Revisions to Ambient Air Monitoring Regulations

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

[Federal Register: January 17, 2006 (Volume 71, Number 10)]
[Proposed Rules]
[Page 2709-2808]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17ja06-22]
[[Page 2710]]

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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 53 and 58
[EPA-HQ-OAR-2004-0018; FRL-8015-9]
RIN 2060-AJ25

AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule; amendments.

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SUMMARY: The EPA is proposing to revise the ambient air monitoring
requirements for criteria pollutants. This proposal establishes ambient
air monitoring requirements in support of the proposed revisions to the
National Ambient Air Quality Standards (NAAQS) for particulate matter
published elsewhere in today's Federal Register, including new minimum
monitoring network requirements for PM_10-2.5 and criteria
for approval of Federal reference and equivalent methods for
PM_10-2.5 (to supplement the Federal reference method for
PM_10-2.5 proposed elsewhere in today's Federal Register).
This proposal also requires each State to operate one to three
monitoring stations that take an integrated, multipollutant approach to
ambient air monitoring. The proposed amendments modify the requirements
for ambient air monitors by focusing requirements on populated areas
with air quality problems and significantly reducing the requirements
for criteria pollutant monitors that have measured ambient air
concentrations well below the applicable NAAQS. Other proposed
amendments revise the requirements for reference and equivalent method
determinations (including specifications and test procedures) for fine
particulate monitors, monitoring network descriptions and periodic
assessments, quality assurance, and data certification. The purpose of
the proposed amendments is to enhance ambient air quality monitoring to
better serve current and future air quality management and research needs.

DATES: Comments must be received on or before April 17, 2006.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2004-0018, by one of the following methods:
? http://www.regulations.gov: Follow the on-line
instructions for submitting comments.
? E-mail: a-and-r-docket@epa.gov.
? Fax: (202) 566-1741.
? Mail: Revisions to Ambient Air Monitoring Regulations,
Docket No. EPA-HQ-OAR-2004-0018, Environmental Protection Agency,
Mailcode 6102T, 1200 Pennsylvania Ave., NW., Washington, DC 20460.
Please include a total of two copies. In addition, please mail a copy
of your comments on the information collection provisions to the Office
of Information and Regulatory Affairs, Office of Management and Budget
(OMB), Attn: Desk Officer for EPA, 725 17th St., NW., Washington, DC 20503.
? Hand Delivery: EPA Docket Center, 1301 Constitution
Avenue, NW., Room B102, Washington, DC 20460. Such deliveries are only
accepted during the Docket's normal hours of operation, and special
arrangements should be made for deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2004-0018. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal
information provided, unless the comment includes information claimed to
be Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov
or e-mail. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA without
going through http://www.regulations.gov your e-mail address
will be automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. For additional information about EPA's public
docket, visit the EPA Docket Center homepage at
http://www.epa.gov/epahome/dockets.htm.
Docket: All documents in the docket are listed in the http://
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the Revisions
to the Ambient Air Monitoring Regulations Docket, EPA/DC, EPA West, Room
B102, 1301 Constitution Ave., NW., Washington, DC. The Public Reading Room
is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the Air Docket is (202)
566-1742.

FOR FURTHER INFORMATION CONTACT: For general questions concerning
today's proposed amendments, please contact Mr. Lewis Weinstock, U.S.
EPA, Office of Air Quality Planning and Standards, Emissions Monitoring
and Analysis Division, Ambient Air Monitoring Group (D243-02), Research
Triangle Park, North Carolina 27711; telephone number: (919) 541-3661;
fax number: (919) 541-1903; e-mail address: weinstock.lewis@epa.gov.
For technical questions, please contact Mr. Tim Hanley, U.S. EPA,
Office of Air Quality Planning and Standards, Emissions Monitoring and
Analysis Division, Ambient Air Monitoring Group (D243-02), Research
Triangle Park, North Carolina 27711; telephone number: (919) 541-4417;
fax number: (919) 541-1903; e-mail address: hanley.tim@epa.gov.

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does This Action Apply to Me?

Categories and entities potentially regulated by this action include:

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Category NAIC code 1 Examples of regulated entities
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Industry...................................................... 334513 Manufacturer, supplier,
541380 distributor, or vendor of
ambient air monitoring
instruments; analytical
laboratories or other
monitoring organizations that
elect to submit an application
for a reference or equivalent
method determination under 40
CFR part 53.

[[Page 2711]]

Federal government............................................ 924110 Federal agencies (that conduct
ambient air monitoring similar
to that conducted by States
under 40 CFR part 58 and that
wish EPA to use their
monitoring data in the same
manner as State data) or that
elect to submit an application
for a reference or equivalent
method determination under 40
CFR part 53.
State/local/tribal government................................. 924110 State, territorial, and local,
air quality management programs
that are responsible for
ambient air monitoring under 40
CFR part 58 or that elect to
submit an application for a
reference or equivalent method
determination under 40 CFR part
53. The proposal also may
affect Tribes that conduct
ambient air monitoring similar
to that conducted by States and
that wish EPA to use their
monitoring data in the same
manner as State monitoring
data.
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1 North American Industry Classification System.

This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. To determine whether your facility or Federal, State, local, or
territorial agency would be regulated by this action, you should
examine the requirements for reference or equivalent method
determinations in 40 CFR part 53, subpart A (General Provisions) and
the applicability criteria in 40 CFR 51.1 of EPA's requirements for
State implementation plans. If you have any questions regarding the
applicability of this action to a particular entity, consult the person
listed in the preceding FOR FURTHER INFORMATION CONTACT section.

B. What Should I Consider as I Prepare My Comments for EPA?

Do not submit information containing Confidential Business
Information (CBI) to EPA through http://www.regulations.gov or e-mail. Send
or deliver information identified as CBI only to the following address:
Roberto Morales, OAQPS Document Control Officer (C404-02), U.S. EPA,
Office of Air Quality Planning and Standards, Research Triangle Park,
North Carolina 27711, Attention Docket ID EPA-HQ-OAR-2004-0018. Clearly
mark the part or all of the information that you claim to be CBI. For
CBI information in a disk or CD ROM that you mail to EPA, mark the
outside of the disk or CD ROM as CBI and then identify electronically
within the disk or CD ROM the specific information that is claimed as
CBI. In addition to one complete version of the comment that includes
information claimed as CBI, a copy of the comment that does not contain
the information claimed as CBI must be submitted for inclusion in the
public docket. Information so marked will not be disclosed except in
accordance with procedures set forth in 40 CFR part 2.

C. Where Can I Get a Copy of This Document and Other Related Information?

In addition to being available in the docket, an electronic copy of
today's proposed amendments is also available on the Worldwide Web
(WWW) through the Technology Transfer Network (TTN). Following the
Administrator's signature, a copy of the proposed amendments will be
placed on the TTN's policy and guidance page for newly proposed or
promulgated rules at http://www.epa.gov/ttn/oarpg. The TTN provides
information and technology exchange in various areas of air pollution
control.

D. Will There Be a Public Hearing?

Public hearings will be held concurrently with the public hearings
on the proposed amendments to the NAAQS for particulate matter
published elsewhere in this Federal Register. The EPA intends to hold
public hearings during February 2006 in Philadelphia, Pennsylvania;
Chicago, Illinois; and San Francisco, California. The EPA will announce
the date, location, and time of the public hearings in a separate
Federal Register notice.

E. Did EPA Conduct a Peer Review Before Issuing This Notice?

The EPA sought expert scientific review of the proposed methods,
technologies, and approach for ambient air monitoring by the Clean Air
Scientific Advisory Committee (CASAC). The CASAC is a Federal advisory
committee established to review scientific and technical information
and make recommendations to the EPA Administrator on issues related to
the air quality criteria and corresponding NAAQS. CASAC constituted a
National Ambient Air Monitoring Strategy (NAAMS) Subcommittee in 2003
to provide advice for a strategy for the national ambient air
monitoring programs. This subcommittee, which operated over a one-year
period, and a new subcommittee on Ambient Air Monitoring and Methods
(AAMM), formed in 2004, provided the input for CASAC on its
consultations, advisories, and peer-reviewed recommendations to the EPA
Administrator.
In July 2003, the CASAC NAAMS Subcommittee held a public meeting to
review EPA's draft National Ambient Air Monitoring Strategy document
(dated September 6, 2002), which contained technical information
underlying planned changes to the ambient air monitoring networks. The
EPA continued to consult with the CASAC AAMM Subcommittee throughout
the development of the proposed amendments. Public meetings were held
in July 2004, December 2004, and September 2005 to discuss the CASAC
review of nearly 20 documents concerning methods and technology for
measurement of particulate matter (PM); data quality objectives for PM
monitoring networks and related performance-based standards for
approval of equivalent continuous PM monitors; reconfiguration of
ambient air monitoring stations; \1\ and other technical aspects of the
proposed amendments. These documents, along with CASAC review comments
and other information are available at:
http://www.epa.gov/ttn/amtic/casacinf.html.

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\1\ ``Station'' and ``site'' are used somewhat interchangeably
in this notice of proposed rulemaking. When there is a difference
``site'' generally refers to the location of a monitor, while
``station'' refers to a suite of measurements at a particular site.
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F. How Is This Document Organized?

The information presented in this preamble is organized as follows:

I. General Information
A. Does this action apply to me?
B. What should I consider as I prepare my comments for EPA?
C. Where can I get a copy of this document and other related
information?
D. Will there be a public hearing?
E. Did EPA conduct a peer review before issuing this notice?
F. How is this document organized?
II. Overview

[[Page 2712]]

A. What is the purpose of today's proposal?
B. What are the major changes proposed to the ambient air
monitoring regulations?
C. When would the proposed amendments affect States, local
governments, tribes, and other stakeholders?
D. How would EPA implement the new requirements?
III. Background
A. What is the role of ambient air monitoring in air quality management?
B. What is the history of ambient air monitoring?
C. What revisions to the National Ambient Air Quality Standards
for particulate matter also are proposed today?
D. How do the monitoring data apply to attainment or
nonattainment designations and findings?
IV. Proposed Monitoring Amendments
A. What are the proposed terminology changes?
B. What are the proposed requirements for approval of reference
or equivalent methods?
C. What are the proposed requirements for quality assurance
programs for the National Ambient Air Monitoring System?
D. What are the proposed monitoring methods for the National
Ambient Air Monitoring System?
E. What are the proposed requirements for the number and
location of monitors to be operated by State and local agencies?
F. What are the proposed probe and monitoring path siting criteria?
G. What are the proposed data reporting, data certification, and
sample retention requirements?
V. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
H. Executive Order 13211: Actions that Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer Advancement Act
J. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income Populations

II. Overview

A. What Is the Purpose of Today's Proposal?

The EPA is proposing a number of changes to the ambient air quality
monitoring requirements of 40 CFR parts 53 and 58 to ensure that the
national network of air monitors will meet the current and future data
needs of EPA (and other Federal), State, local, and tribal air quality
management agencies. While much of today's proposed rule outlines
changes to the monitoring requirements for particulate matter (PM),
there are additional changes relating to all the other criteria
pollutants (ozone (O₃), carbon monoxide (CO), sulfur dioxide
(SO₂), nitrogen dioxide (NO₂), and lead (Pb))
included in this proposal.
Some of these proposed changes are in support of the proposed
revisions to the National Ambient Air Quality Standards (NAAQS) for PM
in 40 CFR part 50 published elsewhere in today's Federal Register.\2\
These changes are essential to implementation of the proposed NAAQS for
PM. Included among these proposed PM-related changes are new provisions
for addition to 40 CFR parts 53 and 58 which address approval of
methods and PM_10-2.5 monitoring requirements. The added
provisions would address federal reference method (FRM) equivalency
determinations for continuous PM_10-2.5 monitors and the
requirements for the number of PM_10-2.5 monitors a State
must deploy. Another important element of the provisions for
PM_10-2.5 is a proposal for the conditions under which a
PM_10-2.5 monitor may be compared to the PM_10-2.5 NAAQS.
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\2\ The proposed amendments to the National Ambient Air Quality
Standards include revised standards for PM_2.5
(particulate mater with an aerodynamic diameter less than or equal
to a nominal 2.5 micrometers) and new standards for
PM_10-2.5 (particulate matter with an aerodynamic diameter
less than or equal to a nominal 10 micrometers and greater than or
equal to a nominal 2.5 micrometers).
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A number of amendments to existing provisions for PM_2.5
monitoring are also proposed. These would be important to the
implementation of the revised PM_2.5 NAAQS because they take
advantage of the experience and insight gained by EPA and the States
during the past 7 years of PM_2.5 monitoring. One of the
proposed PM_2.5 changes involves the criteria for FRM
equivalency determinations for continuous PM_2.5 monitors. We
anticipate that this change would allow States to operate continuous
monitors at more required monitoring sites, providing more robust data
for the PM_2.5 air quality program.
Other proposed changes are based on EPA's assessment that the
monitoring regulations are not fully aligned with current data needs
and opportunities across all the NAAQS pollutants--including PM but
also including O₃, CO, SO₂, NO₂, and
Pb. This misalignment has developed over time as ambient conditions
have improved for some pollutants. Also, new monitoring technologies
have been developed that provide attractive opportunities for obtaining
more robust and useful data. The EPA recognized that changes were
needed several years ago and since then, we have been developing the
specifics of these changes with States and other stakeholders.\3\ This
group of proposed changes includes relaxation of some long-standing
monitoring requirements which we believe are outdated or unnecessarily
inflexible. This group of proposed changes also includes a new
requirement for States to operate a new type of multipollutant
monitoring station, which we plan to call National Core (NCore)
stations. Other proposed changes relate to quality assurance requirements,
monitor siting, special purpose monitoring, and data management.
We are proposing both the PM NAAQS review-related changes as well
as the overarching NAAQS monitoring system changes together because
they are strongly related in terms of regulatory language and in terms
of implementation decision making. Resources for ambient monitoring are
limited, and the cost of new types of monitoring to meet new
requirements such as those for PM_10-2.5 must be offset, at
least in part, by reducing resources for lower value types of
monitoring. The proposed revisions to the monitoring regulations, when
finalized, will improve EPA's and our monitoring partners' abilities to
manage available funds to support monitoring activities and create a
coordinated, integrated, multipurpose, and flexible monitoring system.
In addition, it will be easier for the public to comment on the
proposed changes if they are presented together rather than in
sequential proposals.
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\3\ Our work with States and other monitoring program
stakeholders has included the development of successive versions of
a draft report, ``National Ambient Air Monitoring Strategy''. The
most recent version, dated December 2005, is available in the public
docket. The document describes in more depth the reasons for
proposing many of the changes presented in this notice, excluding
the changes related to PM_10-2.5. It also discusses
strategy elements that are related to, but separate from, the regulatory
provisions in 40 CFR parts 53 and 58 such as funding, training, etc.
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The EPA notes that in the proposed regulatory language for 40 CFR
parts 53 and 58, we are reprinting a number of existing provisions
without change (for example, a number of definitions in current 58.1).
We are doing so solely for the readers' convenience in order that the
provisions we are proposing can appear in a single context. The EPA is
not reproposing, reconsidering, or otherwise reopening any of these
reprinted provisions. We will regard any comments as to these
provisions as outside the scope of this proposal.

[[Page 2713]]

B. What Are the Major Changes Proposed to the Ambient Air Monitoring
Regulations?

The summary of each proposed change given here ends with a
reference to the part(s) of section IV of this preamble that describes
that change in detail.
? We propose to require States to operate from one to three
National Core (NCore) multipollutant monitoring sites.\4\ Monitors at
NCore multipollutant sites would be required to measure particles
(PM_2.5, speciated PM_2.5, PM_10-2.5),
O₃, SO₂, CO, nitrogen oxides (NO/NO₂/
NO_Y), and basic meteorology. Monitors for all the gases
except for O₃ would be required to be more sensitive than
standard Federal reference method (FRM)/Federal equivalent method (FEM)
monitors, so they could accurately report concentrations that are well
below the respective NAAQS but that can be important in the formation
of O₃ and PM. We are not proposing specific locations for
these sites, but instead would collaborate on site selection with
States individually and through multistate organizations. Our objective
is that sites be located in broadly representative urban (about 55
sites) and rural (about 20 sites) locations throughout the country to
help characterize regional and urban patterns of air pollution. We
expect that in many cases States would collocate these new stations
with Photochemical Assessment Monitoring Station (PAMS) sites already
measuring O₃ precursors and/or National Air Toxic Trends
Station (NATTS) sites measuring air toxics.
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\4\ The National Core (NCore) multi-pollutant stations are part
of an overall strategy to integrate multiple monitoring networks and
measurements, including research grade sites and State and local air
monitoring stations (SLAMS). Research grade sites would provide
complex, research-grade monitoring data for special studies; the
proposed amendments do not include requirements for these sites.
SLAMS would include sites needed for National Ambient Air Quality
Standard comparisons and other data needs of monitoring agencies.
The number and placement of SLAMS monitors would vary according to
the pollutant, population, and level of air quality problem. The
April 2004 draft version of the National Ambient Air Monitoring
Strategy presented a taxonomy in which monitoring stations belonged
to three levels, called Level 1 (research sites), Level 2 (what are
called NCore multipollutant sites in this notice), and Level 3 (what
have been called SLAMS/NAMS (national air monitoring stations) in
the past). The three Levels combined were referred to as the NCore
System. We have decided to dispense with the three-level taxonomy
because it does not encompass all relevant monitoring efforts. We
now refer to the collection of all ambient air monitoring--including
research sites, all types of monitoring by States and Tribes, and
all types of ambient monitoring by Federal agencies--as the National
Ambient Air Monitoring System (NAAMS). We are retaining the
``NCore'' label for the multipollutant sites in particular, because
the term with this meaning has become part of the vocabulary of the
State/local monitoring community.
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These sites would still create points of integration among the
existing networks for criteria pollutants, each of which was originally
designed with only a single pollutant in mind. Where collocated with
sites already measuring O₃ precursors or air toxics, the
degree of integration across pollutants of concern would be even
stronger. Data from these NCore sites would be used for several
purposes that cannot be served as well using only data available from
existing networks. Forecasting of the Air Quality Index (AQI) would be
improved by feeding several collocated and interdependent pollutant
concentration measurements into an air quality model in near real-time
to better represent current conditions, from which the model could
provide an improved forecast of O₃ and particle levels for
the public. Studies that track long-term trends of criteria pollutants,
and thereby help demonstrate the accountability of implemented
emissions control programs, would be improved by utilizing higher-
sensitivity monitoring equipment for pollutants whose measured levels
are well below the NAAQS. Air quality model development and validation
efforts would benefit by having a long-term network of several
important and interdependent measurements at improved time-scales
(e.g., hourly instead of daily sample concentrations on PM methods) at
a network of sites expected to remain in place over many years to allow
testing of how well models simulate co-pollutant interactions. Where
applicable siting criteria for PM or O₃ monitoring stations
are met, NCore sites could also be used to satisfy minimum monitoring
requirements for PM and O₃ and data from these stations
could be used in designation decisions and in development of control
strategies.\5\ The NCore proposals are described more fully in section
IV.E.1 of this preamble.
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\5\ While not a part of our rationale for requiring States to
operate these sites, we note that the data from them will also be of
use in future health effects studies.
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? We propose monitoring requirements for PM_10-2.5
which are based on deploying a network of FEM monitors that would be
approved based on criteria for comparability to monitors utilizing the
FRM proposed elsewhere in today's Federal Register. Requirements for
PM_10-2.5 Class I, Class II, and Class III candidate
equivalent methods would be established. The definition of a ``Class
III equivalent method'' would allow for designation of continuous and
semi-continuous ambient air monitoring methods for
PM_10-2.5.\6\ Because we intend that most of the monitors
used in the PM_10-2.5 network will use continuous or semi-
continuous equivalent methods, the proposal for Class III approval
requirements is particularly important for PM_10-2.5. We are
also proposing minimum requirements for a PM_10-2.5
monitoring network, including criteria for the number of FRM/FEM
monitoring sites in each metropolitan area (which would vary from zero
to five) and criteria for how monitors should be placed within an area.
Closely linked to the placement criteria is a proposed test for the
suitability of a PM_10-2.5 monitoring site for comparison
with the PM_10-2.5 NAAQS. We are also proposing that
speciation monitoring of PM_10-2.5 be required in some areas.
These proposals appear in sections IV.B.2, IV.B.3, IV.B.5, and IV.B.6
(dealing with equivalent methods) and section IV.E.2 (dealing with
number of monitors, their placement, and the use of data from them in
comparisons to the NAAQS) of this preamble.
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\6\ Class I equivalent methods have only minor deviations or
modifications from the specified reference method. Class II
equivalent methods include other filter-based, integrated,
gravimetric-type methods similar to the specified reference method
but with greater deviations than allowed for a Class I method. Class
III equivalent methods include all candidate PM_2.5 and
PM_10-2.5 methods not classified as Class I or Class II.
We expect that most candidate Class III equivalent methods will be
continuous or semi-continuous methods.
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? We propose amendments to facilitate the wider use of
continuous PM_2.5 monitors by revising performance-based FEM
equivalence standards for continuous PM_2.5 monitors and
allowing for approved regional methods (ARM) for continuous
PM_2.5 mass monitors. Existing requirements for
PM_2.5 Class I and Class II candidate equivalent methods
would be revised, and new requirements for PM_2.5 Class III
candidate equivalent methods would be added. The definition of a Class
III equivalent method would be revised to allow for designation of
continuous and semi-continuous ambient air monitoring methods for
PM_2.5. These proposals appear in sections IV.B.4, IV.B.5,
and IV.B.6 (FEM equivalence standards) and in section IV.D.2 (approved
regional methods) of this preamble.
? In association with the proposed requirements for new
PM_10-2.5 stations and new NCore multipollutant stations, we
propose to remove the existing requirements for certain numbers of
State and local air FRM/FEM monitoring stations for CO, PM₁₀, SO₂,
and NO₂, and reduce them for Pb.

[[Page 2714]]

However, States would still need EPA approval to move or remove
existing monitoring stations for these pollutants.\7\ To expedite
reviews and provide more certainty to State planning, a specific
process and several substantive criteria are proposed to govern EPA
approval actions. Also, the requirement that EPA approval be obtained
at the Administrator level (rather than the Regional Administrator
level) for the subset of these monitors historically designated as NAMS
would be eliminated, and all changes would be reviewed by the Regional
Administrator.\8\ In addition, the requirements for monitoring of
O₃ precursors under the PAMS program would be reduced by
about 50 percent. These proposed changes allow PAMS monitoring to be
more customized to local data needs rather than meeting so many
specific requirements common to all subject O₃ nonattainment
areas; the PAMS changes would also give States the flexibility to
reduce the overall size of their PAMS programs--within limits--and to
use the associated resources for other types of monitoring they
consider more useful. Requirements for minimum numbers of O₃
and PM_2.5 monitors would be retained, with small
adjustments. The overall impact of these changes would be to retain
comprehensive monitoring networks for PM_2.5 and
O₃, and to reduce the number of SO₂, CO,
NO₂, Pb, and PM₁₀ monitors in areas that do not
have air quality problems for these pollutants. PM_2.5 and
O₃ monitoring would be mostly unaffected because
PM_2.5 and O₃ are current nonattainment challenges
and comprehensive monitoring is needed to support efforts to attain the
NAAQS. Many existing monitors for SO₂, CO, NO₂,
Pb, and PM₁₀ can be discontinued because they are now well
below the applicable NAAQS and the data from most of these monitors
have low value for air quality management and research purposes. We
expect reductions in the number of monitors for these pollutants
nationally to be in the range of about 33 percent for SO₂ to
about 90 percent for NO₂.\9\ This would free up resources to
go beyond minimum requirements for O₃, PM_2.5,
PM_10-2.5, or other pollutants such as air toxics in areas
where there are ongoing or new air quality management challenges. These
proposed changes are described in sections IV.E.3 (number of
PM_2.5 monitors), IV.E.4 (PM₁₀ monitors), IV.E.5
(number of O₃ monitors), IV.E.6 (number of CO,
SO₂, NO₂, and Pb monitors), IV.E.7 (PAMS
monitors), and IV.E.8 (process and criteria for moving or removing
monitors) of this preamble.
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\7\ Where the PM₁₀ annual and 24-hour NAAQS have both
been revoked, the proposed rule does not require prior EPA approval
for discontinuing a PM₁₀ monitor.
\8\ EPA Administrator approval would continue to be required for
changes to some PM_2.5 speciation monitoring stations, to
any required NCore multipollutant station, and to any PAMS station.
\9\ Detailed estimates of the current and expected future number
of each type of monitor over the 3 years following promulgation are
given in the supporting statement to the Information Collection
Request for this action, available in the docket.
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? We propose updated quality assurance (QA) requirements for
all NAAQS pollutants, emphasizing the responsibility of each monitoring
program for its data quality based on the use of data quality
objectives for monitoring precision, data completeness, and bias.
States would be required to provide for adequate, independent
performance audits of FRM/FEM monitoring stations. We describe several
options for how they could meet this audit responsibility. One way
would be to agree to have appropriated State and Territorial Air Grant
(STAG) funds retained by EPA to cover the cost of performing these
audits; another option would be a partnership between State/local
monitoring agencies (or independent subunits within one agency). The
statistics for calculating precision and bias would also would be
revised. Quality assurance requirements would be defined for PM_10-2.5
monitoring. See section IV.C of this preamble for details.
? We propose to revise the provisions regarding special
purpose monitors (SPM) for all NAAQS pollutants. In certain restricted
situations, data from SPM would not be usable for nonattainment
designations. SPM that are FRM, FEM, or ARM monitors would be required
to meet standard quality assurance requirements for their monitor type,
and States would be required to report data from such SPM to the Air
Quality System (AQS). See section IV.E.9 of this preamble for details.
? We propose to require that States conduct in-depth network
assessments every 5 years. These assessments are intended to ensure
that future gaps between data needs and monitoring operations are
identified and filled in a timely manner. See section IV.E.11 of this
preamble for specifics.
? We propose to move requirements for reporting certain
operational data from PM samplers from 40 CFR part 50 to 40 CFR part
58, and to reduce the number of data elements required to be reported.
This would put all similar data reporting requirements together in 40
CFR part 58 and allow them to apply to both FRM and FEM monitors. See
section IV.G.1 of this preamble.
? We propose a new requirement for the reporting of
PM_2.5 field blank data.\10\ Only the data from field blanks
which States are already taking into the field and weighing in their
laboratories would be required to be reported under this proposal.
Having the data from these field blanks available to the national
monitoring community would help EPA and other researchers understand
the relationship between the mass of PM that is sampled and weighed on
a regular PM filter and the PM that is actually present in ambient air.
See section IV.G.2 of this preamble or details.
---------------------------------------------------------------------------

\10\ Field blanks are filters which are handled in the field as
much as possible like actual filters except that ambient air is not
pumped through them, to help quantify contamination and sampling artifacts.
---------------------------------------------------------------------------

? We propose to require State or local agencies to submit
annual data certification letters, by May 1 of each year, to certify
that the ambient air concentration and QA data submitted to EPA's AQS
for the previous year are complete and accurate. These letters are now
required on July 1 of each year. See section IV.G.3 of this preamble.
? We propose to require States to archive PM_2.5
and PM_10-2.5 filters for one year (the current requirement
is only for PM_2.5 filters).\11\ See section IV.G.4 of this preamble.
---------------------------------------------------------------------------

\11\ A PM_10-2.5 ``filter'' from a FRM monitor would
actually consist of the separate PM₁₀ and
PM_2.5 filters. Some equivalent methods, if approved,
could involve a single PM_10-2.5 filter. All filters from
both types of monitors would be subject to the archiving requirement.
---------------------------------------------------------------------------

? We propose to increase the distance that ozone monitors
should be placed downwind of roadways, to reduce the possibility that
ozone readings will be artificially low due to ozone scavenging by NO
emitted by vehicles on roadways. See section IV.F of this preamble.

C. When Would the Proposed Amendments Affect State and Local
Governments, Tribes, and Other Stakeholders?

1. State and Local Governments
Only State governments, and those local governments that have been
assigned responsibility for ambient air monitoring by their States, are
subject to the mandatory requirements of 40 CFR part 58.\12\
---------------------------------------------------------------------------

\12\ Throughout this preamble, ``States'' is meant to also refer
to local governments that have been assigned responsibility for
ambient air monitoring within their respective jurisdiction by their
States. We also use ``monitoring organization'' to refer to States,
local agencies, and/or Tribes conducting monitoring under or guided
by the provisions of 40 CFR part 58.
---------------------------------------------------------------------------

The proposed compliance date for deployment of PM_10-2.5
monitors by States is January 1, 2009. A plan for this

[[Page 2715]]

deployment would be due January 1, 2008, unless an extension is granted
to July 1, 2008. These plans would be subject to EPA approval at the
Regional Office level.
State (or local) agencies would also be required to submit earlier
annual data certification letters and make electronic reports of QA
data to the AQS, starting May 1, 2009.
The proposed amendments require that State (or local) agencies
fully implement the required NCore multipollutant sites by January 1,
2011 (more than 4 years after the expected date of promulgation of the
amendments). A plan for this implementation, including site selection,
would be due July 1, 2009.
Network assessments would be required every 5 years starting July
1, 2009.
State and local agencies would be required to comply with existing
requirements in 40 CFR part 58 (including annual network review and
data reporting), until the compliance date for each new requirement is
reached.
Some provisions in the proposed amendments to 40 CFR part 58 (those
that do not involve deployment of new monitoring stations or new types
of data handling) would be effective as of the effective date of the
final rule.
2. Tribes
Under the Tribal Authority Rule (TAR) (40 CFR part 49), which
implements section 301(d) of the CAA, Tribes may elect to be treated in
the same manner as a State in implementing sections of the CAA.
However, the EPA determined in the TAR that it was inappropriate to
treat Tribes in a manner similar to a State with regard to specific
plan submittal and implementation deadlines for NAAQS-related
requirements, including, but not limited to, such deadlines in CAA
sections 110(a)(1), 172(a)(2), 182, 187, and 191. See 40 CFR 49.4(a).
For example, an Indian tribe may choose, but is not required, to submit
implementation plans for NAAQS related requirements, nor are they
required to monitor. If a Tribe elects to do an implementation plan,
the plan can contain program elements to address specific air quality
problems in a partial program. The EPA will work with the Tribe to
develop an appropriate schedule which meets the needs of each Tribe.
Indian tribes have the same rights and responsibilities as States
under the CAA to implement elements of air quality programs as they
deem necessary. Tribes can choose to engage in ambient air monitoring
activities. In many cases, Indian tribes are required by EPA regions to
institute strict quality assurance programs, utilize FRM or FEM when
comparing their data to the NAAQS, and to insure that the data
collected is qualitative and representative of their respective
airsheds. For FRM and FEM monitors used for NAAQS attainment or
nonattainment determinations, quality assurance requirements of 40 CFR
part 58 must be followed and would be viewed by EPA as an indivisible
element of a regulatory air quality monitoring program.
3. Other Stakeholders
Manufacturers of continuous PM_2.5 and
PM_10-2.5 instruments would be able to apply for designation
of their instruments as FEM as soon as the notice of final rulemaking
is signed. The EPA is eager to receive such applications as soon as
manufacturers can collect and analyze the necessary supporting data.

D. How Would EPA Implement the New Requirements?

After promulgation, we would implement the new requirements using
several mechanisms. We expect to work with each State to develop the
monitoring plans for their new PM_10-2.5 and NCore
multipollutant monitoring stations. For example, we would negotiate the
selection of required new monitoring sites (or new capabilities at
existing sites) and their schedules for start up as well as plans to
discontinue sites that were no longer needed. The EPA would negotiate
with each State its annual grants for air quality management
activities, including ambient monitoring work. We would negotiate
grants that provide funding to meet minimum requirements and which have
milestones for completion of necessary changes. Once States have
established a new monitoring infrastructure to meet the new
requirements, we would review State monitoring activities, submitted
data, and plans for further changes on an annual basis.
The EPA's support for and participation in enhancing the national
ambient air monitoring system to serve current and future air quality
management and research needs will extend beyond ensuring that States
meet the minimum requirements of the monitoring rules, including the
proposed amendments. We will work with each State or local air
monitoring agency to determine what affordable monitoring activities
above minimum requirements would best meet the diverse needs of the
individual air quality management program as well as the needs of other
data users. In particular, we may negotiate with some States, and
possibly with some Tribes, for the establishment and operation of some
additional rural NCore multipollutant monitoring stations to complement
the multipollutant stations that would be required by the proposed
changes to the monitoring regulations. We also expect to work with the
States, and possibly with some Tribes, to establish and operate more
PM_10-2.5 speciation sites than the minimums that would be
required by the proposed amendments. We expect to work with the States,
and possibly with some Tribes, to establish and operate rural
PM_10-2.5 mass concentration sites in less urbanized locations.
An important element of implementing the new requirements will be
EPA's role in encouraging the development and application of Federal
equivalent methods (FEM), in particular for continuous methods of
measuring PM_2.5 and PM_10-2.5. We have determined
that continuous monitoring of PM_2.5 has many advantages over
the filter-based Federal reference method. One of the proposed changes
makes it more practical for manufacturers of continuous
PM_2.5 instruments to obtain designation for them as FEM or
approved regional methods. To ensure objectivity and sound science,
EPA's Office of Research and Development would continue to review
applications for FEM designations based on the criteria proposed today
and would recommend approval or disapproval to the EPA Administrator.
We will also provide technical guidance documents and training
opportunities for State, local, and Tribal monitoring staff to help
them select, operate, and use the data from new types of monitoring
equipment. We have already distributed a technical assistance document
on the precursor gas monitors \13\ that will be part of the
multipollutant sites and we have conducted three training workshops on
these monitors. Additional guidance will be developed and provided on
some other types of monitors with which many State monitoring staff are
currently unfamiliar, and on network design, site selection, quality
assurance, and other topics. While Tribes are not to be subject to the
requirements of the proposed monitoring amendments,

[[Page 2716]]

these technical resources will also be available to them directly from
EPA and via grantees, such as the Institute for Tribal Environmental
Professionals and the Tribal Air Monitoring Support Center.
---------------------------------------------------------------------------

\13\ Technical Assistance Document (TAD) for Precursor Gas
Measurements in the NCore Multipollutant Monitoring Network. Version
4. U.S. Environmental Protection Agency. EPA-454/R-05-003. September
2005. Available at: http://www.epa.gov/ttn/amtic/pretecdoc.html.

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

In partnership with States, we will also continue to plan and
manage State technical assistance grants (STAG) to support the National
Park Service's operation of the IMPROVE monitoring network, which
provides important data for implementing both regional haze and
PM_2.5 attainment programs.\14\
---------------------------------------------------------------------------

\14\ Additional information on EPA/National Park Service IMPROVE
(Interagency Monitoring of Protected Visual Environments) Visibility
Program is available at: http://www.epa.gov/ttn/amtic/visdata.html.

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

We will also continue to operate the Clean Air Status and Trends
Network (CASTNET), which monitors for O₃, PM, and chemical
components of PM in rural areas across the nation.\15\ We are in the
process of revising CASTNET to upgrade its monitoring capabilities to
allow it to provide even more useful data to multiple data users. We
expect that about 20 CASTNET sites will have new capabilities at least
equivalent to the capabilities envisioned for NCore multipollutant
sites. Those sites would reduce the number of, and complement, rural
multipollutant sites funded with limited State/local grant funds.
---------------------------------------------------------------------------

\15\ Additional information on CASTNET is available at:
http://www.epa.gov/castnet/.

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

We recognize that some air quality management issues require
ambient concentration and deposition data that cannot be provided by
the types of monitoring required by the proposed monitoring amendments
and other activities addressed in today's proposal. These issues
include near-roadway exposures to emissions from motor vehicles and
mercury deposition. We are actively researching these issues and
developing plans for monitoring programs to address them, but these
issues are outside the scope of this proposal.

III. Background

A. What Is the Role of Ambient Air Monitoring in Air Quality Management?

Ambient air monitoring systems are a critical part of the nation's
air quality management program infrastructure. We use the ambient air
monitoring data for a wide variety of purposes as part of an iterative
process in managing air quality. This iterative process involves a
continuum of setting standards and objectives, designing and
implementing control strategies, assessing the results of those control
strategies, and measuring progress. The data have many uses throughout
this system, such as: Determining compliance with the National Ambient
Air Quality Standards (NAAQS); characterizing air quality status and
trends; estimating health risks and ecosystem impacts; developing and
evaluating emissions control strategies; and measuring overall progress
for the air pollution control program. Ambient air monitoring data
provide accountability for control strategy reductions by tracking
long-term trends of criteria and noncriteria pollutants and their
precursors. The data also form the basis for air quality forecasting
and other public air quality reports.
More detailed ambient monitoring data are needed to meet current
and future program and research needs. The data collected by State and
local agencies under the proposed monitoring amendments would:
? Provide more timely Air Quality Index reporting to the
public by supporting continuous particle measurements needed for AIRNow
air quality forecasting and other public reporting mechanisms;
? Improve the development of emissions control strategies
through more effective air quality model evaluation and other
observational methods; and
? Support long-term health assessments that contribute to
ongoing reviews of the NAAQS and other scientific studies ranging
across technological, health, and atmospheric process disciplines.

B. What Is the History of Ambient Air Monitoring?

1. Statutory Authority
The EPA rules for ambient air monitoring are authorized under
sections 110, 301(a), and 319 of the Clean Air Act (CAA). Section
110(a)(2)(B) of the CAA requires that each State implementation plan
(SIP) provide for the establishment and operation of devices, methods,
systems, and procedures needed to monitor, compile, and analyze data on
ambient air quality and for the reporting of air quality data to EPA.
Section 301(a) of the CAA authorizes EPA to develop regulations needed
to carry out the Agency's mission and establishes rulemaking
requirements. Uniform criteria to be followed when measuring air
quality and provisions for daily air pollution index reporting are
required by CAA section 319.
2. Ambient Air Monitoring Regulations
The EPA's procedures for determining and designating reference and
equivalent methods (40 CFR part 53) have been in place since 1975 (40
FR 7049, February 18, 1975). Reference methods for criteria pollutants
provide uniform, reproducible measurements of concentrations in the
ambient air. Equivalent methods allow for the introduction of new and
innovative technologies for the same purpose, provided the technologies
produce measurements comparable to reference methods under a variety of
monitoring conditions.
Subpart A of 40 CFR part 53 (General Provisions) establishes
definitions; general requirements for designation of Federal reference
methods (FRM) and Federal equivalent methods (FEM); procedures for
submitting, processing, and approving applications; and associated
provisions. The general requirements identify the applicable
requirements or tests that a candidate method must meet to be approved
as a FRM or FEM. All manual or automated methods must meet the
applicable requirements in 40 CFR part 53, subpart C (Procedures for
Determining Comparability Between Candidate Methods and Reference
Methods). Automated equivalent methods for pollutants other than
PM₁₀ or PM_2.5 also must meet the requirements in
40 CFR part 53, subpart B (Procedures for Testing Performance
Characteristics of Automated Methods for SO₂, CO,
O₃, and NO₂). A manual sampler or automated
method for PM₁₀, Class I equivalent method for
PM_2.5, or Class II equivalent method for PM_2.5
also must meet the requirements in 40 CFR part 53, subpart D
(Procedures for Testing Performance Characteristics of Methods for
PM₁₀), subpart E (Procedures for Testing Physical (Design)
and Performance Characteristics of Reference Methods and Class I
Equivalent Methods for PM_2.5), or subpart F (Procedures for
Testing Performance Characteristics of Class II Equivalent Methods for
PM_2.5), as applicable. The existing rule adopts a case-by-
case approach for PM_2.5 Class III candidate equivalent
methods. The regulations in 40 CFR part 53 have been amended several
times since 1975 to reflect the addition of new and revised reference
methods and advances in monitoring methods and technologies for
criteria pollutants.
In 1979 (44 FR 27558, May 10, 1979), EPA issued the first
regulations for ambient air quality surveillance (40 CFR part 58) for
all pollutants subject to NAAQS. Within 40 CFR part 58, subpart A
(General Provisions) establishes definitions, and subpart B (Monitoring
Criteria) sets requirements for quality assurance, methods, siting,
operating

[[Page 2717]]

schedules, and special purpose monitors. Subpart C (State and Local Air
Monitoring Stations), subpart D (National Air Monitoring Stations), and
subpart E (Photochemical Assessment Monitoring Stations) generally
define the current monitoring networks. Appendices A through G to 40
CFR part 58 contain more detailed requirements on quality assurance;
monitoring methods, network design, and siting criteria; and air
quality reporting. Subpart F (Air Quality Index Reporting), subpart G
(Federal Monitoring), and appendices F and G to 40 CFR part 58 define
annual and daily reporting requirements.
Most of the major amendments to the monitoring regulations made
after 1979 coincide with the NAAQS revisions and include the addition
of provisions for PM₁₀ (52 FR 24740, July 1, 1987) and
PM_2.5 (62 FR 38833, July 18, 1997). Photochemical assessment
monitoring stations (PAMS) were established in 1993 to monitor ozone
and visibility (58 FR 8468, February 12, 1993).
3. Monitoring Networks
More than 5,500 monitors at about 3,000 sites in the State and
local air monitoring stations (SLAMS) and national air monitoring
stations (NAMS) networks comprise the majority of monitors measuring
criteria pollutants using FRM or FEM for direct comparison to the
NAAQS. The NAMS are a subset of SLAMS that are designated as national
trends sites. The PM_2.5 network consists of ambient air
monitoring sites that make mass or chemical speciation measurements.
Within the PM_2.5 network operated by State and local
agencies, there are approximately 1,200 FRM filter-based samplers and
about 450 continuous monitors for mass measurements. Chemical
speciation measurements are made at 54 ``Speciation Trends Network''
sites that are intended to remain in operation indefinitely and about
200 other, potentially less permanent sites used to support SIP
development and other monitoring objectives. These stations collect
aerosol samples and analyze the filters for trace elements, major ions,
and carbon fractions.
Ambient air monitors in the PAMS network measure ozone precursors
at 109 stations in 25 serious, severe, or extreme ozone nonattainment
areas. The PAMS monitors use near-research-grade measurement
technologies to produce continuous data for more than 50 volatile
organic compounds during summer ozone seasons.
In addition to the NAMS/SLAMS/PAMS sites, there are approximately
310 ambient air toxics monitoring sites, the majority of which are
Federally funded and report data to EPA's Air Quality System (AQS).
Ambient air monitoring stations also are operated by Indian Tribes.
Thirty-one Tribes are currently making data from 119 individual
monitors available to EPA and others. Approximately 73 Tribal sites
monitor for PM₁₀ and PM_2.5, and about 16 monitor
for ozone.
The Clean Air Status and Trends Network (CASTNET) is cooperatively
operated and funded by EPA with the National Park Service. The EPA's
Office of Air and Radiation operates a majority of the monitoring
stations with contractor support; however, the National Park Service
operates approximately 30 stations in cooperation with EPA. It the
nation's primary source for data on dry acidic deposition and rural,
ground-level ozone. Operating since 1987, CASTNET is used in
conjunction with other national monitoring networks to provide
information for evaluating the effectiveness of national emission
control strategies. CASTNET consists of over 80 sites across the
eastern and western U.S. The longest data records are primarily at
eastern sites. CASTNET provides atmospheric data on the dry deposition
component of total acid deposition, ground-level ozone and other forms
of atmospheric pollution. More information is available from the
CASTNET program Web site http://www.epa.gov/castnet/.
The EPA is also one of many sponsors of the National Atmospheric
Deposition Program/National Trends Network. The National Atmospheric
Deposition Program/National Trends Network (NADP/NTN) is a nationwide
network of precipitation monitoring stations. The NADP/NTN has over 200
stations spanning the continental U.S., Alaska, and Puerto Rico, and
the Virgin Islands. The purpose of the network is to collect data on
the chemistry of precipitation for monitoring of geographical and
temporal long-term trends. While distinct from ambient air monitoring,
precipitation monitoring is related in that it shares same of the same
objectives, including tracking the effects of emission reduction
programs. More information on NADP is available at its Internet Web
site, http://nadp.sws.uiuc.edu/.
The EPA is a major funding sponsor of the Interagency Monitoring of
Protected Visual Environments (IMPROVE) program. IMPROVE is a
cooperative measurement effort governed by a steering committee
composed of representatives from EPA, National Park Service, other
Federal agencies, and Regional-State organizations. A total of 110
monitoring stations in Class I visibility areas have particulate matter
samplers to measure speciated PM_2.5 and PM₁₀
mass. Select stations also deploy transmissometer and nephelometers to
measure light extinction and scattering respectively, as well as
automatic camera systems. Some IMPROVE stations include an
O₃ monitor. The objectives of IMPROVE are: (1) To establish
current visibility and aerosol conditions in mandatory Class I areas;
(2) to identify chemical species and emission sources responsible for
existing man-made visibility impairment; (3) to document long-term
trends for assessing progress towards the national visibility goal; (4)
and with the enactment of the Regional Haze Rule, to provide regional
haze monitoring representing all visibility-protected Federal Class I
areas where practical. The IMPROVE stations provide very useful
information on regional-scale particulate matter concentrations which
can help States and EPA attribute urban concentrations of
PM_2.5 to local versus regional sources and to types of
sources. More information on the IMPROVE program is available on its
Internet Web site, http://vista.cira.colostate.edu/improve/.
4. Data Storage and Dissemination Systems
a. Air Quality System. The AQS stores data collected from over
10,000 monitors, about 5,500 of which are currently active for criteria
pollutants. The AQS also contains meteorological data, air toxics data,
descriptive information about each monitoring station (including its
geographic location and its operator), and data quality assurance/
quality control information. The EPA and other AQS users rely upon the
system data to assess air quality, assist in attainment and non-
attainment designations, evaluate SIP, perform modeling for permit
review analysis, and other air quality management functions. The AQS
information is also used to prepare reports for Congress as mandated by
the CAA. The AQS Web site address is: http://www.epa.gov/ttn/airs/airsaqs/index.htm.
b. AIRNow. AIRNow is a cross-government Web site (http://airnow.gov/)
that provides the public with easy access to national air
quality information. The Web site offers a daily forecast of conditions
and associated health effects, known as the Air Quality Index (AQI), as
well as real-time conditions for more than 300 cities across country.
The AQI focuses on health effects that may occur within a

[[Page 2718]]

few hours or days after breathing polluted air. The EPA calculates the
AQI for ground-level ozone, particulate matter, carbon monoxide, sulfur
dioxide, and nitrogen dioxide. The AIRNow Web site displays nationwide
and regional real-time PM_2.5 and ozone air quality maps for
48 States and parts of Canada. The air quality data used in these maps
and to generate forecasts are collected using either FRM, FEM, or
techniques approved by State monitoring agencies.
c. Other existing data systems. Other existing data systems for
ambient air quality-related data include EPA's National Emission
Inventory (NEI) and AirData. The NEI database at http://www.epa.gov/ttn/
chief/eiinformation.html provides information about sources that
emit criteria air pollutants and estimates of annual air pollutant
emissions from point, nonpoint, and mobile sources. The EPA compiles
the NEI database from emissions inventories compiled by State and local
environmental agencies based on State reporting requirements in 40 CFR
part 51, agency rulemaking databases, and the Toxic Release Inventory
data from industry. The EPA updates the NEI database every 3 years.
The AirData Web site at http://www.epa.gov/air/data/ provides
annual summaries of ambient monitoring and emissions inventory data
from the AQS and NEI. The database includes emission estimates from all
50 States plus the District of Columbia, Puerto Rico, and the U.S.
Virgin Islands, and provides data in a variety of formats. Other web-
based data systems related to ambient air concentration data include
VIEWS (http://vista.cira.colostate.edu/views/) to support analysis
of visibility-related data from the IMPROVE network, and Web sites to
support analysis of CASTNET (http://www.epa.gov/castnet/data.html)
and NADP (http://nadp.sws.uiuc.edu/) data sets.
5. EPA Funding
The EPA has historically funded part of the cost of installation
and operation of monitors to meet Federal monitoring requirements to
defray costs for State, local, and tribal governments. Sections 103 and
105 of the CAA allow EPA to provide grant funding for programs for
preventing and controlling air pollution and for some research and
development efforts. States must apply for section 103 grants and State
agencies must provide nonfederal matching funds for section 105 grants.

