respirator selection. (i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Equip each air-purifying, full facepiece respirator with a
canister or cartridge approved for protection against formaldehyde.
(C) For escape, provide employees with one of the following
respirator options: A self-contained breathing apparatus operated in
the demand or pressure-demand mode; or a full facepiece respirator
having a chin-style, or a front- or back-mounted industrial-size,
canister or cartridge approved for protection against formaldehyde.
(ii) Employers may substitute an air-purifying, half-mask
respirator for an air-purifying, full facepiece respirator if they
equip the half-mask respirator with a cartridge approved for protection
against formaldehyde and provide the affected employee with effective
gas-proof goggles.
(iii) Employers must provide employees who have difficulty using
negative-pressure respirators with powered air-purifying respirators
permitted for use under paragraph (g)(3)(i)(A) of this standard and
that provide adequate protection against their formaldehyde exposures.
* * * * *
16. In Sec. 1910.1050, remove Table 1 in paragraph (h)(3)(i) and
revise paragraph (h)(3)(i) to read as follows:

Sec. 1910.1050 Methylenedianiline.

* * * * *
(h) * * *
(3) * * *
(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Provide HEPA filters for air-purifying respirators.
(C) For escape, provide employees with one of the following
respirator options: Any self-contained breathing apparatus with a full
facepiece or hood operated in the positive-pressure or continuous-flow
mode; or a full-facepiece, air-purifying respirator.
(D) Provide a combination HEPA filter and organic-vapor canister or
cartridge with air-purifying respirators when MDA is in liquid form or
part of a process requiring heat.
* * * * *
17. In Sec. 1910.1052, remove Table 2 in paragraph (g)(3) and
revise paragraph (g)(3) to read as follows:

Sec. 1910.1052 Methylene chloride.

* * * * *
(g) * * *
(3) Respirator selection. Employers must:
(i) Select, and provide to employees, the appropriate atmosphere-
supplying respirator specified in paragraph (d)(3)(i)(A) of 29 CFR
1910.134; however, employers must not select or use half-masks of any
type because MC may cause eye irritation or damage.
(ii) For emergency escape, provide employees with one of the
following respirator options: A self-contained breathing apparatus
operated in the continuous-flow or pressure-demand; or a gas mask with
an organic-vapor canister.
* * * * *

PART 1915--[AMENDED]

18. The authority citation for part 1915 is revised to read as
follows:

Authority: Section 41, Longshore and Harbor Workers'
Compensation Act (33 U.S.C. 941); Sections 4, 6, and 8 of the
Occupational Safety and Health Act of 1970 (20 U.S.C. 653, 655, and
687); and Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR
111), or 3-2000 (62 FR 50017).

Sections 1915.120 and 1915.152 also issued under 29 CFR 1911.

Subpart Z--[Amended]

19. In Sec. 1915.1001, remove Table 1 in paragraph (h)(2)(iii) and
revise paragraph (h)(2) to read as follows:

Sec. 1915.1001 Asbestos.

* * * * *
(h) * * *
(2) Respirator selection. (i) Employers must select, and provide to
employees at no cost, the appropriate respirators specified in
paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however, employers must not
select or use filtering-facepiece respirators for use against asbestos
fibers.
(ii) Employers are to provide HEPA filters for air-purifying
respirators.
(iii) Employers must:
(A) Inform employees that they may require the employer to provide
a tight-fitting, powered air-purifying respirator (PAPR) permitted for
use under paragraph (h)(2)(i) of this standard instead of a negative-
pressure respirator.
(B) Provide employees with a tight-fitting PAPR instead of a
negative-pressure respirator when the employees choose to use a tight-
fitting PAPR and it provides them with the required protection against
asbestos.
(iv) Employers must provide employees with an air-purifying, half-

[[Page 34118]]

mask respirator, other than a filtering-facepiece respirator, whenever
the employees perform:
(A) Class II or Class III asbestos work for which no negative-
exposure assessment is available.
(B) Class III asbestos work involving disturbance of TSI or
surfacing ACM or PACM.
(v) Employers must provide employees with:
(A) A tight-fitting, powered air-purifying respirator or a full-
facepiece, supplied-air respirator operated in the pressure-demand mode
and equipped with either HEPA egress cartridges or an auxiliary
positive-pressure, self-contained breathing apparatus (SCBA) whenever
the employees are in a regulated area performing Class I asbestos work
for which a negative-exposure assessment is not available and the
exposure assessment indicates that the exposure level will be at or
below 1 f/cc as an 8-hour time-weighted average (TWA).
(B) A full-facepiece, supplied-air respirator operated in the
pressure-demand mode and equipped with an auxiliary positive-pressure
SCBA whenever the employees are in a regulated area performing Class I
asbestos work for which a negative-exposure assessment is not available
and the exposure assessment indicates that the exposure level will be
above 1 f/cc as an 8-hour TWA.
* * * * *

PART 1926--[AMENDED]

Subpart D--[Amended]