C. What Revisions to the National Ambient Air Quality Standards for
Particulate Matter Also Are Proposed Today?

1. PM_2.5: Primary Standards, Secondary Standard, and Federal
Reference Method
Elsewhere in this Federal Register, we are proposing revisions to
the National Ambient Air Quality Standards (NAAQS) for particulate
matter (PM). Under the proposal, the 24-hour primary standard for
PM_2.5 would be reduced from the current level of 65
micrograms per cubic meter ([mu]g/m3) to 35 [mu]g/
m3 (based on the three-year average of the annual 98th
percentile concentrations). We also are proposing to retain the level
of the current annual PM_2.5 standard at 15 [mu]g/
m3 and to add additional constraints to the use of spatial
averaging to demonstrate compliance with that standard. The EPA is also
proposing to revise the current secondary standards for
PM_2.5 by making them identical to the suite of proposed
primary standards.
The NAAQS proposal would also make several changes to the Federal
reference method (FRM) for PM_2.5 in 40 CFR part 50, appendix
L. These changes would improve the operation and maintenance aspects of
the PM_2.5 monitoring network. Specifically, we are proposing
to adopt the ``very sharp cut cyclone'' (VSCC) as an approved second-
stage impactor. The performance of the VSSC separator is equivalent to
that of the WINS (Well Impactor Ninety Six) impactor currently
specified in the proposed reference method and has a considerably
longer service interval. We also are proposing to require dioctyl
sebacate as an alternative oil approved for use in the WINS, to extend
the maximum allowed time to recover filters from samplers, and to
modify the filter transport temperature and post-sampling time
requirements for final laboratory analysis.
2. PM_10-2.5: Primary Standard, Secondary Standard, and
Federal Reference Method
The NAAQS proposal would also revise the current 24-hour primary
standard for PM₁₀ by replacing the indicator with a
PM_10-2.5 indicator. The proposed PM_10-2.5
indicator is qualified so as to include any ambient mix of
PM_10-2.5 that is dominated by resuspended dust from high-
density traffic on paved roads and PM generated by industrial sources
and construction sources, and exclude any ambient mix of
PM_10-2.5 that is dominated by rural windblown dust and soils
and PM generated by agricultural and mining sources. This standard
shall not require control of agricultural sources and mining sources.
The proposed level of the standard is 70 [mu]g/m3, based on
the three-year average of the annual 98th percentile concentrations.
Accordingly, the proposed revisions to the NAAQS include a new FRM
for measuring PM_10-2.5 (Reference Method for the
Determination of Coarse Particulate Matter as PM_10-2.5 in
the Atmosphere) to be codified in a new appendix O to 40 CFR part 50.
The proposed FRM is based on the combination of two low-volume, filter-
based methods, one for measuring PM₁₀ and the other for
measuring PM_2.5, and determines the PM_10-2.5
measurement by subtracting the PM_2.5 measurement from the
concurrent PM₁₀ measurement. The PM_2.5
measurement method is identical to the PM_2.5 FRM currently
specified in 40 CFR part 50, appendix L (Reference Method for the
Determination of Fine Particulate Matter as PM_2.5 in the
Atmosphere), with the proposed changes described above. The
PM₁₀ measurement method is very similar and utilizes a
sampler that is the same as the PM_2.5 sampler, except that
it has no PM_2.5 particle size separator downstream of the
PM₁₀ separator. Thus, this proposed PM_10-2.5 FRM
is based on the same aerodynamic particle size separation and filter-
based, gravimetric technology that is also the basis of the FRM for
PM_2.5 (with the proposed changes described above).
3. Data Handling Procedures for PM_2.5 and PM_10-2.5
In the PM NAAQS proposal published elsewhere in today's Federal
Register, EPA is also proposing to revise the conditions under which
spatial averaging of the annual primary PM_2.5 NAAQS would be
permitted. We also propose to move the criteria for determining if
spatial averaging is acceptable from section 2.8.1.6.1 of appendix D to
40 CFR part 58 to appendix N of 40 CFR part 50 (Interpretation of the
National Ambient Air Quality Standards for PM_2.5). We also
propose to add a new appendix P to 40 CFR part 50 (Interpretation of
the National Ambient Air Quality Standards for PM_10-2.5) to
provide data handling procedures for PM_10-2.5.
4. Revocation of National Ambient Air Quality Standards for PM₁₀
In the PM NAAQS proposal, we are proposing to revoke the current
annual PM₁₀ standard immediately should we finalize the
primary standards for PM_10-2.5 proposed in that notice.
Further, we propose that the current 24-hour PM₁₀ standard
be revoked in all

[[Page 2719]]

areas except for 20 areas listed in section III of the NAAQS proposal
preamble.

D. How Do the Monitoring Data Apply to Attainment or Nonattainment
Designations and Findings?

The criteria for determining when it is appropriate to compare
ambient monitoring data from a specific monitor and period to a
National Ambient Air Quality Standard (NAAQS) is an important element
of the air quality management system because it can identify what
geographic areas have air quality problems and may be designated as
nonattainment.
Later sections of this preamble, discussing the proposed monitoring
requirements for the proposed PM_10-2.5 NAAQS and the
proposed provisions for special purpose monitors (SPM), discuss the use
of monitoring data for attainment or nonattainment designations. We are
also proposing a change related to the required spacing between ozone
(O₃) monitors and roadways. Finally, we are proposing
changes to some quality assurance requirements. This section of the
preamble provides background information on current EPA policy and
regulations in order to facilitate informed public comment on these
aspects of today's proposal.
There are some preconditions to use of data from an ambient monitor
for comparison to an NAAQS that generally apply to the current NAAQS
for O₃, PM₁₀, PM_2.5, CO,
SO₂, NO₂, and Pb, with a few exceptions and/or
the opportunity for waiver by EPA.\16\ These include the following:
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\16\ Monitors that have received waivers are eligible for
comparison to their respective NAAQS.
---------------------------------------------------------------------------

? The monitoring site must represent ambient air, as defined
in 40 CFR 50.1 (i.e., ``that portion of the atmosphere, external to
buildings, to which the general public has access''). In practical
terms, this means that data from monitoring sites within the boundaries
of a privately-owned facility to which public access is restricted, for
example, a storage yard of a factory, are not eligible for comparison
to the NAAQS. (On occasion, EPA has relied on data from such sites when
the air sampled is ambient air, even though the monitor may be sited on
a facility to which public access is restricted (e.g., the monitor is
very close to a fence line and is monitoring the conditions that are
present in the adjacent publicly accessible property.) Data from a
monitor in ambient air as so defined can be compared to the NAAQS even
if members of the public infrequently come near the monitor's location
(e.g., O₃ monitors that are located on the ground on high
elevation mountain sites). However, data from monitors located high
above standing/walking ground level, such as on a high roof or tower,
are not eligible for comparison to an NAAQS. It should be noted that
although monitors are often sited with the intention to represent an
area of a certain geographic scale, in general, a monitor need not be
representative of the ambient air quality across an area of any
specific size to be eligible for comparison to most NAAQS. However, as
described in section IV.E.2 of this preamble, the current annual
PM_2.5 NAAQS is an exception, and the proposed 24-hour
PM_10-2.5 NAAQS would be an exception. (See also the item in
this list regarding proximity of O₃ and CO monitors to roadways.)
? The monitor must use a Federal reference method (FRM) or
Federal equivalent method (FEM).
? The monitoring data must be technically valid so as to be
truly representative of the actual air quality at its location during
the sampline period, subject to the normal limitations of the FRM or
FEM when properly operating. Generally, this means that the monitor's
operation and subsequent sample handling and laboratory analysis, if
applicable, must observe minimum quality assurance (QA) procedures, as
set forth in 40 CFR 58.10 and 40 CFR part 58, appendices A and B
(consolidated into a single appendix A in the proposed amendments), to
guard against equipment malfunction, miscalibration, drift, or operator
error. When States document that these procedures have been followed,
the data are presumed to be valid although specific evidence of
instrument faults or procedural errors can cause EPA to disregard data
from particular periods. When documentation on whether these specific
procedures have been followed is not available to EPA, as may be the
case if a State has not submitted QA data to the Air Quality System
(AQS) or if the monitoring was performed by a non-State organization
not subject to the QA requirements in 40 CFR part 58, appendices A and
B, the validity of data is considered on a case-by-case basis if the
issue is raised by EPA, the State, or another party during an NAAQS
designation process.
? The monitoring probe inlet (or open path, for open path
monitors) must meet certain requirements for distance from adjacent
roadways. This is a feature of the current monitoring requirements in
40 CFR part 58, appendix E (Probe and Monitoring Path Siting Criteria
for Ambient Air Quality Monitoring) and the proposed amendments.\17\
Ozone monitors too close to a roadway may be measuring air in which
O₃ has been scavenged by nitric oxide (NO). Carbon monoxide
and NO₂ monitors that are too close to a roadway can measure
concentrations that do not represent likely human exposures of any
significant frequency or duration. Requirements regarding spacing from
roadways can be waived if no other suitable site is available.
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\17\ Minimum separation distance requirements in the current
rule apply to O₃, NO₂, CO, Pb (for stations
designed to assess concentrations from mobile sources) and PM
(PM₁₀ and PM_2.5). Under the proposed
amendments, minimum separation distance requirements would apply to
O₃, oxides of nitrogen (NO, NO₂,
NO_X, NO_y), CO, PM (PM₁₀,
PM_2.5, PM₁₀-_2.5) and Pb for stations
designed to assess concentrations from stationary or mobile sources.
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? The monitoring probe inlet (or open path, for open path
monitors) must meet certain minimum distance limits for proximity to
nearby obstructions, such as walls of buildings.
? The probe height above the surface on which the public
would stand or walk nearby must be within a certain range so that the
air it samples is reasonably representative of what the public breathes
when near the monitor. This requirement can be waived for practicality
reasons.
? The monitoring data must be sufficiently complete
according to requirements defined for each NAAQS in 40 CFR part 50,
appendices H, I, K, and N (a new appendix P proposed elsewhere in
today's Federal Register would add completeness requirements for
PM_10-2.5).\18\
In addition to these generally applicable preconditions or
restrictions, the current requirements of 40 CFR part 58 contain the
following special provisions for PM_2.5:
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\18\ Interpretation of the 1-Hour Primary and Secondary National
Ambient Air Quality Standards for Ozone; Interpretation of the 8-
Hour Primary and Secondary National Ambient Air Quality Standards
for Ozone; Interpretation of the National Ambient Air Quality
Standards for PM₁₀; Interpretation of the National
Ambient Air Quality Standards for PM_2.5; and
Interpretation of the National Ambient Air Quality Standards for
PM_10-2.5, respectively.
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? Data from a PM_2.5 monitor can be compared to
the annual or 24-hour PM_2.5 NAAQS only if its location is
``population-oriented.'' \19\ ``Population-

[[Page 2720]]

oriented monitoring or sites'' is described in 40 CFR 50.1 as applying
to residential areas, commercial areas, recreational areas, industrial
areas, and other areas where a substantial number of people may spend a
significant fraction of their day.
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\19\ Section 2.8.1.2.3 of appendix D to 40 CFR part 58 states
that PM_2.5 data from state or local air monitoring
systems (SLAMS) and special purpose monitors (SPM) that are ``* * *
representative of relatively unique population-oriented microscale
or localized hot spot or unique population-oriented middle scale
impact sites are only eligible for comparison to the 24-hour
PM_2.5 NAAQS.'' However, under certain circumstances, the
Regional Administrator may approve population-oriented microscale or
middlescale impact sites for comparison to the annual NAAQS.
---------------------------------------------------------------------------

? Data from a PM_2.5 monitor that is located in a
``microscale'' location, meaning it is influenced by a nearby emissions
source while locations somewhat further away would be much less
influenced, can be compared to the annual PM_2.5 NAAQS only
if its location is representative of many other locations in the
surrounding urban area, such that significant numbers of people can be
expected to have similar PM_2.5 concentration exposures as
people living, working, or visiting the location of the monitor in
question (section 2.8.1.2.3 of appendix D to 40 CFR part 58).
? Under certain conditions, a State may, with the approval
of EPA, average data from specified monitors for purposes of comparing
the data to the annual PM_2.5 NAAQS. To be approved for
spatial averaging, as it is known, monitors must meet certain
requirements for relative location and measure concentrations as
specified in section 2.8 of appendix D to 40 CFR part 58 (section 4.7.5
of proposed appendix D to 40 CFR part 58).\20\
---------------------------------------------------------------------------

\20\ Changes to the requirements for spatial averaging are
proposed elsewhere in this Federal Register.
---------------------------------------------------------------------------

? The first two complete calendar years of data from an SPM
for PM_2.5 may be excluded from comparisons to the
PM_2.5 NAAQS, but only if the monitor is not continued beyond
those 2 years (section 2.8.1.2.2 of appendix D to 40 CFR part 58).
The first three of these four special provisions for
PM_2.5 are tied to the reliance by EPA on community
epidemiology studies in setting the form and levels of the annual and
24-hour PM_2.5 NAAQS. In simple terms, EPA determined that
the levels of these NAAQS would be appropriately protective of public
health based on a presumption that NAAQS compliance determinations
would be made using data only from monitors that represented
concentrations to which a large portion of the population would be
exposed, even though some individuals would have higher or lower exposures.
Finally, EPA has policies addressing situations in which natural
events and exceptional events have, or may have, influenced monitored
concentrations. Under these policies, States may make the case that
data from an otherwise eligible monitor from a specific period should
not be used in comparisons to the NAAQS. We expect to revise these
policies and codify them in 40 CFR part 50 in a separate rulemaking.\21\
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\21\ These policies on natural and exceptional events will be
discussed in the preamble to the Natural and Exceptional Events rule
to be published in the near future.
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IV. Proposed Monitoring Amendments

A. What Are the Proposed Terminology Changes?

In 40 CFR 58.1, we propose to replace the definition of ``National
Air Monitoring Stations (NAMS)'' with a new definition for the
``National Core (NCore)'' network. The NCore designation \22\ structure
would be based on a tiered system of measurements including complex
research-oriented stations,\23\ multipollutant stations equipped to
support a better understanding of ozone, particulate matter (PM), and
PM precursors, and sites with as few as one measured pollutant
identified as State and Local Air Monitoring Stations (SLAMS) that are
primarily intended to support compliance with the National Ambient Air
Quality Standards (NAAQS).
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\22\ Because the terms, SLAMS and NAMS, are used extensively
through the current rules, this terminology change results in
numerous changes. For clarity, we are publishing the entire text of
40 CFR part 58, appendix D (Network Design Criteria for Ambient Air
Quality Monitoring).
\23\ The NCore research grade station designation is defined in
the proposed amendments in anticipation that these stations will be
initiated at some time in the future. We are not proposing to
require (or to fund) NCore research grade stations in this notice.
---------------------------------------------------------------------------

We are proposing to add a definition for the term, ``approved
regional methods'' (ARM) to 40 CFR 58.1. This term refers to
alternative PM_2.5 methods that have been approved by EPA for
use specifically within a State, local, or tribal air monitoring
network for purposes of comparison to the NAAQS and to meet other
monitoring objectives, but which may not have been approved as Federal
equivalent methods (FEM) for nationwide use. The proposed testing
criteria for approval of ARM are specified in 40 CFR part 58, appendix
C (Ambient Air Monitoring Methodology).
In 40 CFR 53.1, we are proposing to revise the definition of the
term ``Class III equivalent method'' to apply only to continuous or
semi-continuous methods having 1-hour (or less) measurement resolution.
The revised definition would read:

* * * an equivalent method for PM_2.5 or PM_10-2.5
that is an analyzer capable of providing PM_2.5 or
PM_10-2.5 ambient air measurements representative of 1-hour
or less integrated PM_2.5 or PM_10-2.5
concentrations as well as 24-hour measurements determined as, or
equivalent to, the mean of 24 consecutive 1-hour measurements.
Restricting the Class III definition as proposed would offer a
technical advantage by allowing the establishment of more tolerant
minimum performance limits than would be necessary if non-continuous
methods were included.
We are also proposing to add a definition of the term
``PM_10c'' to 40 CFR 53.1. This term refers to
PM₁₀ measurements obtained with a specially-approved sampler
that meets more demanding performance specifications than high-volume
PM₁₀ samplers described in 40 CFR part 50, appendix J
(Reference Method for the Determination of Particulate Matter as
PM₁₀ in the Atmosphere). Measurements obtained with
PM_10c samplers are intended to be paired with
PM_2.5 measurements from Federal reference method (FRM)
samplers as part of the difference measurement (PM_10-2.5
equals PM_10c minus PM_2.5) specified in the
proposed appendix O to 40 CFR part 50 (Reference Method for the
Determination of Coarse Particulate Matter as PM_10-2.5 in
the Atmosphere) published elsewhere in today's Federal Register.

B. What Are the Proposed Requirements for Approval of Reference or
Equivalent Methods?

The provisions of 40 CFR part 50 and related appendices define
certain ambient air monitoring methods (or methodology) as reference
methods for the purpose of determining attainment of the National
Ambient Air Quality Standards (NAAQS). Under 40 CFR part 53, EPA
designates specific commercial instruments or other versions of methods
as Federal reference methods (FRM). Furthermore, to foster the
development of improved alternative air monitoring methods, EPA also
designates alternative methods that are shown to have comparable
performance as Federal equivalent methods (FEM). Explicit performance
tests, performance standards, and other requirements for designation of
both FRM and FEM are provided in 40 CFR part 53 for each of the
criteria pollutants. Only designated reference or equivalent methods
may be used in the States' air surveillance monitoring networks. A list
of all methods that EPA has designated as either FRM or FEM for all
criteria pollutants is available at
http://www.epa.gov/ttn/amtic/criteria.html.
Elsewhere in this Federal Register, EPA is proposing a new reference
method (40 CFR part 50, appendix O) for the measurement of coarse

[[Page 2721]]

particulate matter (PM) in the ambient air. Concurrent with the
proposal of this new reference method, EPA is also proposing amendments
to 40 CFR part 53 to extend the designation provisions to methods for
PM_10-2.5. These proposed amendments would set forth explicit
tests, performance standards, and other requirements for designation of
specific commercial samplers, sampler configurations, or analyzers as
either FRM or FEM for PM_10-2.5, as appropriate.
The EPA recognizes that the PM_10-2.5 reference method,
while providing a good standard of performance for comparison to other
methods, is not itself optimal for routine use in large
PM_10-2.5 monitoring networks. Accordingly, EPA is
specifically encouraging the development of alternative methods (and
particularly continuous monitoring methods) for PM_10-2.5 by
focusing on the explicit test and qualification requirements necessary
for designation of such types of methods as equivalent methods for
PM_10-2.5. Virtual-impactor technology provides a more direct
measurement of PM_10-2.5 and can provide an integrated
PM_10-2.5 sample filter for chemical species analyses that
can be important in the development of PM_10-2.5 control
strategies. Continuous (or semi-continuous) methods for
PM_10-2.5 typically provide significant operational
advantages over 24-hour integrated monitoring methods, such as a self-
contained automatic measurement process for output of nearly real-time
measurements, reduced on-site service and off-site filter analysis and
support requirements, and measurement resolution of one-hour or less.
In addition, corresponding provisions for considering the designation
of continuous or semi-continuous equivalent methods for
PM_2.5 are also being proposed, since such provisions are
similar to those for PM_10-2.5 and are not currently included
in 40 CFR part 53. The nature of the proposed new provisions for
automated methods, which can accommodate a wide range of potential
PM_10-2.5 or PM_2.5 measurement technologies, is
based primarily on ambient air testing at diverse monitoring sites to
demonstrate that the level of comparability to collocated reference
method measurements is adequate to meet established data quality
objectives. Furthermore, some existing requirements for designation of
alternative, non-continuous methods for PM_2.5 would be
modified to be more consistent with the more advanced new requirements
for non-continuous methods for PM_10-2.5 and for continuous
methods.\24\
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\24\ For this reason, we view our proposal as consistent with
the objectives of section 6102 of the Transportation Equity Act for
the 21st Century. See section VI.5 of the preamble for the proposed
amendments to the National Ambient Air Quality Standards for
particulate matter published elsewhere in this Federal Register.
---------------------------------------------------------------------------

1. Proposed Requirements for Candidate Reference Methods for
PM_10-2.5
Because of the nearly complete similarity between the
specifications of the proposed PM_10-2.5 reference method and
the existing PM_2.5 reference method, the proposed
designation requirements for PM_10-2.5 reference methods are
essentially the same as those for PM_2.5 reference
methods.\25\ In fact, EPA proposes that a PM_10-2.5 sampler
pair consisting of samplers that have been shown to meet the
PM_2.5 reference method requirements (except for the
PM_2.5 particle size separator in the case of the
PM_10c sampler) may be designated as a PM_10-2.5
reference method without further testing.
---------------------------------------------------------------------------

\25\ The proposed PM_10-2.5 reference method specifies
a pair of samplers consisting of a conventional PM_2.5
sampler and a special PM₁₀ sampler. The PM_2.5
sampler must meet all requirements for a PM_2.5 reference
method in 40 CFR part 50, appendix L. However, the PM₁₀
sampler required by the proposed method is not a conventional
PM₁₀ sampler as described in 40 CFR part 50, appendix J;
rather, it is a sampler specified to be identical to the
PM_2.5 sampler of the pair, except that the
PM_2.5 particle size separator is removed. This special
PM₁₀ sampler is identified as a ``PM_10c''
sampler to differentiate it from conventional PM₁₀
samplers that meet the lesser requirements of 40 CFR part 50, appendix J.
---------------------------------------------------------------------------

2. Proposed Requirements for Candidate Equivalent Methods for PM_10-2.5
As noted, EPA will strive to encourage the development of improved
alternative air monitoring methods by providing for their designation
as equivalent methods. But developing suitable qualification
requirements for equivalent methods for PM_10-2.5 is
complicated by the complex physical and chemical nature of PM, the
definition of PM_10-2.5 that to some extent incorporates the
nature of the measurement technique defined in the reference method,
and a wide variety of alternative PM_2.5 measurement
techniques that are or may become available or may be technically
feasible. Alternative methods must be shown to provide concentration
measurements closely comparable to those obtained with reference
methods. Thus, the requirements established for designation of
equivalent methods must identify candidate methods that can achieve
that goal, while also having reasonable testing protocols that are not
so extensive or burdensome as to effectively inhibit approval of
adequate and suitable improved or alternative candidate methods.
In light of these constraints, EPA previously defined three classes
of PM_2.5 candidate equivalent methods in 40 CFR part 53 with
progressively greater equivalent method qualification burdens. Class I
equivalent methods are limited to methods having ``* * * only minor
deviations or modifications * * *'' from the specified reference method
and have the most modest requirements for equivalent method designation
(in addition to the applicable reference method designation
requirements). Class II equivalent methods include other filter-based,
integrated, gravimetric-type methods similar to the reference method,
but with greater deviation than allowed for Class I. Class III
equivalent methods include all other candidate PM_2.5 methods
not classified as Class I or II. The proposed amendments would extend
the definition of Class I, Class II, and Class III candidate equivalent
methods to PM_10-2.5.
Because Class I equivalent methods for PM_10-2.5 differ
only very modestly from PM_10-2.5 reference methods,
designation requirements would also be very similar. The EPA is
proposing that PM_10-2.5 Class I equivalent methods be
designated if the samplers of the PM_10-2.5 sampler pair are
shown to meet all requirements for either PM_2.5 reference
methods or Class I equivalent methods. As for PM_10-2.5
reference methods, no further tests would be required.
One type of Class II equivalent sampler for PM_10-2.5
could be based on virtual impactor technology, which is designed to
separate coarse mode aerosols from fine mode aerosols. The resulting
size-segregated filter samples could be of great importance to State,
local, and tribal agencies to obtain PM_10-2.5 sample filters
for chemical speciation analyses. Class II methods, having greater
deviation from the reference method, would have more extensive
designation requirements. These methods still typically have many
similarities to the reference method, and therefore, many of the
reference method designation requirements would apply to Class II
candidate equivalent methods. Generally, these methods must be subject
to extensive laboratory and wind-tunnel tests to determine their
performance relative to the performance of the reference method.
However, for methods that have only one substantial difference from the
reference method specifications (such as a virtual impactor particle-
size separator), only those laboratory tests pertaining to the

[[Page 2722]]

performance of the deviating component would be required. Further, for
methods that have more deviation from the reference method
specifications, the proposed requirements would provide an option to
substitute more extensive field comparison tests for some or all of the
extensive laboratory tests that would otherwise be required. Since such
additional field tests would be similar to field test requirements
proposed for PM_10-2.5 methods, concurrent field testing for
PM_2.5 and PM_10-2.5 methods could be carried out.
Concurrent testing would substantially reduce the testing burden for
candidate equivalent methods that measure both PM_2.5 and
PM_10-2.5 (such as a dichotomous, virtual impactor sampler),
which could be tested simultaneously for designation as an equivalent
method for both PM indicators.
3. Continuous Methods for PM_10-2.5
The EPA recognizes that filter-based measurement methods for either
PM_2.5 or PM_10-2.5 that require manual gravimetric
analysis, as embodied in the corresponding reference methods, as well
as Class I and Class II equivalent methods, are by nature very labor
intensive. They are expensive to operate in routine monitoring networks
and can generally provide only delayed reporting of multiple-hour
integrated measurements. Self-contained, continuous-type automated
monitoring methods (analyzers), such as those that are commonly used
for monitoring various gaseous pollutants, overcome many of these
shortcomings. Various types of continuous (or nearly continuous)
analyzers have been developed or are under development for
PM_2.5 and PM_10-2.5 that offer substantial
advantages over manual methods for implementation in routine air
monitoring. These advantages include reduced operational cost, greater
practicality for daily operation, availability of short-term
measurements such as one-hour averages, and the possibility for near
real-time, telemetered measurement acquisition. Accordingly, EPA is
very interested in encouraging the further development of these
continuous-type methods by providing requirements for designating such
methods as Class III equivalent methods, so that they can be used in
monitoring networks. Because no such explicit requirements exist, EPA
is today proposing new Class III designation requirements for both
PM_2.5 and PM_10-2.5.
Unfortunately, the continuous-type methods for PM_2.5 and
PM_10-2.5 often tend to have performance characteristics
somewhat different than those of the corresponding reference method.
Consequently, adequate comparability to the corresponding reference
method measurements may be technically difficult to achieve. Thus, the
comparability testing requirements for Class III candidate methods must
be sufficiently sophisticated to effectively differentiate between a
method that shows adequate comparability and one that does not. At the
same time, the designation qualification requirements must not be
impractically extensive or burdensome, such that monitoring instrument
manufacturers seeking designation for their analyzers cannot afford or
economically justify the testing regimen.
We are proposing to narrow the definition of Class III equivalent
methods to apply only to continuous or semi-continuous analyzer methods
having one-hour (or less) measurement resolution, because such methods
are of the most interest to the air quality monitoring community. While
it would be possible to develop new, noncontinuous (or non-
semicontinuous) PM_2.5 or PM_10-2.5 methods that
would be categorized as Class III as currently defined, there is
little, if any, technical need or economic incentive for instrument
manufacturers to do so. Restricting the Class III definition to
continuous analyzers, as proposed, would offer a substantial technical
advantage by allowing the establishment of somewhat more tolerant
limits of adequate comparability than would be necessary if non-
continuous methods were included. This statistical advantage arises
because the analyzers are operated continuously rather than on an
intermittent, one-in-six day or one-in-three day schedule, which is
typical of manually operated sampler methods.
Any of the currently existing or proposed requirements for
designation of reference methods and Class I and Class II equivalent
methods for PM_2.5 or PM_10-2.5 that would or
should reasonably apply to a specific Class III candidate method would
be required for the candidate Class III equivalent method, as well. But
because of the wide variety of measurement techniques or technologies
possible for a Class III candidate method, many of these existing
requirements would not, or may not, apply. Therefore, the proposed
requirements for PM_2.5 and PM_10-2.5 Class III
candidate equivalent methods are based largely on demonstrating
comparability between candidate method measurements and concurrent
reference method measurements when both methods are collocated at
several diverse monitoring and during different seasonal periods. These
proposed requirements would be added to subpart C of 40 CFR part 53.
Because we intend that most of the PM_10-2.5 monitors in the
network use continuous or semi-continuous methods, the proposal of
Class III approval requirements is particularly important for PM_10-2.5.
Although candidate PM_2.5 and PM_10-2.5 Class
III equivalent methods would have hourly measurement resolution, this
capability would not be subject to comparability requirements because
both PM_2.5 and PM_10-2.5 FRM have only 24-hour
measurement capability.
In developing these proposed new requirements for PM_2.5
and PM_10-2.5 Class III candidate equivalent methods, EPA has
attempted to provide requirements that effectively reject inadequately
comparable methods while minimizing the testing burden to the extent
possible. Because the performance characteristics of Class III methods
are likely to vary at monitoring sites having differing climatic and
aerosol conditions, comparison tests would be required at sites in
three specified areas of the continental U.S. during winter and summer
seasons (winter in only one of the areas). The EPA believes these
requirements would provide the minimum of test venues necessary to
represent an adequate degree of monitoring site diversity for
designation of a candidate equivalent method. However, EPA specifically
solicits comments on the adequacy of the proposed geographical test
areas, the appropriateness of the proposed seasonal requirements, and
whether an additional test site may be needed (including the nature of
such an additional site).
4. Specific Requirements for Class III Equivalent Methods
The proposed amendments to 40 CFR part 53 would revise the
requirements for comparison tests and the allowable quantitative
deviation from reference method measurements that are based on
statistical analyses. The EPA has previously used a documented
procedure \26\ and a special computer software aid \27\ to establish
data quality objectives (DQO) for PM_2.5 monitoring data so
that such data can be used effectively in making decisions regarding
attainment of the NAAQS for PM. Using these established DQO and the
software, statistical analyses of both

[[Page 2723]]

actual and simulated PM_2.5 monitoring data 28 29
were carried out to confirm the suitability of the statistical
parameters selected to describe a comparison relationship between the
candidate and reference methods and to set appropriate and optimal
limits for their values in the proposed Class III equivalent method
tests. These quantitative requirements then define the minimum
candidate method comparability performance that would be necessary to
provide PM_2.5 monitoring data of sufficient quality to meet
the established DQO.\30\ The DQO for PM_10-2.5 monitoring
data have recently been developed and are incorporated into 40 CFR part
58, appendix A. These DQO are similar to the DQO for PM_2.5.
Accordingly, the requirements proposed for PM_10-2.5 methods
are similar to those proposed for PM_2.5 methods.\31\
Furthermore, similar or parallel requirements are also proposed for
Class II equivalent methods for PM_10-2.5 as well as for
PM_2.5. However, the proposed requirements for Class II
equivalent methods for PM_10-2.5 are stricter with regard to
additive bias (intercept) since this method would also support other
monitoring objectives. These latter requirements proposed for
PM_2.5 Class II methods would replace the existing test
requirements with the more advanced, DQO-based requirements.
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\26\ U.S. Environmental Protection Agency. Guidance for the Data
Quality Objectives Process. EPA QA/G-4, EPA/600/R-96/055. August 2000.
\27\ U.S. Environmental Protection Agency (2004b) DQO Companion
Tool, Version 2.0. 2004. http://www.epa.gov/ttn/amtic/dqotool.html.
\28\ Data Quality Objectives for PM Continuous Methods. Prepared
for U.S. Environmental Protection Agency by ManTech Environmental
Technology, Inc. EPA Contract 68-D-00-206, Report TR-4423-03-08, June 2003.
\29\ Data Quality Objectives for PM Continuous Methods II.
Prepared for U.S. Environmental Protection Agency by ManTech Environmental
Technology, Inc. EPA Contract 68-D-00-206. Report TR-CAN-04-02, June 2004.
\30\ Criteria for Designation of Equivalence Methods for
Continuous Surveillance of PM_2.5 Ambient Air Quality.
Prepared for U.S. Environmental Protection Agency by B. Coutant and
J. Sanford, Battelle Columbus, EPA Contract 68-D-02-061, 2004.
\31\ Method Equivalency Development for PM_10-2.5.
Prepared for U.S. Environmental Protection Agency by B. Coutant,
Battelle Columbus, 2005.
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The parameters selected to estimate the performance of
PM_2.5 and PM_10-2.5 Class II and Class III
candidate method measurements relative to the performance of the
reference method in the proposed field tests are precision,
correlation, and the linear regression slope and intercept of a linear
plot fitted to corresponding candidate and reference method mean
measurement data pairs. Statistical analyses based on the DQO model
show that the precision of a candidate method is not, statistically,
very important to annual concentration averages used for NAAQS
attainment decisions, but would be important for a daily standard.
Precision is also consequential for other important aspects and
applications of the PM_2.5 or PM_10-2.5 monitoring
data. Accordingly, the proposed amendments would include a minimum
requirement for an estimate of the candidate method precision for 24-
hour measurements.
A minimum requirement for an estimate of reference method precision
in the tests, as well as a test for possible anomalous reference method
measurement values, also are proposed to ensure that the quality of the
reference method measurements used for the test meets the expected
reference method performance. The proposed numerical limits for the
Class II and III precision test requirements for both the reference and
candidate methods are somewhat larger than those currently prescribed
for Class I PM_2.5 methods because the Class II and III
precision would be calculated as the root mean square average, rather
than the simple average, of the daily precision values determined from
multiple samplers or instruments. This more statistically appropriate
aggregation of precision is consistent with the way precision would be
expressed under proposed revisions to the data quality assessment
provisions in appendix A to 40 CFR part 58.
As noted above, the proposed revision to the definition for Class
III equivalent methods would require such methods to provide one-hour
(or less) concentration measurements, because such short-term
measurements are useful for a variety of applications. The EPA proposes
that hourly measurements from Class III comparability tests be recorded
and submitted as part of the required test data. No requirement for the
precision of these hourly measurements is included in the proposed
amendments because no one-hour DQO have been established for either
PM_2.5 or PM_10-2.5 measurements and neither of the
PM_2.5 or PM_10-2.5 reference methods provide one-
hour data or performance goals. Nevertheless, in view of the
substantial potential utility of one-hour PM_2.5 and
PM_10-2.5 measurements, EPA solicits comments on whether
requirements for one-hour measurement precision should be included in
the Class III equivalent method designation requirements. In
particular, comments are requested on whether such requirements, if
included, should provide merely an assessment of one-hour precision or
a specified standard of performance, and if the latter, to what extent
would it be appropriate to reject a candidate method that exhibited
poor one-hour precision but adequate 24-hour precision.
The regression comparability parameters proposed for Class II and
Class III candidate methods would be interpreted in ways somewhat
different from those now used for determining candidate method
comparability for other types of candidate equivalent methods for PM.
The slope (multiplicative bias) and intercept (additive bias) are the
performance parameters most critical in achieving the DQO for making
correct attainment decisions. However, these parameters are
interrelated, and statistical analyses of simulated PM_2.5
data \32\ show that the allowable limits for the intercept can be
somewhat less stringent if they are made to be variable and related to
the value obtained for the slope. Accordingly, EPA is proposing
variable, slope-dependant limits for the intercept.
---------------------------------------------------------------------------

\32\ Battelle Columbus (2004).
---------------------------------------------------------------------------

Further, because Class III PM_2.5 and PM_10-2.5
equivalent methods would be redefined as continuous or semi-continuous
methods, such methods would normally be operated continuously, just as
continuous gaseous pollutant analyzers are, rather than on a one-day-
in-six sampling schedule typically used for PM_2.5 reference
method sampling. Again, statistical analyses \33\ show that this more
frequent (daily) sampling allows the intercept limits to be set even
wider than would be needed for one-in-six day sampling and still meet
the established DQO. The actual intercept limits for
PM_10-2.5 methods proposed today are somewhat more
restrictive than the analyses would indicate to provide a factor of
safety to account for inherent differences between the way candidate
methods would be operated in the proposed equivalent method tests and
the way they would be operated routinely in State monitoring networks.
---------------------------------------------------------------------------

\33\ ManTech Environmental Technology, Inc. (June 2003); ManTech
Environmental Technology, Inc. (June 2004); Battelle Columbus
(2004); Battelle Columbus (2005).
---------------------------------------------------------------------------

Another difference in the way the conventional comparison
parameters would be interpreted relates to the proposed lower limit
requirement for the comparison correlation. The correlation test is
instrumental in detecting longer-term method variability, such as
seasonal bias. By its nature, the correlation value calculated for the
comparison is quite dependent on the range of concentrations measured
in the tests. The comparison tests are subject to the actual
PM_2.5 or PM_10-2.5 concentrations available at the
test site, which are generally related to variable atmospheric
conditions during the test period and consequently may

[[Page 2724]]

sometimes occur in a rather narrow range. Therefore, the minimum value
proposed for this statistic is not a fixed value but rather a variable
that is related to the concentration coefficient of variation (CCV),
which is a measure of the range of the concentrations measured in the
test. This variable limit for correlation would provide a more
effective test without unnecessarily failing test data representative
of an unfortunately limited range of test concentrations.
One minor difference from the reference method would be
necessitated by the proposed Class III comparison tests. The proposed
reference methods for PM_2.5 and PM_10-2.5 specify
a sampling period tolerance of 23 to 25 hours. Experience has shown
that in multiple-sampler candidate method tests, which may be
frequently combined with tests of additional instruments to reduce
overall testing costs, the time required to properly change sample
filters and service the samplers and other instruments between sample
periods often requires more than one hour. Accordingly, the proposed
test protocol would allow a 22-hour minimum sample period for the
reference method to allow complete sample set acquisition within a 24-
hour period. This proposed revision in the reference method protocol
should have very little, if any, adverse impact on the results of the
comparability tests.
The proposed requirements for PM_10-2.5 and
PM_2.5 Class II and Class III equivalent methods are the
least stringent requirements that would provide reasonable assurance
that candidate methods meeting these requirements will produce
monitoring data of quality commensurate with the quality of reference
method data and that the data will meet the DQO established for
PM_2.5 and the proposed DQO for PM_10-2.5. While
recent field studies suggest some potential PM_10-2.5
continuous methods look promising,\34\ it is not certain at this time
whether any current commercial continuous or nearly continuous methods
can yet meet the proposed requirements for Class III methods. However,
EPA believes that the establishment of these requirements would provide
a definitive goal which instrument manufacturers could achieve.
---------------------------------------------------------------------------

\34\ U.S. Environmental Protection Agency. Multi-Site
Evaluations of Candidate Methodlogies for Determining Coarse
Particulate Matter (PM_10-2.5) Concentrations: August 2005
Updated Report Regarding Second-generation and New
PM_10-2.5 Samplers.
---------------------------------------------------------------------------

5. Proposed Changes to Requirements for PM₁₀ and
PM_2.5 Class I and Class II Equivalent Methods
The proposed amendments would revise the existing provisions for
PM₁₀ and PM_2.5 Class I and II candidate
equivalent methods. These changes would clarify or simplify current
provisions or implement minor improvements to test protocols suggested
by experience and information acquired in processing equivalent method
applications for these methods. The proposed changes would have very
little, if any, impact on the nature, efficacy, or extent of any of the
test requirements.
In the tests for PM₁₀ and PM_2.5 Class I and
II candidate equivalent methods, the minimum separation distance
between sampler or analyzer inlets is proposed to be reduced from 2
meters to 1 meter for instruments having flow rates less than 200
liters per minute. One meter separation has been found to be entirely
adequate for such low-flow-rate instruments, and the change is
consistent with a similar minimum separation allowance for audit
samplers used in assessing the precision of network PM_2.5
samplers.\35\ An identical change is also proposed for appendix A to 40
CFR part 58.
---------------------------------------------------------------------------

\35\ Quality Assurance Guidance Document: Field Standard
Operating Procedures for the PM_2.5 Performance Evaluation
Program. U.S. Environmental Protection Agency. Office of Air Quality
Planning and Standards, November 1998, Section 4, page 8.
---------------------------------------------------------------------------

Another proposed change would replace existing requirements for
Class II PM_2.5 equivalent methods with similar but new DQO-
based requirements. These proposed requirements are similar to the
Class III requirements and would be based on daily sampling. Therefore,
PM_10-2.5 and PM_2.5 Class II equivalent methods
used for determining compliance with the PM NAAQS would generally be
restricted to daily operation. However, as discussed previously,
filter-based integrated methods (such as Class II equivalent methods)
are not likely to be widely used for compliance monitoring. These
methods would be used more for chemical analysis of samples to
characterize the species of PM in a monitoring area, which would not
require daily operation of the samplers. For Class II methods (for
either PM_2.5 and PM_10-2.5 methods), the test
sites would be similar in character to those for Class III methods, but
only two test sites (one eastern and one western) rather than three,
and tests in only one season at any time of year rather than two
seasons, would be required. These requirements would allow tests for
PM_2.5 and PM_10-2.5 methods (or for Class II and
Class III method) to be tested simultaneously, to reduced testing
costs. Flow rates in the existing PM_2.5 FRM and proposed
PM_10-2.5 FRM would be operated under conditions of actual
ambient temperature and barometric pressure, ensuring compatibility of
the measured sample flows. The EPA solicits comments on the adequacy
and appropriateness of these tests requirements for Class II methods.
In addition, the proposed amendments would lower many of the
minimum concentration limit specifications for various existing test
requirements for PM₁₀ and PM_2.5 Class I and Class
II candidate equivalent methods. These minimum limits were established
either to avoid possible difficulties with interpretation of test
results due to increased measurement variability that often occurs at
very low concentrations or to require a wide range of concentration
measurements for the test. However, experience has shown that these
lower limits are unnecessarily conservative and can be decreased
considerably without encountering undue variability in the measurements
or an insufficient range of concentrations. Further, applicants often
have difficulty obtaining a sufficient number of measurement sets that
meet some of these minimum limits. The proposed decreases in these
minimum limits would reduce the number of test measurement sets that
are rejected as unacceptable due to test concentration levels failing
to meet the test requirements without compromising the efficacy of the
tests. These changes would reduce the costs to applicants of conducting
the tests.
6. Other Proposed Changes
The proposed amendments would make subpart C of 40 CFR part 53
easier to understand by consolidating the provisions for the various
types of candidate equivalent methods. This reorganization results in
numerous minor editorial and section number changes of no technical
impact. The entire text of 40 CFR part 53, subpart C is reprinted in
the proposed amendments.
We are proposing numerous minor changes which are needed to
incorporate new provisions for PM_10-2.5 methods into
subparts A, C, E, and F of 40 CFR part 53, as well as a few minor
changes that would apply to methods for PM_2.5 or other
pollutants. As noted above, the definition of a ``Class III equivalent
method'' in 40 CFR 53.1 would be modified to include only methods that
provide automated

[[Page 2725]]

continuous or semi-continuous measurements of PM_2.5 and
PM_10-2.5 with one-hour or less resolution. We are also
proposing definitions for the terms, ``PM'', ``PM_10-2.5
sampler'', and ``PM_10C sampler''. Another proposed change,
to paragraph (4) of 40 CFR 53.3 (General requirements for an equivalent
method), would clarify that Class III PM_10-2.5 and
PM_2.5 candidate equivalent methods would be subject to
applicable requirements for PM_10-2.5 or PM_2.5
reference methods contained in those reference methods (40 CFR part 50,
appendixes L and O) and applicable requirements for Class I and Class
II equivalent methods contained in subparts E and F of 40 CFR part 53,
in addition to the proposed amendments to subpart C. The requirement in
40 CFR 53.5 (Processing of applications) to publish a notice in the
Federal Register upon receipt of an application would be deleted, as
would the requirements in 40 CFR 53.51(f)(2) and 53.2(a) for
manufacturers of PM_2.5 designated method samplers to submit
an annual Product Manufacturing Checklist. These requirements have
proved to be of little value, and the significant cost burden to the
Government and to applicants for these activities can therefore be
eliminated. The proposed amendments would also delete the requirement
in 40 CFR 53.8 (Designation of reference and equivalent methods) for
publishing a notice of designation in the Federal Register no later
than 15 days after the date of the determination. We are proposing to
delete the 15-day requirement because it is not achievable within the
confines of EPA's internal review process.

C. What Are the Proposed Requirements for Quality Assurance Programs of
the National Ambient Air Monitoring System?

A quality system provides a framework for planning, implementing
and assessing work performed by an organization and for carrying out
required quality assurance (QA) and quality control (QC) activities.
The proposed amendments to 40 CFR part 58, appendix A would provide the
requirements necessary to develop quality systems for the NCore, State
and Local Air Monitoring Stations (SLAMS), and Prevention of
Significant Deterioration (PSD) networks. The proposed revisions
address responsibilities for implementing the quality system for both
EPA and monitoring organizations, as well as adherence to the Agency's
QA policy, data quality objectives (DQO), and the minimum QC
requirements and performance evaluations needed to assess the data
quality indicators of precision, bias, detectability, and completeness.
In addition, the proposed amendments would describe the required
frequency of the QC requirements and performance evaluations, the data
to be collected, and the statistical calculations for estimates of the
data quality indicators at various levels of aggregation. The revised
statistical calculations would be used to determine attainment of the
DQO. The proposed amendments would also identify national programs that
help determine data quality comparability across individual monitoring
programs.
The EPA has not conducted a thorough review of the quality system
for many years. Based on our review of the existing QA program in 40
CFR part 58, appendices A and B, we are proposing changes to make the
requirements consistent with our current QA policy, meet the objectives
of the NCore, SLAMS, and PSD monitoring networks, and make the
requirements more user-friendly. These proposed changes would produce a
more consistent QA program across pollutant categories that fosters use
of new technologies by more directly linking instrument performance
with programmatic objectives. The proposed revisions were developed
with the assistance of a stakeholder group (QA Strategy Workgroup)
composed of QA representatives from EPA, State, local, and tribal
monitoring organizations. Recommendations from the workgroup are
provided in one of the draft versions of the National Ambient Air
Quality Strategy document.\36\ We solicit comments on all of the
following proposed amendments to 40 CFR part 58, appendix A.
---------------------------------------------------------------------------

\36\ The National Ambient Air Monitoring Strategy (Final Draft).
U.S. Environmental Protection Agency. Office of Air Quality Planning
and Standards, APril 2004. Some of the detailed content of the April
2004 draft, including some of the workgroup recommendations are not
included in the subsequent December 2005 version.
---------------------------------------------------------------------------

1. Consolidation of Quality Assurance Requirements
The requirements for State and local air monitoring stations
(SLAMS) and prevention of significant deterioration (PSD) monitoring
stations have been combined from two separate appendices, 40 CFR part
58, appendices A and B, into one single appendix A because both
programs have similar QA requirements.
2. Realignment to Current EPA Quality Assurance Policies
EPA Order 5360.1 A2 requires agencies that accept Federal grant
funding for their air monitoring programs to have a QA program with
certain elements including quality management plans (QMP), quality
assurance project plans (QAPP), and a person designated as the quality
assurance manager. Many of these elements are not in the existing
regulations, which predate EPA Order 5360.1 A2 (revised in 2000), but
would now be added under today's proposal. Grantee agencies have been
following the requirements of EPA Order 5360.1 A2 for several years,
and as a result, we do not expect these proposed revisions would have a
significant impact on resources beyond the existing program. Copies of
EPA Order 5360.1 A2 are available in the docket for this proposal as
well as on EPA's Internet site http://www.epa.gov/quality1.
A QMP is a document that describes an organization's quality system
including its policy and procedures, functional responsibilities of
management and staff, and other general practices of its data
collection program. Project-specific details are documented in a QAPP.
A QAPP would document, for example, how the PM_2.5 air
monitoring network will be operated and how sampler performance will be
controlled and data quality evaluated.
EPA Order 5360.1 A2 requires grantee agencies involved with data
collection activities to identify a quality assurance manager. The
proposed amendments to 40 CFR part 58, appendix A would require each
State (or delegated monitoring agency) to identify and maintain a ``QA
management function''. This proposed language captures the essence of
the requirements in EPA Order 5360.1A2, while befitting the nature of
the ambient air monitoring community which is made up of large and
small (local and tribal) organizations.
The EPA also proposes to revise the QA program by emphasizing the
DQO process. A DQO is a qualitative and quantitative statement that
defines the appropriate quality of data needed for a particular
decision--for example, the data quality necessary for EPA or a
monitoring organization to make data comparisons against the National
Ambient Air Quality Standards (NAAQS). The DQO help to establish the
requirements for precision, bias, completeness, and detectability and
the rationale for their acceptance criteria.
The proposed amendments would require monitoring organizations to

[[Page 2726]]

evaluate PM_10-2.5 and ozone monitoring system performance
through the DQO process. This is consistent with the existing
requirement for organizations to evaluate their PM_2.5
monitoring system performance using the DQO process. Priority for these
evaluations is placed on PM_2.5, PM_10-2.5, and
ozone as these are the pollutants of most concern across the country.
Quality assurance procedures such as determining precision through
collocated sampling and determining bias through an independent
performance evaluation program for PM_10-2.5 are proposed to
follow the same basic approach as the PM_2.5 monitoring
network. The proposed precision and bias measurement uncertainty goals
are identified in 40 CFR part 58, appendix A. The proposed amendments
to appendix A would also specify that EPA is responsible for the
development of the DQO for NCore multi-pollutant stations and State and
local air monitoring stations (SLAMS).
3. Quality Assurance Requirements for PM₁₀,
PM_10-2.5 and PM_2.5
The proposed QA requirements for PM_10-2.5 would follow
the same approach as the requirements that currently apply to both
automated and manual PM₁₀ and PM_2.5 monitors.
These requirements would include the implementation of flow rates
audits conducted by the monitoring organization, collocated monitoring,
and performance evaluations. Statistical evaluations have allowed us to
reduce collocation and performance evaluation sampling frequencies
without significant affects to data quality assessments.
We are proposing to amend the PM_2.5 and PM₁₀
collocation sampling frequency requirement. Statistical assessments of
the collocated PM_2.5 and PM₁₀ data reveal that
adequate estimates of precision at the primary quality assurance
organization could be made at a reduced sampling frequency.
Consequently, we are proposing to reduce the frequency from every 6
days to every 12 days. This change would reduce the burden on the
monitoring organization without a significant effect on precision
estimates. This proposal does not include a reduction in the
collocation requirements for total suspended particulate (TSP) or PSD
monitors. In addition, we are proposing to revise the concentration
limits applicable to collocated pairs of monitors that are used to
provide precision estimates. The concentration limits would be reduced
from 6 micrograms per cubic meter ([mu]g/m3) to 3 [mu]g/
m3 for PM_2.5 and from 20 [mu]g/m3 to
15 [mu]g/m3 for PM₁₀ (high-volume samplers).
Statistical evaluation of three years of PM_2.5 and
PM₁₀ data revealed comparable estimates of precision using
data from both of these reduced concentration ranges, and that the
addition of the data at these lower ranges will increase the level of
confidence in the precision estimates. This proposed change would make
the collocation sampling frequency requirement consistent for
PM_2.5 PM₁₀ and PM_10-2.5. A document
describing the possible new approach is available in the docket.\37\
---------------------------------------------------------------------------

\37\ Proposal to Change the PM_2.5 and PM₁₀
Collocation Sampling Frequency Requirement, http://www.epa.gov/ttn/amtic/pmqainf.html
We are proposing to revise the sampling frequency for the
implementation of the PM Performance Evaluation Program (PEP). This
proposed approach used historical PM_2.5 precision and bias
data to identify the minimum number of performance evaluations required
for all primary quality assurance organizations to provide an adequate
assessment of bias, rather than the current requirement that a uniform
25 percent of monitors in a primary quality assurance organization be
evaluated each year. The revision would establish an equitable sampling
frequency of five valid audits a year for organizations with less than
or equal to five monitoring sites and eight valid audits a year for
those organizations with greater than five monitoring sites. A valid
performance evaluation audit means that both the primary monitor and
PEP audit concentrations are valid and above 3 [mu]g/m3. As
an example, if a primary quality assurance organization had 20
monitoring sites, the current requirement would require five sites (25
percent of network) to be audited four times each year (one each
quarter) for a total of 20 audits. The new proposal would simply
require eight audits be provided (distributed across each quarter) and
that all monitoring sites be audited within a six year period in order
to provide a representative estimate of bias for the monitoring
network. This would equate to distributing eight audits (or five for
networks less than or equal to 5) at 15 percent of the monitoring
network sites. In addition, each method designation must be audited.
Therefore, if a primary quality assurance organization had two
different monitoring instruments in their network, both would need PEP
audits each year. Since bias data quality objectives are evaluated on 3
years of PEP audits, both sampling frequencies should provide us with
reasonable assessments of bias. Preliminary assessments of the impact
of the possible new method show that organizations with smaller
networks would need more audits but fewer audits would be needed at
organizations with larger networks. The net result across all primary
quality assurance organizations would be fewer audits, comparable bias
results, and reduced resource burden. A document describing this
possible approach is available in the docket.\38\
---------------------------------------------------------------------------

\38\ Review of the Potential to Reduce or Provide a More Cost
Efficient Means to Implement the PM_2.5 Performance
Evaluation Program, http://www.epa.gov/ttn/amtic/pmpep.html.

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

4. Requirements to Ensure Adequate Independent Quality Assurance for
All Pollutants Subject to National Ambient Air Quality Standards
We are proposing to revise the current regulatory requirements
dealing with responsibilities for independent assessments of monitoring
system performance. These evaluations are the subject of sections 2.4
and 3.5.3.1 of the current appendix A to 40 CFR part 58. Section 2.4 of
appendix A to 40 CFR part 58 applies to all National Ambient Air
Quality Standards (NAAQS) pollutants and section 3.5.3.1 is applicable
only to PM_2.5. Currently, section 2.4 of appendix A requires
the monitoring organization to ``participate'' in EPA's National
Performance Audit Program (NPAP). For the last few years, EPA has
considered that monitoring organizations are in compliance with the
requirements of section 2.4 if, at a minimum, the organizations made
their monitoring sites and equipment accessible to EPA or contractors
for conducting the performance evaluations. For continuous gas
instruments, a performance evaluation involves the introduction of a
gas or gases of independently known concentration to determine the bias
of the local monitor.
Section 3.5.3.1 of appendix A to 40 CFR part 58 describes the
Performance Evaluation Program (PEP) for PM_2.5. The PEP
requirements are functionally similar to the NPAP requirements but
differ in its specifics because of the nature of particulate matter
sampling (i.e., it is not possible to introduce air with a known
concentration of PM_2.5 into a monitor). Under the PEP for
PM_2.5, a local monitor is evaluated by placing a second,
independently-maintained Federal reference method (FRM) monitor next to
the local monitor and allowing both monitors to sample for 24 hours.
The filter from the independent FRM monitor is then shipped to an
independent laboratory

[[Page 2727]]

where it is weighed and the resulting independently calculated
concentration is compared to the concentration from the local monitor.
The resulting difference in concentrations between the independent FRM
monitor and local monitor is used to calculate the bias between the
sampler results.
The monitoring organization is responsible for having these
PM_2.5 performance evaluations take place, or only for giving
access to its sites for EPA staff or contractors to perform them. In
practice, most monitoring organizations comply with the requirements in
section 3.5.3.1 by giving access to EPA staff or contractors and by
accepting that EPA funds this activity by holding back part of the
grant funding that might otherwise go directly to the monitoring
organization. One State complies with requirements in section 3.5.3.1
by having independent audits in one part of the State performed by
personnel and laboratories from the monitoring organization that is
responsible for daily operations in another part of the State.
The EPA proposes to revise the text of 40 CFR part 58, appendix A
to clearly provide that it is the responsibility of each monitoring
organization to make arrangements for, and to provide any necessary
funding for, the conduct of adequate independent performance
evaluations of all its FRM or Federal equivalent method (FEM) criteria
pollutant monitors. The proposed language would also clearly indicate
that it is the monitoring organization's choice whether to obtain its
independent performance evaluations through EPA's NPAP and
PM_2.5 PEP programs, or from some other independent
organization. An independent organization could be another unit of the
same agency that is sufficiently separated in terms of organizational
reporting and which can provide for independent filter weighing and
audit gas naming. This proposed approach would ensure that adequate and
independent audits will be performed but would provide flexibility in
the implementation approach.
Monitoring organizations that choose to comply with the revised
provisions of appendix A to 40 CFR part 58 regarding performance
evaluations by relying on EPA audits, for PM_2.5,
PM_10-2.5, and/or other NAAQS pollutants, would be required
to agree that EPA hold back part of the grant funds they would
otherwise receive directly. The EPA intends to develop guidance for
monitoring organizations that choose to comply by obtaining audit
services from elsewhere. To ensure national consistency and effective
audits, this guidance will include provisions for EPA certification of
data comparability for audit services not provided by EPA and for
traceability of gases and other audit standards to national standards
maintained by the National Institute for Standards and Technology.
5. Revisions to Precision and Bias Statistics
We are also proposing to change the statistics for assessment of
precision and bias for criteria pollutants. Two important data quality
indicators that are needed to assess the achievement of DQO are bias
and precision. Statistics in the current requirements of 40 CFR part
58, appendix A (with the exception of PM_2.5) combine
precision and bias together into a probability limit at the primary
quality assurance organization level of aggregation. In addition, the
statistical calculations of precision and bias vary among criteria
pollutants and between manual and automated methods within the same
pollutant. Since the DQO process uses separate estimates of precision
and bias, we examined assessment methods that were statistically
reasonable and simple. The proposed assessment methods are based on the
QA measurements that are currently required in 40 CFR part 58, appendix A.
For sulfur dioxide (SO₂), nitrogen dioxide
(NO₂), carbon monoxide (CO), and ozone (O₃), we
are proposing to estimate precision and bias on confidence intervals at
the site level of data aggregation rather than the primary quality
assurance organization. Estimates at the site level can be accomplished
with the automated methods for SO₂, NO₂, CO and
O₃ because there is sufficient QC information collected at
the site level to perform adequate assessments. Since the criteria
pollutant data are used for very important decisions (comparison to the
NAAQS), providing precision and bias estimates at upper confidence
limits would provide a higher probability of making appropriate
decisions. The intent of this proposed change is to move organizations
to a ``performance-based'' quality system. Organizations that
demonstrate acceptable performance would be allowed the flexibility to
reduce the frequency of certain QC checks. These agencies are expected
to shift resources used for these QC checks into higher priority QA
work. A document describing this possible new approach is available in
the docket.\39\
---------------------------------------------------------------------------

\39\ Proposal: New Method for Estimating Precision and Bais for
Gaseous Automated Methods for Ambient Air Monitoring Program,
http://www.epa.gov/ttn/amtic/files/ambient/gagc/proprecision.pdf.

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

The precision and bias statistics for PM measurements
(PM₁₀, PM_10-2.5 and PM_2.5) would be
generated at a primary quality assurance organization level because,
unlike the gaseous pollutants, only a percentage of the sites have
precision and bias checks performed in any year. As with the gaseous
pollutants, the statistics would use the confidence limit approach.
Using a consistent set of statistics would simplify procedures by
removing a significant number of equations and confusing language in
the appendix.
We are also proposing to change the precision and bias statistics
for lead (Pb) to provide a framework for developing and assessing DQO.
The QC checks for Pb come in three forms: flow rate audits, Pb audit
strips, and collocation. The EPA proposes to combine information from
the flow rate audits and the Pb audit strips to provide an estimate of
bias. Precision estimates would still be made using collocated sampling
but the estimates would be based on the upper 95 percent confidence
limit of the coefficient of variation, similar to the method described
for the automated instruments.
6. Program Updates
We are also proposing several QA program changes to update the
existing requirements in 40 CFR part 58 to reflect current program
needs and terminology:
? We are proposing to remove SO₂ and
NO₂ manual audit checks. A review of all SLAMS/NAMS/PAMS
sites by monitor type revealed that no monitoring organizations are
using manual SO₂ or NO₂ methods, nor are any
monitoring organizations expected to use these older technologies.
Instead of the old manual methods, monitoring sites are using
continuous methods to perform these audit checks. We are proposing to
remove the manual method QC checks because the continuous check methods
are covered by the current QA procedures.
? We are proposing to change the concentration ranges for QC
checks and annual audit concentrations. The one-point QC check
concentrations for the gaseous pollutants SO₂,
NO₂, O₃ and CO would be expanded to include lower
concentrations. Lower audit ranges would also be added to concentration
ranges in the annual audit concentrations. Adding or expanding the
required range to lower concentration ranges is appropriate due to the
lower measured concentrations at many monitoring sites as well as the
potential for NCore stations to monitor areas where concentrations are
at trace ranges. In addition, EPA proposes that

[[Page 2728]]

the selection of QC check gas concentration must reflect the routine
concentrations normally measured at sites within the monitoring network
in order to appropriately estimate the precision and bias at these
routine concentration ranges.
? We are proposing to revise the PM₁₀ collocation
requirement. Currently, 15 percent of all PM_2.5 sites are
required to maintain collocated samplers. For consistency, the proposed
amendments would change the PM₁₀ collocation requirement to
match the PM_2.5 requirement. This proposed change would make
the collocation requirement consistent for PM_2.5 PM₁₀ and PM_10-2.5.
? We are proposing to amend the PM_2.5 and
PM₁₀ collocation sampling frequency requirement. Statistical
assessments of the collocated PM_2.5 and PM₁₀ data
reveal that adequate estimates of precision at the primary quality
assurance organization could be made at a reduced sampling frequency.
Consequently, we are proposing to reduce the frequency from every 6
days to every 12 days. This change would reduce the burden on the
monitoring organization without a significant effect on precision
estimates. This proposal does not include a reduction in the
collocation requirements for total suspended particulate (TSP) or PSD
monitors. In addition, we are proposing to revise the concentration
limits applicable to collocated pairs of monitors that are used to
provide precision estimates. The concentration limits would be reduced
from 6 micrograms per cubic meter ([mu]g/m₃) to 3 [mu]g/
m₃ for PM_2.5 and from 20 [mu]g/m₃ to
15 [mu]g/m₃ for PM₁₀ (high-volume samplers).
Statistical evaluation of 3 years of PM_2.5 and
PM₁₀ data revealed comparable estimates of precision using
data from both of these reduced concentration ranges, and that the
addition of the data at these lower ranges will increase the level of
confidence in the precision estimates. This proposed change would make
the collocation sampling frequency requirement consistent for
PM_2.5 PM₁₀ and PM_10-2.5.
? We are proposing to revise the requirements for
PM_2.5 flow rate audits. Based on an evaluation of flow rate
data and discussions within the QA Strategy Workgroup, we are proposing
to reduce the frequency of flow rate audits from quarterly to
semiannually and remove the alternative method which allows for
obtaining the precision check from the analyzers internal flow meter
without the use of an external flow rate transfer standard. Most
monitoring organizations participating in the QA Strategy Workgroup
considered auditing with a external transfer standard to be the
preferred method and believed that the quarterly audit data
demonstrates the instruments are sufficiently stable to reduce the
audit frequency. The proposed amendments would provide an efficient and
effective approach by reducing audit frequency to an adequate level
while ensuring the use of a preferred approach.

D. What Are the Proposed Monitoring Methods for the National Ambient
Air Monitoring System?

1. Federal Reference Methods and Federal Equivalent Methods
Monitoring methods used in the multi-pollutant NCore and SLAMS
networks would include Federal reference methods (FRM), Federal
equivalent methods (FEM), and other methods designed to meet the data
quality objectives of the network being deployed. When appropriate, the
proposed amendments place emphasis on continuous methods over filter-
based methods to provide for highly time-resolved data for better
characterization of diurnal patterns of air pollution and for timely
public availability of data. While more emphasis is placed on
continuous methods, a limited number of filter-based methods would
still be retained in most networks to tie together historical data sets
with new monitoring data. EPA's strategy for selecting the proposed
monitoring methods for the National ambient air monitoring system was
to select methods that meet data quality objectives for each pollutant
and that have the most utility to support multiple monitoring
objectives. Specifics on the monitoring methods proposed for use at
each type of site are described below.
? A wide variety of research, FRM/FEM or other routine
methods could be used at NCore research-grade stations. Maximum
flexibility is provided in the proposed amendments for these sites
because they would be used to investigate the atmospheric processes and
air chemistry that go beyond the capabilities of characterizing the air
with routine monitoring methods.
? NCore multi-pollutant stations would use FRM or FEM for
criteria pollutants when the expected concentration of the pollutants
are at or near the level of the National Ambient Air Quality Standards
(NAAQS). For criteria pollutant measurements of carbon monoxide (CO)
and sulfur dioxide (SO₂), where the level of the pollutant
is well below the NAAQS, it may be more appropriate to operate higher
sensitivity monitors than FRM or FEM. In these cases, the higher
sensitivity methods are expected to support different monitoring
objectives than the FRM or FEM. In some limited cases, higher-
sensitivity gas monitors have also been approved as FEM and can serve
both NAAQS and other monitoring objectives. Options for high-
sensitivity measurements of CO, SO₂, and total reactive
nitrogen (NO) are described in the report, ``Technical Assistance
Document for Precursor Gas Measurements in the NCore Multipollutant
Monitoring Network.''
? State and local air monitoring stations would use FRM or
FEM for criteria pollutants. For PM_2.5, these sites could
also use approved regional methods (ARM), which are described in
section IV.D.2 of this preamble.
? Photochemical assessment monitoring stations (PAMS) would
use the ozone (O₃) ultraviolet photometry FEM and the nitric
oxide (NO) and nitrogen dioxide (NO₂) chemiluminescence FRM
for criteria pollutant measurements. Methods for volatile organic
compounds (VOC) including carbonyls, additional measurements of gaseous
nitrogen, such as NO_y, and meteorological measurements are
routinely operated at PAMS. Because these measurements are not of
criteria pollutants, the methods are not subject to the requirements
for reference or equivalent methods. However, these methods are
described in detail in the report, ``Technical Assistance Document
(TAD) for Sampling and Analysis of Ozone Precursors.''\40\
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\40\ Technical Assistance Document (TAD) for Sampling and
Analysis of Ozone Precursors. U.S. Environmental Protection Agency.
HUman Exposure and Atmospheric Sciences Division. EPA/600-R-98/161.
September 1998. Available at: http://www.epa.gov/ttn/amtic/pams.html.

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? Special purpose monitoring (SPM) sites have no
restrictions on the type of method to be utilized. While FRM and FEM
can be employed at SPM sites, other methods, not limited to continuous,
high-sensitivity, and passive methods, may also be utilized. Because
SPM sites are designed to encourage monitoring, agencies are expected
to design SPM sites with methods to meet specific monitoring objectives
that may not be achievable with FRM or FEM. For instance, a community
may be concerned with a source impacting their neighborhood. Because
many PM FRMs are filter-based manual methods, having a 24-hour sample
may not indicate if the source impacted the neighborhood because of the
meteorological variability during the sample collection period. However,
a continuous method may be able to provide the high-time resolution

[[Page 2729]]

necessary to detect the short-term impacts of a plume on a
neighborhood. Another example could be the utilization of passive
monitors deployed at many locations to determine the location of
maximum concentrations within a neighborhood. Additional information on
SPM is included in section IV.E.9 of this preamble.
2. Approved Regional Methods for PM_2.5
The proposed amendments also expand the use of alternative
PM_2.5 measurement methods through approved regional methods
(ARM). The proposed amendments to 40 CFR part 58, appendix C extend the
existing provisions for EPA approval of a nondesignated
PM_2.5 method as a substitute for a FRM or FEM at a specific
individual site to a network of sites. This approval would be extended
on a network basis to allow for flexibility in operating a hybrid
network of PM_2.5 FRM and continuous monitors. The size of
the network, in which the ARM could be approved, would be based on the
location of test sites operated during the testing of the candidate
ARM. The proposed amendments require that test sites be located in
urban and rural locations that characterize a wide range of aerosols
expected across the network. A hybrid network of monitors would be
operated to address monitoring objectives beyond just determining
compliance with NAAQS. The hybrid network would lead to a reduced
number of existing FRM samplers for direct comparison to NAAQS and an
increase in continuous samplers that meet specified performance
criteria related to their ability to produce sound comparisons to FRM
data. Those ARM that meet the specified performance criteria would be
approved for direct comparison to PM_2.5 NAAQS.
Performance criteria for approval of ARM would be used to determine
whether the continuous measurements are sufficiently comparable for
integration into the PM_2.5 network used in NAAQS decisions.
These criteria are the same criteria for precision, correlation, and
additive and multiplicative bias that are proposed for approval of
continuous PM_2.5 Class III equivalent methods, described in
section IV.B.3 of this preamble. These performance criteria would be
demonstrated by monitoring agencies independently or in cooperation
with instrument manufacturers under actual operational conditions using
one to two FRM and one to two candidate monitors each. This would be a
departure from the very tightly-controlled approach used for national
equivalency demonstration in which three FRM and three candidate
monitors are operated. The ARM would be validated periodically in
recognition of changing aerosol composition and instrument performance.
These validations would be performed on at least two levels: (1)
Through yearly assessments of data quality provided for as part of the
on-going quality assurance (QA) requirements in 40 CFR part 58,
appendix A, and (2) through network assessments conducted at least
every 5 years as described in section IV.E.11 of this preamble.
The testing criteria EPA is proposing for approval of
PM_2.5 continuous methods as ARM are intended to be robust
but not overly burdensome. The two main facets of testing are the
duration and location(s) of testing. The duration is expected to be one
year to provide understanding of the quality of the data on a seasonal
basis. The locations for testing are expected to be a subset of sites
in a network where the State desires the PM_2.5 continuous
monitor to be approved as an ARM. Testing would be carried out in
multiple locations to include up to two Core-based Statistical Area/
Combined Statistical Areas (CBSA/CSA) and one rural area or small city
for a new method. For methods that have already been approved by EPA in
other networks, one CBSA/CSA and one rural area or small city would be
required.
To ensure that approvals of new methods are made consistently on a
national basis, the procedures for approval of methods would be similar
to the requirements specified in 40 CFR part 53, i.e., the EPA
Administrator (or delegated office) would approve the application.
However, to optimize flexibility in the approval process, all other
monitoring agencies seeking approval of a method that is already
approved in another agency's monitoring network may seek approval
through their own EPA Regional Administrator. This approach should
provide a streamlined approval process, as well as an incentive for
consistency in selection and operation of PM_2.5 continuous
monitors across various monitoring agency networks.
The proposed QA requirements for approval of continuous
PM_2.5 ARM at a network of sites would be the same as for FEM
in 40 CFR part 58, appendix A, except that 30 percent of the required
sites that utilize a PM_2.5 ARM would be collocated with an
FRM and required to operate at a sample frequency of at least a one-in-
six day schedule. The higher collocation requirement would support the
main goal of the particulate matter continuous monitoring
implementation plan, which is to have an optimized FRM and
PM_2.5 continuous monitoring network that can serve several
monitoring objectives. The current 15 percent collocation requirement
in 40 CFR part 58, appendix A is adequate to provide an estimate of
site and network precision; however, a higher amount of collocation is
necessary to retain a minimum number of FRM for continued validation of
the ARM, direct comparison to NAAQS, and for long-term trends that are
consistent with the historical data set archived in the Air Quality
System. The collocated sites are to be located at the highest
concentration sites, starting with one site in each of the largest
population CBSA or CSA in the network and working to the next highest-
population CBSA or CSA with the second site and so forth.

E. What are the Proposed Requirements for the Number and Locations of
Monitors To Be Operated by State and Local Agencies?

The proposed amendments modify the requirements in appendix D to 40
CFR part 58 for the number and locations of monitors necessary to
support ambient air data objectives. This proposal requires States to
deploy a new network of multipollutant monitoring stations called the
National Core (NCore) network; requires States to maintain robust
networks for PM_2.5 and ozone (O₃) and to
establish a robust monitoring network for PM_10-2.5; allows
States to make major reductions in monitoring for other criteria
pollutants, where concentration data are well below the applicable
National Ambient Air Quality Standards (NAAQS) and are not expected to
pose future air quality problems; and allows States to reduce the
number of stations required for the NCore photochemical assessment
monitoring stations (PAMS) network. We also propose to establish or
modify certain monitoring frequency requirements.
This proposal allows for reductions in air pollution monitoring for
select pollutants in geographic areas that do not have or are not
expected to have related air quality problems, while increasing or
maintaining monitoring sites in areas with continuing or new air
quality problems. The proposal allows for reductions in the carbon
monoxide (CO), sulfur dioxide (SO₂), nitrogen dioxide
(NO₂), PM₁₀, and lead (Pb) air monitoring
networks in geographic areas with historically low concentrations of
these specific pollutants, except cases in which the State
implementation plan (SIP) or source permits specifically require

[[Page 2730]]

certain monitoring. However, monitoring requirements that are part of a
SIP or permit should be revisited as part of the network assessments
described in section IV.E.11 of this preamble. Overall, a limited
number of these monitors are still expected, but not required, to be
operated to support studies of air quality trends, to allow accountability
for emissions control programs, and for health effects studies.
This proposal also requires States to increase or maintain
monitoring sites in most areas with continuing or new air quality
problems for O₃ and PM_2.5. However, with EPA
agreement, States would be allowed to move some monitors to better
characterize the spatial variability of these pollutants.
As discussed in section IV.E.2 of this preamble, we also are
proposing requirements for the minimum monitoring network for the
proposed PM_10-2.5 NAAQS published elsewhere in this Federal
Register.\41\
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\41\ Continuous PM_2.5 and PM_10-2.5 methods
that can meet multiple monitoring objectives are being promoted by
proposing new performance-based criteria for approval of these
methods. See section IV.B of this preamble.
---------------------------------------------------------------------------

Under the proposed monitoring amendments, the PAMS network would
remain a requirement for serious, severe, and extreme ozone
nonattainment areas. However, EPA is promoting the development of more
individualized PAMS networks to suit the specific data needs for a PAMS
area. We propose to make the PAMS requirements more flexible to allow
for this redesign.
Minimum criteria pollutant monitoring requirements, where proposed
for retention or addition, would be based in part on population
statistics. The Office of Management and Budget (OMB) has established
standards for defining metropolitan and micropolitan statistical areas
that replace metropolitan statistical areas defined in the 1990
standards (65 FR 82227, December 27, 2000). The EPA has traditionally
used the 1990 metropolitan statistical area definitions within many of
the air monitoring requirements including the numbers of monitoring
sites within a network and the Air Quality Index (AQI) reporting
requirements. The proposed amendments use the new OMB standards for
defining metropolitan and micropolitan areas, as well as the new
standards for Core-based Statistical Areas (CBSA) and Combined
Statistical Areas (CSA).
1. Proposed Requirements for Operation of Multipollutant Monitoring
Stations Identified as the National Core Network (NCore).
The EPA is proposing requirements applicable to States individually
that may, in the aggregate, cause the deployment of a new network of
monitors in approximately 60 mostly urban multipollutant stations. Most
States would be required to operate at least one urban station;
however, rural stations could be substituted in States that have
limited dense urban exposures. States with Core-Based Statistical Areas
(CBSA) often also have multiple air sheds with unique characteristics
and, often, elevated air pollution. These States include, at a minimum,
California, Florida, Illinois, Michigan, New York, North Carolina,
Ohio, Pennsylvania, and Texas. These States would be required to
identify one to two additional NCore stations in order to account for
their unique situations. These stations, combined with about 20
multipollutant rural stations, which are not specifically being
required of the States, would form the new multipollutant NCore
network. The rural NCore stations will be negotiated using grant
authority as part of an overall design of the network that is expected
to leverage existing rural networks such as IMPROVE, CASTNET and, in
some cases, State-operated rural sites.
These multipollutant NCore stations are intended to track long-term
trends for accountability of emissions control programs and health
assessments that contribute to ongoing reviews of the NAAQS; support
development of emissions control strategies through air quality model
evaluation and other observational methods; support scientific studies
ranging across technological, health, and atmospheric process
disciplines; and support ecosystem assessments. Of course, these
stations together with the more numerous PM_2.5 and
O₃ sites would also provide data for use in the NAAQS decision
making process and for public reporting and forecasting of the AQI.
The EPA proposes that these multipollutant NCore stations be
required to measure O₃; high-sensitivity measurements, where
appropriate, of CO, SO₂, and total reactive nitrogen
(NO_y); PM_2.5 with both a Federal reference method
(FRM) and a continuous monitor, PM_2.5 chemical speciation,
and PM_10-2.5 with a continuous FEM; and meteorological
measurements of temperature, wind speed, wind direction, and relative
humidity. High-sensitivity measurements are necessary for CO,
SO₂, and NO_y to adequately measure a signal for
these pollutants in most air sheds for data purposes beyond NAAQS
attainment determinations. For the other listed pollutants,
conventional ambient air monitoring methods could be used.
At least one NCore station would be required in each State, unless
a State determines through the network design process that a site which
meets their obligation can be reasonably represented by a site in a
second State, and the second State has committed to establishing and
operating that site. Any State, local, or tribal agency could propose
modifications to these requirements for approval by the Administrator.
While the proposed amendments do not specify the cities in which the
States must place their multipollutant NCore Level 2 monitoring
stations, EPA anticipates that the overall result will be a network
that has a diversity of locations to support the purposes listed
earlier. For example, there would be sites with different levels and
compositions of PM_2.5 and PM_10-2.5, allowing air
quality strategies to be evaluated under a range of conditions.
These sites would be located in a manner that represents as large
an area of relatively uniform land use and ambient air concentrations
as possible (i.e., out of the area of influence of specific local
sources, unless exposure to the local source(s) is typical of exposures
across the urban area). Neighborhood-scale sites may be appropriate for
multipollutant NCore monitoring stations in cases where the site is
expected to be similar to many other neighborhood scale locations
throughout the area. In some instances, State and local agencies may
have a long-term record of several measurements at an existing location
that deviates from the siting criteria in the proposed amendments. The
State or local agency may propose utilizing these kinds of sites as the
multipollutant NCore monitoring station to take advantage of that
record. The EPA will approve these sites, considering both existing and
expected new users of the data. The multipollutant NCore stations
should be collocated, when appropriate, with other multipollutant air
monitoring stations including PAMS, National Air Toxic Trends Station
(NATTS) sites, and the PM_2.5 chemical Speciation Trends
Network (STN) sites. Collocation would allow use of the same monitoring
platform and equipment to meet the objectives of multiple programs
where possible and advantageous.
The proposed amendments would require operation of the 60 NCore

[[Page 2731]]

stations by January 1, 2011. However, up to 35 of these stations are
already being operated on a voluntary and EPA-funded basis with
acquisition of high-sensitivity monitors for CO, SO₂, and
NO_y. These three new measurements and other existing
measurements for O₃,PM_2.5, and meteorology are
the foundation of this highly leveraged network. PM_10-2.5
measurements would also be added to these stations once the continuous
technologies are approved as FEM and are commercially available.
Once these multipollutant NCore stations are established, it is
EPA's intention that they operate for many years in their respective
locations. Therefore, State and local agencies are encouraged to insure
long-term accessability to the sites proposed for NCore monitoring
stations. Relocating these stations would require EPA approval, which
would be based on the data needs of the host State and other clients of
the information.
We may negotiate with some States, and possibly with some Tribes,
for the establishment and operation of some additional rural NCore
multipollutant monitoring stations to complement the multipollutant
stations that would be required by the proposed changes to the
monitoring regulations. We are in the process of revising CASTNET to
upgrade its monitoring capabilities to allow it to provide even more
useful data to multiple data users. We expect that about 20 CASTNET
sites will have new capabilities at least equivalent to the
capabilities envisioned for NCore multipollutant sites. Those sites
would reduce the number of, and complement, rural multipollutant sites
funded with limited State/local grant funds.
2. Proposed Monitoring Requirements for the Proposed Primary National
Ambient Air Quality Standard for PM_10-2.5
The EPA is proposing elsewhere in today's Federal Register a new
primary standard for coarse particulate matter (PM), and a new
indicator for that standard: PM_10-2.5, qualified so as to
include any mix of PM_10-2.5 dominated by resuspended dust
from high-density traffic on paved roads and PM generated by industrial
sources and construction sources, and excludes any ambient mix of
PM_10-2.5 that is dominated by rural windblown dust and soils
and PM generated by agricultural and mining sources. See section III.D
of the 40 CFR part 50 proposal.\42\
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\42\ As explained in section III of the NAAQS proposal
(published elsewhere in this Federal Register), the focus on coarse
particles associated with these source types is derived from the
available epidemiological studies that examined exposures to the
ambient mix of PM_10-2.5 in urban areas, and the study
which examined exposure to unenriched natural crustal materials, as
well as dosimetric evidence and toxicological studies. Adverse
health effects associated with PM_10-2.5 concentrations
have been noted in studies conducted in urban areas, while limited
evidence does not support the association of health effects with
PM_10-2.5 concentrations resulting from the suspension by
wind of uncontaminated natural crustal materials of geologic origin.
Furthermore, available evidence does not support either the
existence or the lack of causative associations for community
exposures to coarse particle emissions from agricultural or mining sources.
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Accordingly, EPA is proposing new provisions in 40 CFR Part 58 to
establish the minimum requirements for States to deploy and monitor for
this proposed NAAQS. A main goal of the minimum required network will
be the support of NAAQS designation decisions. Other data objectives
include the improved characterization of the composition of coarse
particles to support source apportionment studies and the development
of control strategies; support of epidemiological and toxicological
research efforts; public reporting of real-time concentration levels
through the AQI and particle pollution forecasting programs; the
quantification of coarse particle trends over time; and identifying and
quantifying the factors that have contributed to changes over time for
purposes of program accountability.
Requirements for monitor placement by States that are specific, for
example requirements regarding the target distances of monitors from
sources of concern, will also ensure a level of consistency in network
design that allows monitoring results to be generally comparable among
areas where minimum monitoring requirements apply.
This section begins with a discussion of the monitoring methods,
types, and sampling frequencies to be used in the proposed network. We
then turn to the description of the proposed minimum requirements for
the PM_10-2.5 monitoring network including the proposed
number of monitors to be required in affected areas and proposed
requirements for where those monitors should be located within the
areas. States would have the discretion (and would be encouraged) to
place additional monitors to supplement these minimum required monitors.
Monitoring for an indicator described in qualified terms poses
issues regarding how and when to determine the sites at which the
ambient mix of PM_10-2.5 would be dominated by resuspended
dust from high-density traffic on paved roads and PM generated by
industrial sources and construction sources, and where it would not be
dominated by rural windblown dust and soils and PM generated by
agricultural and mining sources. The proposed new provisions for 40 CFR
part 58 described in this section address this issue.
a. Monitor type, methods, and frequency of sampling.
We are proposing a Federal reference method (FRM) for
PM_10-2.5 in a new appendix 0 to 40 CFR part 50 (Reference
Method for the Determination of Coarse Particulate Matter in the
Atmosphere), in section VI of the preamble to the Part 50 proposal
elsewhere in this Federal Register. See also section IV.B above. The
proposed FRM for measuring PM_10-2.5 is based on the
combination of two conventional low-volume filter-based methods, one
for measuring PM₁₀ and the other for measuring
PM_2.5, and determining the PM_10-2.5 measurement
by subtracting the PM_2.5 measurement from the concurrent
PM₁₀ measurement.\43\
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\43\ As noted in section VI.A.5 ``Relationship of Proposed FRM
to Section 6012 of the Safe, Accountable, Flexible, Efficient
Transportation Equity Act: A Legacy for Users (SAFETEA-LU) (PL 109-
59)'' of the part 50 NAAQS proposal, section 6012 of SAFETEA-LU
requires the Administrator to ``develop a Federal reference method
to measure directly particles that are larger than 2.5 micrometers
in diameter without reliance on subtracting from coarse particle
measurements those particles that are equal to or smaller than 2.5
micrometers in diameter.''
As explained above in section IV.B of this preamble and in the
NAAQS proposal, EPA, consistent with Clean Air Scientific Advisory
Committee (CASAC) Peer Review and recommendation, is proposing a
difference method as the Federal reference method (FRM). We are
doing so because other methods are not yet sufficiently developed to
serve as an FRM. We have further explained, however, that we believe
that other methods, notably certain types of continuous monitoring
and dichotomous methods, are potential Federal equivalent methods,
and indeed, that we expect actual monitoring networks to utilize
these other means of monitoring. We are also continuing to
investigate the possibility of promulgating the dichotomous method
as an FRM, and if technically justified, will do so.
We view these actions as consistent with the new statutory
provisions. We are taking the steps necessary to develop a
compliance network using non-difference, continuous methods as the
principal means of monitoring for PM_10-2.5. We are
further devoting substantial effort to the possibility of
promulgating dichotomous methods as an alternative FRM. The EPA will
also submit the required reports by August 10, 2007, the deadline
specified by SAFETEA-LU.
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The new filter-based FRM would not be required to be widely
deployed in the operational PM_10-2.5 network, but rather
would serve as the basis of comparison for the equivalency procedures
in 40 CFR part 53 described in section IV.B of this preamble. The EPA
intends (but would not require) that the majority of the monitors
comprising the PM_10-2.5 network be based on continuous
methods that will provide an hourly