20. The authority citation for subpart D of part 1926 is revised to
read as follows:

Authority: Section 107, Contract Work Hours and Safety Standards
Act (Construction Safety Act) (40 U.S.C. 333); sections 4, 6, and 8
of the Occupational Safety and Health Act of 1970 (29 U.S.C. 653,
655, and 657); Secretary of Labor's Orders 12-71 (36 FR 8754), 8-76
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR
111), or 3-2000 (62 FR 50017); and 29 CFR part 11.
Sections 1926.58, 1926.59, 1926.60, and 1926.65 also issued
under 5 U.S.C. 553 and 29 CFR part 1911.
Section 1926.62 also issued under section 1031 of the Housing
and Community Development Act of 1992 (42 U.S.C. 4853).

Section 1926.65 of 29 CFR also issued under section 126 of the
Superfund Amendments and Reauthorization Act of 1986, as amended (29
U.S.C. 655 note), and 5 U.S.C. 553.
21. In Sec. 1926.60, remove Table 1 and revise paragraph (i)(3)(i)
to read as follows:

Sec. 1926.60 Methylenedianiline.

* * * * *
(i) * * *
(3) * * *
(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Provide HEPA filters for air-purifying respirators.
(C) For escape, provide employees with one of the following
respirator options: Any self-contained breathing apparatus with a full
facepiece or hood operated in the positive-pressure or continuous-flow
mode; or a full-facepiece, air-purifying respirator.
(D) Provide a combination HEPA filter and organic-vapor canister or
cartridge with air-purifying respirators when MDA is in liquid form or
part of a process requiring heat.
* * * * *
22. In Sec. 1926.62, remove Table 1 in paragraph (f)(3) and revise
paragraph (f)(3)(i) to read as follows:

Sec. 1926.62 Lead.

Subpart Z--[Amended]

23. The authority citation for subpart Z of part 1926 is revised to
read as follows:

Authority: Sections 4, 6, and 8 of the Occupational Safety and
Health Act of 1970 (29 U.S.C. 653, 655, 657); Secretary of Labor's
Orders 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736),
1-90 (55 FR 9033), 6-96 (62 FR 111), or 3-2000 (62 FR 50017); and 29
CFR part 11.
Section 1926.1102 not issued under 29 U.S.C. 655 or 29 CFR part
1911; also issued under 5 U.S.C. 553.

24. In Sec. 1926.1101, remove Table 1 in paragraph (h)(3)(i) and
revise paragraph (h)(3) to read as follows:

Sec. 1926.1101 Asbestos.

* * * * *
(h) * * *
(3) Respirator selection. (i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in paragraph (d)(3)(i)(A) of 29 CFR 1910.134; however,
employers must not select or use filtering-facepiece respirators for
use against asbestos fibers.
(B) Provide HEPA filters for air-purifying respirators.
(ii) Employers must provide an employee with tight-fitting, powered
air-purifying respirator (PAPR) instead of a negative-pressure
respirator selected according to paragraph (h)(3)(i)(A) of this
standard when the employee chooses to use a PAPR and it provides
adequate protection to the employee.
(iii) Employers must provide employees with an air-purifying, half-
mask respirator, other than a filtering-facepiece respirator, whenever
the employees perform:
(A) Class II or Class III asbestos work for which no negative-
exposure assessment is available.
(B) Class III asbestos work involving disturbance of TSI or
surfacing ACM or PACM.
(iv) Employers must provide employees with:
(A) A tight-fitting, powered air-purifying respirator or a full-
facepiece, supplied-air respirator operated in the pressure-demand mode
and equipped with either HEPA egress cartridges or an auxiliary
positive-pressure, self-contained breathing apparatus (SCBA) whenever
the employees are in a regulated area performing Class I asbestos work
for which a negative-exposure assessment is not available and the
exposure assessment indicates that the exposure level will be at or
below 1 f/cc as an 8-hour time-weighted average (TWA).
(B) A full-facepiece, supplied-air respirator operated in the
pressure-demand mode and equipped with an auxiliary positive-pressure
SCBA whenever the employees are in a regulated area performing Class I
asbestos work for which a negative-exposure assessment is not available
and the exposure assessment indicates that the exposure level will be
above 1 f/cc as an 8-hour TWA.
* * * * *
25. In Sec. 1926.1127, remove Table 1 in paragraph (g)(3)(i) and
revise paragraph (g)(3)(i) to read as follows:

Sec. 1926.1127 Cadmium.

* * * * *
(g) * * *
(3) * * *
(i) Employers must:
(A) Select, and provide to employees, the appropriate respirators
specified in

[[Page 34119]]

paragraph (d)(3)(i)(A) of 29 CFR 1910.134.
(B) Provide employees with full-facepiece respirators when they
experience eye irritation.
(C) Provide HEPA filters for air-purifying respirators.
* * * * *
[FR Doc. 03-13749 Filed 6-5-03; 8:45 am]
BILLING CODE 4510-26-P

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