[[Page 2732]]

time resolution. At sites with locally measured wind data and
continuous PM_10-2.5 monitors, hourly time resolution will
help States and EPA understand the emission sources that are most
important to control, by relating wind direction and source locations
in particular hours with peaks, and/or by matching the hourly pattern
of concentrations with known temporal patterns of sources such as
traffic. It may also, in some cases, help in understanding whether
natural events have influenced a day's 24-hour concentration. Whatever
method a State chooses to deploy, all PM_10-2.5 monitors
counted by a State as part of its compliance with the required minimum
number of PM_10-2.5 monitoring sites (proposed below) would
be required to sample every day. The EPA's data quality objective
process has found daily sampling to be a key factor in reducing
statistical uncertainty at concentration levels near the proposed daily
PM_10-2.5 NAAQS. The automation inherent in continuous
methods would provide a more cost-effective alternative to manual
filter-based sampling for achieving this daily sampling frequency.
The EPA is proposing January 1, 2009, as the deadline for
deployment of PM_10-2.5 monitors. This will provide over 2
years from promulgation of the final rule for one or more continuous
PM_10-2.5 monitors to be approved by EPA as meeting the
proposed Class III FEM requirements in 40 CFR part 53 and for the
States to procure and deploy those instruments. We believe this will be
sufficient time for the steps that are required by monitor vendors,
EPA, and the States. At least two monitor vendors have already
developed prototype continuous instruments expected to be candidates
for approval as equivalent methods. These prototypes have already been
the subject of field trials in cooperation with EPA. We expect vendors
to make improvements based on this field experience so that final
designs can be field tested in the winter of 2006/2007, after
promulgation of the final rule, and in the summer of 2007. Under 40 CFR
section 53.5, the Administrator has up to 120 days to act on
equivalency applications. Thus, it is feasible for applications to be
submitted and EPA to approve one or more applications in late 2007 or
early 2008 and for States (or EPA on behalf of States) to place orders
in time for monitors to be manufactured, shipped, and installed by
January 1, 2009.
A small percentage of continuous PM_10-2.5 samplers
(minimum of 15 percent) would be required to have a collocated filter-
based FRM sampler or collocated continuous FEM monitor at the same site
for QA purposes (see proposed 40 CFR part 58, appendix A, Quality
Assurance Requirements for SLAMS, NCore, and Prevention of Significant
Deterioration (PSD) Air Monitoring. While we have determined that all
of the PM_10-2.5 monitors should be of the continuous type,
except for these collocated FRM samplers, we are not requiring the sole
use of continuous methods, in order to maintain flexibility in the use
of manual sampling technology that can meet the proposed
PM_10-2.5 FRM or FEM requirements, and potentially address
additional goals such as speciation.
We have considered the issue of whether a State should be allowed
to operate an appropriately sited PM₁₀ monitor in lieu of a
required PM_10-2.5 monitor in a situation in which the
probability of a PM_10-2.5 NAAQS violation is small. Some
State monitoring officials have expressed interest in such an option to
save resources or to spread the need for monitor investments over
time.\44\ We expect that in the types of areas where
PM_10-2.5 is dominated by emissions generated from high
density traffic on paved roads, industrial sources, and construction
activity, a substantial fraction of PM₁₀ is likely to be
PM_2.5. While a PM₁₀ monitor will capture this
PM_2.5 and thus would provide a conservative estimate (i.e.,
an overestimate) of PM_10-2.5 concentrations, there are
complicating considerations.
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\44\ The Clean Air Scientific Advisory Committee (CASAC) also
supported this concept, although without explicit discussion of the
complicating implementation considerations discussed here.
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Without data from FRM or FEM PM_10-2.5 monitors, an area
would be initially designated unclassifiable for
PM_10-2.5.\45\ Some designated PM₁₀ FRM
instruments have relatively poor precision compared to the proposed
requirements for the PM_10-2.5 FRM and FEMs. It is possible
that an area might appear to meet the PM_10-2.5 NAAQS based
on PM₁₀ monitor readings but actually not be in compliance.
It is also possible that a PM₁₀ monitor might unexpectedly
indicate a high enough concentration of PM₁₀ as to suggest a
possible violation of the PM_10-2.5 NAAQS. In such a
situation, the result could be a delay in efforts to meet the
PM_10-2.5 NAAQS relative to what would have been the case had
an approved FRM or FEM PM_10-2.5 monitor been deployed initially.
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\45\ An area without a PM_10-2.5 monitor could in
concept be included in an adjacent nonattainment area because of its
contribution to concentrations in the latter area. Given the
typically short transport distance of PM_10-2.5, this
would be unusual.
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On balance, EPA believes it is appropriate to allow use of any
PM₁₀ FRM or FEM monitor in lieu of a required
PM_10-2.5 monitor, with restrictions, including the
requirement for daily sampling at such PM₁₀ monitors. This
could only be initiated at monitoring sites where the 98th percentile
value for the most recent complete calendar year of PM₁₀
monitoring data \46\, reported at local conditions of temperature and
pressure as specified for PM_10-2.5 , is less than the
proposed PM_10-2.5 NAAQS.\47\ During any calendar year of
PM₁₀ sampling in lieu of a required PM_10-2.5
sampler, if more than seven 24-hour average PM₁₀
concentrations exceed the numerical value of the proposed
PM_10-2.5 NAAQS, the State would have to deploy a FRM or FEM
PM_10-2.5 monitor within a one year period. We invite comment
on this subject, including other possible provisions for more limited
use of PM₁₀ monitors in lieu of PM_10-2.5
monitors, such as limiting the use of PM₁₀ monitors to a
period of 3 years after the first approval of a continuous FEM
PM_10-2.5 method.
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\46\ PM₁₀ data used to qualify a site for
PM₁₀ monitoring in place of PM_10-2.5
monitoring must be based on a 1-in-3 day sampling frequency, or more
frequent sampling.
\47\ The EPA's intention regarding the substitution of
PM₁₀ monitors for required PM_10-2.5 monitors
is that siting criteria would not be affected, i.e., the
PM₁₀ monitor that will substitute for a
PM_10-2.5 monitor would have to be located at a site that
would be appropriate for a required PM_10-2.5 monitor.
(What sites are appropriate for required PM_10-2.5
monitors is addressed below.) Also, PM₁₀ data used to
qualify a site for PM₁₀ monitoring in place of
PM_10-2.5 monitoring must also be from--or clearly
representative of--the site where a PM₁₀ monitor will
substitute for a PM_10-2.5 monitor.
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b. Network design.
i. Number of required monitors. The discussion of network design
requirements for PM_10-2.5 begins with the questions of how
to define the geographic units which should be separately subject to
minimum monitoring requirements and how many monitors should be
required in each such area. We propose that the geographic unit for
individual application of monitoring requirements be the Metropolitan
Statistical Area (MSA) (i.e., a CBSA which contains an urbanized area
with a population of at least 50,000 persons).\48\ We also propose that
only those MSAs that contain all or part of an urbanized area with a
population of at least 100,000 or more be required to have monitors.
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\48\ Defined metropolitan and micropolitan statistical areas
based on application of 2000 standards (which appeared in the
Federal Register on December 27, 2000) to 2000 decennial census data.
http://www.census.gov/population/www/estimates/00-32997.txt.

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[[Page 2733]]

Some MSAs contain multiple urbanized areas with populations of
100,000 people or more, each containing emission sources of interest
for PM_10-2.5, which could be separately subject to
monitoring requirements; however, we believe applying minimums at the
urbanized area level is not necessary to support implementation of the
proposed NAAQS.\49\ Where more than one MSA is part of a Combined
Statistical Area (CSA), each MSA would be treated separately. We
believe separate treatment of MSAs is appropriate in light of the
typically short transport distance of PM_10-2.5 and the
diversity of situations that can exist in a CSA. For comparison,
PM_2.5 and O₃ monitoring, minimum requirements
apply at the CSA level, because a broader geographic frame is
appropriate for those photochemically formed pollutants.
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\49\ Factors which contribute to this assessment include the
consideration that multiple urbanized areas in a single Metropolitan
statistical area (MSA) will tend to have similar situations
affecting PM_10-2.5 concentrations, for example similar
meteorological conditions which can favor or suppress emissions of
PM_10-2.5 from paved roadways and construction sites.
Also, applying monitoring requirements separately to urbanized areas
would both increase the total number of required monitors and reduce
State flexibility in siting the required monitors since any
requirements would have to be met separately in each urbanized area.
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Consistent with both the current State and Local Air Monitoring
Station (SLAMS) minimum requirements for PM_2.5 described in
40 CFR part 58, appendix D and the proposed minimum requirements for
PM_2.5 described in section IV.E.3 of this preamble, EPA
proposes that States be required to have more PM_10-2.5
monitors in higher-population MSA than in lower-population MSA. A
higher-population MSA typically has more total roadway surface, higher
traffic counts, more and larger industrial sources, and more ongoing
construction at any given time, all of which make it more likely that
the MSA contains more locations with high concentrations of coarse
particles attributable to these sources. Also, a higher-population MSA
potentially contains more distinct types of emissions situations
causing PM_10-2.5 nonattainment, i.e., more distinct mixes of
emission sources affecting different locations, such that separate
monitoring may be needed to identify these and to develop and track the
success of control strategies for them. More monitors will also be
useful in helping to define nonattainment boundaries in larger and
potentially more complex MSAs. Accordingly, we are proposing minimum
requirements for the number of PM_10-2.5 monitoring stations
in each MSA based, in part, on the total population of the MSA.\50\
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\50\ April 1, 2000 population in Metropolitan and Micropolitan
Statistical Areas in Alphabetical Order and Numerical and Percent
Change for the United States and Puerto Rico: 1990 and 2000, Source:
U.S. Census Bureau, Census 2000 and 1990 Census. Internet Release
date: December 30, 2003. http://www.census.gov/population/cen2000/phc-t29/tab01a.xls.

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We are proposing that the actual or estimated PM_10-2.5
design value (three-year average of 98th percentile 24-hour
concentrations) of an MSA, where one can be calculated, be used as a
second factor to increase the minimum number of monitors in MSA with
higher estimated ambient coarse particle levels and to reduce
requirements in MSA with lower estimated levels. Given the imprecision
of current estimates of PM_10-2.5 ambient concentrations and
the resulting non-robust design value statistics that will initially be
available to States when they develop their monitoring plans, we are
proposing three categories of design values defined by percentages of
the proposed 24-hour PM_10-2.5 NAAQS. The proposed amendments
categorize MSA design values as either low (less than 50 percent of the
proposed PM_10-2.5 NAAQS), medium (50 percent to 80 percent),
or high (greater than 80 percent).
The EPA will assist States with the development of
PM_10-2.5 design values by analyzing the concentrations from
existing collocated or nearly collocated PM₁₀ and
PM_2.5 monitors in each MSA and identifying which pairs meet
the proposed siting criteria appropriate for comparison to the proposed
PM_10-2.5 NAAQS. Monitoring agencies may propose other
procedures for calculating estimated PM_10-2.5 design values
as a substitute for EPA-calculated values, subject to Regional Office
approval of the monitoring methods, site characteristics, and data
handling procedures being used to calculate substitute estimated design
values. PM_10-2.5 design values for purposes of determining
the number of required monitors would be calculated using data only
from sites which are suitable for comparison to the NAAQS under the
criteria presented later in this section. If no such sites exist,
medium area MSA minimum requirements would apply. After actual data
using FRM or FEM monitors is available to establish a true design value
based on 3 years of data, a State would be allowed to reduce or be
required to increase the number of monitors based on that design value.
This process of adjustment would be ongoing, and would be a specific
aspect of the periodic network assessment that would be required by the
proposed amendments.
Table 1 of this preamble presents the specifics of the proposed
requirements for the minimum number of monitors in an MSA, relating the
minimum number of PM_10-2.5 monitors to total MSA population
and design value. For example, an MSA with a total population of
between 1 million and 5 million people that contains all or part of an
urbanized area with a population of at least 100,000 people, with an
actual or estimated PM_10-2.5 design value of between 50
percent and 80 percent of the proposed PM_10-2.5 NAAQS would
be required to have at least two monitors. In another example, an MSA
with a total population between 100,000 and 500,000 people with an
actual or estimated PM_10-2.5 design value of less than 50
percent of the proposed PM_10-2.5 NAAQS would not be required
to have any monitors, although States could deploy discretionary monitors.
We invite comment on whether there should be a different minimum
size for an MSA required to have monitors, rather than applying the
criteria in Table 1 of this preamble to all MSA that contain all or
part of an urbanized area with a population of at least 100,000
persons. We also invite comment on whether factors in addition to MSA
population and estimated design value should enter into the
determination of the number of required monitors, for example, MSA or
urbanized area(s) population density, and if so, in what way.

[[Page 2734]]

Table 1.--PM10-2.5 Minimum Monitoring Requirements
----------------------------------------------------------------------------------------------------------------
Most recent 3- Most recent 3- Most recent 3-
year design year design year design
MSA total population 1 5 value 2 >80% value 50%-80% value <50% of
of PM10-2.5 of PM10-2.5 PM10-2.5 NAAQS
NAAQS 3 NAAQS 3 4 3
----------------------------------------------------------------------------------------------------------------
> 5,000,000..................................................... 5 3 2
1,000,000-< 5,000,000............................................ 4 2 1
500,000-< 1,000,000.............................................. 3 1 0
100,000-< 500,000................................................ 2 1 0
----------------------------------------------------------------------------------------------------------------
\1\ Metropolitan Statistical Area (MSA) as defined by the Office of Management of Budget. The requirements of
this table apply only to MSAs that contain all or part of an urbanized area with a population of at least
100,000 persons. Metropolitan and micropolitan statistical areas based on application of 2000 standards (which
appeared in the Federal Register on December 27, 2000) to 2000 decennial census data.
\2\ A database of estimated PM10-2.5 design values will be provided by EPA until the network is fully deployed
for 3 years.
\3\ The proposed PM10-2.5 National Ambient Air Quality Standards (NAAQS) levels and forms are defined in 40 CFR
part 50.
\4\ These minimum monitoring requirements would apply in the absence of a design value.
\5\ Population based on latest available census figures.

The EPA estimates that the size of the minimum required
PM_10-2.5 network will be approximately 250 monitors based on
the proposed requirements and our current estimates of
PM_10-2.5 design values. Figure 1 of this preamble
illustrates our current estimates of how many monitors would be
required in each MSA based on the criteria in Table 1, census data on
MSA populations, and current estimates of design value.\51\ We are not
proposing a specific number of monitors for any MSA. The actual initial
number of monitors required in a given MSA and the initial size of the
minimum required national network may be different if monitoring
agencies propose and we approve alternate approaches to estimating
design values for this purpose. It may be that later review by States
may determine that one or more of the PM₁₀ monitors we have
used to estimate PM_10-2.5 design values is not appropriate.
Also, consideration of exceptional events may be appropriate and may
affect estimated design values. The size of the required network may
vary after its startup depending on long-term changes in total MSA
population and design values.
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\51\ A document listing the current estimate of
PM_10-2.5 design values used in constructing figure 1 of
this preamble is available in the docket.
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BILLING CODE 6560-50-C
Figure 1 of this preamble shows that the proposed minimum network
criteria could (depending on estimated design values as of the time the
States develop their monitor siting plans) have the effect of putting
relatively more monitors in the eastern States than in western States.
This occurs in part because of currently estimated design values but
also in part because there are so many individual MSA in eastern States
compared to western States. In western States, there are fewer small
and medium-sized cities which are in separate MSA and thus qualify for
separate monitoring under the proposed criteria, because the larger
size of

[[Page 2736]]

counties in the western States means that many smaller cities are
subsumed within relatively few MSA.
We request comment on whether the proposed minimum requirements
appropriately address the need for monitoring data in both eastern and
western States, whether additional or fewer monitors could be needed,
and whether additional monitors in some areas, if needed, should be
required by the regulations or deployed through collaborative planning
and grant support. A possibility on which we request comment is to not
adhere to the formal county-based definition of MSA in the West and in
some way to require separate monitoring of more urbanized areas that
are not distinct MSA and, therefore, would not be separately subject to
the minimum monitoring requirements as proposed. For example, some MSA
in some western states are divided into distinct nonattainment areas
for ozone, reflecting natural barriers to transport between air basins.
This division or similar divisions of a large MSA in a western state
could perhaps play a role in determining which population centers
should require separate monitoring for PM_10-2.5. We also
request comment on approaches that would aggregate officially distinct
MSAs in eastern States for the purpose of determining the required
number of monitors.
ii. Location of required monitors and comparability to the NAAQS.
We now turn to the criteria that should be used to locate required
monitoring sites within an MSA (the number of monitors to be sited
being determined by the total MSA population and estimated design value
criteria as just described). As stated in the introduction to this
section, a main goal of the minimum required monitors in a given MSA
will be to support NAAQS designation decisions, including decisions on
nonattainment area boundaries. As detailed in the NAAQS proposal also
in today's Federal Register, the purpose of the proposed qualified
coarse particle indicator and standard is to protect against coarse
particle mixes that are likely to be similar to those present in the
urban epidemiological studies upon which the proposed standard is
based. The indicator for the NAAQS includes any ambient mix of
PM_10-2.5 that is dominated by resuspended dust from high-
density traffic on paved roads and PM generated by industrial sources
and construction sources, and excludes any ambient mix of
PM_10-2.5 that is dominated by rural windblown dust and soils
and PM generated by agricultural and mining sources. In order to
implement the proposed standard, it is necessary to separate where the
mix is dominated by the emissions of PM from listed sources and where
it is not. We have been mindful of this goal in developing the
following proposals regarding monitor siting. In particular we have
been mindful that the strategy for locating PM_10-2.5
monitors must be developed in light of the qualified indicator for the
NAAQS. Monitors should therefore be placed in locations where
concentrations of PM_10-2.5 are dominated by PM emissions
generated from high density traffic on paved roads, industrial sources,
and construction activities.
We have also been mindful that the strategy for locating
PM_10-2.5 monitors must be developed in light of the approach
used to set the level of the proposed PM_10-2.5 NAAQS. As
explained in the NAAQS proposal notice elsewhere in today's Federal
Register, the proposed level of 70 [mu]g/m3 for
PM_10-2.5 (98th percentile form) was selected to be of
equivalent stringency to the current 24-hour PM₁₀ NAAQS of
150 [mu]g/m3 (one-expected exceedance form). As discussed
below, the approach used to determine that these levels are equivalent
in stringency has implications for PM_10-2.5 monitor placement.
The EPA recognizes that each MSA will be characterized by a unique
mix of moderate to highly populated areas together with unique
arrangements of paved roads, areas of construction, and industrial
sources of coarse particles. Therefore, we are proposing network design
requirements that leave room for later agreement between EPA and each
State on specific sites but that provide the binding principles for
those agreements.
We envision that a typical PM_10-2.5 monitoring network
in a large MSA would include some sites with heavy impacts from PM
emissions generated from highly traveled roadways and/or major
industrial sources, but with a relatively small exposed population
because the area around the site is not a dense residential or
commercial area, and some sites in densely populated areas with
somewhat less proximity to such sources. It could also include some
sites in lower-density suburban-type population areas that are
nonetheless affected by sources with emissions of concern. Within each
of these three categories of sites, there are some sites that are not
suitable for required monitors because the sites have a good
possibility of not being dominated by PM emissions generated from high
density traffic on paved roads, industrial sources, and construction
activities, or because placement of monitors for comparison to the
NAAQS in those locations would be inconsistent with the intended
stringency of the NAAQS. The following proposal addresses both how the
required number of monitors should be assigned to the three categories
of sites, and what types of sites are suitable or unsuitable for
placement of monitors.
We are proposing a five-part test of whether a potential monitoring
site is suitable for comparison to the NAAQS, and two rules for how
required monitors should be assigned among such suitable sites. All
five parts of the suitability test must be met. The suitability test
also would be used to determine whether non-required or special purpose
monitors are suitable for comparison with the proposed
PM_10-2.5 NAAQS.
The first two parts of the five-part suitability test are based on
using readily available Census data to help ensure that
PM_10-2.5 monitoring sites are located near and will be
dominated by PM emissions from paved roads, construction, and
industrial sources. The first part is that a monitoring site must be
within a U.S. Census Bureau-defined urbanized area that has a
population of at least 100,000 persons. Restricting suitable sites to
only those within an urbanized area of this size increases the
likelihood that the ambient mix of PM_10-2.5 will be
dominated by resuspended dust from high-density traffic on paved roads
and PM generated by industrial sources and construction sources, rather
than rural windblown dust and soils and PM generated by agricultural
and mining sources which are more typical of rural areas.
The second part of the suitability test is a minimum threshold for
the population density of the block group containing the monitoring
site. This provides more assurance that resuspended dust from high-
density traffic on paved roads and PM generated by industrial sources
and construction sources will dominate in the vicinity of the
monitoring site.
We propose to employ population density in addition to simple
presence within an urbanized area because population density is highly
correlated to traffic density and is available on a relevant geographic
scale. It is appropriate to expect that mixes of PM_10-2.5
monitored at sites located in areas of sufficiently high population
density are dominated by resuspended dust from high-density traffic on
paved roads and PM generated by industrial sources and construction
sources.
Accordingly, we have based the proposed suitability test for a
candidate monitoring site on the population

[[Page 2737]]

density of the census block group in which the site is located. There
is a strong correlation of county-level estimates of Vehicle Miles
Traveled (VMT) density with county-based population density.\52\ It is
reasonable to presume that this county-level correlation indicates an
association between population density and vehicular traffic and
resulting emissions of resuspended dust at smaller geographic scales
also, although exceptions to the association no doubt become more
common. To a lesser extent, there may also be associations between
population density and the presence of other industrial sources and
construction activities.\53\ It is thus appropriate to expect that
mixes of PM_10-2.5 monitored at sites located in areas of
sufficiently high population density are dominated by resuspended dust
from high-density traffic on paved roads and PM generated by industrial
sources and construction sources, and are not dominated by rural windblown
dust and soils and PM generated by agricultural and mining sources.
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\52\ Review of the National Ambient Air Quality Standards for
Particulate Matter: Policy Assessment of Scientific and Technical
Information, OAQPS Staff Paper, EPA-452/R-05-005, June 2005, p. 5-
59. Counties are the geographic unit at which vehicle miles traveled
(VMT) is most readily available from State departments of
transportation. The Federal Highway Administration maintains VMT
statistics at a higher level of aggregation.
\53\ Manufacturing and service industry facilities, and areas of
long-term construction such as commercial development and roadway
construction, tend--with exceptions--to be in the general area of
populated areas that create the demand for such activities and
provide their workers.
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The available census geographic entities for which population
density is published by the U.S. Census are counties, urbanized areas,
urban clusters, census tracts, and block groups. Block groups typically
encompass one-half to two square miles, and thus they provide a spatial
resolution of about one mile. On average, there are approximately 200
block groups for each of the 370 MSA in the U.S. In a State such as
Michigan, for example, the average land area in a county is 700 square
miles as compared to just over 20 square miles for a census tract and
to about 0.5 square miles for a block group. A large-scale unit of
density analysis, say the urbanized area level, would not be as helpful
for guiding monitor placement since it would be a mix of low and high
density sub-units that could have quite different source mixes.
We considered a range of block group population density thresholds
for use in identifying block groups within an urbanized area that may
be suitable for comparison to the NAAQS, depending on other parts of
the suitability test. A low population density threshold would tend to
identify as suitable low density ``edge'' block groups, which because
of their proximity to surrounding non-urbanized lands could tend to
have PM_10-2.5 concentrations that are from emission sources
that are not of concern, as these are explicitly rural sources
(windblown rural dust and soil) or sources that are more typical in
rural lands (agriculture and mining). A low population density
threshold would also tend to identify internal or ``enclave'' low
density block groups which may well have significant paved road,
industrial, and construction emission sources but happen not to have
many residences; later we return to such ``enclave'' block groups as an
exceptional case. A population density threshold that is too high could
leave out areas where PM_10-2.5 concentrations are dominated
by PM emissions from high density traffic on paved roads, industrial
sources, and construction activities.
We first noted that the U.S. Census Bureau uses a population
density of 500 persons per square mile in one step of defining the
``Initial Core'' of an urbanized area. The initial core of an urbanized
area always includes core census block groups or blocks with a density
of at least 1,000 persons per square mile and contiguous block groups
that have a density of at least 500 persons per square mile.\54\
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\54\ See Urban Area Criteria for Census 2000, March 15, 2002, 51
FR 11663. The Census Bureau adds to each urbanized area additional
non-contiguous block groups below and above 500 persons per square
mile using detailed ``hop'' and ``jump'' criteria. Any additional
block groups below 500 persons per square mile would not be included
in our proposed suitability test because such areas are less likely
to have a dense concentration of paved roads, construction, and
industrial sources and may be in close proximity to sources of
emissions that are not of concern.
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We have investigated for comparison the population densities of
block groups in which States and EPA have agreed in the past to place
PM₁₀ monitors. We observe that States have typically located
PM₁₀ monitors in block groups of population densities that
are higher than 500 people per square mile. The median block group
population density of the approximately 1,200 PM₁₀
monitoring sites active in the U.S. between 2002 and 2004 is 1,390
people per square mile. Sixty-three percent of the approximately 1,200
PM₁₀ monitoring sites are in block groups with a density
higher than 500 persons per square mile.
We have also investigated for comparison the block group population
densities for those PM₁₀ monitors which are sited with or
near a PM_2.5 monitor. The PM_2.5 monitoring
program was set up to be more urban oriented than the PM₁₀
monitoring program. Thus, this smaller set is of more relevance to the
structure of a PM_10-2.5 monitoring program. Among the 710
such monitors, the median block group density is 2,306 persons per
square mile. Seventy-eight percent of the 710 monitoring sites are in
block groups with a density higher than 500 persons per square mile.
After examining on an empirical basis in a sampling of MSA the
block groups identified by population density thresholds of 500 persons
per square mile, values lower than 500, and values above 500, and in
light of the practices of the U.S. Census Bureau, we selected 500 as
the proposed threshold value for the second part of the suitability
test because it appears to result in inclusion of most of the related
urbanized area while omitting fringe areas where paved roads,
construction sites, and industrial sources are few in number and/or low
in emissions mass, and whose emissions and ambient impact could be
exceeded by the impact of rural soil, dust, and emissions from
agricultural and mining sources.
Regarding the above-mentioned issue of enclaves within an urbanized
area, we are concerned not to exclude low population density block
groups that contain paved roads, construction sites, and/or industrial
sources and do not contain significant agricultural or mining sources.
The Census incorporates enclaves consisting of block groups with
population density below 500 persons per square mile if certain
conditions are satisfied. Enclaves of less than five square miles are
always incorporated. Even larger enclaves can be included as well. We
are concerned that such large enclaves may not be industrial zones or
transportation corridors that happen to have little resident population
(which could be appropriate for monitoring) but instead could contain
agricultural or mining operations (which could make them inappropriate
for monitoring). Therefore, we propose that block group(s) with
population densities less than 500 persons per square mile, even if
part of an urbanized area, will be considered to pass the second part
of the suitability test if those block groups comprise an enclave of
less than five square miles in land area. We invite comment on this
special exception.
We propose that the third necessary condition for siting a required
monitor and comparing any PM_10-2.5 monitor to the PM_10-2.5
NAAQS be that the monitor be population-oriented. The term

[[Page 2738]]

``population-oriented sites'' is presently defined in 40 CFR 58.1 as
sites in residential areas, recreational areas, industrial areas, and
other areas where a substantial number of people may spend a
significant fraction of their day.\55\ The concept plays an important
role in the PM_2.5 monitoring network in that a
PM_2.5 monitor must be population-oriented to be appropriate
for comparison to either the annual or 24-hour PM_2.5 NAAQS.
We believe that this restriction is also appropriate for
PM_10-2.5 for the same reasons as for PM_2.5.
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\55\ Population density of a block group and population-
orientation of a monitoring site are distinct concepts. A monitoring
site may not be population-oriented even though it is within a block
group of high population density. Population-orientation refers to
the presence of people in a geographic area around a monitoring site
that may be much smaller than the block group. If there is not a
substantial number of people spending a significant fraction of
their day in the area around the monitor with ambient concentrations
of about the magnitude indicated by a monitor, the monitor is not
population oriented, regardless of the population density of the
surrounding census block group. For example, there could be a
portion of a high-density block group that is near a source but
which has few residents or visitors because of its land use type,
for example.
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The fourth part of the five-part suitability test is a restriction
against monitoring sites that are adjacent to a large emissions source
or otherwise within the micro scale environment affected by a large
source.\56\ This restriction is intended to help ensure that monitor
siting is consistent with the intended stringency of the proposed
NAAQS. The relatively large size of coarse particles and resulting high
rate of deposition under most weather conditions, and the fact that
nearly all coarse particles are primary\57\, mean that the ambient
concentration of PM_10-2.5 measured in a specific location
will be more dependent on the distance of that monitor from coarse
particle sources than would typically be the case for ambient
PM_2.5 and associated sources of fine particles.\58\ Monitors
placed adjacent to coarse particle sources would typically measure
higher ambient concentrations than monitors placed farther away. A
PM_10-2.5 monitoring site located adjacent to a high emitting
industrial source or a heavily traveled highway, for example, might
measure high ambient concentrations, but these concentrations could be
characteristic only of the relatively small area around the monitor,
notably a smaller area than in the case of a similarly sited
PM_2.5 monitor. Even if there are people living or working at
the monitor site, thus qualifying it as population-oriented, applying
the proposed NAAQS level to the concentration level measured at such a
monitor would be inconsistent with the level of community protection
intended through the proposed NAAQS. As explained in section III.G of
the NAAQS preamble, the EPA intends that the proposed 24-hour
PM_10-2.5 NAAQS be equivalent in stringency to the current
24-hour PM₁₀ NAAQS. In determining the level for the
PM_10-2.5 NAAQS that would achieve this equivalency, we
relied on the relationship between PM_10-2.5 and
PM₁₀ observed at PM₁₀ monitoring sites all or
most of which were not adjacent to large emission sources. If
PM_10-2.5 monitors were placed at sites that are adjacent to
emission sources, the effect would be to make the proposed NAAQS less
community-oriented and more stringent than intended. The EPA therefore
believes it is appropriate to have a restriction that
PM_10-2.5 monitors in source-influenced micro-environments,
such as on facility fence lines or along the edge of traffic lanes, are
not appropriate for comparison to the NAAQS even if there is some
population subject to exposure in that location (even if EPA or the
State believes that there are other micro-environments similarly
affected by other sources of the same type). PM_10-2.5
monitors placed in such micro environment-types of situations thus
would not be eligible for comparison to the NAAQS \59\ and would not
count toward meeting minimum EPA monitoring requirements.
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\56\ A microscale environment is one in which there are
significant differences in concentrations between locations that are
10 meters to 100 meters apart, and generally are areas that are
impacted by immediately adjacent sources such as industrial sites,
roadways, or construction sites.
\57\ i.e., coarse particles typically are deposited in the form
most recently emitted by their original source (or in the form they
had when resuspended after having deposited to a roadway or
construction site) rather than being created or modified by
atmospheric chemical reactions during their generally short
transport from the point of original emission (or resuspension).
Particles that have been resuspended may have incorporated
secondarily formed compounds at some time in their prior history.
\58\ Air Quality Criteria for Particulate Matter, Volume I of
II, EPA/600/P-99/002aF, October 2004, p. 2-49. See also section
III.G in the NAAQS proposal elsewhere in today's Federal Register.
\59\ We note that this proposed language is more restrictive for
the proposed 24-hour PM_10-2.5 NAAQS than parallel
language for the 24-hour PM_2.5 NAAQS (which allows such
data to be used for comparison with the 24-hour PM_2.5
NAAQS, see present 40 CFR part 58, appendix D, section 2.8.1.2.3).
As explained in the text above, this is because coarse PM is
transported over shorter distances such that a microscale
PM_10-2.5 monitor would not be representative of
community-wide conditions.
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The fifth part of the suitability test, which would only need to be
considered for sites that satisfy all of the first four parts, is that
a site-specific assessment shows that the ambient mix of
PM_10-2.5 sampled at that site would be dominated by
resuspended dust from high-density traffic on paved roads and PM
generated by industrial sources and construction sources, and would not
be dominated by rural windblown dust and soils and PM generated by
agricultural and mining sources. The first four parts of the
suitability test make it unlikely that a candidate site would be
dominated by rural windblown dust (other than perhaps during
exceptional events), but the site-specific assessment may determine
otherwise. The site-specific assessment may also reveal the presence of
a dominant agricultural or mining operation, for example, a gravel or
sand extraction and material handling operation.
As an example of how this five-part suitability test would work,
consider the Riverside-San Bernardino-Ontario, California MSA. The
first part of the test excludes any site outside the Census-designated
urbanized areas within the MSA, of which there are several. The second
part of the test would indicate that a monitoring site within a certain
boundary around the densest parts of the Riverside-San Bernardino
urbanized area, the Indio-Cathedral City-Palm Springs urbanized area,
or any of the other urbanized areas in the MSA that have a population
of at least 100,000 persons, is possibly suitable for comparison with
the NAAQS, while a monitoring site in the small Yucca Valley urban
cluster would definitely not be suitable. Each boundary would follow
block group borders, and would leave out less dense parts of its
associated urbanized area. The third part of the test (population-
orientation) would disqualify some sites within these boundaries
because of the small number of people subject to exposure in the
vicinity that has concentrations similar to what would be monitored at
the site. The fourth part would disqualify sites adjacent to major
roadways (a source-influenced microenvironment). The fifth part would
assess the remaining candidate sites to verify that they are not
exposed to windblown rural dust and soils or PM generated by
agriculture and mining sources to such an extent that emissions from
those sources would dominate the mix of PM_10-2.5 sampled at
that site.
We invite comment on possible variations of the proposed test for
suitability for comparison to the NAAQS, for example the use of census
tracts in place of block groups or different values for population
density or total population of a aggregation of block groups or tract
groups. Census

[[Page 2739]]

tracts are defined as combinations of (usually a few) block groups, and
would provide a somewhat larger scale of analysis around a candidate
monitoring site.
While the issue of setting boundaries for nonattainment areas is
not a subject of this rulemaking, we note that the considerations that
underlie the proposed suitability test, having to do with the influence
of sources on measured concentrations, may also be relevant to the
setting of such boundaries.
The five-part suitability test will leave as suitable many sites in
a MSA, falling into the three broad categories described earlier. We
believe that States should be given further direction on placement of
the required monitors among these sites. A network design strategy
should not allow all required PM_10-2.5 monitoring sites to
be located so far from large emissions sources that they measure
ambient concentrations lower than would be representative of the impact
of coarse particle sources on well populated urban areas. We propose to
address this issue by adopting some of the elements of the monitoring
siting approach that has been used for the PM₁₀ NAAQS. We
propose that 50 percent of required PM_10-2.5 monitors \60\
be required to represent population-oriented middle scale-sized areas
\61\ \62\ near but not adjacent to large sources of PM (i.e., heavily
traveled paved roadways, long-term construction sites, large industrial
sources) to characterize air quality in significant-sized areas that
are affected by emissions from these sources where people may spend a
greater part of their day.\63\ The placement of a monitor on the
grounds of a school within a residential community that is near but not
adjacent to an industrial facility would be an example of such a site.
With this requirement for middle scale PM_10-2.5 sites, EPA's
proposal provides the intended degree of protection in populated areas
with high coarse particle concentrations by requiring sites that are
likely to measure the maximum concentrations (among sites meeting the
suitability test) in one or more of the populated areas that are
impacted by the heaviest PM emissions from roadways and/or industrial/
construction sources.
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\60\ Fractional monitor requirements would round up. MSA with
one, two, three, four, or five required monitors would place one,
one, two, two, or three monitors in this manner, respectively.
\61\ A middle scale-sized area is one in which there are
significant differences in concentrations between locations that are
100 meters to 500 meters apart, and generally are areas that are
impacted by nearly adjacent (but not immediately adjacent) sources,
such as industrial sites, roadways, or construction sites. Middle
scale sites are common in PM₁₀ monitoring (see present 40
CFR part 58, appendix D, section 2.8.0.2) and typical of the
PM₁₀ sites used to establish the equivalency of the
proposed PM_10-2.5 NAAQS to the current PM₁₀ NAAQS.
\62\ Additional information on middle-scale siting, and on all
such monitoring scales, can be found in the document: Guidance For
Network Design and Optimum Site Exposure For PM_2.5 and
PM₁₀. U.S. Environmental Protection Agency. EPA-454/R-99-
022. December 1997. Available on the web at:
http://www.epa.gov/ttn/amtic/files/ambient/pm25/network/r-99-022.pdf.
\63\ If only one monitor is required, then that monitor would
need to conform to this siting requirement (if the monitor is to be
considered as part of the minimum network design).
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For those areas with monitoring requirements greater than one
required monitor, we propose that at least one of the required monitors
must be sited in a neighborhood scale-sized area \64\ that is highly
populated and which may be somewhat further away from emission sources
but is still expected to have elevated levels of coarse particles of
concern. These sites would typically still be impacted by roadway and/
or industrial/construction source emissions, but to a lesser extent
than sites expected to measure maximum concentrations. Among such
sites, the State should select a site characterized by a very large
number of people subject to exposure; typically, this population number
would be higher than the population at sites expected to record maximum
concentrations. A site located within a heavily populated residential
and commercial area that is in proximity to roadways with high
vehicular traffic would be an example of this type of monitor
placement. A site of this type is useful for several reasons. It will
help define the spatial gradients of PM_10-2.5
concentrations, which may be useful in setting nonattainment area
boundaries. It likely will provide concentration data that are relevant
for informing a large segment of the population of their exposure
levels on a given day. Also, areas of this type may have
PM_10-2.5 nonattainment problems that are caused by a
different source mix than problems found at the first type of site, and
require a different approach to reducing concentrations. For example,
the mix of industrial and paved road emissions may be different or the
mix of types of vehicles on paved roads may be different.
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\64\ A neighborhood scale-sized are is one in which there are
not typically significant differences in concentrations between
locations that are 500 meters to four kilometers apart, and
generally are areas that are impacted by the more well-mixed
emissions of urban industrial and mobile sources in the general
vicinity of the site.
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For MSA with a requirement for one, two, or three monitors, the
above two siting provisions address the siting of all required monitors
with respect to proximity to specific sources and populations. For MSA
with a requirement for four or five monitors, there is one remaining
required monitor not yet addressed. We propose that the siting of this
monitor be left to the discretion of the State or local monitoring
agency, subject to a restriction that the site satisfy the suitability
test described above. This site could be placed in locations similar to
those that would be eligible as monitoring sites for the other required
monitors, i.e., at other sites that meet one of the above two proposed
siting requirements. A State may also choose to place the site in a
location that is somewhat more distant from downtown areas, main
industrial source regions, or areas of highest traffic density, such as
in a highly populated suburban residential community. The comparison of
ambient PM_10-2.5 concentrations between such suburban
monitors and those monitors located at the previously described maximum
exposure-type of sites would provide comparative data for assessing the
spatial variation of PM_10-2.5 concentrations over a
metropolitan area.
While we expect the proposed suitability test described above will
appropriately identify areas where the ambient mix of
PM_10-2.5 is dominated by resuspended dust from high-density
traffic on paved roads and PM generated by industrial sources and
construction sources, it may not identify them all. We recognize that
it does not address the possibility that high density traffic on paved
roads, large industrial emission sources, and/or construction
activities may be located outside an urbanized area (including outside
any MSA) or in parts of an urbanized area that do not satisfy the
second part of the suitability test (related to population density)
such that monitoring sites near these sources would not meet the
proposed test, yet persons living or working near the source could be
exposed to concentrations of PM_10-2.5 which are dominated by
the PM emissions from these sources. We invite comment on alternative
approaches that would examine areas where States may wish to place non-
required monitors that do not meet the proposed suitability test, but
are locations of industrial emissions or high traffic on paved roads
which create the potential for ambient mixes of coarse particles of the
type intended to be included by the indicator. In particular, EPA
solicits comment on a modification of the proposed test that would
specify that a site meeting only the third, fourth, and fifth parts of the

[[Page 2740]]

suitability test could be compared to the NAAQS if it were close enough
to an industrial source of coarse particles of a defined high enough
emissions level (for example, 100 tons per year or more of emissions)
that the ambient mix would be dominated by PM generated by that
industrial source. The term ``industrial'' would be made operational by
using a source's assigned industry code under the North American
Industry Classification System (NAICS) and excluding sources with codes
corresponding to agricultural or mining industries.\65\ As noted, the
site would have to population-oriented and could not be in the micro-
scale environment affected by a large source. A site-specific
assessment (the fifth part of the suitability test) would still be
required, and would consider the local mix of emission source types and
sizes, their relative locations to the potential monitoring site, and
local factors affecting transport and deposition of
PM_10-2.5. Such monitors, even if determined to be comparable
to the NAAQS through the site-specific assessment, would not count
toward the minimum number of monitors required for each MSA.
---------------------------------------------------------------------------

\65\ Information on the NAICS is avaialble at
http://www.census.gov/epcd/naics02/.

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We also invite comment on the possibility of another, similar
modification to the proposed suitability test as that just described
for industrial sources, but addressing emissions from vehicle traffic
on roadways. Non-required State sites otherwise excluded from
comparison to the NAAQS, based on their location outside of a U.S.
Census Bureau-defined urbanized area and/or their location in block
groups with population density below the proposed threshold, but are
population oriented and within some distance of a roadway with a
certain traffic volume per day, could be the subject of site-specific
analysis to determine if they are in fact suitable for comparison to
the NAAQS based on the PM emissions from sources that dominate
PM_10-2.5 concentrations at those sites. Such sites would
have to be population-oriented and could not be in the micro-scale
environment affected by the roadway. The site-specific assessment would
consider the local mix of emission source types and sizes, their
relative locations to the potential monitoring site, and local factors
affecting transport and deposition of PM_10-2.5. We seek
comment on whether such sites would be appropriate for comparison to
the NAAQS, and, if so, what levels of VMT must occur and/or other
conditions exist before comparison to the NAAQS could be considered. We
note that traffic volume alone is not a direct predictor of emissions
of resuspended dust and other PM_10-2.5 emissions, since the
load of dust on the highway and the mix of vehicle types matter also.
Such monitors, even if determined to be comparable to the NAAQS through
the site-specific assessment, would not count toward the minimum number
of monitors required for each MSA.
iii. Non-required monitoring. States may deploy PM_10-2.5
monitors in addition to those that would be required. For example,
additional monitors in areas that are required to have one or more
monitors may be very useful for determining nonattainment area
boundaries. States might also want to site monitors near large point
sources, if the final rule provides for the suitability of monitoring
sites near such sources. The EPA will work with States as they consider
what additional monitors to deploy and operate.
The proposed suitability test for comparison with the
PM_10-2.5 NAAQS applies to all non-required monitors (as well
as all required monitors). Data from monitors that do not meet the
suitability test could not be used for nonattainment determinations.
For example, as with required monitors, non-required monitors must also
be population-oriented as defined above in order to be used for
nonattainment designations. Also, as with required monitors, non-
required monitors could not be compared to the NAAQS if they are
located in source-influenced micro-environments, such as on facility
fence lines or along the edge of traffic lanes.
iv. Speciation monitoring. In addition to sites measuring
PM_10-2.5 mass concentration, our experience with
PM_2.5 suggests that it would be useful to have a long-term
PM_10-2.5 speciation network of 50 to 100 sites to assess
physical and chemical characteristics at a nationally diverse set of
locations. Speciation data would help identify the specific source
types, address the relative contribution of anthropogenic and natural
sources to ambient concentrations, and support future research
concerning the health risks of coarse particles of various compositions
and source origins. We propose that one speciation site be located in
each of the MSAs with total population greater than 500,000 people and
that also have an estimated PM_10-2.5 design value greater
than 80 percent of the proposed PM_10-2.5 NAAQS. We expect
that approximately 25 MSAs will be required to have speciation monitors
based on these proposed criteria. These sites will gather data in areas
that have a higher probability of exceeding the proposed NAAQS and also
have larger exposed populations at risk, and would support the
characterization of coarse particles concentrations that control the
attainment/nonattainment status of the area. States would be required
to operate any of these speciation sites that were located inside their
borders. In some cases, monitors could be collocated with
PM_2.5 speciation monitors at urban NCore multipollutant
monitoring stations to provide comparative chemical characterization
studies between fine and coarse particles. The PM_10-2.5 mass
concentration data obtained with speciation monitors would be
comparable to the NAAQS only in situations where the underlying
sampling method used to obtain the filters was an approved FRM or FEM
and the site met the suitability test described earlier in this section.
We will collaborate with States to select and fund additional sites
based on data requirements, individual State needs, and availability of
funds. The EPA solicits comment on all aspects of the
PM_10-2.5 speciation network including the number of required
sites, the total size of the network, the criteria for choosing the
number of required monitors in each area, the sampling method used to
obtain filters, and frequency and types of analyses that would be
performed on those filters.
c. Monitoring plan requirements and approval process.
We propose that each State be required to submit to the respective
EPA Regional Administrator a plan proposing how all affected monitoring
organizations within the State will comply with the requirements
described above for the type, sampling schedule, number, and location
of PM_10-2.5 monitoring stations. The plan would also provide
supporting information for why each monitoring site which the State
proposes to count towards the requirement for a minimum number of
monitors is suitable for comparison to the PM_10-2.5 NAAQS,
based on the criteria described above. In addition, for each non-
required monitoring site which the State intends to deploy and which
the State considers would be appropriate for comparison to the proposed
PM_10-2.5 NAAQS, the plan would also provide evidence that
the monitor is suitable for comparison, based on the criteria described
above. The State would be required to make this plan available for
public inspection for at least 30 days prior to submission to EPA.
This plan would be due to EPA January 1, 2008. The EPA Regional
Administrator may extend this due date

[[Page 2741]]

to July 1, 2008, for example to allow it to be consolidated with the
overall annual monitoring review and plan due at that time.
The EPA Regional Administrator will review the submitted plan and
approve or disapprove it by a letter to the submitting State official
within 120 days of submittal. The EPA Regional Administrator will be
required to invite public comment; he/she must consider relevant public
comments, if any are received in response to the invitation. We are not
proposing a specific mechanism for the Regional Administrator to make
the plan available for public comment, but we invite comment now on
mechanisms that would be practical for the Regional Administrators and
effective for persons likely to want to comment. The approval, if
given, will include confirmation that EPA will treat each planned
monitoring site as suitable or not suitable for comparison to the
PM_10-2.5 NAAQS, along with the reasons for each
determination. This confirmation will be a final EPA action applicable
to subsequent determinations of attainment or nonattainment. This
status will then be recorded in AQS for each monitor by the State.
Elsewhere in this notice (section IV.E.11), we are proposing a new
requirement for States to conduct and submit to EPA a comprehensive
monitoring system assessment at five-year intervals. The status of each
PM_10-2.5 monitoring site with respect to comparability to
the NAAQS should be re-examined during these assessments, starting with
the first assessment which is submitted not less than 5 years after EPA
Regional Administrator approval of the initial PM_10-2.5
monitoring plan. The State may also propose a change in the status of a
PM_10-2.5 monitor whenever a large existing source of
PM_10-2.5 near the monitor ceases (or begins) operation and
is expected to remain shut down (or to continue operation)for three or
more years, if the type of source involved is such that its shut down
or start up could materially affect what types of emissions dominate
the PM_10-2.5 measured at the site.
We invite comment on this proposed process and possible
alternatives or additions to it, for example on whether there should be
review by the EPA Administrator before the approval or disapproval is
considered a final Agency action, or an opportunity for appeal to the
Administrator to alter the final action.
3. Monitoring Requirements for the Proposed Primary and Secondary
National Ambient Air Quality Standards for PM_2.5
The current PM_2.5 network includes over 1,200 FRM
samplers at approximately 900 sites that are operated to determine
compliance with the NAAQS; track trends, development, and
accountability of emission control programs; and provide data for
health and ecosystem assessments that contribute to periodic reviews of
the NAAQS. Over 450 continuous PM_2.5 monitors are operated
to support public reporting and forecasting of the AQI.
For PM_2.5, EPA proposes to modify the network minimum
requirements for PM_2.5 monitoring so that multiple urban
monitors in the same CBSA are not required if they are redundant or
measuring concentrations well below the NAAQS. We propose to base
minimum monitoring requirements for PM_2.5 on
PM_2.5 concentrations as represented by a design value, and
on the census population of the CBSA. Overall, this is expected to
result in a lower number of required sites; however, we recommend and
anticipate that States continue to operate a high percentage of the
existing sites now utilizing FRM, but with FEM and ARM continuous
methods replacing the FRM monitors at many of these sites.\66\
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\66\ An approved regional method (ARM) is a PM_2.5
method that has been approved specifically within a State, local, or
tribal air monitoring network for purposes of comparison to the
National Ambient Air Quality Standards and to meet other monitoring
objectives. See section IV.D.2 of this preamble.
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We are proposing to require that all sites counted by a State
towards meeting the minimum requirement for the number of
PM_2.5 sites have an FRM, FEM, or ARM monitor. We are also
proposing that at least one-half of all the required PM_2.5
sites be required to operate PM_2.5 continuous monitors of
some type even if not an FEM or ARM. This requirement would ensure that
continuous methods continue to be well utilized throughout the network
to support monitoring objectives such as public reporting and
forecasting of the AQI not readily addressed by FRM and filter-based FEM.
As noted, EPA proposes to use design value and population as inputs
in deciding the minimum required PM_2.5 monitoring sites in
each CSA/CBSA. We are proposing these inputs so that monitoring
resources are prioritized based on the number of people who may be
exposed to a problem and the level of exposure of that population.
Metropolitan areas with smaller populations would not be required to
perform as much monitoring as larger areas. If ambient air
concentrations as indicated by historical monitoring are low enough,
these smaller population areas would not be required to continue to
perform any PM_2.5 monitoring.
The proposed amendments would require fewer sites when design
values are well above (rather than near) the NAAQS to allow more
flexibility in the use of monitoring resources in these areas where
States and EPA are already more certain of the severity and extent of
the PM_2.5 problem and possibly in more need of other types
of data to address it. For instance, an agency may wish to operate more
speciation samplers rather than FRM to get a better understanding of
the atmospheric chemistry of an area. We invite comments on this
approach, versus requiring more FRM/FEM monitors in areas well above
the NAAQS.
The proposed siting criteria for PM_2.5 monitors would
remain the same as current requirements, which have an emphasis on
population-oriented sites at neighborhood scale and larger. Population-
oriented middle scale sites would remain a part of the network for
comparison to both the daily and annual standard when a site can
represent many other middle-scale locations where people are exposed.
For middle-scale sites that are unique, only the daily NAAQS would be
considered when comparing data to the standard.
Background and transport sites would remain a required part of each
State's network to support characterization of regional transport and
regional scale episodes of PM_2.5. To meet these
requirements, IMPROVE samplers may be used even though they would not
be eligible for comparison to the PM_2.5 NAAQS; these
samplers are currently used in visibility monitoring programs in Class
I areas and national parks. Sites in other States which are located at
places that make them appropriate as background and transport sites can
also fulfill these minimum siting requirements.
The proposed change in the primary 24-hour PM_2.5 NAAQS
from 65 [mu]g/m\3\ to 35 [mu]g/m\3\ raises the issue of whether any
commensurate changes would be needed in the PM_2.5 ambient
monitoring network regulations. The current specific network design
criteria for PM_2.5 in appendix D to 40 CFR part 58 directs
States to select sites mostly representative of community-oriented
area-wide PM_2.5 exposure levels at locations of neighborhood
or larger scale, except in cases where a certain population-oriented
microscale or middle-scale PM_2.5 site is determined to
represent similar locations that

[[Page 2742]]

collectively form a larger region of localized high ambient
PM_2.5 concentrations. The EPA believes that these current
design criteria remain appropriate for implementation of the proposed
primary PM_2.5 NAAQS. The existing minimum requirements
effectively ensure that monitors are placed in locations that
appropriately reflect the community-oriented area-wide concentrations
levels used in the epidemiological studies that support the proposed
lowering of the 24-hour NAAQS.
Most often, the current location of maximum monitors around
PM_2.5 concentrations is the same as the location of maximum
monitored 24-hour PM_2.5 concentrations, suggesting that no
shifts in monitors would be needed to implement the proposed 24-hour
NAAQS. In a relatively small number of cases \67\, certain microscale
PM_2.5 monitors that have not been eligible for comparison to
the annual PM_2.5 NAAQS and that have been complying with the
24-hour PM_2.5 NAAQS, and therefore have not impacted the
attainment status, may become more influential to attainment status
under a more stringent 24-hour form of the NAAQS. Some sites that have
not measured high concentrations relative to the current 24-hour NAAQS
may also become more influential to attainment status under the
proposed more stringent 24-hour NAAQS. In these cases, States may
choose to move accompanying speciation and continuous monitors to the
new site of particular interest to get a better characterization of PM
at that location. States and EPA may also agree on changing the
location of some PM_2.5 FRM/FEM sites to insure measurements
at the population-oriented location(s) of most interest.
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\67\ EPA is presently aware of less than 10 PM_2.5
monitors that are sited in a manner that is unsuitable for
comparison to the annual NAAQS.
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In proposed changes to 40 CFR 58.10 (Monitoring Network Description
and Periodic Assessments), monitoring agencies would be required to
provide a network plan that includes the identification of any
PM_2.5 sites that are not suitable for comparison against the
annual PM_2.5 NAAQS. The proposed requirements would also
provide for a public hearing and review of changes to a
PM_2.5 monitoring network that impact the location of a
violating PM_2.5 monitor, prior to requesting EPA approval of
the changes. Through this process, monitoring agencies would be able to
consider changes to their PM_2.5 monitoring networks made in
response to the proposed NAAQS, and inform the public about the
potential implications on design values and resulting attainment and
nonattainment decisions.
In today's NAAQS proposal (published elsewhere in this Federal
Register), EPA requests comments on the alternative of basing a
PM_2.5 secondary standard on a shorter-term averaging
interval of less than 24-hours to provide protection against visibility
impairment primarily in urban areas.
If the alternative short-term secondary standard is promulgated,
EPA envisions that compliance would be assessed with data from
continuous PM_2.5 monitoring methods capable of providing
hourly time resolution. Continuous monitors would be required to comply
with FEM or ARM requirements. Hourly PM_2.5 data values would
be averaged over the appropriate short-term averaging interval (e.g.,
four to eight hours) to assess compliance with the proposed short-term
secondary NAAQS. The alternative short-term secondary NAAQS would also
require minor additions to the current PM_2.5 siting
requirements. Some continuous monitors would likely be required to be
sited on a neighborhood and urban scale to form the basis of a network
representing ambient PM_2.5 conditions along corridors that
influence visibility of important scenic resources in and around urban
areas. Sites might also want to consider collocating such monitors with
automated haze-cam systems to quantify local relationships between
short-term PM_2.5 concentrations and visual range.
4. Proposed Monitoring Requirements for PM₁₀
In the PM NAAQS proposal published elsewhere in this Federal
Register, EPA proposes to revoke the PM₁₀ annual standard.
Further, consistent with the more targeted nature of the proposed new
PM_10-2.5 indicator, the Administrator proposes to revoke the
current 24-hour PM₁₀ standard everywhere except in areas
where there is at least one monitor that violates the 24-hour
PM₁₀ standard. In areas where both applicable
PM₁₀ NAAQS are revoked, we propose to have no minimum
PM₁₀ monitoring requirements and to allow discontinuation of
PM₁₀ monitors without prior EPA approval, although
monitoring organizations would have the option of funding and operating
PM₁₀ monitors as needed to satisfy any still-applicable SIP
commitments or to monitor compliance with non-Federal air quality
standards. In areas where the PM₁₀ NAAQS are not both
revoked, we propose to have no minimum requirements, but to require
prior EPA approval for changes to existing monitors. See also section
IV.E.8 of this preamble.
5. Proposed Requirements for Operation of Ozone Monitoring Sites
Ozone (O₃) monitoring sites are operated to determine
compliance with the NAAQS; to track trends, development, and
accountability of emission control programs; to provide data for health
and ecosystem assessments that contribute to ongoing reviews of the
NAAQS; and to support public reporting and forecasting of the AQI. For
O₃, EPA proposes to change the minimum network requirement
from at least two sites in ``any urbanized area having a population of
more than 200,000'' to an approach that considers the level of exposure
of O₃, as indicated by the design value and the census
population of an area. Larger population CSA and CBSA with design
values near the O₃ NAAQS would be required to operate at
least four sites. Smaller CSA and CBSA would be required to operate as
few as one site, provided the design values were sufficiently low
enough. Similar to the proposal for PM_2.5, EPA proposes that
areas with measured ambient concentrations significantly above the
NAAQS be required to operate fewer sites than areas with measured
ambient concentrations near the NAAQS to allow flexibility of resources
in those areas. We invite comments on this approach.
The O₃ monitoring network is primarily based on
continuous FEM using ultraviolet analysis. The network is well deployed
throughout the country at about 1,100 sites with most metropolitan
areas already operating more O₃ monitors than would be
required by today's proposed amendments. The EPA does not anticipate or
recommend significant changes to the size of this network because
O₃ remains a pollutant with measured levels near or above
the NAAQS in many areas throughout the country. However, the proposed
amendments would help to better prioritize monitoring resources depending
on the population and relative levels of O₃ in an area.
6. Proposed Requirements for Operation of Carbon Monoxide, Sulfur
Dioxide, Nitrogen Dioxide, and Lead Monitoring Sites
Criteria pollutant monitoring networks for the measurement of CO,
SO₂, NO₂, and Pb are primarily operated to
determine compliance with the NAAQS and to track trends and
accountability of emission control

[[Page 2743]]

programs as part of a SIP. Because these criteria pollutant
concentrations are typically well below the NAAQS, there is limited use
for public reporting to the AQI, except for a very small number of
locations with on-going local air quality issues.
Gas measurements of CO, SO₂, and NO₂ utilize
continuous technologies. Lead (Pb) is sampled by collecting total
suspended particulates (TSP) on a high-volume sampler and analyzed in a
laboratory.
We are proposing to revoke all minimum requirements for CO,
SO₂, and NO₂, monitoring networks, and reduce the
requirements for Pb. This proposal allows for reductions in ambient air
monitoring for CO, SO₂, NO₂, and Pb, particularly
where measured levels are well below the applicable NAAQS and air
quality problems are not expected, except in cases with ongoing
regulatory requirements for monitoring such as SIP or permit
provisions. In these cases, EPA encourages States to comment on ways to
reduce these potentially unnecessary monitors. We will also work with
some States on a voluntary basis to make sure that at least some
monitors for these pollutants remain in place in each EPA region.
Measurement of CO, SO₂, and NO_y are being
proposed as required measurements at NCore sites. There may be little
regulatory purpose for keeping many other sites showing low
concentrations, other than specific State, local, or tribal commitments
to do so. However, in limited cases, some of these monitors may be part
of a long-term record utilized in a health effects study. The EPA
expects State and local agencies to seek input on which monitors are
being used for heath effects studies prior to shutting down a monitor.
See also section IV.E.8 of this preamble (Proposed criteria and process
for discontinuing monitors).
7. Proposed Changes to Minimum Requirements for Ozone Precursor Monitoring
Section 182(c)(1) of the CAA required us to promulgate rules
requiring enhanced monitoring of ozone, oxides of nitrogen, and
volatile organic compounds in ozone nonattainment areas classified as
serious, severe, or extreme. On February 12, 1993, we promulgated
requirements for State and local monitoring agencies to establish
Photochemical Assessment Monitoring Stations (PAMS) as part of their
SIP monitoring networks in ozone nonattainment areas classified as
serious, severe, or extreme. During 2001, we formed a workgroup
consisting of EPA, State, and local monitoring experts to evaluate the
existing PAMS network. The PAMS workgroup recommended that the existing
PAMS requirements be streamlined to allow for more individualized PAMS
networks to suit the specific data needs for a PAMS area.
We are proposing changes to the minimum PAMS monitoring
requirements in 40 CFR part 58 to implement the recommendations of the
PAMS workgroup. Specifically, we are proposing the following changes:
? The number of required PAMS sites would be reduced. Only
one Type 2 site would be required per area regardless of population and
Type 4 sites would not be required. Only one Type 1 or one Type 3 site
would be required per area.
? The requirements for speciated VOC measurements would be
reduced. Speciated VOC measurements would only be required at Type 2
sites and one other site (either Type 1 or Type 3) per PAMS area.
? Carbonyl sampling would only be required in areas
classified as serious or above for the 8-hour O₃ standard.
? NO₂/NO_X monitors would only be required at Type 2 sites.
? NO_y will be required at one site per PAMS area
(either Type 1 or Type 3).
? Trace level CO would be required at Type 2 sites.
Note that on April 15, 2004, we revised some O₃
nonattainment classifications, under the 8-hour O₃ standard
(69 FR 23951). While the number of areas classified as serious, severe,
or extreme ozone nonattainment under the 8-hour O₃ standard
has been greatly reduced (69 FR 23857), areas that had previously been
classified as serious, severe, or extreme ozone nonattainment under the
1-hour O₃ standard are required to comply with the PAMS
monitoring requirements until they achieve compliance with the 8-hour
ozone standard. See 40 CFR 51.900(f)(9). In addition, the PAMS
requirements would apply to any new areas that are classified or
reclassified as serious, severe, or extreme O₃ nonattainment
under the 8-hour O₃ standard.
We solicit comments on the proposed revisions to the PAMS
monitoring program requirements including the measurements to be made,
the sampling frequencies, and the location and numbers of required
monitoring sites proposed.
8. Proposed Criteria and Process for Discontinuing Monitors
The EPA has determined that many single-pollutant monitors operated
by State and local agencies, specifically many of those measuring CO,
Pb, PM₁₀, SO₂, and NO₂, are providing
data that have limited usefulness in air quality management. This is
likely the case for monitors whose data indicate current attainment of
the corresponding NAAQS with little prospect for future nonattainment.
Accordingly, consistent with the draft National Ambient Air Monitoring
Strategy (NAAMS), we are proposing to eliminate the current
requirements for operation of a certain minimum number of monitors for
CO, PM₁₀, SO₂, and NO₂, and to reduce
the requirements for Pb monitors, as described in section IV.E.6 of
this preamble. We are also proposing changes to loosen the minimum
requirements for monitoring of O₃ precursors in the PAMS
program, as described in section IV.E.7 of this preamble. We are also
proposing changes to the minimum requirements for O₃ and
PM_2.5 monitoring that may have the effect of reducing the
minimum number of these monitors in some areas. We note that the
remaining specific minimum requirements (limited to O₃,
PM_2.5, and PM_10-2.5) are intended to be necessary
but are not always sufficient to meet the requirement in section
110(a)(2)(B) of the Clean Air Act (CAA) that SIP provide for operation
of appropriate systems to monitor, compile, and analyze data on ambient
air quality. We intend to require many States to operate some monitors
for these pollutants, but to determine what monitoring is appropriate
on a more case-by-case basis. The EPA encourages, and in fact the
proposed amendments to 40 CFR part 58 would require, all States to
assess their monitoring networks periodically to determine what changes
should be made, including which monitors should be discontinued and
which retained. Local situations will differ, and should be considered
individually. Reducing low-value monitoring expenditures would allow
resources to be devoted to under-served and new monitoring purposes.
Some monitors in excess of the remaining minimums may be necessary
to the State/local air quality management process, or for other uses,
such as development and validation of air quality models. We are
proposing to continue to require States to propose changes in their
monitoring networks and obtain EPA approval before making changes, even
when the remaining minimum requirements for number of monitors would
still be met. This EPA review and approval can take place through the
mechanism of the annual monitoring plan. The current rule already
requires State agencies to prepare and submit the plan on July 1

[[Page 2744]]

of each year for EPA approval at the Regional Office level. We are
proposing to retain this current requirement. We will approve proposed
changes to a monitoring plan provided the proposed network will still
meet any applicable SIP provisions related to ambient monitoring and
will provide data needed to support the air quality control program.
Based on assessments that we and individual States have done to date,
we generally expect to find that a large percentage--between 33 percent
for SO₂ and 90 percent for NO₂--of current
monitors for CO, PM₁₀, SO₂, and NO₂
can be removed; that most O₃ monitors should continue
although some should be moved to more productive locations; that some
filter-based PM_2.5 monitors can be removed; and that some
filter-based PM_2.5 monitors should be replaced by continuous
instruments when models that have been approved as FEM or ARM are available.
While local situations need to be considered individually, we
believe that certain general principles can be articulated regarding
reductions in monitoring networks. We have incorporated these
principles in the proposed amendments to reduce uncertainties in the
process and thereby facilitate an efficient and timely process for
review and approval or disapproval of proposed changes. These
principles would apply independently. A monitor meeting any one of them
would qualify for EPA approval for discontinuation. Situations not
addressed by these criteria would be considered on a case-by-case
basis. The EPA Regional Offices would have more time to give this case-
by-case consideration to the exceptional cases because cases meeting
one of the following criteria could be disposed of more quickly.
? Any PM_2.5, O₃, CO, PM₁₀,
SO₂, Pb, or NO₂ monitor which has shown
attainment during the previous 5 years, that has a probability of less
than 10 percent of exceeding 80 percent of the NAAQS during the next 3
years based on the levels, trends, and variability observed in the
past, and which is not specifically required by an attainment plan or
maintenance plan, can be removed or moved to another
location.68, 69 Few if any O₃ monitors in urban
areas would likely meet this criterion, but some PM_2.5
monitors may do so. This criterion would not apply to a
PM_2.5 monitor that is part of a spatial averaging plan.
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\68\ The concept of using historical data to statistically
predict the probability of a future violation is an element of EPA's
current policy memo on ``Limited Maintenance Plan Option for
Moderate PM₁₀ Nonattainment Areas,'' August 9, 2001. See
http://www.epa.gov/ttn/oarpg/t1/fact_sheets/lmp_fs.pdf and
http://www.epa.gov/ttn/oarpg/t1/memoranda/cdv.pdf. EPA believes that this
paragraph, but the details of the probability estimation method(s)
will likely differ.
\69\ Five years of historical data means five successive
calendar years of data sufficient for making an attainment determination.
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? A monitor for CO, PM₁₀, SO₂, or
NO₂, which has consistently measured lower concentrations
than another monitor for the same pollutant in the same county and same
nonattainment area during the previous 5 years, and which is not
specifically required by an attainment plan or maintenance plan, could
be removed or moved to another location, if control measures scheduled
to be implemented or discontinued during the next 5 years would apply
to the areas around both monitors and have similar effects on measured
concentrations, such that the retained monitor would remain the higher
reading of the two monitors being compared.\70\
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\70\ PM_2.5 and O₃ are not included in this
proposed criterion because of the value of even low-reading monitors
in understanding the causes of nonattainment and in informing the
public about potential exposures. Lead (Pb) is not included because
Pb concentrations are often very dependent on effective control of
Pb emissions of individual sources very close to the monitor and we
believe it would be too risky to depend on area-wide generalizations
about the effect of scheduled controls. Also, we believe the
effectiveness of emission controls on Pb sources may be more
variable over time than of CO, SO₂, PM₁₀, and
NO₂ emission controls on sources of those pollutants.
---------------------------------------------------------------------------

? For any pollutant, the highest reading monitor (which may
be the only monitor) in a county (or portion of a county within a
distinct nonattainment or maintenance area) could be removed or moved
to a new location provided the monitor has not measured NAAQS
violations in the previous 5 years, the CBSA within which the county
lies (if in any) would still meet requirements for the minimum number
of monitors for the applicable pollutant if any, and the approved SIP
provides for a specific, reproducible approach to representing the air
quality of the affected county in the absence of actual monitoring
data. For example, the SIP could provide that a continuing monitor in a
neighboring county will always be taken by the State and EPA to
represent both counties for purposes of nonattainment and other
regulatory determinations. Because EPA would review and approve any SIP
revision that provides such an approach to representing air quality in
the affected county, EPA can ensure its technical validity and
protectiveness. We intend to take a cautious approach to allowing
removal of such monitors, particularly in urban areas. While approval
of such SIP revisions would be delegated to the Regional Offices, EPA
Headquarters officials would participate in the review of proposed
revisions that present the first instance of specific approaches, and
would resolve issues of national consistency if such issues arise.
? A monitor, which EPA has determined cannot be compared to
the relevant NAAQS because of the siting of the monitor, could be moved
or removed. For example, a PM_2.5 monitor must be population-
oriented to be comparable to the daily or annual NAAQS, and one that is
not population-oriented could be removed.\71\
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\71\ Section 2.8.1.2.3 of appendix D to 40 CFR part 58 (Network
Design for State and Local Air Monitoring Stations (SLAMS)).
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? A monitor that is designed to measure concentrations
upwind of an urban area for purposes of characterizing transport into
the area and that has not recorded violations of the relevant NAAQS in
the previous 5 years could be moved to another location where
information on transport will be more useful to SIP development.
? A monitor not eligible for removal under any of the above
criteria could be moved to a nearby location with the same scale of
representation if logistical problems beyond the State's control make
it impossible to continue operation at its current site. For example,
the State may lose access to a monitoring site not owned by the State
itself, and this criterion would ensure approval of a new site that was
nearby and that had the same scale of representation (e.g., middle-
scale or neighborhood-scale). A move to a more distant site would
require case-by-case EPA review of the appropriateness of the new
location compared to other alternatives.
In the situations covered by these proposed criteria, the State
would need to make a factual showing that the specified conditions are
met. Once the EPA Regional Office accepts that showing, the proposed
amendments would require approval of the State's request as part of the
Regional Office action on the annual monitoring plan. We may issue
guidance suggesting appropriate ways these showings can be made.
We invite comments on the specific details of these proposed
criteria, and on other criteria that would be appropriate.
In order to help information be available to the State and to EPA
that could be relevant to the appropriateness of monitoring network
changes, we propose that each State be required to make available for
public inspection its draft annual monitoring plan for a

[[Page 2745]]

period of at least 30 days prior to submitting it to the EPA Regional
Office for approval. The State could, for example, satisfy this
proposed requirement by making the draft plan available for download
via the air agency's Internet Web site. We also propose that when
submitting the annual monitoring plan for EPA approval, the State
provide evidence that: (1) The State has considered the ability of the
proposed network to support air quality characterization for areas with
relatively high populations of susceptible individuals (e.g., children
with asthma); and (2) if the State proposes to discontinue any
monitoring sites, the State has considered how discontinuing monitoring
sites would affect data users other than the monitoring agency itself,
such as nearby States and tribes or health effects research studies. We
invite comment on where EPA should provide opportunity to examine and
comment on monitoring plans after they are reviewed by the Regional Office.
9. Special Purpose Monitors
The development of today's proposed amendments has given EPA
occasion to re-examine the longstanding issue of whether the ambient
air monitoring rules and current policies regarding use of monitoring
data for regulatory determinations have the effect of creating undue
and counterproductive disincentives to States and other organizations
deploying discretionary monitors that overall and in the long run would
benefit air quality management efforts. The EPA is proposing a limited
change in the monitoring rules on this issue.
At present, each State at any given time is required to operate a
certain set of monitors under the monitoring regulations and its own
approved monitoring plan, or to meet commitments it has made in its SIP
and/or grant agreement(s) with EPA. If a State chooses to deploy an
additional monitor, it may designate it as a special purpose monitor
(SPM). Such designation can afford the State certain flexibility it
would not have if the monitor were designated as an NCore station or
State and local air monitoring station (SLAMS).\72\ However, regardless
of whether a monitor is designated as an SPM, if it is an
appropriately-sited FRM or FEM monitor and if its operation meets the
QA requirements of 40 CFR part 58, or if the data are otherwise
determined to be technically valid, EPA considers all available data
from that monitor whenever we make a determination of attainment or
nonattainment. The possibility that data from an SPM could result in a
nonattainment designation of an area that would otherwise not be so
designated may discourage the State from deploying a new monitor or
supporting the deployment of a monitor by another organization, such as
a university, even when the monitor would provide useful information
for determining the extent, severity, causes, and possible solutions of
a known or suspected air quality problem. Thus, a State that might have
voluntarily addressed a nonattainment problem may never become aware of
the problem. Also, affected persons may also be left unaware and unable
to reduce their own exposures by modifying their behavior or to
advocate for State action to address the problem.
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\72\ A special purpose monitor (SPM) is one which the State does
not count when showing compliance with the minimum requirements for
the number and siting of monitors and which it has designated as an
SPM by so labeling it in the Air Quality System (AQS) data system
and/or in its monitoring plan. In common practice EPA does not
overrule such designations provided the rest of the monitoring
network meets minium requirements. Monitors carrying special purpose
status need not use Federal reference or equivalent methods, are not
subject to the quality system requirements of 40 CFR part 58 that
apply to State and local air monitoring stations (SLAMS), and are
not subject to siting requirements such as probe height or distance
from nearby obstructions (or, in this proposal, the proposed siting
suitability requirements for monitors which can be used for
comparison with the proposed 24-hour PM_10-2.5 standard.
Their data are not required to be submitted to AQS, and they may be
discontinued at will by the State (assuming no grant commitment
exists for their continued operation). States start up and designate
monitors as special purpose as a flexible and economical way to meet
various local monitoring objectives, such as exploring a possible
air quality problem in response to citizen concerns.
---------------------------------------------------------------------------

We addressed this issue in the 1997 rulemaking that established the
current requirements for PM_2.5 monitoring, and created a
narrow exception to the practice that all known, good air quality data
be considered in such determinations. (See preamble discussion at 62 FR
38770, July 18, 1997 and in existing 40 CFR 58.14(b).) That narrow
exception addressed only new SPM for PM_2.5 concentrations.
It provides that PM_2.5 NAAQS violation determinations shall
not be exclusively made based on data produced at a population-oriented
SPM site during the first two complete years of its operation, but only
if monitoring is not continued beyond those 2 years. More recently,
during the development of the draft NAAMS and today's proposal, EPA has
received input from various parties, including the Clear Air Act
Advisory Committee, to the effect that EPA ``should promote policies to
avoid disincentives to monitoring'' by limiting the regulatory use of
data from such monitoring.\73\ A moratorium on any use of data from the
first 3 years after the deployment of a discretionary monitor,
applicable to all NAAQS pollutants, was a specific approach discussed
in some of our consultations with State and local monitoring officials
during the development of this proposal. Such a moratorium would give
States time to address the air quality problem with more flexibility
than it would have if the area were designated nonattainment and
subject to CAA requirements for nonattainment areas.
---------------------------------------------------------------------------

\73\ See recommendation 1.4 in Recommendations to the Clean Air
Act Advisory Committee (CAAAC), Air Quality Management Workgroup,
January 2005, transmitted by the CAAAC as a Committee recommendation
to Administrator Michael O. Leavitt on January 19, 2005.
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We understand and, to some degree, sympathize with the States'
perception that the current requirements create disincentives to
monitoring. We agree that it is conceivable, and perhaps likely, that
it might ultimately be more protective of public health to have more
monitoring data in hand even if the early years of data from each
additional, discretionary monitor could not be used for regulatory
purposes, compared to never having that data at all. However, we
believe we may not ignore technically valid air quality data from FRM
and FEM monitors when making attainment or nonattainment
determinations. If we know that an area is actually not meeting an
NAAQS based on valid data, we cannot ignore those data. This is
premised on the provisions of the CAA that the Agency must follow in
determining whether an area is attainment or nonattainment. Section
107(d)(1)(A)(i) of the CAA defines ``nonattainment'' as ``any area that
does not meet'' an NAAQS and CAA section 107(d)(1)(A)(ii) defines
``attainment'' as any area ``that meets'' an NAAQS. In light of this
explicit language, EPA does not believe we could affirmatively
determine an area to be an attainment area for a particular criteria
pollutant, (i.e., an area ``that attains'' the NAAQS) if we had the
requisite years of valid data from appropriately sited FRM or FEM
monitors showing that the area was in fact not attaining the standard.
In light of this legal requirement, we believe that two limited
exclusions on use of data from SPM are possible. We are proposing that:
(1) The limited two-year moratorium on the use of data from SPM in
determinations of NAAQS violations established in the 1997 rulemaking
for PM_2.5 be extended to the annual PM₁₀ NAAQS
(if it is retained rather than revoked as proposed

[[Page 2746]]

elsewhere in today's Federal Register), the O₃ NAAQS, and
the proposed 24-hour PM_10-2.5 NAAQS, rather than any more
extensive data exclusion approach; and (2) for CO, SO₂,
NO₂, Pb, and 24-hour PM₁₀, that data from the
first 2 years of a SPM would not be used for nonattainment designations
but would be used in making findings of whether a nonattainment area
has attained the NAAQS. In both cases, data from the first 2 years of
operation of a new SPM would not be used provided the monitor does not
continue operation beyond those 2 years. If the monitor does continue
operation beyond 2 years, all years of data will be given full
consideration. This policy would in some situations facilitate special
purpose monitoring that would otherwise be discouraged by the risk of a
nonattainment finding, but we acknowledge that these situations will be
limited.
This proposed approach would have no practical effect for those
NAAQS for which three consecutive years of data are always required
before a determination of attainment/nonattainment can be made, i.e.,
the 24-hour and annual PM_2.5 NAAQS, the annual
PM₁₀ NAAQS, the proposed PM_10-2.5 NAAQS, and the
O₃ NAAQS. For these NAAQS, the proposed rule provision would
make it clear that there is no risk of a nonattainment outcome based on
a two-year period of SPM operation.
The CO, SO₂, NO₂, 24-hour PM₁₀,
and Pb NAAQS present a different issue, because under the form of these
NAAQS a single year of data can be sufficient to make a finding of
nonattainment. We note that until such time as we revise one of these
NAAQS, we are under no mandatory duty to designate an area from
attainment or unclassifiable to nonattainment, so it is within our
discretion to simply not take such an action if the critical data
indicating nonattainment is from the first 2 years of an SPM.
However, if we are requested by a State to redesignate a
nonattainment area to attainment, we do have a mandatory duty to act on
that request. Consequently, we cannot overlook some SPM data that is
contrary to the redesignation request by simply not taking an action.
We must respond to a request for redesignation from nonattainment to
attainment, and if there are valid data indicating that nonattainment
still exists we could not approve the redesignation request. Therefore,
we can use the fact that future designation of any new CO,
SO₂, NO₂, 24-hour PM₁₀, or Pb
nonattainment areas is discretionary to protect States from use of 2
years of data from a new SPM for one of these pollutants resulting in a
nonattainment designation, but we cannot protect an area from use of
such data in a finding on whether an already designated nonattainment
area has subsequently attained the relevant NAAQS. Consequently, the
proposed two-year data moratorium should remove the disincentive to
place new monitors in attainment areas for CO, SO₂,
NO₂, 24-hour PM₁₀, or Pb, but may leave in place
disincentives to add monitors in nonattainment areas that may appear to
have reached attainment or be approaching attainment.
Despite the limited nature of the proposed moratorium, States and
other organizations would still be able to perform many useful types of
discretionary monitoring without fear of triggering a near-term
nonattainment designation. In the case of PM_2.5,
PM₁₀, and the proposed PM_10-2.5 NAAQS, many of
the most useful types of monitors for purposes of understanding the
causes and possible solutions to a nonattainment problem are not FRM,
FEM, or ARM monitors, and therefore these monitors can be deployed for
two or even more years without any concern about use of the data in
nonattainment designations. This includes a number of filter-based
sampler models including the samplers used in the IMPROVE program, all
types of speciation samplers for PM_2.5, PM₁₀, and
the proposed PM_10-2.5, and all existing continuous monitors
for PM_2.5. There are also non-FRM/FEM for some of the other
NAAQS that currently can be deployed indefinitely to characterize air
quality problems better without fear of nonattainment designation
consequences (e.g., passive monitors).
Another situation in which the limited nature of the proposed two-
year moratorium would have no practical disincentive effect is when the
siting of a monitor precludes comparison to the applicable NAAQS, even
though it is an FRM or FEM monitor that meets quality system
requirements. It could, for example, be placed in an location that is
not ambient air and does not represent ambient air. It could also be
placed inconsistently with siting criteria found in the rules which
specify when monitoring data can be used for comparison with the NAAQS.
See existing 40 CFR part 58, appendix D, section 2.8.1.2.3 and the
suitability criteria proposed for the PM_10-2.5 monitoring
network discussed in section IV.E.2 of this preamble.
The limited nature of the moratorium would have a disincentive
effect on discretionary monitoring relative to a hypothetically more
encompassing moratorium. For example, a State could still be
discouraged from operating an O₃ or PM_2.5 monitor
beyond 2 years, and thus may miss becoming aware of an actual public
health problem. Therefore, we invite comment on the Agency's legal
interpretation, which has shaped today's proposal for the described
limited moratorium, and on what provisions for SPM data we should adopt
if EPA was to change the legal interpretation in light of public
comments. In particular, we invite comments on an approach in which the
first 3 years of data from any SPM would be permanently protected from
use in nonattainment determinations regardless of whether it operates
beyond 3 years, but any monitor showing a violation in the first 3
years would be required to continue operation unless its
discontinuation is approved as part of EPA's review of the State's
annual monitoring plan. This approach would result in the State having
some time to address the NAAQS violation before three usable years of
data became available to make an official nonattainment/attainment
determination from the fourth through sixth year of operation.
Special purpose monitors are presently not subject to the quality
system requirements of 40 CFR part 58. With respect to data quality,
EPA wishes to encourage all State and local monitoring agencies to
adhere to the quality system requirements of 40 CFR part 58 for all
FRM, FEM, and ARM monitors (the monitor types to which such
requirements are applicable). Substandard quality system practices
should not be deliberately used as a way to prevent EPA from using data
from an SPM beyond the protection offered by the proposed two-year
moratorium. However, under the current monitoring rules, States may do
so and some have done so. Accordingly, EPA proposes to amend 40 CFR
part 58 to require that all FRM, FEM, and ARM monitors operated by
States (or delegated local agencies) comply with the quality system
requirement in 40 CFR part 58 relevant to the monitor type(s) being
used. We propose that this requirement take effect 2 years after the
date of publication of the final rule, to provide States time to
prepare to meet the requirement and to choose transition dates that fit
with other network plans. We also invite comment on the alternative of
using grant agreements to attempt to achieve quality system objectives
for SPM instead of including a specific requirement in the proposed
amendments.

[[Page 2747]]

We also propose that States be required to submit to the Air
Quality System (AQS) all data collected by all FRM, FEM, and ARM
special purpose monitors, starting no later than 2 years after the date
of publication of the final amendments. In the past, when SPM were not
required to follow quality system requirements, the uncertain data
quality from such monitors was a reason to allow States discretion
regarding submission of data to AQS. With the proposed requirement that
FRM, FEM, and ARM special purpose monitors follow quality system
requirements, there is no rationale for their data not being submitted
to AQS to provide transparency in the air quality management process.
We propose to retain and clarify that a State may discontinue use
of an SPM at any time, without need for EPA approval. However, we
encourage States to continue the use of monitors that have gone beyond
the two-year point of operation if they have recorded a violation of a
NAAQS. Otherwise, EPA may designate the area as nonattainment and the
State would lack clear evidence to show subsequent attainment.
10. Flexibility and Resources for Non-Required Monitoring
The EPA wishes to clarify that while 40 CFR part 58, including the
proposed amendments, contains a number of minimum requirements for
States to operate ambient monitors, ensure data quality, and report
data, these requirements are not a complete blueprint for the
monitoring networks that we believe should and we hope will be operated
by State and local agencies. Many specific features of minimum
requirements for these networks, such as selection of specific
monitoring sites for PM_10-2.5, are left to be made later at
the State level with EPA Regional Office approval, so that the best
information and local insights can be applied to deciding those
features. Also, not every type of monitoring that is needed can be
required through the provisions of 40 CFR part 58 in this rulemaking
because, in some cases, the specific State that should be responsible
for a monitoring activity cannot be identified with confidence at this
time. For example, the proposed amendments to 40 CFR part 58 do not
require any State to operate a rural NCore multipollutant NCore
monitoring station, even though we estimate that the Nation needs about
20 such sites, because it would be premature and too rigid at this time
to select those sites. Instead, we will work with States as they
determine the location of their required urban NCore multipollutant
site or sites, and we will most likely negotiate for the voluntary
operation of some rural sites as well.
The provisions of 40 CFR part 58 can and should only require the
number and types of monitoring activities that will surely be needed in
any State over a reasonably long time period, to avoid the need for
frequent amendments to allow States to stop the use of obsolete
monitors. However, aggregation of hypothetical State networks that just
met the minimum requirements of 40 CFR part 58, including the proposed
amendments, would be inadequate to meet the needs of air quality
management at the State and national levels. We will negotiate with
States for monitoring activities that go beyond the minimum
requirements of 40 CFR part 58 using the draft National Ambient Air
Monitoring Strategy as a starting point for those negotiations. The EPA
will generally provide at least partial funding for such additional
monitoring through grants, sometimes very specifically and sometimes
though more general air quality management support grants. Where
current monitoring activities by a State exceed the final minimum
requirements in 40 CFR part 58, EPA may need to negotiate reductions in
is funding for those activities if the data they produce are not
sufficiently valuable to the air quality management process.
In particular, we anticipate that we will be negotiating with
States in the next several years the specifics of the following
directional changes in their networks:
? Creation and operation of rural NCore multipollutant
stations. We expect that some of the need for rural monitoring data can
be met by required stations that some states choose to place in
suitable rural areas and/or by planned federally-operated rural
monitoring stations. We will identify the remaining needed sites and
recruit and fund specific States to establish and operate them.
? Creation and operation of more PM_10-2.5
speciation sites than the minimum required in the proposed amendments.
? Creation and operation of rural PM_10-2.5 mass
concentration sites. In addition to the urban PM_10-2.5 sites
required by this proposal, having some PM_10-2.5 mass
concentration sites in rural areas may be useful to provide ambient
data to compare with the higher coarse particle concentrations that are
typically found in urban locations. Since these rural sites would
typically be located outside of any MSA and would be characterized by
lower population densities than in metropolitan areas, most would
likely not be appropriate for NAAQS comparisons. We may work with
selected States to establish such rural sites, taking into account
existing siting opportunities such as the CASTNET and IMPROVE networks,
and we solicit comment on the need for and siting strategy for such
rural monitors. We note that monitoring sites in rural areas may be
useful in future health effects research.
? Reduction in the number of PM_2.5 filter-based monitors
and replacement of some such monitors with continuous instruments.
? Reduction in the number of CO, SO₂,
NO₂, PM₁₀, and Pb monitoring sites.
? Changes in the number and/or locations of PM_2.5
speciation monitoring sites. The EPA and the States have been assessing
these sites in the last year or so, and some changes are underway. A
new factor to consider will be the speciation data needs of areas that
may now be attaining the current PM_2.5 NAAQS but appear
likely to be nonattainment with the proposed NAAQS.
? Changes in PAMS networks. The proposed minimum
requirements for PAMS monitoring would mean that many current State
networks exceed minimum requirements, providing the opportunity for
reassessment and redesign to better meet local conditions and data needs.
? Other changes that would result in networks that better
meet State data goals, which can be so individualistic that they cannot
be given consideration in a rulemaking such as this, or even in a
nonbinding national strategy.
11. Proposed Requirements for Network Assessments
In addition to annual network reviews, EPA proposes to require
periodic and detailed network assessments as a way to maintain
relevancy of ambient air monitoring to emerging air program needs and
scientific findings. The EPA proposes that State and local agencies
conduct a technical network assessment every 5 years to consider
whether stations should be removed or added, or whether new program
elements should be adopted to account for changes in air quality,
population growth, emission sources, and other parameters. The first
assessments would be due July 1, 2009. These assessments would also
evaluate the adequacy of existing technologies deployed in the network
compared to commercially available methods that could potentially be
deployed to improve the network. Network assessments are intended to
probe the

[[Page 2748]]

current and expected relevancy of air monitoring networks through a
combination of stakeholder participation and technical analyses. This
would be accomplished, in part, by periodically questioning the overall
usefulness of the existing sites and identifying locations where
additional monitoring may be necessary. Typical topics addressed in
network assessments would include reviewing data objectives and data
quality, prioritizing measurement needs, identifying redundant
monitoring, and identifying specific gaps in location and measurement
parameters. The EPA anticipates developing non-binding guidance on how
to conduct these proposed network assessments. We solicit comment on
the proposed requirements and schedule for network assessments.
12. Related Federal Monitoring
The EPA conducts or supports three ambient monitoring programs
directly, related to but separate from, the State, local, and tribal
monitoring programs that are the subject of today's proposal. These are
CASTNET, NADP, and IMPROVE programs, described in section III.B.3 of
this preamble. Today's proposals do not apply to these programs, but
the following brief description of these programs may assist the public
in commenting on today's proposal.
The EPA plans to upgrade the monitoring capabilities of many of the
CASTNET sites in the next couple of years in ways that would allow them
to meet the same multipollutant monitoring objectives as the proposed
State-operated rural NCore stations. As these plans become more
developed, EPA expects to adjust its targets for the number of rural
NCore stations that are voluntarily operated by States under grant
agreements with EPA.
The EPA is exploring with the National Atmospheric Deposition
Network (NADP) sponsors the possibility of expanding NADP's objectives
and monitoring infrastructure to investigate measurement of spatial
monitoring concentrations, from which dry deposition could be
estimated. Also, NADP stations potentially provide efficient
opportunities to site ambient air monitors for other purposes.
At present, the IMPROVE program employs different sampling hardware
and laboratory analytical procedures to measure speciated
PM_2.5 compared to most PM_2.5 speciation
monitoring in urban areas. The EPA is working to achieve more
consistency between the two programs, so that monitoring results at the
two types of stations are more directly comparable. We are also
reviewing the current IMPROVE site list to determine which are of
higher versus lower priority for long-term continuation.

F. What Are the Proposed Probe and Monitoring Path Siting Criteria?

The EPA is proposing minor organizational changes to 40 CFR 58,
appendix E (Probe and Monitoring Path Siting Criteria for Ambient Air
Quality Monitoring). The EPA also is proposing specific criteria for
the placement of PM_10-2.5 samplers. Current vertical
placement requirements permit microscale PM₁₀ and
PM_2.5 monitors to be located 2 to 7 meters above ground
level to allow for security, instrument servicing, and operator safety,
as well as sampling particulate matter at the breathing height. The EPA
is proposing that the same 2- to 7-meter vertical placement
requirements apply to microscale PM_10-2.5 sites.\74\ The EPA
is also proposing that the 2- to 7-meter vertical placement requirement
apply to middle-scale PM_10-2.5 sites, which differs from the
existing PM_2.5 vertical placement requirement permitting
middle-scale sites to have samplers placed 2 to 15 meters above ground.
We recognize that significant PM_10-2.5 vertical
concentration gradients may exist due to re-entrainment of coarse
particles from the surfaces that typically surround monitoring sites,
such as adjacent streets, parking lots, and landscaped surfaces, and
such vertical gradients may introduce additional complexities in the
comparison of data from samplers at widely varying heights. The EPA
seeks to reduce this variability by restricting the vertical placement
of PM_10-2.5 samplers at middle-scale sites to the 2 to 7
meter requirement while recognizing that PM_10-2.5 monitors
that would have been at a higher level (e.g., 15 meters above ground)
would have likely measured lower ambient concentrations. The EPA
proposes that PM_10-2.5 sites with neighborhood, urban, and
regional scales have identical horizontal and vertical requirements
with PM_2.5 sites in consideration of the lesser gradients of
coarse particle ambient concentrations likely with sites representing
larger, more homogeneous conditions. The EPA acknowledges the
logistical complexity of having different vertical placement
requirements for middle-scale PM_10-2.5 and PM_2.5
sites, and solicits comment on all aspects of PM_10-2.5 probe
siting criteria.
---------------------------------------------------------------------------

\74\ The proposed network design criteria for
PM_10-2.5 would consider such data to be ineligible for
comparison to the NAAQS (see preamble section IV.E.2.B.ii).
---------------------------------------------------------------------------

Motor vehicle nitric oxide emissions are known to scavenge ozone,
and EPA recognizes the difficulty that monitoring agencies face when
trying to locate ozone air monitors in areas with multiple roadways and
streets. Based upon concern about the scavenging effects of motor
vehicle emissions on ozone, EPA proposes to increase the minimum
distances between ozone monitors and roadways in certain cases. Recent
field studies have shown significant effects of roadway emissions at
the distances currently listed in 40 CFR part 58, appendix E. Summary
information on this work is included in the docket for this proposal.
The EPA solicits comments on these proposed minimum distance requirements.

G. What Are the Proposed Data Reporting, Data Certification, and Sample
Retention Requirements?

1. Reduction of PM_2.5 Supplemental Data Reporting Requirements
The EPA is proposing to reduce the data reporting requirements
associated with PM_2.5 Federal Reference Methods (FRM) to
reduce the data management burden for monitoring agencies. The
following Air Quality System (AQS) reporting requirements are proposed
for elimination: Maximum and minimum ambient temperature, maximum and
minimum ambient pressure, flow rate coefficient of variation
(C_V), total sample volume, and elapsed sample time. AQS
reporting requirements are being retained for average ambient
temperature and average ambient pressure, and any applicable sampler flags.
Supplemental monitoring parameters were required to be reported to
AQS along with FRM mass concentration data to evaluate the performance
of the FRM as implemented through the newly developed sampler hardware
that was purchased by EPA for State and local agencies at the beginning
of the PM_2.5 monitoring program. Since that time, these
supplemental data, along with statistical analyses conducted on data
from collocated sampling and independent Performance Evaluation Program
(PEP) audits, have confirmed that the PM_2.5 FRM samplers are
producing data that meet or exceed the data quality objectives
developed for the method. As a result, the AQS reporting requirement
for many of the supplemental data parameters can be discontinued with
no adverse effect on PM_2.5 data quality. Monitoring agencies
would still be expected to retain supplemental data as required by their

[[Page 2749]]

approved Quality Assurance Program Plans (QAPP).
AQS reporting requirements for average ambient temperature and
average ambient pressure are being retained to provide data useful for
the comparison of mass concentrations based on actual and standard
operating conditions.
EPA is also proposing amendments to 40 CFR 58.16 (Data submittal)
to add the remaining PM_2.5 supplemental data reporting
requirements, which presently are only found in the FRM requirements
(Table L-1 of appendix L of part 50). This change will ensure that
supplemental data are reported for future PM_2.5 samplers
designated as a Class I or Class II Federal equivalent method under the
proposed amendments to 40 CFR part 53.
2. PM_2.5 Field Blank Data Reporting Requirement
We are proposing amendments to 40 CFR part 58.16 to require the
submission of data on PM_2.5 field blank mass in addition to
PM_2.5 filter-based measurements. Field blanks are filters
which are handled in the field as much as possible like actual filters
except that ambient air is not pumped through them, to help quantify
contamination and sampling artifacts. Only the data from field blanks
which States are already taking into the field and weighing in their
laboratories would be required to be reported under this proposal.
Quantifying field blank mass is important in order to complete the
material balance of the major components of sampled PM_2.5.
In addition, fluctuations of the field blank value are a useful quality
control metric which can be used to help evaluate the performance of
filter-based samplers and the quality of the sampled PM_2.5
values. However, there is currently limited information available to
EPA and other users of ambient air quality data on the magnitude and
trends in the blank concentrations from PM_2.5 Federal
reference method (FRM) samplers. These data are produced by State and
local air pollution agencies on a regular basis throughout the year,
but the data are not currently submitted to EPA. Having the data from
these field blanks available to the national monitoring community would
help EPA and other researchers better understand the relationship
between the mass of PM that is sampled and weighed on a regular PM
filter and the PM that is actually present in ambient air. The EPA
solicits comment on this additional PM_2.5 reporting requirement.
3. Data Certification Schedule
To enhance timely certification of each year's air quality data to
allow more timely reporting to the public and more timely regulatory
findings and actions based on those data, EPA proposes to speed up
official certification of air quality data by moving the annual data
certification date from July 1 to May 1 of each year. We believe it can
be met through more expeditious administrative clearance processes with
State/local agencies and will not require significant changes in
monitoring practices or equipment. The EPA solicits comments on this
proposed change to the certification schedule. The EPA solicits
comments identifying possible barriers to meeting the proposed
certification date and information on how agencies that presently
certify their data ahead of the current schedule accomplish this.
4. Particulate Matter Filter Archive
During the regulatory development process, various governmental
agencies and health scientists indicated that archiving particulate
matter filters for FRM and Federal equivalent methods would be useful
for later chemical speciation analyses, mass analyses, or other
analyses. Therefore, we propose to require archiving PM_2.5,
PM_10-2.5, and PM_10C filters for one year (the
current requirement is only for PM_2.5 filters). The EPA
solicits comment on this proposed requirement, specifically from those
agencies or scientists interested in using these filters.

V. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

Under Executive Order 12866 (58 FR 51735, October 4, 1993), EPA
must determine whether the regulatory action is ``significant'' and
therefore subject to review by the Office of Management and Budget
(OMB) and to the requirements of the Executive Order. The Executive
Order defines a ``significant regulatory action'' as one that is likely
to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more or
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;
(2) Create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
(4) Raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order.
Pursuant to the terms of Executive Order 12866, OMB has notified
EPA that it considers this a ``significant regulatory action'' within
the meaning of the Executive Order. EPA has submitted this action to
OMB for review. Changes made in response to OMB suggestions or
recommendations will be documented in the public record.

B. Paperwork Reduction Act

The information collection requirements in the proposed rule have
been submitted for approval to the Office of Management and Budget
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. The
Information Collection Request (ICR) documents prepared by EPA have
been assigned EPA ICR No. 0559.09 (2080-0005) for 40 CFR part 53 and
0940.19 (2060-0084) for 40 CFR part 58. The provisions in 40 CFR parts
53 and 58 have been previously approved by OMB under control numbers
2080-0005 (EPA ICR number 0559.07) and 2060-0084 (EPA ICR number
0940.17), respectively.
The monitoring, record keeping, and reporting requirements in 40
CFR parts 53 and 58 are specifically authorized by section 319 of the
CAA (42 U.S.C. 7619). All information submitted to EPA pursuant to the
monitoring, record keeping, and reporting requirements for which a
claim of confidentiality is made is safeguarded according to Agency
policies in 40 CFR part 2, subpart B.
The information collected under 40 CFR part 53 (e.g., test results,
monitoring records, instruction manual, and other associated
information) is needed to determine whether a candidate method intended
for use in determining attainment of the National Ambient Air Quality
Standards (NAAQS) in 40 CFR part 50 will meet the design, performance,
and/or comparability requirements for designation as a Federal
reference method (FRM) or Federal equivalent method (FEM). The proposed
amendments would add requirements for PM_10-2.5 FEM and FRM
determinations, Class II equivalent methods for PM_10-2.5 and
Class III equivalent methods for PM_2.5 and
PM_10-2.5; reduce certain monitoring and data collection
requirements; and streamline EPA administrative requirements.

[[Page 2750]]

The incremental annual reporting and record keeping burden for this
collection of information under 40 CFR part 53 (averaged over the first
3 years of this ICR) for one additional respondent per year is
estimated to increase by a total of 2,774 labor hours per year with an
increase in costs of $32,000/year. The capital/startup costs for test
equipment and qualifying tests are estimated at $3,832 with operation
and maintenance costs of $27,772.
The information collected and reported under 40 CFR part 58 is
needed to determine compliance with the NAAQS, to characterize air
quality and associated health and ecosystems impacts, to develop
emission control strategies, and to measure progress for the air
pollution program. The proposed amendments would revise the technical
requirements for certain types of sites, add provisions for monitoring
of PM_10-2.5, and reduce certain monitoring requirements for
criteria pollutants of than particulate matter and ozone. Monitoring
agencies would be required to submit annual monitoring network plans,
establish PM_2.5 sites by January 1, 2009, establish NCore
sites by January 1, 2011, conduct network assessments every 5 years,
and perform quality assurance activities.
The annual average reporting burden for the collection under 40 CFR
part 58 (averaged over the first 3 years of this ICR) for 168
respondents is estimated to decrease by a total of 336,650 labor hours
per year with a decrease in costs of $31,600,362. State, local, and
tribal entities are eligible for State assistance grants provided by
the Federal government under the CAA for monitors and related activities.
Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
An agency may not conduct or sponsor, and a person is not required
to respond to a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR parts 53 and 58 are listed in 40 CFR part 9.
To comment on the Agency's need for the information, the accuracy
of the provided burden estimates, and any suggested methods for
minimizing respondent burden, including the use of automated collection
techniques, EPA has established a public docket for the proposed
amendments, which includes the ICR for 40 CFR part 58, under Docket ID
number EPA-HQ-OAR-2004-0018. Submit any comments related to the ICR for
the proposed amendments to 40 CFR part 58 to EPA and OMB. See the
ADDRESSES section at the beginning of this notice for where to submit
comments to EPA. Send comments to OMB at the Office of Information and
Regulatory Affairs, Office of Management and Budget, 725 17th Street,
NW., Washington, DC 20503, Attention: Desk Office for EPA. Since OMB is
required to make a decision concerning the ICR between 30 and 60 days
after January 17, 2006, a comment to OMB is best assured of having its
full effect if OMB receives it by February 16, 2006. The final
amendments will respond to any OMB or public comments on the
information collection requirements for 40 CFR part 58 contained in
this proposal.

C. Regulatory Flexibility Act

The Regulatory Flexibility Act generally requires an agency to
prepare a regulatory flexibility analysis of any rule subject to notice
and comment rulemaking requirements under the Administrative Procedure
Act or any other statute unless the agency certifies that the rule will
not have a significant economic impact on a substantial number of small
entities. Small entities include small businesses, small not-for-profit
enterprises, and small governmental jurisdictions.
For the purposes of assessing the impacts of today's proposed
amendments on small entities, small entity is defined as: (1) A small
business as defined by the Small Business Administration; (2) a
government jurisdiction that is a government of a city, county, town,
school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise which is independently owned and operated and that is not
dominant in its field.
After considering the economic impacts of today's proposed
amendments on small entities, I certify that this action will not have
a significant economic impact on a substantial number of small
entities. The proposed requirements in 40 CFR part 53 for applications
for designation of equivalent methods do not address small entities.
The requirement to apply is voluntary and, the criteria for approval
are the minimum necessary to ensure that alternative methods meet the
same technical standards as the proposed federal method. The proposed
amendments to 40 CFR part 58 would reduce annual ambient air monitoring
costs for State and local agencies by approximately $8.5 million and
40,000 labor hours from present levels. State assistance grant funding
provided by the federal government can be used to defray the costs of
new or upgraded monitors for the NCore and PM_10-2.5
networks. We continue to be interested in the potential impacts of the
proposed amendments on small entities and welcome comments on issues
related to such impacts.

D. Unfunded Mandates Reform Act

Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and Tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and Tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including Tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory

[[Page 2751]]

proposals with significant Federal intergovernmental mandates, and
informing, educating, and advising small governments on compliance with
the regulatory requirements.
EPA has determined that the proposed rule does not contain a
Federal mandate that may result in expenditures of $100 million or more
for State, local, and Tribal governments, in the aggregate, or the
private sector in any one year. The proposed amendments to 40 CFR part
58 would reduce annual ambient air monitoring costs for State and local
agencies by approximately $8.5 million and 40,000 labor hours from
present levels. The costs for reconfiguring the existing ambient air
monitoring requirements to implement the NCore network would be borne
by the Federal government in the form of State assistance grants. Thus,
the proposed amendments are not subject to the requirements of sections
202 and 205 of the UMRA.
EPA has determined that the proposed rule contains no regulatory
requirements that might significantly or uniquely affect small
governments. Small governments that may be affected by the proposed
amendments are already meeting similar requirements under the existing
rules, the proposed amendments would substantially reduce the costs of
the existing rules, and the costs of changing the network design
requirements would be borne by the Federal government through State
assistance grants. Therefore, the proposed rule is not subject to the
requirements of section 203 of the UMRA.

E. Executive Order 13132: Federalism

Executive Order 13132 (64 FR 43255, August 10, 1999), requires EPA
to develop an accountable process to ensure ``meaningful and timely
input by State and local officials in the development of regulatory
policies that have federalism implications.'' ``Policies that have
federalism implications'' is defined in the Executive Order to include
regulations that have ``substantial direct effects on the States, on
the relationship between the national government and the States, or on
the distribution of power and responsibilities among the various levels
of government.''
This proposed rule does not have federalism implications. It will
not have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. States currently implement
similar ambient air monitoring requirements under 40 CFR parts 53 and
58, and the costs of implementing new requirements would be borne by
the Federal government through State assistance grants. Thus, Executive
Order 13132 does not apply to this proposed rule.
Although section 6 of the Executive Order does not apply to this
proposed rule, EPA did consult with representatives of State and local
governments early in the process of developing this proposed rule. In
2001, EPA organized a National Monitoring Steering Committee (NMSC) to
provide oversight and guidance in reviewing the existing air pollution
monitoring program and in developing a comprehensive national ambient
air monitoring strategy. The NMSC membership includes representatives
EPA, State and local agencies, State and Territorial Air Pollution
Program Administrators/Association of Local Air Pollution Control
Officials (STAPPA/ALAPCO), and tribal governments to reflect the
partnership between EPA and governmental agencies that collect and use
ambient air data. The NMSC formed workgroups to address quality
assurance, technology, and regulatory review of the draft ambient air
monitoring strategy (NAAMS). These workgroups met several times by
phone and at least once in a face-to-face workshop to detail out
recommendations for improving the ambient air monitoring program. A
record of the Steering Committee members, workgroup members, and
workshop are available on the web at:
http://www.epa.gov/ttn/amtic/monitor.html.
In the spirit of Executive Order 13132, and consistent with EPA
policy to promote communications between EPA and State and local
governments, EPA specifically solicits comments on the proposed rule
from State and local officials.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (59 FR 22951, November 9, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by tribal officials in the development of regulatory
policies that have tribal implications.'' This proposed rule does not
have tribal implications, as specified in Executive Order 13175. The
proposed amendments would not directly apply to Tribal governments.
However, a tribal government may elect to conduct ambient air
monitoring and report the data to AQS. Since it is possible that tribal
governments may choose to establish and operate NCore sites as part of
the national monitoring program, EPA consulted with tribal officials
early in the process of developing the proposed rule to permit them to
have meaningful and timely input into its development. As discussed in
section V.E of this preamble, tribal agencies were represented on both
the NMSSC and the workgroups that developed the NAAMS document and
proposed monitoring requirements. Tribal monitoring programs were
represented on both the Quality Assurance and Technology work groups.
Participation was also open to tribal monitoring programs on the
regulatory review workgroup. EPA specifically solicits additional
comment on the proposed amendments from tribal officials.

G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks

Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any
rule that: (1) Is determined to be ``economically significant'' as
defined under Executive Order 12866, and (2) concerns an environmental
health or safety risk that EPA has reason to believe may have a
disproportionate effect on children. If the regulatory action meets
both criteria, the Agency must evaluate the environmental health or
safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.
EPA interprets Executive Order 13045 as applying only to those
regulatory actions that are based on health or safety risks, such that
the analysis required under section 5-501 of the Order has the
potential to influence the regulation. The proposed rule is not subject
to Executive Order 13045 because it is based on technology and not on
health or safety risks.

H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use

The proposed rule is not a ``significant energy action'' as defined
in Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use'' (66 FR 28355,
May 22, 2001) because it is not likely to have a significant adverse
effect on the supply, distribution, or use of energy. No significant
change in the use of energy is expected because the total number of
monitors for ambient air

[[Page 2752]]

quality measurements will not increase above present levels. Further,
we have concluded that this proposed rule is not likely to have any
adverse energy effects.

I. National Technology Transfer Advancement Act

Section 12(d) of the National Technology Transfer Advancement Act
of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272 note)
directs EPA to use voluntary consensus standards in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. The NTTAA directs EPA to provide
Congress, through OMB, explanations when the Agency decides not to use
available and applicable voluntary consensus standards.
The proposed amendments involve environmental monitoring and
measurement. Ambient air concentrations of PM_2.5 are
currently measured by the Federal reference method in 40 CFR part 50,
appendix L (Reference Method for the Determination of Fine Particulate
as PM_2.5 in the Atmosphere) or by an a Federal reference or
equivalent method that meets the requirements in 40 CFR part 53.
Ambient air concentrations of PM_10-2.5 would be measured by
the proposed Federal reference method in 40 CFR part 50, appendix O
(Reference Method for the Determination of Coarse Particulate Matter as
PM_10-2.5 in the Atmosphere) published elsewhere in this
Federal Register or by a Federal reference or equivalent method that
meets the requirements in 40 CFR part 53. As discussed in section IV.B
of this preamble, the proposed Federal reference method for
PM_10-2.5 is similar to the existing methods for
PM_2.5 and PM₁₀.
In the preamble to the proposed NAAQS revisions published elsewhere
in this Federal Register, EPA requests comments on selection of an
alternative filter-based dichotomous sampler as the Federal reference
method for PM_10-2.5. Procedures are included in the proposed
monitoring amendments that would allow for approval of a candidate
equivalent method for PM_10-2.5 that is similar to the
proposed Federal reference method or to the alternative method proposed
for comment. Any method that meets the performance criteria for a
candidate equivalent method could be approved for use as a Federal
reference or equivalent method.
This approach is consistent with the Agency's Performance-Based
Measurement System (PBMS). The PBMS approach is intended to be more
flexible and cost effective for the regulated community; it is also
intended to encourage innovation in analytical technology and improved
data quality. EPA is not precluding the use of any method, whether it
constitutes a voluntary consensus standard or not, as long as it meets
the specified performance criteria. EPA welcomes comments on this
aspect of the proposed amendments and, specifically invites the public
to identify potentially applicable voluntary consensus standards and to
explain why such standards should be used in the regulation.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

Executive Order 12848 (58 FR 7629, February 11, 1994) requires that
each Federal agency make achieving environmental justice part of its
mission by identifying and addressing, as appropriate,
disproportionately high and adverse human health or environmental
effects of its programs, policies, and activities on minorities and
low-income populations. These requirements have been addressed to the
extent practicable in the Regulatory Impact Analysis for the proposed
revisions to the NAAQS for particulate matter.

List of Subjects in 40 CFR Parts 53 and 58

Environmental protection, Administrative practice and procedure,
Air pollution control, Intergovernmental relations, Reporting and
recordkeeping requirements.

Dated: December 20, 2005.
Stephen L. Johnson,
Administrator.
For the reasons set out in the preamble, title 40, chapter I, parts
53 and 58 of the Code of Federal Regulations are proposed to be amended
as follows:

PART 53--[AMENDED]

1. The authority citation for part 53 continues to read as follows:

Authority: Sec. 301(a) of the Clean Air Act (42 U.S.C. sec.
1857g(a)), as amended by sec. 15(c)(2) of Pub. L. 91-604, 84 Stat.
1713, unless otherwise noted.

Subpart A--[Amended]

2. Revise Sec. Sec. 53.1 through 53.5 to read as follows:

Sec. 53.1 Definitions.

Terms used but not defined in this part shall have the meaning
given them by the Act.
Act means the Clean Air Act (42 U.S.C. 1857-1857l), as amended.
Additive and multiplicative bias means the linear regression
intercept and slope of a linear plot fitted to corresponding candidate
and reference method mean measurement data pairs.
Administrator means the Administrator of the Environmental
Protection Agency (EPA) or his or her authorized representative.
Agency means the Environmental Protection Agency.
Applicant means a person or entity who submits an application for a
reference or equivalent method determination under Sec. 53.4, or a
person or entity who assumes the rights and obligations of an applicant
under Sec. 53.7. Applicant may include a manufacturer, distributor,
supplier, or vendor.
Automated method or analyzer means a method for measuring
concentrations of an ambient air pollutant in which sample collection
(if necessary), analysis, and measurement are performed automatically
by an instrument.
Candidate method means a method for measuring the concentration of
an air pollutant in the ambient air for which an application for a
reference method determination or an equivalent method determination is
submitted in accordance with Sec. 53.4, or a method tested at the
initiative of the Administrator in accordance with Sec. 53.7.
Class I equivalent method means an equivalent method for
PM_2.5 or PM_10-2.5 which is based on a sampler
that is very similar to the sampler specified for reference methods in
appendix L or appendix O (as applicable) of part 50 of this chapter,
with only minor deviations or modifications, as determined by EPA.
Class II equivalent method means an equivalent method for
PM_2.5 or PM_10-2.5 that utilizes a
PM_2.5 sampler or PM_10-2.5 sampler in which
integrated PM_2.5 samples or PM_10-2.5 samples are
obtained from the atmosphere by filtration and subjected to a
subsequent filter conditioning process followed by a gravimetric mass
determination, but which is not a Class I equivalent method because of
substantial deviations from the design specifications of the sampler
specified for reference methods in appendix L or appendix O (as

[[Page 2753]]

applicable) of part 50 of this chapter, as determined by EPA.
Class III equivalent method means an equivalent method for
PM_2.5 or PM_10-2.5 that is an analyzer capable of
providing PM_2.5 or PM_10-2.5 ambient air
measurements representative of one-hour or less integrated
PM_2.5 or PM_10-2.5 concentrations as well as 24-
hour measurements determined as, or equivalent to, the mean of 24 one-
hour consecutive measurements.
CO means carbon monoxideide.
Collocated means two or more air samplers, analyzers, or other
instruments that are operated simultaneously while located side by
side, separated by a distance that is large enough to preclude the air
sampled by any of the devices from being affected by any of the other
devices, but small enough so that all devices obtain identical or
uniform ambient air samples that are equally representative of the
general area in which the group of devices is located.
Equivalent method means a method for measuring the concentration of
an air pollutant in the ambient air that has been designated as an
equivalent method in accordance with this part; it does not include a
method for which an equivalent method designation has been canceled in
accordance with Sec. 53.11 or Sec. 53.16.
ISO 9001-registered facility means a manufacturing facility that is
either:
(1) An International Organization for Standardization (ISO) 9001-
registered manufacturing facility, registered to the ISO 9001 standard
(by the Registrar Accreditation Board (RAB) of the American Society for
Quality Control (ASQC) in the United States), with registration
maintained continuously.
(2) A facility that can be demonstrated, on the basis of
information submitted to the EPA, to be operated according to an EPA-
approved and periodically audited quality system which meets, to the
extent appropriate, the same general requirements as an ISO 9001-
registered facility for the design and manufacture of designated
reference and equivalent method samplers and monitors.
ISO-certified auditor means an auditor who is either certified by
the Registrar Accreditation Board (in the United States) as being
qualified to audit quality systems using the requirements of recognized
standards such as ISO 9001, or who, based on information submitted to
the EPA, meets the same general requirements as provided for ISO-
certified auditors.
Manual method means a method for measuring concentrations of an
ambient air pollutant in which sample collection, analysis, or
measurement, or some combination thereof, is performed manually. A
method for PM₁₀ or PM_2.5 which utilizes a sampler
that requires manual preparation, loading, and weighing of filter
samples is considered a manual method even though the sampler may be
capable of automatically collecting a series of sequential samples.
NO means nitrogen oxide.
NO₂ means nitrogen dioxide.
NO_X means oxides of nitrogen and is defined as the sum
of the concentrations of NO₂ and NO.
O₃ means ozone.
Operated simultaneously means that two or more collocated samplers
or analyzers are operated concurrently with no significant difference
in the start time, stop time, and duration of the sampling or
measurement period.
Pb means lead.
PM means PM₁₀, PM_10C, PM_2.5,
PM_10-2.5, or particulate matter of unspecified size range.
PM₁₀ means particulate matter as defined in section 1.1
of appendix J to part 50 of this chapter.
PM_2.5 means particulate matter as defined in section 1.1
of appendix L to part 50 of this chapter.
PM_10-2.5 means particulate matter as defined in section
1.1 of appendix O to part 50 of this chapter.
PM_10C means PM₁₀ particulate matter or
PM₁₀ measurements obtained with a PM_10C sampler.
PM_2.5 sampler means a device, associated with a manual
method for measuring PM_2.5, designed to collect
PM_2.5 from an ambient air sample, but lacking the ability to
automatically analyze or measure the collected sample to determine the
mass concentrations of PM_2.5 in the sampled air.
PM₁₀ sampler means a device, associated with a manual
method for measuring PM₁₀, designed to collect
PM₁₀ from an ambient air sample, but lacking the ability to
automatically analyze or measure the collected sample to determine the
mass concentrations of PM₁₀ in the sampled air.
PM_10C sampler means a PM₁₀ sampler that meets
the special requirements for a PM_10C sampler that is part of
a PM_10-2.5 reference method sampler, as specified in
appendix O to part 50 of this chapter, or a PM₁₀ sampler
that is part of a PM_10-2.5 sampler that has been designated
as an equivalent method for PM_10-2.5.
PM_10-2.5 sampler means a sampler, or a collocated pair
of samplers, associated with a manual method for measuring
PM_10-2.5 and designed to collect either PM_10-2.5
directly or PM_10C and PM_2.5 separately and
simultaneously from concurrent ambient air samples, but lacking the
ability to automatically analyze or measure the collected sample(s) to
determine the mass concentrations of PM_10-2.5 in the sampled air.
Reference method means a method of sampling and analyzing the
ambient air for an air pollutant that is specified as a reference
method in an appendix to part 50 of this chapter, or a method that has
been designated as a reference method in accordance with this part; it
does not include a method for which a reference method designation has
been canceled in accordance with Sec. 53.11 or Sec. 53.16.
Sequential samples for PM samplers means two or more PM samples for
sequential (but not necessarily contiguous) time periods that are
collected automatically by the same sampler without the need for
intervening operator service.
SO₂ means sulfur dioxide.
Test analyzer means an analyzer subjected to testing as part of a
candidate method in accordance with subparts B, C, D, E, or F of this
part, as applicable.
Test sampler means a PM₁₀ sampler, PM_2.5
sampler, or PM_10-2.5 sampler subjected to testing as part of
a candidate method in accordance with subparts C, D, E, or F of this part.
Ultimate purchaser means the first person or entity who purchases a
reference method or an equivalent method for purposes other than resale.

Sec. 53.2 General requirements for a reference method determination.

The following general requirements for a reference method
determination are summarized in table A-1 of this subpart.
(a) Manual methods. (1) Sulfur dioxide (SO₂) and lead.
For measuring SO₂ and lead, appendices A and G of part 50 of
this chapter specify unique manual reference methods for measuring
these pollutants. Except as provided in Sec. 53.16, other manual
methods for SO₂ and lead will not be considered for
reference method determinations under this part.
(2) PM₁₀. A reference method for measuring
PM₁₀ must be a manual method that meets all requirements
specified in appendix J of part 50 of this chapter and must include a
PM₁₀ sampler that has been shown in accordance with this
part to meet all requirements specified in this subpart A and subpart D
of this part.
(3) PM_2.5. A reference method for measuring
PM_2.5 must be a manual method that meets all requirements
specified in appendix L of part 50 of

[[Page 2754]]

this chapter and must include a PM_2.5 sampler that has been
shown in accordance with this part to meet the applicable requirements
specified in this subpart A and subpart E of this part. Further,
reference method samplers must be manufactured in an ISO 9001-registered
facility, as defined in Sec. 53.1 and as set forth in Sec. 53.51.
(4) PM_10-2.5. A reference method for measuring
PM_10-2.5 must be a manual method that meets all requirements
specified in appendix O of part 50 of this chapter and must include
PM_10C and PM_2.5 samplers that have been shown in
accordance with this part to meet the applicable requirements specified
in this subpart A and subpart E of this part. Further,
PM_10-2.5 reference method samplers must be manufactured in
an ISO 9001-registered facility, as defined in Sec. 53.1 and as set
forth in Sec. 53.51.
(b) Automated methods. An automated reference method for measuring
CO, O₃, or NO₂ must utilize the measurement
principle and calibration procedure specified in the appropriate
appendix to part 50 of this chapter and must have been shown in
accordance with this part to meet the requirements specified in this
subpart A and subpart B of this part.

Sec. 53.3 General requirements for an equivalent method determination.

(a) Manual methods. A manual equivalent method must have been shown
in accordance with this part to satisfy the applicable requirements
specified in this subpart A and subpart C of this part. In addition, a
PM sampler associated with a manual equivalent method for
PM₁₀, PM_2.5, or PM_10-2.5 must have
been shown in accordance with this part to satisfy the following
additional requirements, as applicable:
(1) PM₁₀. A PM₁₀ sampler associated with a
manual method for PM₁₀ must satisfy the requirements of
subpart D of this part.
(2) PM_2.5 Class I. A PM_2.5 Class I equivalent
method sampler must also satisfy all requirements of subpart E of this
part, which shall include appropriate demonstration that each and every
deviation or modification from the reference method sampler
specifications does not significantly alter the performance of the sampler.
(3) PM_2.5 Class II. (i) A PM_2.5 Class II
equivalent method sampler must also satisfy the applicable requirements
of subparts E and F of this part or the alternative requirements in
paragraph (a)(3)(ii) of this section.
(ii) In lieu of the applicable requirements specified for Class II
PM_2.5 methods in subparts C and F of this part, a Class II
PM_2.5 equivalent method sampler may alternatively meet the
applicable requirements in paragraphs (b)(3)(i) through (iii) of this
section and the testing, performance, and comparability requirements
specified for Class III equivalent methods for PM_2.5 in
subpart C of this part.
(4) PM_10-2.5 Class I. A PM_10-2.5 Class I
equivalent method sampler must also satisfy the applicable requirements
of subpart E of this part (there are no additional requirements
specifically for Class I PM_10-2.5 methods in subpart C of
this part).
(5) PM_10-2.5 Class II. (i) A PM_10-2.5 Class
II equivalent method must also satisfy the applicable requirements of
subpart C of this part and also the applicable requirements and
provisions of paragraphs (b)(3)(i) through (iii) of this section, or
the alternative requirements in paragraph (a)(5)(ii) of this section.
(ii) In lieu of the applicable requirements specified for Class II
PM_10-2.5 methods in subpart C of this part and in paragraph
(b)(3)(iii) of this section, a Class II PM_10-2.5 equivalent
method sampler may alternatively meet the applicable requirements in
paragraphs (b)(3)(i) and (ii) of this section and the testing,
performance, and comparability requirements specified for Class III
equivalent methods for PM_10-2.5 in subpart C of this part.
(6) ISO 9001. All designated equivalent methods for
PM_2.5 or PM_10-2.5 must be manufactured in an ISO
9001-registered facility, as defined in Sec. 53.1 and as set forth in
Sec. 53.51.
(b) Automated methods. All types of automated equivalent methods
must have been shown in accordance with this part to satisfy the
applicable requirements specified in this subpart A and subpart C of
this part. In addition, an automated equivalent method must have been
shown in accordance with this part to satisfy the following additional
requirements, as applicable:
(1) An automated equivalent method for pollutants other than PM
must be shown in accordance with this part to satisfy the applicable
requirements specified in subpart B of this part.
(2) An automated equivalent method for PM₁₀ must be
shown in accordance with this part to satisfy the applicable
requirements of subpart D of this part.
(3) A Class III automated equivalent method for PM_2.5 or
PM_10-2.5 must be shown in accordance with this part to
satisfy the requirements in paragraphs (b)(3)(i) through (iii) of this
section, as applicable.
(i) All pertinent requirements of 40 CFR part 50, appendix L,
including sampling height, range of operational conditions, ambient
temperature and pressure sensors, outdoor enclosure, electrical power
supply, control devices and operator interfaces, data output port,
operation/instruction manual, data output and reporting requirements,
and any other requirements that would be reasonably applicable to the
method, unless adequate (as determined by the Administrator) rationale
can be provided to support the contention that a particular requirement
does not or should not be applicable to the particular candidate method.
(ii) All pertinent tests and requirements of subpart E of this
part, such as instrument manufacturing quality control; final assembly
and inspection; manufacturer's audit checklists; leak checks; flow rate
accuracy, measurement accuracy, and flow rate cut-off; operation
following power interruptions; effect of variations in power line
voltage, ambient temperature and ambient pressure; and aerosol
transport; unless adequate (as determined by the Administrator)
rationale can be provided to support the contention that a particular
test or requirement does not or should not be applicable to the
particular candidate method.
(iii) Candidate methods shall be tested for and meet any
performance requirements, such as inlet aspiration, particle size
separation or selection characteristics, change in particle separation
or selection characteristics due to loading or other operational
conditions, or effects of surface exposure and particle volatility,
determined by the Administrator to be necessary based on the nature,
design, and specifics of the candidate method and the extent to which
it deviates from the design and performance characteristics of the
reference method. These performance requirements and the specific
test(s) for them will be determined by Administrator for each specific
candidate method or type of candidate method and may be similar to or
based on corresponding tests and requirements set forth in subpart F of
this part or may be special requirements and tests tailored by the
Administrator to the specific nature, design, and operational
characteristics of the candidate method. For example, a candidate
method with an inlet design deviating substantially from the design of
the reference method inlet would likely be subject to an inlet
aspiration test similar to that set forth in Sec. 53.63. Similarly, a
candidate method having an inertial fractionation system substantially
different from that of the reference method would likely be

[[Page 2755]]

subject to a static fractionation test and a loading test similar to
those set forth in Sec. Sec. 53.64 and 53.65, respectively. A
candidate method with more extensive or profound deviations from the
design and function of the reference method may be subject to other
tests, full wind-tunnel tests similar to those described in Sec.
53.62, or to special tests adapted or developed individually to
accommodate the specific type of measurement or operation of the
candidate method.
(4) All designated equivalent methods for PM_2.5 or
PM_10-2.5 must be manufactured in an ISO 9001-registered
facility, as defined in Sec. 53.1 and as set forth in Sec. 53.51.

Sec. 53.4 Applications for reference or equivalent method determinations.

(a) Applications for reference or equivalent method determinations
shall be submitted in duplicate to: Director, National Exposure
Research Laboratory, Reference and Equivalent Method Program (MD-D205-
03), U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina 27711 (Commercial delivery address: 4930 Old Page Road,
Durham, North Carolina 27703).
(b) Each application shall be signed by an authorized
representative of the applicant, shall be marked in accordance with
Sec. 53.15 (if applicable), and shall contain the following:
(1) A clear identification of the candidate method, which will
distinguish it from all other methods such that the method may be
referred to unambiguously. This identification must consist of a unique
series of descriptors such as title, identification number, analyte,
measurement principle, manufacturer, brand, model, etc., as necessary
to distinguish the method from all other methods or method variations,
both within and outside the applicant's organization.
(2) A detailed description of the candidate method, including but
not limited to the following: The measurement principle, manufacturer,
name, model number and other forms of identification, a list of the
significant components, schematic diagrams, design drawings, and a
detailed description of the apparatus and measurement procedures.
Drawings and descriptions pertaining to candidate methods or samplers
for PM_2.5 or PM_10-2.5 must meet all applicable
requirements in reference 1 of appendix A of this subpart, using
appropriate graphical, nomenclature, and mathematical conventions such
as those specified in references 3 and 4 of appendix A of this subpart.
(3) A copy of a comprehensive operation or instruction manual
providing a complete and detailed description of the operational,
maintenance, and calibration procedures prescribed for field use of the
candidate method and all instruments utilized as part of that method
(under Sec. 53.9(a)).
(i) As a minimum this manual shall include:
(A) Description of the method and associated instruments.
(B) Explanation of all indicators, information displays, and controls.
(C) Complete setup and installation instructions, including any
additional materials or supplies required.
(D) Details of all initial or startup checks or acceptance tests
and any auxiliary equipment required.
(E) Complete operational instructions.
(F) Calibration procedures and descriptions of required calibration
equipment and standards.
(G) Instructions for verification of correct or proper operation.
(H) Trouble-shooting guidance and suggested corrective actions for
abnormal operation.
(I) Required or recommended routine, periodic, and preventative
maintenance and maintenance schedules.
(J) Any calculations required to derive final concentration
measurements.
(K) Appropriate references to any applicable appendix of part 50 of
this chapter; reference 6 of appendix A of this subpart; and any other
pertinent guidelines.
(ii) The manual shall also include adequate warning of potential
safety hazards that may result from normal use and/or malfunction of
the method and a description of necessary safety precautions. (See
Sec. 53.9(b).) However, the previous requirement shall not be
interpreted to constitute or imply any warranty of safety of the method
by EPA. For samplers and automated methods, the manual shall include a
clear description of all procedures pertaining to installation,
operation, preventive maintenance, and troubleshooting and shall also
include parts identification diagrams. The manual may be used to
satisfy the requirements of paragraphs (b)(1) and (2) of this section
to the extent that it includes information necessary to meet those
requirements.
(4) A statement that the candidate method has been tested in
accordance with the procedures described in subparts B, C, D, E, and/or
F of this part, as applicable.
(5) Descriptions of test facilities and test configurations, test
data, records, calculations, and test results as specified in subparts
B, C, D, E, and/or F of this part, as applicable. Data must be
sufficiently detailed to meet appropriate principles described in part
B, sections 3.3.1 (paragraph 1) and 3.5.1 and part C, section 4.6 of
reference 2 of appendix A of this subpart; and in paragraphs 1 through
3 of section 4.8 (Records) of reference 5 of appendix A of this
subpart. Salient requirements from these references include the following:
(i) The applicant shall maintain and include records of all
relevant measuring equipment, including the make, type, and serial
number or other identification, and most recent calibration with
identification of the measurement standard or standards used and their
National Institute of Standards and Technology (NIST) traceability.
These records shall demonstrate the measurement capability of each item
of measuring equipment used for the application and include a
description and justification (if needed) of the measurement setup or
configuration in which it was used for the tests. The calibration
results shall be recorded and identified in sufficient detail so that
the traceability of all measurements can be determined and any
measurement could be reproduced under conditions close to the original
conditions, if necessary, to resolve any anomalies.
(ii) Test data shall be collected according to the standards of
good practice and by qualified personnel. Test anomalies or
irregularities shall be documented and explained or justified. The
impact and significance of the deviation on test results and
conclusions shall be determined. Data collected shall correspond
directly to the specified test requirement and be labeled and
identified clearly so that results can be verified and evaluated
against the test requirement. Calculations or data manipulations must
be explained in detail so that they can be verified.
(6) A statement that the method, analyzer, or sampler tested in
accordance with this part is representative of the candidate method
described in the application.
(c) For candidate automated methods and candidate manual methods
for PM₁₀, PM_2.5, and PM_10-2.5 the
application shall also contain the following:
(1) A detailed description of the quality system that will be
utilized, if the candidate method is designated as a reference or
equivalent method, to ensure that all analyzers or samplers offered for
sale under that designation will have essentially the same

[[Page 2756]]

performance characteristics as the analyzer(s) or samplers tested in
accordance with this part. In addition, the quality system requirements
for candidate methods for PM_2.5 and PM_10-2.5 must
be described in sufficient detail, based on the elements described in
section 4 of reference 1 (Quality System Requirements) of appendix A of
this subpart. Further clarification is provided in the following
sections of reference 2 of appendix A of this subpart: part A
(Management Systems), sections 2.2 (Quality System and Description),
2.3 (Personnel Qualification and Training), 2.4 (Procurement of Items
and Services), 2.5 (Documents and Records), and 2.7 (Planning); part B
(Collection and Evaluation of Environmental Data), sections 3.1
(Planning and Scoping), 3.2 (Design of Data Collection Operations), and
3.5 (Assessment and Verification of Data Usability); and part C
(Operation of Environmental Technology), sections 4.1 (Planning), 4.2
(Design of Systems), and 4.4 (Operation of Systems).
(2) A description of the durability characteristics of such
analyzers or samplers (see Sec. 53.9(c)). For methods for
PM_2.5 and PM_10-2.5 the warranty program must
ensure that the required specifications (see Table A-1 to this subpart)
will be met throughout the warranty period and that the applicant
accepts responsibility and liability for ensuring this conformance or
for resolving any nonconformities, including all necessary components
of the system, regardless of the original manufacturer. The warranty
program must be described in sufficient detail to meet appropriate
provisions of the ANSI/ASQC and ISO 9001 standards (references 1 and 2
in appendix A of this subpart) for controlling conformance and
resolving nonconformance, particularly sections 4.12, 4.13, and 4.14 of
reference 1 in appendix A of this subpart.
(i) Section 4.12 in reference 1 of appendix A of this subpart
requires the manufacturer to establish and maintain a system of
procedures for identifying and maintaining the identification of
inspection and test status throughout all phases of manufacturing to
ensure that only instruments that have passed the required inspections
and tests are released for sale.
(ii) Section 4.13 in reference 1 of appendix A of this subpart
requires documented procedures for control of nonconforming product,
including review and acceptable alternatives for disposition; section
4.14 in reference 1 of appendix A of this subpart requires documented
procedures for implementing corrective (4.14.2) and preventive (4.14.3)
action to eliminate the causes of actual or potential nonconformities.
In particular, section 4.14.3 requires that potential causes of
nonconformities be eliminated by using information such as service reports
and customer complaints to eliminate potential causes of nonconformities.
(d) For candidate reference or equivalent methods for
PM_2.5 and Class II or Class III equivalent methods for
PM_10-2.5, the applicant, if requested by EPA, shall provide
to EPA for test purposes one sampler or analyzer that is representative
of the sampler or analyzer associated with the candidate method. The
sampler or analyzer shall be shipped FOB destination to Director,
National Exposure Research Laboratory, Reference and Equivalent Method
Program (MD-D205-03), U.S. Environmental Protection Agency, 4930 Old
Page Road, Durham, North Carolina 27703, scheduled to arrive concurrent
with or within 30 days of the arrival of the other application
materials. This analyzer or sampler may be subjected to various tests
that EPA determines to be necessary or appropriate under Sec. 53.5(f),
and such tests may include special tests not described in this part. If
the instrument submitted under this paragraph malfunctions, becomes
inoperative, or fails to perform as represented in the application
before the necessary EPA testing is completed, the applicant shall be
afforded an opportunity to repair or replace the device at no cost to
EPA. Upon completion of EPA testing, the analyzer or sampler submitted
under this paragraph shall be repacked by EPA for return shipment to
the applicant, using the same packing materials used for shipping the
instrument to EPA unless alternative packing is provided by the
applicant. Arrangements for, and the cost of, return shipment shall be
the responsibility of the applicant. EPA does not warrant or assume any
liability for the condition of the analyzer or sampler upon return to
the applicant.

Sec. 53.5 Processing of applications.

After receiving an application for a reference or equivalent method
determination, the Administrator will, within 120 calendar days after
receipt of the application, take one or more of the following actions:
(a) Send notice to the applicant, in accordance with Sec. 53.8,
that the candidate method has been determined to be a reference or
equivalent method.
(b) Send notice to the applicant that the application has been
rejected, including a statement of reasons for rejection.
(c) Send notice to the applicant that additional information must
be submitted before a determination can be made and specify the
additional information that is needed (in such cases, the 120-day
period shall commence upon receipt of the additional information).
(d) Send notice to the applicant that additional test data must be
submitted and specify what tests are necessary and how the tests shall
be interpreted (in such cases, the 120-day period shall commence upon
receipt of the additional test data).
(e) Send notice to the applicant that the application has been
found to be substantially deficient or incomplete and cannot be
processed until additional information is submitted to complete the
application and specify the general areas of substantial deficiency.
(f) Send notice to the applicant that additional tests will be
conducted by the Administrator, specifying the nature of and reasons
for the additional tests and the estimated time required (in such
cases, the 120-day period shall commence 1 calendar day after the
additional tests have been completed).
2a. Revise Sec. Sec. 53.8 and 53.9 to read as follows:

Sec. 53.8 Designation of reference and equivalent methods.

(a) A candidate method determined by the Administrator to satisfy
the applicable requirements of this part shall be designated as a
reference method or equivalent method (as applicable) by and upon
publication of a notice of the designation in the Federal Register.
(b) Upon designation, a notice indicating that the method has been
designated as a reference method or an equivalent method shall be sent
to the applicant.
(c) The Administrator will maintain a current list of methods
designated as reference or equivalent methods in accordance with this
part and will send a copy of the list to any person or group upon
request. A copy of the list will be available for inspection or copying
at EPA Regional Offices and may be available via the Internet or other
sources.

Sec. 53.9 Conditions of designation.

Designation of a candidate method as a reference method or
equivalent method shall be conditioned to the applicant's compliance
with the following requirements. Failure to comply with any of the
requirements shall constitute a ground for

[[Page 2757]]

cancellation of the designation in accordance with Sec. 53.11.
(a) Any method offered for sale as a reference or equivalent method
shall be accompanied by a copy of the manual referred to in Sec.
53.4(b)(3) when delivered to any ultimate purchaser, and an electronic
copy of the manual suitable for incorporating into user specific
standard operating procedure documents shall be readily available to
any users.
(b) Any method offered for sale as a reference or equivalent method
shall generate no unreasonable hazard to operators or to the
environment during normal use or when malfunctioning.
(c) Any analyzer, PM₁₀ sampler, PM_2.5
sampler, or PM_10-2.5 sampler offered for sale as part of a
reference or equivalent method shall function within the limits of the
performance specifications referred to in Sec. 53.20(a), Sec.
53.30(a), Sec. 53.50, or Sec. 53.60, as applicable, for at least 1
year after delivery and acceptance when maintained and operated in
accordance with the manual referred to in Sec. 53.4(b)(3).
(d) Any analyzer, PM₁₀ sampler, PM_2.5
sampler, or PM_10-2.5 sampler offered for sale as a reference
or equivalent method shall bear a prominent, permanently affixed label
or sticker indicating that the analyzer or sampler has been designated
by EPA as a reference method or as an equivalent method (as applicable)
in accordance with this part and displaying any designated method
identification number that may be assigned by EPA.
(e) If an analyzer is offered for sale as a reference or equivalent
method and has one or more selectable ranges, the label or sticker
required by paragraph (d) of this section shall be placed in close
proximity to the range selector and shall indicate clearly which range
or ranges have been designated as parts of the reference or equivalent
method.
(f) An applicant who offers analyzers, PM₁₀ samplers,
PM_2.5 samplers, or PM_10-2.5 samplers for sale as
reference or equivalent methods shall maintain an accurate and current
list of the names and mailing addresses of all ultimate purchasers of
such analyzers or samplers. For a period of 7 years after publication
of the reference or equivalent method designation applicable to such an
analyzer or sampler, the applicant shall notify all ultimate purchasers
of the analyzer or sampler within 30 days if the designation has been
canceled in accordance with Sec. 53.11 or Sec. 53.16 or if adjustment
of the analyzer or sampler is necessary under Sec. 53.11(b).
(g) If an applicant modifies an analyzer, PM₁₀ sampler,
PM_2.5 sampler, or PM_10-2.5 sampler that has been
designated as a reference or equivalent method, the applicant shall not
sell the modified analyzer or sampler as a reference or equivalent
method nor attach a label or sticker to the modified analyzer or
sampler under paragraph (d) or (e) of this section until the applicant
has received notice under Sec. 53.14(c) that the existing designation
or a new designation will apply to the modified analyzer or sampler or
has applied for and received notice under Sec. 53.8(b) of a new
reference or equivalent method determination for the modified analyzer
or sampler.
(h) An applicant who has offered PM_2.5 or
PM_10-2.5 samplers or analyzers for sale as part of a
reference or equivalent method may continue to do so only so long as
the facility in which the samplers or analyzers are manufactured
continues to be an ISO 9001-registered facility, as set forth in
subpart E of this part. In the event that the ISO 9001 registration for
the facility is withdrawn, suspended, or otherwise becomes
inapplicable, either permanently or for some specified time interval,
such that the facility is no longer an ISO 9001-registered facility,
the applicant shall notify EPA within 30 days of the date the facility
becomes other than an ISO 9001-registered facility, and upon such
notification, EPA shall issue a preliminary finding and notification of
possible cancellation of the reference or equivalent method designation
under Sec. 53.11.
(i) An applicant who has offered PM_2.5 or
PM_10-2.5 samplers or analyzers for sale as part of a
reference or equivalent method may continue to do so only so long as
updates of the Product Manufacturing Checklist set forth in subpart E
of this part are submitted annually. In the event that an annual
Checklist update is not received by EPA within 12 months of the date of
the last such submitted Checklist or Checklist update, EPA shall notify
the applicant within 30 days that the Checklist update has not been
received and shall, within 30 days from the issuance of such
notification, issue a preliminary finding and notification of possible
cancellation of the reference or equivalent method designation under
Sec. 53.11.
Table A-1 to subpart A of part 53 is revised to read as follows:

Table A-1 to Subpart A of Part 53.--Summary of Applicable Requirements for Reference and Equivalent Methods for Air Monitoring of Criteria Pollutants
--------------------------------------------------------------------------------------------------------------------------------------------------------
Applicable subparts of part 53
Pollutant Ref. or equivalent Manual or automated Applicable part 50 ------------------------------------------------------
appendix A B C D E F
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO\2\............................ Reference........... Manual............. A.................. ...... ...... ...... ...... ...... .............
Equivalent.......... Manual............. ................... [bchec ...... [bchec ...... ...... .............
k]
k]
Automated.......... ................... [bchec [bchec [bchec ...... ...... .............
k]
k]
k]
CO............................... Reference........... Automated.......... C.................. [bchec [bchec ...... ...... ...... .............
k]
k]
Equivalent.......... Manual............. ................... [bchec ...... [bchec ...... ...... .............
k]
k]
Automated.......... ................... [bchec [bchec [bchec ...... ...... .............
k]
k]
k]
O3............................... Reference........... Automated.......... D.................. [bchec [bchec ...... ...... ...... .............
k]
k]
Equivalent.......... Manual............. ................... [bchec ...... [bchec ...... ...... .............
k]
k]
Automated.......... ................... [bchec [bchec [bchec ...... ...... .............
k]
k]
k]
NO2.............................. Reference........... Automated.......... F.................. [bchec [bchec ...... ...... ...... .............
k]
k]
Equivalent.......... Manual............. ................... [bchec ...... [bchec ...... ...... .............
k]
k]
Automated.......... ................... [bchec [bchec [bchec ...... ...... .............
k]
k]
k]
Pb............................... Reference........... Manual............. G.................. ...... ...... ...... ...... ...... .............
Equivalent.......... Manual............. ................... [bchec ...... [bchec ...... ...... .............
k]
k]
PM10............................. Reference........... Manual............. J.................. [bchec ...... ...... [bchec ...... .............
k]
k]
Equivalent.......... Manual............. ................... [bchec ...... [bchec [bchec ...... .............
k]
k]
k]
Automated.......... ................... [bchec ...... [bchec [bchec ...... .............
k]
k]
k]
PM2.5............................ Reference........... Manual............. L.................. [bchec ...... ...... ...... [bchec .............
k]
k]
Equivalent Class I.. Manual............. L.................. [bchec ...... [bchec ...... [bchec .............
k]
k]
k]
Equivalent Class II. Manual............. L\1\............... [bchec ...... \2\[bc ...... [bchec \1\
k]
heck]
k] \2\[bcheck]

[[Page 2758]]

Equivalent Class III Automated.......... L\1\............... [bchec ...... [bchec ...... \1\[bc \1\[bcheck]
k]
k]
heck]
PM10-2.5......................... Reference........... Manual............. O\2\............... [bchec ...... ...... ...... [bchec .............
k]
k]
Equivalent.......... ................... ................... ...... ...... ...... ...... ...... .............
Equivalent Class II. Manual............. O\2\............... [bchec ...... \2\[bc ...... \1\[bc \1\
k]
heck]
heck] \2\[bcheck]
Equivalent Class III Automated.......... L\1\, O\1\ \2\..... [bchec ...... [bchec ...... \1\[bc \1\[bcheck]
k]
k]
heck]
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Some requirements may apply, based on the nature of each particular candidate method, as determined by the Administrator.
\2\ Alternative Class III requirements may be substituted.

4. Paragraph (6) of appendix A to subpart A of part 53 is revised
to read as follows:

Appendix A to Subpart A of Part 53--References

* * * * *
(6) Quality Assurance Guidance Document 2.12. Monitoring
PM_2.5 in Ambient Air Using Designated Reference or Class I
Equivalent Methods. U.S. EPA, National Exposure Research Laboratory,
Research Triangle Park, NC, November 1998 or later edition. Currently
available at http://www.epa.gov/ttn/amtic/pmqainf.html.

Subpart C--[Amended]

5. Section 53.30 is revised to read as follows:

Sec. 53.30 General provisions.

(a) Determination of comparability. The test procedures prescribed
in this subpart shall be used to determine if a candidate method is
comparable to a reference method when both methods measure pollutant
concentrations in ambient air. Minor deviations in testing requirements
and acceptance requirements set forth in this subpart, in connection
with any documented extenuating circumstances, may be determined by the
Administrator to be acceptable, at the discretion of the Administrator.
(b) Selection of test sites. (1) Each test site shall be in an area
which can be shown to have at least moderate concentrations of various
pollutants. Each site shall be clearly identified and shall be
justified as an appropriate test site with suitable supporting evidence
such as a description of the surrounding area, characterization of the
sources and pollutants typical in the area, maps, population density
data, vehicular traffic data, emission inventories, pollutant
measurements from previous years, concurrent pollutant measurements,
meteorological data, and other information useful in supporting the
suitability of the site for the comparison test or tests.
(2) If approval of one or more proposed test sites is desired prior
to conducting the tests, a written request for approval of the test
site or sites must be submitted to the address given in Sec. 53.4. The
request should include information identifying the type of candidate
method and one or more specific proposed test sites along with a
justification for each proposed specific site as described in paragraph
(b)(1) of this section. The EPA will evaluate each proposed site and
approve the site, disapprove the site, or request more information
about the site. Any such pre-test approval of a test site by the EPA
shall indicate only that the site meets the applicable test site
requirements for the candidate method type; it shall not indicate,
suggest, or imply that test data obtained at the site will necessarily
meet any of the applicable data acceptance requirements. The
Administrator may exercise discretion in selecting a different site (or
sites) for any additional tests the Administrator decides to conduct.
(c) Test atmosphere. Ambient air sampled at an appropriate test
site or sites shall be used for these tests. Simultaneous concentration
measurements shall be made in each of the concentration ranges
specified in tables C-1, C-3, or C-4 of this subpart, as appropriate.
(d) Sampling or sample collection. All test concentration
measurements or samples shall be taken in such a way that both the
candidate method and the reference method obtain air samples that are
alike or as nearly identical as practical.
(e) Operation. Set-up and start-up of the test analyzer(s), test
sampler(s), and reference method analyzers or samplers shall be in
strict accordance with the applicable operation manual(s).
(f) Calibration. The reference method shall be calibrated according
to the appropriate appendix to part 50 of this chapter (if it is a
manual method) or according to the applicable operation manual(s) (if
it is an automated method). A candidate method (or portion thereof)
shall be calibrated according to the applicable operation manual(s), if
such calibration is a part of the method.
(g) Submission of test data and other information. All recorder
charts, calibration data, records, test results, procedural
descriptions and details, and other documentation obtained from (or
pertinent to) these tests shall be identified, dated, signed by the
analyst performing the test, and submitted. For candidate methods for
PM_2.5 and PM_10-2.5, all submitted information
must meet the requirements of the ANSI/ASQC E4 Standard, sections
3.3.1, paragraphs 1 and 2 (reference 1 of appendix A of this subpart).

Sec. 53.31 [Removed]

6. Section 53.31 is removed and reserved.
7. Section 53.32 is revised to read as follows:

Sec. 53.32 Test procedures for methods for SO₂, CO,
O₃, and NO₂.

(a) Comparability. Comparability is shown for SO₂, CO,
O₃, and NO₂ methods when the differences between:
(1) Measurements made by a candidate manual method or by a test
analyzer representative of a candidate automated method, and;
(2) Measurements made simultaneously by a reference method are less
than or equal to the values for maximum discrepancy specified in table
C-1 of this subpart.
(b) Test measurements. All test measurements are to be made at the
same test site. If necessary, the concentration of pollutant in the
sampled ambient air may be augmented with artificially generated
pollutant to facilitate measurements in the specified ranges, as
described under paragraph (f)(4) of this section.
(c) Requirements for measurements or samples. All test measurements
made or test samples collected by means of a

[[Page 2759]]

sample manifold as specified in paragraph (f)(4) of this section shall
be at a room temperature between 20[deg]
and 30[deg]C, and at a line
voltage between 105 and 125 volts. All methods shall be calibrated as
specified in Sec. 53.30(f) prior to initiation of the tests.
(d) Set-up and start-up. (1) Set-up and start-up of the test
analyzer, test sampler(s), and reference method shall be in strict
accordance with the applicable operation manual(s). If the test
analyzer does not have an integral strip chart or digital data
recorder, connect the analyzer output to a suitable strip chart or
digital data recorder. This recorder shall have a chart width of at
least 25 centimeters, a response time of 1 second or less, a deadband
of not more than 0.25 percent of full scale, and capability of either
reading measurements at least 5 percent below zero or offsetting the
zero by at least 5 percent. Digital data shall be recorded at
appropriate time intervals such that trend plots similar to a strip chart
recording may be constructed with a similar or suitable level of detail.
(2) Other data acquisition components may be used along with the
chart recorder during the conduct of these tests. Use of the chart
recorder is intended only to facilitate visual evaluation of data submitted.
(3) Allow adequate warmup or stabilization time as indicated in the
applicable operation manual(s) before beginning the tests.
(e) Range. (1) Except as provided in paragraph (e)(2) of this
section, each method shall be operated in the range specified for the
reference method in the appropriate appendix to part 50 of this chapter
(for manual reference methods), or specified in table B-1 of subpart B
of this part (for automated reference methods).
(2) For a candidate method having more than one selectable range,
one range must be that specified in table B-1 of subpart B of this
part, and a test analyzer representative of the method must pass the
tests required by this subpart while operated on that range. The tests
may be repeated for a broader range (i.e., one extending to higher
concentrations) than the one specified in table B-1 of subpart B of
this part, provided that the range does not extend to concentrations
more than two times the upper range limit specified in table B-1 of
subpart B of this part and that the test analyzer has passed the tests
required by subpart B of this part (if applicable) for the broader
range. If the tests required by this subpart are conducted or passed
only for the range specified in table B-1 of subpart B of this part,
any equivalent method determination with respect to the method will be
limited to that range. If the tests are passed for both the specified
range and a broader range (or ranges), any such determination will
include the broader range(s) as well as the specified range.
Appropriate test data shall be submitted for each range sought to be
included in such a determination.
(f) Operation of automated methods. (1) Once the test analyzer has
been set up and calibrated and tests started, manual adjustment or
normal periodic maintenance, as specified in the manual referred to in
Sec. 53.4(b)(3), is permitted only every 3 days. Automatic adjustments
which the test analyzer performs by itself are permitted at any time.
The submitted records shall show clearly when manual adjustments were
made and describe the operations performed.
(2) All test measurements shall be made with the same test
analyzer; use of multiple test analyzers is not permitted. The test
analyzer shall be operated continuously during the entire series of
test measurements.
(3) If a test analyzer should malfunction during any of these
tests, the entire set of measurements shall be repeated, and a detailed
explanation of the malfunction, remedial action taken, and whether
recalibration was necessary (along with all pertinent records and
charts) shall be submitted.
(4) Ambient air shall be sampled from a common intake and
distribution manifold designed to deliver homogenous air samples to
both methods. Precautions shall be taken in the design and construction
of this manifold to minimize the removal of particulate matter and
trace gases, and to insure that identical samples reach the two
methods. If necessary, the concentration of pollutant in the sampled
ambient air may be augmented with artificially generated pollutant.
However, at all times the air sample measured by the candidate and
reference methods under test shall consist of not less than 80 percent
ambient air by volume. Schematic drawings, physical illustrations,
descriptions, and complete details of the manifold system and the
augmentation system (if used) shall be submitted.
(g) Tests. (1) Conduct the first set of simultaneous measurements
with the candidate and reference methods:
(i) Table C-1 of this subpart specifies the type (1- or 24-hour)
and number of measurements to be made in each of the three test
concentration ranges.
(ii) The pollutant concentration must fall within the specified
range as measured by the reference method.
(iii) The measurements shall be made in the sequence specified in
table C-2 of this subpart, except for the 1-hour SO₂
measurements, which are all in the high range.
(2) For each pair of measurements, determine the difference
(discrepancy) between the candidate method measurement and reference
method measurement. A discrepancy which exceeds the discrepancy
specified in table C-1 of this subpart constitutes a failure. Figure C-
1 of this subpart contains a suggested format for reporting the test results.
(3) The results of the first set of measurements shall be
interpreted as follows:
(i) Zero failures: The candidate method passes the test for comparability.
(ii) Three or more failures: The candidate method fails the test
for comparability.
(iii) One or two failures: Conduct a second set of simultaneous
measurements as specified in table C-1 of this subpart. The results of
the combined total of first-set and second-set measurements shall be
interpreted as follows:
(A) One or two failures: The candidate method passes the test for
comparability.
(B) Three or more failures: The candidate method fails the test for
comparability.
(iv) For SO₂, the 1-hour and 24-hour measurements shall
be interpreted separately, and the candidate method must pass the tests
for both 1- and 24-hour measurements to pass the test for comparability.
(4) A 1-hour measurement consists of the integral of the
instantaneous concentration over a 60-minute continuous period divided
by the time period. Integration of the instantaneous concentration may
be performed by any appropriate means such as chemical, electronic,
mechanical, visual judgment, or by calculating the mean of not less
than 12 equally-spaced instantaneous readings. Appropriate allowances
or corrections shall be made in cases where significant errors could
occur due to characteristic lag time or rise/fall time differences
between the candidate and reference methods. Details of the means of
integration and any corrections shall be submitted.
(5) A 24-hour measurement consists of the integral of the
instantaneous concentration over a 24-hour continuous period divided by
the time period. This integration may be performed by any appropriate
means such as chemical, electronic, mechanical, or by calculating the mean

[[Page 2760]]

of twenty-four (24) sequential 1-hour measurements.
(6) For O₃ and CO, no more than six 1-hour measurements
shall be made per day. For SO₂, no more than four 1-hour
measurements or one 24-hour measurement shall be made per day. One-hour
measurements may be made concurrently with 24-hour measurements if
appropriate.
(7) For applicable methods, control or calibration checks may be
performed once per day without adjusting the test analyzer or method.
These checks may be used as a basis for a linear interpolation-type
correction to be applied to the measurements to correct for drift. If
such a correction is used, it shall be applied to all measurements made
with the method, and the correction procedure shall become a part of
the method.
8. Section 53.33 is revised to read as follows:

Sec. 53.33 Test procedure for methods for Pb.

(a) Comparability. Comparability is shown for Pb methods when the
differences between:
(1) Measurements made by a candidate method, and
(2) Measurements made by the reference method on simultaneously
collected Pb samples (or the same sample, if applicable), are less than
or equal to the value specified in table C-3 of this subpart.
(b) Test measurements. Test measurements may be made at any number
of test sites. Augmentation of pollutant concentrations is not
permitted, hence an appropriate test site or sites must be selected to
provide Pb concentrations in the specified range.
(c) Collocated samplers. The ambient air intake points of all the
candidate and reference method collocated samplers shall be positioned
at the same height above the ground level, and between 2 meters (1
meter for samplers with flow rates less than 200 liters per minute (L/
min)) and 4 meters apart. The samplers shall be oriented in a manner
that will minimize spatial and wind directional effects on sample
collection.
(d) Sample collection. Collect simultaneous 24-hour samples
(filters) of Pb at the test site or sites with both the reference and
candidate methods until at least 10 filter pairs have been obtained. A
candidate method which employs a sampler and sample collection
procedure that are identical to the sampler and sample collection
procedure specified in the reference method, but uses a different
analytical procedure, may be tested by analyzing common samples. The
common samples shall be collected according to the sample collection
procedure specified by the reference method and each shall be divided
for respective analysis in accordance with the analytical procedures of
the candidate method and the reference method.
(e) Audit samples. Three audit samples must be obtained from the
address given in Sec. 53.4(a). The audit samples are 3/4 x 8-inch
glass fiber strips containing known amounts of Pb at the following
nominal levels: 100 micrograms per strip ([mu]g/strip); 300 [mu]g/
strip; 750 [mu]g/strip. The true amount of Pb, in total [mu]g/strip,
will be provided with each audit sample.
(f) Filter analysis. (1) For both the reference method samples and
the audit samples, analyze each filter extract three times in
accordance with the reference method analytical procedure. The analysis
of replicates should not be performed sequentially, i.e., a single
sample should not be analyzed three times in sequence. Calculate the
indicated Pb concentrations for the reference method samples in
micrograms per cubic meter ([mu]g/m\3\) for each analysis of each
filter. Calculate the indicated total Pb amount for the audit samples
in [mu]g/strip for each analysis of each strip. Label these test
results as R_1A, R_1B, R_1C,
R_2A, R_2B, * * *, Q_1A, Q_1B,
Q_1C, * * * ., where R denotes results from the reference
method samples; Q denotes results from the audit samples; 1, 2, 3
indicate the filter number, and A, B, C indicate the first, second, and
third analysis of each filter, respectively.
(2) For the candidate method samples, analyze each sample filter or
filter extract three times and calculate, in accordance with the
candidate method, the indicated Pb concentration in [mu]g/m\3\ for each
analysis of each filter. Label these test results as C_1A,
C_1B, C_2C, . . ., where C denotes results from the
candidate method. For candidate methods which provide a direct
measurement of Pb concentrations without a separable procedure,
C_1A=C_1B=C_1C,
C_2A=C_2B=C_2C, etc.
(g) Average Pb concentration. For the reference method, calculate
the average Pb concentration for each filter by averaging the
concentrations calculated from the three analyses using equation 1 of
this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.005

where, i is the filter number.
(h) Accuracy. (1)(i) For the audit samples, calculate the average
Pb concentration for each strip by averaging the concentrations
calculated from the three analyses using equation 2 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.006

where, i is audit sample number.
(ii) Calculate the percent difference (D_q) between the
indicated Pb concentration for each audit sample and the true Pb
concentration (T_q) using equation 3 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.007

(2) If any difference value (D_qi) exceeds ±5
percent, the accuracy of the reference method analytical procedure is
out-of-control. Corrective action must be taken to determine the source
of the error(s) (e.g., calibration standard discrepancies, extraction
problems, etc.) and the reference method and audit sample
determinations must be repeated according to paragraph (f) of this
section, or the entire test procedure (starting with paragraph (d) of
this section) must be repeated.
(i) Acceptable filter pairs. Disregard all filter pairs for which
the Pb concentration, as determined in paragraph (g) of this section by
the average of the three reference method determinations, falls outside
the range of 0.5 to 4.0 [mu]g/m\3\. All remaining filter pairs must be
subjected to the tests for precision and comparability in paragraphs
(j) and (k) of this section. At least five filter pairs must be within
the 0.5 to 4.0 [mu]g/m\3\ range for the tests to be valid.
(j) Test for precision. (1) Calculate the precision (P) of the
analysis (in percent) for each filter and for each method, as the
maximum minus the minimum divided by the average of the three
concentration values, using equation 4 or equation 5 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.008

[[Page 2761]]
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.009

where, i indicates the filter number.
(2) If any reference method precision value (P_Ri)
exceeds 15 percent, the precision of the reference method analytical
procedure is out-of-control. Corrective action must be taken to
determine the source(s) of imprecision, and the reference method
determinations must be repeated according to paragraph (f) of this
section, or the entire test procedure (starting with paragraph (d) of
this section) must be repeated.
(3) If any candidate method precision value (P_Ci)
exceeds 15 percent, the candidate method fails the precision test.
(4) The candidate method passes this test if all precision values
(i.e., all P_Ri's and all P_Ci's) are less than 15
percent.
(k) Test for comparability. (1) For each filter or analytical
sample pair, calculate all nine possible percent differences (D)
between the reference and candidate methods, using all nine possible
combinations of the three determinations (A, B, and C) for each method
using equation 6 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.010

where, i is the filter number, and n numbers from 1 to 9 for the nine
possible difference combinations for the three determinations for each
method (j = A, B, C, candidate; k = A, B, C, reference).
(2) If none of the percent differences (D) exceeds ±20
percent, the candidate method passes the test for comparability.
(3) If one or more of the percent differences (D) exceed < plus-
minus>20 percent, the candidate method fails the test for comparability.
(4) The candidate method must pass both the precision test
(paragraph (j) of this section) and the comparability test (paragraph
(k) of this section) to qualify for designation as an equivalent method.
9. Section 53.34 is revised to read as follows:

Sec. 53.34 Test procedure for methods for PM₁₀ and Class I
methods for PM_2.5.

(a) Comparability. Comparability is shown for PM₁₀
methods and for Class I methods for PM_2.5 when the
relationship between:
(1) Measurements made by a candidate method, and
(2) Measurements made by a corresponding reference method on
simultaneously collected samples (or the same sample, if applicable) at
each of one or more test sites (as required) is such that the linear
regression parameters (slope, intercept, and correlation coefficient)
describing the relationship meet the requirements specified in table C-
4 of this subpart.
(b) Methods for PM10. Test measurements must be made, or derived
from particulate samples collected, at not less than two test sites,
each of which must be located in a geographical area characterized by
ambient particulate matter that is significantly different in nature
and composition from that at the other test site(s). Augmentation of
pollutant concentrations is not permitted, hence appropriate test sites
must be selected to provide the minimum number of test PM₁₀
concentrations in the ranges specified in table C-4 of this subpart.
The tests at the two sites may be conducted in different calendar
seasons, if appropriate, to provide PM₁₀ concentrations in
the specified ranges.
(c) PM10 methods employing the same sampling procedure as the
reference method but a different analytical method. Candidate methods
for PM₁₀ which employ a sampler and sample collection
procedure that are identical to the sampler and sample collection
procedure specified in the reference method, but use a different
analytical procedure, may be tested by analyzing common samples. The
common samples shall be collected according to the sample collection
procedure specified by the reference method and shall be analyzed in
accordance with the analytical procedures of both the candidate method
and the reference method.
(d) Methods for PM2.5. Augmentation of pollutant concentrations is
not permitted, hence appropriate test sites must be selected to provide
the minimum number of test measurement sets to meet the requirements
for PM_2.5 concentrations in the ranges specified in table C-
4 of this subpart. Only one test site is required, and the site need
only meet the PM_2.5 ambient concentration levels required by
table C-4 of this subpart. A total of 10 valid measurement sets is required.
(e) Collocated measurements. (1) Set up three reference method
samplers collocated with three candidate method samplers or analyzers
at each of the number of test sites specified in table C-4 of this subpart.
(2) The ambient air intake points of all the candidate and
reference method collocated samplers or analyzers shall be positioned
at the same height above the ground level, and between 2 meters (1
meter for samplers or analyzers with flow rates less than 200 L/min)
and 4 meters apart. The samplers shall be oriented in a manner that
will minimize spatial and wind directional effects on sample collection.
(3) At each site, obtain as many sets of simultaneous
PM₁₀ or PM_2.5 measurements as necessary (see
table C-4 of this subpart), each set consisting of three reference
method and three candidate method measurements, all obtained simultaneously.
(4) Candidate PM₁₀ method measurements shall be nominal
24-hour (±1 hour) integrated measurements or shall be
averaged to obtain the mean concentration for a nominal 24-hour period.
PM_2.5 measurements may be either nominal 24- or 48-hour
integrated measurements. All collocated measurements in a measurement
set must cover the same nominal 24- or 48-hour time period.
(5) For samplers, retrieve the samples promptly after sample
collection and analyze each sample according to the reference method or
candidate method, as appropriate, and determine the PM₁₀ or
PM_2.5 concentration in [mu]g/m3. If the conditions of
paragraph (c) of this section apply, collect sample sets only with the
three reference method samplers. Guidance for quality assurance
procedures for PM_2.5 methods is found in ``Quality Assurance
Document 2.12'' (reference (2) in appendix A to this subpart).
(f) Sequential samplers. For sequential samplers, the sampler shall
be configured for the maximum number of sequential samples and shall be
set for automatic collection of all samples sequentially such that the
test samples are collected equally, to the extent possible, among all
available sequential channels or utilizing the full available
sequential capability.
(g) Calculation of reference method averages and precisions. (1)
For each of the measurement sets, calculate the average PM₁₀
or PM_2.5 concentration obtained with the reference method
samplers, using equation 7 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.011

Where:

[[Page 2762]]

R = The concentration measurements from the reference methods;
i = The sampler number; and
j = The measurement set number.
(2) For each of the measurement sets, calculate the precision of
the reference method PM₁₀ or PM_2.5 measurements
as the standard deviation, PR_j, using equation 8 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.012

(3) For each measurement set, also calculate the precision of the
reference method PM₁₀ or PM_2.5 measurements as
the relative standard deviation, RP_Rj, in percent, using
equation 9 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.013

(h) Acceptability of measurement sets. Each measurement set is
acceptable and valid only if the three reference method measurements
and the three candidate method measurements are obtained and are valid,
R_j falls within the acceptable concentration range specified
in table C-4 of this subpart, and either PR_j or
RP_Rj is within the corresponding limit for reference method
precision specified in table C-4 of this subpart. For each site, table
C-4 of this subpart specifies the minimum number of measurement sets
required having R_j above and below specified concentrations
for 24- or 48-hour samples. Additional measurement sets shall be
obtained, as necessary, to provide the minimum number of acceptable
measurement sets for each category and the minimum total number of
acceptable measurement sets for each test site. If more than the
minimum number of measurement sets are collected that meet the
acceptability criteria, all such measurement sets shall be used to
demonstrate comparability.
(i) Candidate method average concentration measurement. For each of
the acceptable measurement sets, calculate the average PM₁₀
or PM_2.5 concentration measurements obtained with the
candidate method samplers, using equation 10 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.014

Where:

C = The concentration measurements from the candidate methods;
i = The measurement number in the set; and
j = The measurement set number.

(j) Test for comparability. (1) For each site, plot all of the
average PM₁₀ or PM_2.5 measurements obtained with
the candidate method (C_j) against the corresponding average
PM₁₀ or PM_2.5 measurements obtained with the
reference method (R_j). For each site, calculate and record
the linear regression slope and intercept, and the correlation coefficient.
(2) To pass the test for comparability, the slope, intercept, and
correlation coefficient calculated under paragraph (j)(1) of this
section must be within the limits specified in table C-4 of this
subpart for all test sites.
10. Section 53.35 is added to read as follows:

Sec. 53.35 Test procedure for Class II and Class III methods for
PM_2.5 and PM_10-2.5.

(a) Overview. Class II and Class III candidate equivalent methods
shall be tested for comparability of PM_2.5 or
PM_10-2.5 measurements to corresponding collocated
PM_2.5 or PM_10-2.5 reference method measurements
at each of multiple field sites, as required. Comparability is shown
for the candidate method when simultaneous collocated measurements made
by candidate and reference methods meet the comparability requirements
specified in this section Sec. 53.35 and in table C-4 of this subpart
at each of the required test sites.
(b) Test sites and seasons. (1) Test sites. Comparability testing
is required at each of the applicable test sites required by this
paragraph (b). Each test site must also meet the general test site
requirements specified in Sec. 53.30(b).
(i) PM2.5 Class II and Class III candidate methods. Test sites
should be chosen to provide representative chemical and meteorological
characteristics with respect to nitrates, sulfates, organic compounds,
and various levels of humidity, wind, and elevation. For Class III
methods, one test site shall be selected in each of the following
general locations. For Class II methods, two test sites, one eastern
site and one western site, shall be selected from these locations. Test
site A shall be in the Los Angeles basin area in a location that is
characterized by relatively high PM_2.5, nitrates, and semi-
volatile organic pollutants. Test site B shall be in a northeastern or
mid-Atlantic U.S. city that is seasonally characterized by high sulfate
concentrations, high relative humidity, and wintertime conditions. Test
site C shall be in a western U.S. city such as Denver, Salt Lake City,
or Albuquerque in a location that is in an area characterized by cold
weather, higher elevation, winds, and dust.
(ii) PM10-2.5 Class II and Class III candidate methods. Test sites
shall be chosen to provide modest to high levels of PM_10-2.5
representative of locations in proximity to urban sources of
PM_10-2.5 such as high-density traffic on paved roads,
industrial sources, and construction activities. For Class III methods,
one test site shall be selected in each of the following general
locations. At least one of the test sites shall have characteristic
wintertime temperatures of 0[deg]C or lower. For Class II methods, two
test sites, one eastern site and one western site, shall be selected
from these locations. Test site A shall be in the Los Angeles basin or
the California Central Valley area. Test site B shall be in a large
U.S. city east of the Mississippi River, having characteristically high
humidity levels. Test site C shall be in a western U.S. city
characterized by a high ratio of PM_10-2.5 to
PM_2.5, with exposure to rural windblown dust, such as Las
Vegas or Phoenix.
(2) Test seasons. (i) For PM_2.5 and PM_10-2.5
Class III candidate methods, test campaigns are required in both summer
and winter seasons at test sites A and B. A test campaign is required
only in the winter season at test site C. (A total of 5 test campaigns
is required.) The summer season shall be defined as the typically
warmest 3 or 4 months of the year at the site; the winter season shall
be defined as the typically coolest 3 or 4 months of the year at the site.
(ii) For Class II PM_2.5 and PM_10-2.5
candidate methods, only one test campaign is required at each site, at
any time of year (total of 2 test campaigns).
(3) Test concentrations. The test sites should be selected to
provide ambient concentrations within the concentration limits
specified in table C-4 of this subpart, and also to provide a wide
range of test concentrations. A narrow range of test concentrations may
result in a low concentration coefficient of variation statistic for
the test measurements, making the test for correlation coefficient more
difficult to pass (see paragraph (h) of this section, test for
comparison correlation).

[[Page 2763]]

(4) Pre-approval of test sites. The EPA recommends that the
applicant seek EPA approval of each proposed test site prior to
conducting test measurements at the site. To do so, the applicant
should submit a request for approval as described in Sec. 53.30(b)(2).
(c) Collocated measurements. (1) For each test campaign, three
reference method samplers and three candidate method samplers or
analyzers shall be installed and operated concurrently at each test
site within each required season (if applicable), as specified in
paragraph (b) of this section. All reference method samplers shall be
of single-filter design (not multi-filter, sequential sample design).
Each candidate method shall be setup and operated in accordance with
its associated manual referred to in Sec. 53.4(b)(3) and in accordance
with applicable guidance in ``Quality Assurance Document 2.12''
(reference (2) in appendix A to this subpart). All samplers or
analyzers shall be placed so that they sample or measure air
representative of the surrounding area (within one kilometer) and are
not unduly affected by adjacent buildings, air handling equipment,
industrial operations, traffic, or other local influences. The ambient
air inlet points of all samplers and analyzers shall be positioned at
the same height above the ground level and between 2 meters (1 meter
for instruments having sample inlet flow rates less than 200 L/min) and
4 meters apart.
(2) A minimum of 23 valid and acceptable measurement sets of
PM_2.5 or PM_10-2.5 24-hour (nominal) concurrent
concentration measurements shall be obtained during each test campaign
at each test site. To be considered acceptable for the test, each
measurement set shall consist of at least two valid reference method
measurements and at least two valid candidate method measurements, and
the PM_2.5 or PM_10-2.5 measured concentration, as
determined by the average of the reference method measurements, must
fall within the acceptable concentration range specified in table C-4
of this subpart. Each measurement set shall include all valid
measurements obtained. For each measurement set containing fewer than
three reference method measurements or fewer than three candidate
method measurements, an explanation and appropriate justification shall
be provided to account for the missing measurement or measurements.
(3) More than 23 valid measurement sets may be obtained during a
particular test campaign to provide a more advantageous range of
concentrations, more representative conditions, additional higher or
lower measurements, or to otherwise improve the comparison of the
methods. All valid data sets obtained during each test campaign shall
be submitted and shall be included in the analysis of the data.
(4) The integrated-sample reference method measurements shall be of
at least 22 hours and not more than 25 hours duration. Each reference
method sample shall be retrieved promptly after sample collection and
analyzed according to the reference method to determine the
PM_2.5 or PM_10-2.5 measured concentration in
[mu]g/m3. Guidance and quality assurance procedures
applicable to PM_2.5 or PM_10-2.5 reference methods
are found in ``Quality Assurance Document 2.12'' (reference (2) in
appendix A to this subpart).
(5) Candidate method measurements shall be timed or processed and
averaged as appropriate to determine an equivalent mean concentration
representative of the same time period as that of the concurrent
integrated-sample reference method measurements, such that all
measurements in a measurement set shall be representative of the same
time period. In addition, hourly average concentration measurements
shall be obtained from each of the Class III candidate method analyzers
for each valid measurement set and submitted as part of the application
records.
(6) In the following tests, all measurement sets obtained at a
particular test site, from both seasonal campaigns if applicable, shall
be combined and included in the test data analysis for the site. Data
obtained at different test sites shall be analyzed separately. All
measurements should be reported as normally obtained, and no
measurement values should be rounded or truncated prior to data
analysis. In particular, no negative measurement value, if otherwise
apparently valid, should be modified, adjusted, replaced, or eliminated
merely because its value is negative. Calculated mean concentrations or
calculated intermediate quantities should retain at least one order-of-
magnitude greater resolution than the input values. All measurement
data and calculations shall be recorded and submitted in accordance
with Sec. 53.30(g), including hourly test measurements obtained from
Class III candidate methods.
(d) Calculation of mean concentrations. (1) Reference method
outlier test. For each of the measurement sets for each test site,
check each reference method measurement to see if it might be an
anomalous value (outlier) as follows, where R_i,j is the
measurement of reference method sampler i on test day j. In the event
that one of the reference method measurements is missing or invalid due
to a specific, positively-identified physical cause (e.g., sampler
malfunction, operator error, accidental damage to the filter, etc.; see
paragraph (c)(2) of this section), then substitute zero for the missing
measurement, for the purposes of this outlier test only.
(i) Calculate the quantities 2 x R_{1, j}/(R_{1, j}
+ R_{2, j}) and 2 x R_{1, j}/(R_{1, j} +
R_{3, j}). If both quantities fall outside of the interval,
(0.93, 1.07), then R_{1, j} is an outlier.
(ii) Calculate the quantities 2 x R_{2, j}/
(R_{2, j} + R_{1, j}) and 2 x R_{2, j}/
(R_{2, j} + R_{3, j}). If both quantities fall outside
of the interval, (0.93, 1.07), then R_{2, j} is an outlier.
(iii) Calculate the quantities 2 x R_3,j/(R_3,j
+ R_1,j) and 2 x R_3,j/(R_3,j +
R_2,j). If both quantities fall outside of the interval,
(0.93, 1.07), then R_3,j is an outlier.
(iv) If this test indicates that one of the reference method
measurements in the measurement set is an outlier, the outlier
measurement shall be eliminated from the measurement set, and the other
two measurements considered valid. If the test indicates that more than
one reference method measurement in the measurement set is an outlier,
the entire measurement set (both reference and candidate method
measurements) shall be excluded from further data analysis for the
tests of this section.
(2) For each of the measurement sets for each test site, calculate
the mean concentration for the reference method measurements, using
equation 11 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.015

Where:
R_j = The mean concentration measured by the reference method
for the measurement set;
R_i,j = The measurement of reference method sampler i on test
day j; and
n =The number of valid reference method measurements in the measurement
set (normally 3).
(3) Any measurement set for which R_j does not fall in
the acceptable concentration range specified in table C-4 of this
subpart is not valid, and the entire measurement set (both reference
and candidate method measurements) must be eliminated from further data
analysis.

[[Page 2764]]

(4) For each of the valid measurement sets at each test site,
calculate the mean concentration for the candidate method measurements,
using equation 12 of this section. (The outlier test in paragraph
(d)(1) of this section shall not be applied to the candidate method
measurements.)
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.016

where:

C_j = The mean concentration measured by the candidate method
for the measurement set;
C_{i, j} = The measurement of candidate method analyzer i on
test day j; and
m = The number of valid candidate method measurements in the
measurement set (normally 3).

(e) Test for reference method precision. (1) For each of the
measurement sets for each site, calculate an estimate for the relative
precision of the reference method measurements, RP_j, using
equation 13 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.017

(2) For each site, calculate an estimate of reference method
relative precision for the site, RP, using the root mean square
calculation of equation 14 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.018

where, J is the total number of valid measurement sets for the site.
(3) Verify that the estimate for reference method relative
precision for the site, RP, is not greater than the value specified for
reference method precision in table C-4 of this subpart. A reference
method relative precision greater than the value specified in table C-4
of this subpart indicates that quality control for the reference method
is inadequate, and corrective measures must be implemented before
proceeding with the test.
(f) Test for candidate method precision. (1) For each of the
measurement sets, for each site, calculate an estimate for the relative
precision of the candidate method measurements, CP_j, using
equation 15 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.019

(2) For each site, calculate an estimate of candidate method
relative precision for the site, CP, using the root mean square
calculation of equation 16 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.020

where, J is the total number of valid measurement sets for the site.
(3) To pass the test for precision, the mean candidate method
relative precision at each site must not be greater than the value for
candidate method precision specified in table C-4 of this subpart.
(g) Test for additive and multiplicative bias (comparative slope
and intercept). (1) For each test site, calculate the mean
concentration measured by the reference method, R, using equation 17 of
this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.021

(2) For each test site, calculate the mean concentration measured
by the candidate method, C, using equation 18 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.022

(3) For each test site, calculate the linear regression slope and
intercept of the mean candidate method measurements (C_j)
against the mean reference method measurements (R_j), using
equations 19 and 20 of this section, respectively:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.023

[GRAPHIC]
[TIFF OMITTED]
TP17JA06.024

(4) To pass this test, at each test site:
(i) The slope must be in the interval specified for regression
slope in table C-4 of this subpart; and
(ii) The intercept must be in the interval specified for regression
intercept in table C-4 of this subpart.
(iii) The slope and intercept limits are illustrated in figures C-2
and C-3 of this subpart.
(h) Tests for comparison correlation. (1) For each test site,
calculate the (Pearson) correlation coefficient, r (not the coefficient
of determination, r \2\), using equation 21 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.025

(2) For each test site, calculate the concentration coefficient of
variation, CCV, using equation 22 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.026

(3) To pass the test, the correlation coefficient, r, for each test
site must not be less than the values, for various values of CCV,
specified for correlation in table C-4 of this subpart. These limits
are illustrated in figure C-4 of this subpart.
11. Tables C-1, C-2, C-3, and C-4 to subpart C are revised to read
as follows:

[[Page 2765]]

Table C-1 to Subpart C of Part 53.--Test Concentration Ranges, Number of Measurements Required, and Maximum
Discrepancy Specification
----------------------------------------------------------------------------------------------------------------
Simultaneous measurements required
------------------------------------ Maximum
Concentration range 1-hr 24-hr discrepancy
Pollutant parts per million ------------------------------------ specification,
First Second First Second parts per
set set set set million
----------------------------------------------------------------------------------------------------------------
Ozone............................... Low 0.06 to 0.10...... 5 6 ....... ....... 0.02
Med 0.15 to 0.25...... 5 6 ....... ....... .03
High 0.35 to 0.45..... 4 6 ....... ....... .04
Total................. 14 18 ....... ....... ..............
Carbon monoxide..................... Low 7 to 11........... 5 6 ....... ....... 1.5
Med 20 to 30.......... 5 6 ....... ....... 2.0
High 35 to 45......... 4 6 ....... ....... 3.0
Total................. 14 18 ....... ....... ..............
Sulfur dioxide...................... Low 0.02 to 0.05...... ....... ....... 3 3 0.02
Med 0.10 to 0.15...... ....... ....... 2 3 .03
High 0.30 to 0.50..... 7 8 2 2 .04
Total................. 7 8 7 8 ..............
Nitrogen dioxide.................... Low 0.02 to 0.08...... ....... ....... 3 3 0.02
Med 0.10 to 0.20...... ....... ....... 2 3 .03
High 0.25 to 0.35..... ....... ....... 2 2 .03
Total................. ....... ....... 7 8 ..............
----------------------------------------------------------------------------------------------------------------

Table C-2 to Subpart C of Part 53.--Sequence of Test Measurements
------------------------------------------------------------------------
Concentration range
Measurement ---------------------------------------
First set Second set
------------------------------------------------------------------------
1............................... Low............... Medium.
2............................... High.............. High.
3............................... Medium............ Low.
4............................... High.............. High.
5............................... Low............... Medium.
6............................... Medium............ Low.
7............................... Low............... Medium.
8............................... Medium............ Low.
9............................... High.............. High.
10.............................. Medium............ Low.
11.............................. High.............. Medium.
12.............................. Low............... High.
13.............................. Medium............ Medium.
14.............................. Low............... High.
15.............................. .................. Low.
16.............................. .................. Medium.
17.............................. .................. Low.
18.............................. .................. High.
------------------------------------------------------------------------

Table C-3 to Subpart C of Part 53.--Test Specifications for Pb Methods
------------------------------------------------------------------------
Concentration range, [mu]g/m\3\ 0.5-4.0
------------------------------------------------------------------------
Minimum number of 24-hr measurements....................... 5
Maximum analytical precision, percent...................... 15
Maximum analytical accuracy, percent....................... < plus-
minus>5
Maximum difference, percent of reference method............ < plus-
minus>20
------------------------------------------------------------------------

Table C-4 to Subpart C.--Test Specifications for PM10, PM2.5 and PM10-2.5 Candidate Equivalent Methods
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
PM2.5 PM10-2.5
Specification PM10 -----------------------------------------------------------------------------------------------------------------------------------
Class I Class II Class III Class II Class III
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Acceptable concentration range 15-300................... 3-200.................... 3-200.................... 3-200................... 3-200................... 3-200
(Rj), [mu]g/m\3\.
Minimum number of test sites..... 2........................ 1........................ 2........................ 3....................... 2....................... 3
Minimum number of candidate 3........................ 3........................ 3 \1\.................... 3 \1\................... 3 \1\................... 3 \1\
method samplers or analyzers per
site.
Number of reference method 3........................ 3........................ 3 \1\.................... 3 \1\................... 3 \1\................... 3 \1\
samplers per site.
Minimum number of acceptable
sample sets per site for PM10
methods:.
Rj < 60 [mu]g/m\3\............... 3
Rj > 60 [mu]g/m\3\............... 3
Total........................ 10
Minimum number of acceptable
sample sets per site for
PM2.5 and PM10-2.5 candidate
equivalent methods:.
Rj < 30 [mu]g/m\3\ for 24-hr or ......................... 3
Rj < 20 [mu]g/m\3\ for 48-hr
samples.

[[Page 2766]]

Rj > 30 [mu]g/m\3\ for 24-hr or ......................... 3
Rj > 20 [mu]g/m\3\ for 48-hr
samples.
Each season...................... ......................... 10....................... 23....................... 23...................... 23...................... 23
Total, each site............. ......................... 10....................... 23....................... 46 (23 for single season 23...................... 46
site). (23 for single season site)
Precision of replicate reference 5 [mu]g/m\3\ or 7%....... 2 [mu]g/m\3\ or 5%....... 10% \2\.................. 10% \2\................. 10% \2\................. 10% \2\
method measurements, PRj or
RPRj, respectively; RP for Class
II or III PM2.5 or PM10-2.5,
maximum.
Precision of PM2.5 or PM10-2.5 ......................... ......................... 10% \2\.................. 15% \2\................. 15% \2\................. 15% \2\
candidate method, CP, each site.
Slope of regression relationship. 1±0.1......... 1±0.05........ 1±0.10........ 1±0.10....... 1±0.10....... 1±0.12
Intercept of regression 0±5........... 0±1........... Between: 13.55-(15.05 x Between: 15.05-(17.32 x Between: 59.93-(70.50 x Between: 70.50-(82.93 x
relationship, [mu]g/m\3\. slope), but not less slope); and 15.05- slope), but not less slope); and 70.50-
than -1.5; and 16.56- (13.20 x slope). than -7.0; and 81.08- (61.16 x slope)
(15.05 x slope), but not (70.50 x slope), but
more than +1.5. not more than +7.0.
Correlation of reference method >=0.97................... >=0.97................... >=0.93 for CCV<=0.4; >=0.85+0.2xCCV for 0.4<=CCV<=0.5; >=0.95 for CCV>=0.5
and candidate method
measurements.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Some missing daily measurement values may be permitted; see test procedure.
\2\ Calculated as the root mean square over all measurement sets.

11. Figure C-1 to subpart C is revised to read as follows:
BILLING CODE 6560-50-U

[[Page 2767]]
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.072

13. Figures C-2, C-3, and C-4 are added to subpart C to read as follows:

[[Page 2768]]
[GRAPHIC]
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TP17JA06.001
[[Page 2769]]
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.002
[[Page 2770]]
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.003
BILLING CODE 6560-50-C
14. Appendix A to subpart C is amended by adding reference (2) to
read as follows:

Appendix A to Subpart C--References

* * * * *
(2) Quality Assurance Guidance Document 2.12. Monitoring
PM_2.5 in Ambient Air Using Designated Reference or Class I
Equivalent Methods. U.S. EPA, National Exposure Research Laboratory,
Research Triangle Park, NC, November 1998 or later edition. Currently
available at http://www.epa.gov/ttn/amtic/pmqainf.html.

Subpart E--Procedures for Testing Physical (Design) andPerformance
Characteristics of Reference Methods and Class I and Class II
Equivalent Methods for PM2.5 or PM10-2.5

15. The heading for subpart E is revised as set out above.
16. Section 53.50 is revised to read as follows:

Sec. 53.50 General provisions.

(a) A candidate method for PM_2.5 or PM_10-2.5
described in an application for a reference or equivalent method
determination submitted under Sec. 53.4 shall be determined by the EPA
to be a reference method or a Class I, II, or III equivalent method on
the basis of the definitions for such methods given in Sec. 53.1. This
subpart sets forth the specific tests that must be carried out and the
test results, evidence, documentation, and other materials that must be
provided to EPA to demonstrate that a PM_2.5 or
PM_10-2.5 sampler associated with a candidate reference
method or Class I or Class II equivalent method meets all design and
performance specifications set forth in appendix L or O, respectively,
of part 50 of this chapter as well as additional requirements specified
in this subpart E. Some or all of these tests may also be applicable to
a candidate Class III equivalent method or analyzer, as may be
determined under Sec. 53.3(b)(3).
(b) PM2.5 methods. (1) Reference method. A sampler associated with
a candidate reference method for PM_2.5 shall be subject to
the provisions, specifications, and test procedures prescribed in
Sec. Sec. 53.51 through 53.58.
(2) Class I method. A sampler associated with a candidate Class I
equivalent method for PM_2.5 shall be subject to the
provisions, specifications, and test procedures prescribed in all
sections of this subpart.
(3) Class II method. A sampler associated with a candidate Class II
equivalent method for PM_2.5 shall be subject to the
provisions, specifications, and test procedures prescribed in all
applicable sections of this subpart, as specified in subpart F of this
part or as specified in Sec. 53.3(a)(3).
(c) PM10-2.5 methods. (1) Reference method. A sampler associated
with a reference method for PM_10-2.5, as specified in
appendix O to part 50 of this chapter, shall be subject to the
requirements in this paragraph (c)(1).
(i) The PM_2.5 sampler of the PM_10-2.5 sampler
pair shall be verified to be either currently designated under this
part 53 as a reference method for PM_2.5, or shown to meet
all requirements for designation as a reference method for
PM_2.5, in accordance with this part 53.
(ii) The PM_10c sampler of the PM_10-2.5
sampler pair shall be verified to be of like manufacturer, design,
configuration, and fabrication to the PM_2.5 sampler of the
PM_10-2.5 sampler pair, except for replacement of the
particle size separator specified in

[[Page 2771]]

section 7.3.4 of appendix L to part 50 of this chapter with the
downtube extension as specified in Figure O-1 of appendix O to part 50
of this chapter.
(iii) For samplers that meet the provisions of paragraphs (c)(1)(i)
and (ii) of this section, the candidate PM_10-2.5 reference
method may be determined to be a reference method without further testing.
(2) Class I method. A sampler associated with a Class I candidate
equivalent method for PM_10-2.5 shall meet the requirements
in this paragraph (c)(2).
(i) The PM_2.5 sampler of the PM_10-2.5 sampler
pair shall be verified to be either currently designated under this
part 53 as a reference method or Class I equivalent method for
PM_2.5, or shown to meet all requirements for designation as
a reference method or Class I equivalent method for PM_2.5,
in accordance with this part 53.
(ii) The PM_10c sampler of the PM_10-2.5
sampler pair shall be verified to be of similar design to the
PM_10-2.5 sampler and to meet all requirements for
designation as a reference method or Class I equivalent method for
PM_2.5, in accordance with this part 53, except for
replacement of the particle size separator specified in section 7.3.4
of appendix L to part 50 of this chapter with the downtube extension as
specified in Figure O-1 of appendix O to part 50 of this chapter.
(iii) For samplers that meet the provisions of paragraphs (c)(2)(i)
and (ii) of this section, the candidate PM_10-2.5 method may
be determined to be a Class I equivalent method without further testing.
(3) Class II method. A sampler associated with a Class II candidate
equivalent method for PM_10-2.5 shall be subject to the
applicable requirements of this subpart E, as described in Sec. 53.3(a)(5).
(d) The provisions of Sec. 53.51 pertain to test results and
documentation required to demonstrate compliance of a candidate method
sampler with the design specifications set forth in 40 CFR part 50,
appendix L or O, as applicable. The test procedures prescribed in
Sec. Sec. 53.52 through 53.59 pertain to performance tests required to
demonstrate compliance of a candidate method sampler with the
performance specifications set forth in 40 CFR part 50, appendix L or
O, as applicable, as well as additional requirements specified in this
subpart E. These latter test procedures shall be used to test the
performance of candidate samplers against the performance
specifications and requirements specified in each procedure and
summarized in table E-1 of this subpart.
(e) Test procedures prescribed in Sec. 53.59 do not apply to
candidate reference method samplers. These procedures apply primarily
to candidate Class I or Class II equivalent method samplers for
PM_2.5 or PM_10-2.5 that have a sample air flow
path configuration upstream of the sample filter that is modified from
that specified for the reference method sampler, as set forth in 40 CFR
part 50, appendix L, Figures L-1 to L-29 or 40 CFR part 50 appendix O,
Figure O-1, if applicable, such as might be necessary to provide for
sequential sample capability. The additional tests determine the
adequacy of aerosol transport through any altered components or
supplemental devices that are used in a candidate sampler upstream of
the filter. In addition to the other test procedures in this subpart,
these test procedures shall be used to further test the performance of
such an equivalent method sampler against the performance
specifications given in the procedure and summarized in table E-1 of
this subpart.
(f) A 10-day operational field test of measurement precision is
required under Sec. 53.58 for both reference and Class I equivalent
method samplers for PM_2.5. This test requires collocated
operation of 3 candidate method samplers at a field test site. For
candidate equivalent method samplers, this test may be combined and
carried out concurrently with the test for comparability to the
reference method specified under Sec. 53.34, which requires collocated
operation of three reference method samplers and three candidate
equivalent method samplers.
(g) All tests and collection of test data shall be performed in
accordance with the requirements of reference 1, section 4.10.5 (ISO
9001) and reference 2, part B, section 3.3.1, paragraphs 1 and 2 and
Part C, section 4.6 (ANSI/ASQC E4) in appendix A of this subpart. All
test data and other documentation obtained specifically from or
pertinent to these tests shall be identified, dated, signed by the
analyst performing the test, and submitted to EPA in accordance with
subpart A of this part.
17. Section 53.51 is revised to read as follows:

Sec. 53.51 Demonstration of compliance with design specifications and
manufacturing and test requirements.

(a) Overview. (1) The subsequent paragraphs of this section specify
certain documentation that must be submitted and tests that are
required to demonstrate that samplers associated with a designated
reference or equivalent method for PM_2.5 or
PM_10-2.5 are properly manufactured to meet all applicable
design and performance specifications and have been properly tested
according to all applicable test requirements for such designation.
Documentation is required to show that instruments and components of a
PM_2.5 or PM_10-2.5 sampler are manufactured in an
ISO 9001-registered facility under a quality system that meets ISO-9001
requirements for manufacturing quality control and testing.
(2) In addition, specific tests are required by paragraph (d) of
this section to verify that critical features of reference method
samplers--the particle size separator and the surface finish of
surfaces specified to be anodized--meet the specifications of 40 CFR
part 50, appendix L or appendix O, as applicable. A checklist is
required to provide certification by an ISO-certified auditor that all
performance and other required tests have been properly and
appropriately conducted, based on a reasonable and appropriate sample
of the actual operations or their documented records. Following
designation of the method, another checklist is required initially to
provide an ISO-certified auditor's certification that the sampler
manufacturing process is being implemented under an adequate and
appropriate quality system.
(3) For the purposes of this section, the definitions of ISO 9001-
registered facility and ISO-certified auditor are found in Sec. 53.1.
An exception to the reliance by EPA on ISO-certified auditors is the
requirement for the submission of the operation or instruction manual
associated with the candidate method to EPA as part of the application.
This manual is required under Sec. 53.4(b)(3). The EPA has determined
that acceptable technical judgment for review of this manual may not be
assured by ISO-certified auditors, and approval of this manual will
therefore be performed by EPA.
(b) ISO registration of manufacturing facility. The applicant must
submit documentation verifying that the samplers identified and sold as
part of a designated PM_2.5 or PM_10-2.5 reference
or equivalent method will be manufactured in an ISO 9001-registered
facility and that the manufacturing facility is maintained in
compliance with all applicable ISO 9001 requirements (reference 1 in
appendix A of this subpart). The documentation shall indicate the date
of the original ISO 9001 registration for the facility and shall
include a copy of the most recent certification of continued ISO 9001
facility registration. If the manufacturer

[[Page 2772]]

does not wish to initiate or complete ISO 9001 registration for the
manufacturing facility, documentation must be included in the
application to EPA describing an alternative method to demonstrate that
the facility meets the same general requirements as required for
registration to ISO-9001. In this case, the applicant must provide
documentation in the application to demonstrate, by required ISO-
certified auditor's inspections, that a quality system is in place
which is adequate to document and monitor that the sampler system
components and final assembled samplers all conform to the design,
performance and other requirements specified in this part and in 40 CFR
part 50, appendix L.
(c) Sampler manufacturing quality control. The manufacturer must
ensure that all components used in the manufacture of PM_2.5
or PM_10-2.5 samplers to be sold as part of a reference or
equivalent method and that are specified by design in 40 CFR part 50,
appendix L or O (as applicable), are fabricated or manufactured exactly
as specified. If the manufacturer's quality records show that its
quality control (QC) and quality assurance (QA) system of standard
process control inspections (of a set number and frequency of testing
that is less than 100 percent) complies with the applicable QA
provisions of section 4 of reference 4 in appendix A of this subpart
and prevents nonconformances, 100 percent testing shall not be required
until that conclusion is disproved by customer return or other
independent manufacturer or customer test records. If problems are
uncovered, inspection to verify conformance to the drawings,
specifications, and tolerances shall be performed. Refer also to
paragraph (e) of this section-final assembly and inspection requirements.
(d) Specific tests and supporting documentation required to verify
conformance to critical component specifications. (1) Verification of
PM_2.5 (WINS) impactor jet diameter. For samplers utilizing
the WINS impactor particle size separator specified in paragraphs
7.3.4.1, 7.3.4.2, and 7.3.4.3 of appendix L to part 50 of this chapter,
the diameter of the jet of each impactor manufactured for a
PM_2.5 or PM_10-2.5 sampler under the impactor
design specifications set forth in 40 CFR part 50, appendix L, shall be
verified against the tolerance specified on the drawing, using
standard, NIST-traceable ZZ go/no go plug gages. This test shall be a
final check of the jet diameter following all fabrication operations,
and a record shall be kept of this final check. The manufacturer shall
submit evidence that this procedure is incorporated into the
manufacturing procedure, that the test is or will be routinely
implemented, and that an appropriate procedure is in place for the
disposition of units that fail this tolerance test.
(2) VSCC separator. For samplers utilizing the BGI
VSCCTM Very Sharp Cut Cyclone particle size separator
specified in paragraph 7.3.4.4 of appendix L to part 50 of this
chapter, the VSCC manufacturer shall identify the critical dimensions
and manufacturing tolerances for the device, develop appropriate test
procedures to verify that the critical dimensions and tolerances are
maintained during the manufacturing process, and carry out those
procedures on each VSCC manufactured to verify conformance of the
manufactured products. The manufacturer shall also maintain records of
these tests and their results and submit evidence that this procedure
is incorporated into the manufacturing procedure, that the test is or
will be routinely implemented, and that an appropriate procedure is in
place for the disposition of units that fail this tolerance test.
(3) Verification of surface finish. The anodization process used to
treat surfaces specified to be anodized shall be verified by testing
treated specimen surfaces for weight and corrosion resistance to ensure
that the coating obtained conforms to the coating specification. The
specimen surfaces shall be finished in accordance with military
standard specification 8625F, Type II, Class I (reference 4 in appendix
A of this subpart) in the same way the sampler surfaces are finished,
and tested, prior to sealing, as specified in section 4.5.2 of
reference 4 in appendix A of this subpart.
(e) Final assembly and inspection requirements. Each sampler shall
be tested after manufacture and before delivery to the final user. Each
manufacturer shall document its post-manufacturing test procedures. As
a minimum, each test shall consist of the following: Tests of the
overall integrity of the sampler, including leak tests; calibration or
verification of the calibration of the flow measurement device,
barometric pressure sensor, and temperature sensors; and operation of
the sampler with a filter in place over a period of at least 48 hours.
The results of each test shall be suitably documented and shall be
subject to review by an ISO-certified auditor.
(f) Manufacturer's audit checklists. Manufacturers shall require an
ISO-certified auditor to sign and date a statement indicating that the
auditor is aware of the appropriate manufacturing specifications
contained in 40 CFR part 50, appendix L or O (as applicable), and the
test or verification requirements in this subpart. Manufacturers shall
also require an ISO-certified auditor to complete the checklists, shown
in figures E-1 and E-2 of this subpart, which describe the
manufacturer's ability to meet the requirements of the standard for
both designation testing and product manufacture.
(1) Designation testing checklist. The completed statement and
checklist as shown in figure E-1 of this subpart shall be submitted
with the application for reference or equivalent method determination.
(2) Product manufacturing checklist. Manufacturers shall require an
ISO-certified auditor to complete a Product Manufacturing Checklist
(figure E-2 of this subpart), which evaluates the manufacturer on its
ability to meet the requirements of the standard in maintaining quality
control in the production of reference or equivalent devices. The
completed checklist shall be submitted with the application for
reference or equivalent method determination.
18. Section 53.52 is amended by revising paragraph (e)(1) to read
as follows:

Sec. 53.52 Leak check test.

* * * * *
(e) Test setup. (1) The test sampler shall be set up for testing as
described in the sampler's operation or instruction manual referred to
in Sec. 53.4(b)(3). The sampler shall be installed upright and set up
in its normal configuration for collecting PM samples, except that the
sample air inlet shall be removed and the flow rate measurement adaptor
shall be installed on the sampler's downtube.
* * * * *
19. Section 53.53 is amended by revising paragraph (e)(1) to read
as follows:

Sec. 53.53 Test for flow rate accuracy, regulation, measurement
accuracy, and cut-off.

* * * * *
(e) Test setup. (1) Setup of the sampler shall be as required in
this paragraph (e) and otherwise as described in the sampler's
operation or instruction manual referred to in Sec. 53.4(b)(3). The
sampler shall be installed upright and set up in its normal
configuration for collecting PM samples. A sample filter and (or) the
device for creating an additional 55 mm Hg pressure drop shall be
installed for the duration of these tests. The sampler's ambient
temperature, ambient pressure, and flow rate measurement

[[Page 2773]]

systems shall all be calibrated per the sampler's operation or
instruction manual within 7 days prior to this test.
* * * * *
20. Section 53.54 is amended by revising paragraph (d)(1) to read
as follows:

Sec. 53.54 Test for proper sampler operation following power interruptions.

* * * * *
(d) Test setup. (1) Setup of the sampler shall be performed as
required in this paragraph (d) and otherwise as described in the
sampler's operation or instruction manual referred to in Sec.
53.4(b)(3). The sampler shall be installed upright and set up in its
normal configuration for collecting PM samples. A sample filter and
(or) the device for creating an additional 55 mm Hg pressure drop shall
be installed for the duration of these tests. The sampler's ambient
temperature, ambient pressure, and flow measurement systems shall all
be calibrated per the sampler's operating manual within 7 days prior to
this test.
* * * * *
21. Section 53.55 is amended as follows:
a. By revising paragraphs (a)(1) introductory text and (a)(2).
b. By revising paragraph (e)(1).
c. By revising paragraph (g)(5)(i).

Sec. 53.55 Test for effect of variations in power line voltage and
ambient temperature.

(a) Overview. (1) This test procedure is a combined procedure to
test various performance parameters under variations in power line
voltage and ambient temperature. Tests shall be conducted in a
temperature controlled environment over four 6-hour time periods during
which reference temperature and flow rate measurements shall be made at
intervals not to exceed 5 minutes. Specific parameters to be evaluated
at line voltages of 105 and 125 volts and temperatures of -20 [deg]C
and +40 [deg]C are as follows:
* * * * *
(2) The performance parameters tested under this procedure, the
corresponding minimum performance specifications, and the applicable
test conditions are summarized in table E-1 of this subpart. Each
performance parameter tested, as described or determined in the test
procedure, must meet or exceed the associated performance specification
given. The candidate sampler must meet all specifications for the
associated PM_2.5 or PM_10-2.5 method (as
applicable) to pass this test procedure.
* * * * *
(e) * * * (1) Setup of the sampler shall be performed as required
in this paragraph (e) and otherwise as described in the sampler's
operation or instruction manual referred to in Sec. 53.4(b)(3). The
sampler shall be installed upright and set up in the temperature-
controlled chamber in its normal configuration for collecting PM
samples. A sample filter and (or) the device for creating an additional
55 mm Hg pressure drop shall be installed for the duration of these
tests. The sampler's ambient temperature, ambient pressure, and flow
measurement systems shall all be calibrated per the sampler's operating
manual within 7 days prior to this test.
* * * * *
(g) * * *
(5) * * * (i) Calculate the absolute value of the difference
between the mean ambient air temperature indicated by the test sampler
and the mean ambient (chamber) air temperature measured with the
ambient air temperature recorder as:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.027

Where:

T_ind,ave = mean ambient air temperature indicated by the
test sampler,[deg]C; and
T_ref,ave = mean ambient air temperature measured by the
reference temperature instrument,[deg]C.
* * * * *
22. Section 53.56 is amended by revising paragraphs (a)(2) and
(e)(1) to read as follows:

Sec. 53.56 Test for effect of variations in ambient pressure.

(a) * * *
(2) The performance parameters tested under this procedure, the
corresponding minimum performance specifications, and the applicable
test conditions are summarized in table E-1 of this subpart. Each
performance parameter tested, as described or determined in the test
procedure, must meet or exceed the associated performance specification
given. The candidate sampler must meet all specifications for the
associated PM_2.5 or PM_10-2.5 method (as
applicable) to pass this test procedure.
* * * * *
(e) * * * (1) Setup of the sampler shall be performed as required
in this paragraph (e) and otherwise as described in the sampler's
operation or instruction manual referred to in Sec. 53.4(b)(3). The
sampler shall be installed upright and set up in the pressure-
controlled chamber in its normal configuration for collecting PM
samples. A sample filter and (or) the device for creating an additional
55 mm Hg pressure drop shall be installed for the duration of these
tests. The sampler's ambient temperature, ambient pressure, and flow
measurement systems shall all be calibrated per the sampler's operating
manual within 7 days prior to this test.
* * * * *
23. Section 53.57 is amended by revising paragraphs (a), (b), and
(e)(1) to read as follows:

Sec. 53.57 Test for filter temperature control during sampling and
post-sampling periods.

(a) Overview. This test is intended to measure the candidate
sampler's ability to prevent excessive overheating of the PM sample
collection filter (or filters) under conditions of elevated solar
insolation. The test evaluates radiative effects on filter temperature
during a 4-hour period of active sampling as well as during a
subsequent 4-hour non-sampling time period prior to filter retrieval.
Tests shall be conducted in an environmental chamber which provides the
proper radiant wavelengths and energies to adequately simulate the
sun's radiant effects under clear conditions at sea level. For
additional guidance on conducting solar radiative tests under
controlled conditions, consult military standard specification 810-E
(reference 6 in appendix A of this subpart). The performance parameters
tested under this procedure, the corresponding minimum performance
specifications, and the applicable test conditions are summarized in
table E-1 of this subpart. Each performance parameter tested, as
described or determined in the test procedure, must meet or exceed the
associated performance specification to successfully pass this test.
(b) Technical definition. Filter temperature control during
sampling is the ability of a sampler to maintain the temperature of the
particulate matter sample filter within the specified deviation (5
[deg]C) from ambient temperature during any active sampling period.
Post-sampling temperature control is the ability of a sampler to
maintain the temperature of the particulate matter sample filter within
the specified deviation from ambient temperature during the period from
the end of active sample collection by the sampler until the filter is
retrieved from the sampler for laboratory analysis.
* * * * *

[[Page 2774]]

(e) * * * (1) Setup of the sampler shall be performed as required
in this paragraph (e) and otherwise as described in the sampler's
operation or instruction manual referred to in Sec. 53.4(b)(3). The
sampler shall be installed upright and set up in the solar radiation
environmental chamber in its normal configuration for collecting PM
samples (with the inlet installed). The sampler's ambient and filter
temperature measurement systems shall be calibrated per the sampler's
operating manual within 7 days prior to this test. A sample filter
shall be installed for the duration of this test. For sequential
samplers, a sample filter shall also be installed in each available
sequential channel or station intended for collection of a sequential
sample (or at least 5 additional filters for magazine-type sequential
samplers) as directed by the sampler's operation or instruction manual.
* * * * *
24. Section 53.58 is revised to read as follows:

Sec. 53.58 Operational field precision and blank test.

(a) Overview. This test is intended to determine the operational
precision of the candidate sampler during a minimum of 10 days of field
operation, using three collocated test samplers. Measurements of PM are
made at a test site with all of the samplers and then compared to
determine replicate precision. Candidate sequential samplers are also
subject to a test for possible deposition of particulate matter on
inactive filters during a period of storage in the sampler. This
procedure is applicable to both reference and equivalent methods. In
the case of equivalent methods, this test may be combined and conducted
concurrently with the comparability test for equivalent methods
(described in subpart C of this part), using three reference method
samplers collocated with three candidate equivalent method samplers and
meeting the applicable site and other requirements of subpart C of this
part.
(b) Technical definition. (1) Field precision is defined as the
standard deviation or relative standard deviation of a set of PM
measurements obtained concurrently with three or more collocated
samplers in actual ambient air field operation.
(2) Storage deposition is defined as the mass of material
inadvertently deposited on a sample filter that is stored in a
sequential sampler either prior to or subsequent to the active sample
collection period.
(c) Test site. Any outdoor test site having PM_2.5 (or
PM_10-2.5, as applicable) concentrations that are reasonably
uniform over the test area and that meet the minimum level requirement
of paragraph (g)(2) of this section is acceptable for this test.
(d) Required facilities and equipment. (1) An appropriate test site
and suitable electrical power to accommodate three test samplers are
required.
(2) Teflon sample filters, as specified in section 6 of 40 CFR part
50, appendix L, conditioned and preweighed as required by section 8 of
40 CFR part 50, appendix L, as needed for the test samples.
(e) Test setup. (1) Three identical test samplers shall be
installed at the test site in their normal configuration for collecting
PM samples in accordance with the instructions in the associated manual
referred to in Sec. 53.4(b)(3) and also in accordance with applicable
supplemental guidance provided in reference 3 in appendix A of this
subpart. The test samplers' inlet openings shall be located at the same
height above ground and between 2 (1 for samplers with flow rates less
than 200 L/min.) and 4 meters apart horizontally. The samplers shall be
arranged or oriented in a manner that will minimize the spatial and
wind directional effects on sample collection of one sampler on any
other sampler.
(2) Each test sampler shall be successfully leak checked,
calibrated, and set up for normal operation in accordance with the
instruction manual and with any applicable supplemental guidance
provided in reference 3 in appendix A of this subpart.
(f) Test procedure. (1) Install a conditioned, preweighed filter in
each test sampler and otherwise prepare each sampler for normal sample
collection. Set identical sample collection start and stop times for
each sampler. For sequential samplers, install a conditioned,
preweighed specified filter in each available channel or station
intended for automatic sequential sample filter collection (or at least
5 additional filters for magazine-type sequential samplers), as
directed by the sampler's operation or instruction manual. Since the
inactive sequential channels are used for the storage deposition part
of the test, they may not be used to collect the active PM test samples.
(2) Collect either a nominal 24-hour or 48-hour atmospheric PM
sample simultaneously with each of the three test samplers.
(3) Following sample collection, retrieve the collected sample from
each sampler. For sequential samplers, retrieve the additional stored
(blank, unsampled) filters after at least 5 days (120 hours) storage in
the sampler if the active samples are 24-hour samples, or after at
least 10 days (240 hours) if the active samples are 48-hour samples.
(4) Determine the measured PM mass concentration for each sample in
accordance with the applicable procedures prescribed for the candidate
method in appendix L or appendix O, as applicable, of part 50 of this
chapter, or in accordance with the associated manual referred to in
Sec. 53.4(b)(3) and supplemental guidance in reference 2 in appendix A
of this subpart. For sequential samplers, also similarly determine the
storage deposition as the net weight gain of each blank, unsampled
filter after the 5-day (or 10-day) period of storage in the sampler.
(5) Repeat this procedure to obtain a total of 10 sets of any
combination of (nominal) 24-hour or 48-hour PM measurements over 10
test periods. For sequential samplers, repeat the 5-day (or 10-day)
storage test of additional blank filters once for a total of two sets
of blank filters.
(g) Calculations. (1) Record the PM concentration for each test
sampler for each test period as C_{i, j,} where i is the
sampler number (i = 1,2,3) and j is the test period (j = 1,2, * * * 10).
(2)(i) For each test period, calculate and record the average of
the three measured PM concentrations as C_{ave, j} where j is
the test period using equation 26 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.028

(ii) If C_{ave, j} <3 [mu]g/m\3\ for any test period, data
from that test period are unacceptable, and an additional sample
collection set must be obtained to replace the unacceptable data.
(3)(i) Calculate and record the precision for each of the 10 test
periods, as the standard deviation, using equation 27 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.029

(ii) For each of the 10 test periods, also calculate and record the
precision as the relative standard deviation, in

[[Page 2775]]

percent, using equation 28 of this section:
[GRAPHIC]
[TIFF OMITTED]
TP17JA06.030

(h) Test results. (1) The candidate method passes the precision
test if either P_j or RP_j is less than or equal to
the corresponding specification in table E-1 of this subpart for all 10
test periods.
(2) The candidate sequential sampler passes the blank filter
storage deposition test if the average net storage deposition weight
gain of each set of blank filters (total of the net weight gain of each
blank filter divided by the number of filters in the set) from each
test sampler (six sets in all) is less than 50 [mu]g.
25. Section 53.59 is amended by revising paragraphs (a) and (b)(5)
to read as follows:

Sec. 53.59 Aerosol transport test for Class I equivalent method samplers.

(a) Overview. This test is intended to verify adequate aerosol
transport through any modified or air flow splitting components that
may be used in a Class I candidate equivalent method sampler such as
may be necessary to achieve sequential sampling capability. This test
is applicable to all Class I candidate samplers in which the aerosol
flow path (the flow path through which sample air passes upstream of
sample collection filter) differs significantly from that specified for
reference method samplers as specified in 40 CFR part 50, appendix L or
appendix O, as applicable. The test requirements and performance
specifications for this test are summarized in table E-1 of this subpart.
(b) * * *
(5) An added component is any physical part of the sampler which is
different in some way from that specified for a reference method
sampler in 40 CFR part 50, appendix L or appendix O, as applicable,
such as a device or means to allow or cause the aerosol to be routed to
one of several channels.
* * * * *
26. Table E-1 to subpart E is revised to read as follows:

Table E-1 to Subpart E.--Summary of Test Requirements for Reference and Class I Equivalent Methods for PM2.5 and
PM10-2.5
----------------------------------------------------------------------------------------------------------------
Performance Part 50, Appendix L
Subpart E procedure Performance test specification Test conditions reference
----------------------------------------------------------------------------------------------------------------
Sec. 53.52 Sample Sampler leak check External leakage: 80 Controlled leak flow Sec. 7.4.6.
leak check test facility mL/min, max rate of 80 mL/min
Internal leakage: 80
mL/min, max
Sec. 53.53 Base Sample flow rate 1. 67.67 < plus- (a) 6-hour normal Sec. 7.4.1, Sec.
flow rate test 1. Mean minus>5% L/min operational test 7.4.2, Sec. 7.4.3,
2. Regulation 2. 2%, max plus flow rate cut- Sec. 7.4.4, Sec.
3. Meas accuracy 3. 2%, max off test 7.4.5.
4. CV accuracy 4. 0.3% max (b) Norman conditions
5. Cut-off 5. Flow rate cut-off (c) Additional 55 mm
if flow rate Hg pressure drop to
deviates more than simulate loaded
10% from design flow filter
rate for >6030 seconds restrictions used
for cut-off test
Sec. 53.54 Power Sample flow rate: 1. 16.67 ± (a) 6-hour normal Sec. 7.4.1, Sec.
interruption test 1. Mean 5% L/min operational test 7.4.2, Sec. 7.4.3,
2. Regulation 2. 2%, max (b) Nominal Sec. 7.4.5, Sec.
3. Meas. accuracy 3. 2%, max conditions 7.4.12, Sec.
4. CV accuracy 4. 0.3 max (c) Additional 55 mm 7.4.13, Sec.
5. Occurrence time of 5. ±2 min Hg pressure drop to 7.4.15.4, Sec.
power interruptions if >60 seconds simulate loaded 7.4.15.5.
6. Elapsed sample 6. ±20 filter
time seconds (d) 6 power
7. Sample volume 7. ±2%, interruptions of
max various durations
Sec. 53.55 Sample flow rate 1. 16.67 ± (a) 6-hour normal Sec. 7.4.1, Sec.
Temperature and line 1. Mean 5% L/min operational test 7.4.2, Sec. 7.4.3,
voltage test 2. Regulation 2. 2%, max (b) Normal conditions Sec. 7.4.5, Sec.
3. Meas. accuracy 3. 2%, max (c) Additional 55 mm 7.4.8, Sec.
4. CV accuracy 4. 0.3 max Hg pressure drop to 7.4.15.1.
5. Temperature meas. 5 2 [deg]C simulate loaded
accuracy filter
6. Proper operation (d) Ambient
temperature at -20
and +40 [deg]C
(e) Line voltage: 105
Vac to 125 Vac
Sec. 53.56 Sample flow rate 1. 16.67 ± (a) 6-hour normal Sec. 7.4.1, Sec.
Barometric pressure 1. Mean 5% L/min operational test 7.4.2, Sec. 7.4.3,
effect test 2. Regulation 2. 2%, max (b) Normal conditions Sec. 7.4.5, Sec.
3. Meas. accuracy 3. 2%, max (c) Additional 55 mm 7.4.9.
4. CV accuracy 4. 0.3% max Hg pressure drop to
5. Pressure meas. 5. 10 mm Hg simulate loaded
accuracy filter
6. Proper operation (d) Barometer
pressure at 600 and
800 mm Hg

[[Page 2776]]

Sec. 53.57 Filter 1. Filter temp meas. 1. 2 [deg]C (a) 4-hour simulated Sec. 7.4.8, Sec.
temperature control accuracy 2. 2 [deg]C solar radiation, 7.4.10, Sec.
test 2. Ambient temp. 3. Not more than 5 sampling 7.4.11.
meas. accuracy [deg]C above ambient (b) 4-hour simulated
3. Filter temp. temp. for more than solar radiation, non-
control accuracy, 30 min. sampling
sampling and non- (c) Solar flux of
sampling 1000 ±50
W/m2
Sec. 53.58 Field 1 Measurement 1. Pj < 2 [mu]g/m3 or (a) 3 collocated Sec. 5.1, Sec.
precision test precision RPj < 5% samples at 1 site 7.4.5, Sec. 8, Sec.
2. Storage deposition 2. 50 [mu]g max. for at least 10 9, Sec. 10.
test for sequential average weight gain/ days;
samplers blank filter (b) PM2.5 conc. > 3
[mu]g/m3
(c) 25- or 48-hour
samples
(d) 5- or 10-day
storage period for
inactive stored
filters
----------------------
The Following Requirement Is Applicable to Class I Candidate Equivalent Methods Only
----------------------------------------------------------------------------------------------------------------
Sec. 53.59 Aerosol Aerosol transport 97%, min. for all Determine aerosol ....................
transport test channels transport through
any new or modified
components with
respect to the
reference method
sampler before the
filter for each
channel.
----------------------------------------------------------------------------------------------------------------

27. References (3) and (5) in appendix A to subpart E of part 53
are revised to read as follows:

Appendix A to Subpart E of Part 53--References

* * * * *
(3) Quality Assurance Guidance Document 2.12. Monitoring
PM_2.5 in Ambient Air Using Designated Reference or Class I
Equivalent Methods. U.S. EPA, National Exposure Research Laboratory,
Research Triangle Park, NC, November 1998 or later edition. Currently
available at http://www.epa.gov/ttn/amtic/pmgainf.html.

* * * * *
(5) Quality Assurance Handbook for Air Pollution Measurement
Systems, Volume IV: Meteorological Measurements. Revised March, 1995.
EPA-600/R-94-038d. Available from National Technical Information
Service, Springfield, VA 22161, (800-553-6847, http://www.ntis.gov).
NTIS number PB95-199782INZ.
* * * * *

Subpart F--[Amended]

28. Section 53.60 is amended by revising paragraphs (b), (c), (d)
introductory text, and (f)(4) to read as follows:

Sec. 53.60 General provisions.

* * * * *
(b) A candidate method described in an application for a reference
or equivalent method determination submitted under Sec. 53.4 shall be
determined by the EPA to be a Class II candidate equivalent method on
the basis of the definition of a Class II equivalent method given in
Sec. 53.1.
(c) Any sampler associated with a Class II candidate equivalent
method (Class II sampler) must meet all applicable requirements for
reference method samplers or Class I equivalent method samplers
specified in subpart E of this part, as appropriate. Except as provided
in Sec. 53.3(a)(3), a Class II PM_2.5 sampler must meet the
additional requirements as specified in paragraph (d) of this section.
(d) Except as provided in paragraphs (d)(1), (2), and (3) of this
section, all Class II samplers are subject to the additional tests and
performance requirements specified in Sec. 53.62 (full wind tunnel
test), Sec. 53.65 (loading test), and Sec. 53.66 (volatility test).
Alternative tests and performance requirements, as described in
paragraphs (d)(1), (2), and (3) of this section, are optionally
available for certain Class II samplers which meet the requirements for
reference method or Class I equivalent method samplers given in 40 CFR
part 50, appendix L, and in subpart E of this part, except for specific
deviations of the inlet, fractionator, or filter.
* * * * *
(f) * * *
(4) Loading test. The loading test is conducted to ensure that the
performance of a candidate sampler is not significantly affected by the
amount of particulate deposited on its interior surfaces between
periodic cleanings. The candidate sampler is artificially loaded by
sampling a test environment containing aerosolized, standard test dust.
The duration of the loading phase is dependent on both the time between
cleaning as specified by the candidate method and the aerosol mass
concentration in the test environment. After loading, the candidate's
performance must then be evaluated by Sec. 53.62 (full wind tunnel
evaluation), Sec. 53.63 (wind tunnel inlet aspiration test), or Sec.
53.64 (static fractionator test). If the results of the appropriate
test meet the criteria presented in table F-1 of this subpart, then the
candidate sampler passes the loading test under the condition that it
be cleaned at least as often as the cleaning frequency proposed by the
candidate method and that has been demonstrated to be acceptable by
this test.
* * * * *
29. The section heading of Sec. 53.61 is revised to read as follows.

Sec. 53.61 Test conditions.

* * * * *
30. Section 53.66 is amended by revising paragraph (e)(2)(iii) to
read as follows:

[[Page 2777]]

Sec. 53.66 Test procedure: Volatility test.

* * * * *
(e) * * *
(2) * * *
(iii) Operate the candidate and the reference samplers such that
they simultaneously sample the test aerosol for 2 hours for a candidate
sampler operating at 16.7 L/min or higher, or proportionately longer
for a candidate sampler operating at a lower flow rate.
* * * * *
31. Table F-1 to subpart F is revised to read as follows:

Table F-1 to Subpart F.--Performance Specifications for PM2.5 Class II
Equivalent Samplers
------------------------------------------------------------------------
Performance test Specifications Acceptance criteria
------------------------------------------------------------------------
Sec. 53.62 Full Wind Solid VOAG produced Dp50 = 2.5 [mu]m
Tunnel Evaluation. aerosol at 2 km/hr ± 0.2
and 24 km/hr. [mu]m
Numerical Analysis
Results: 95%
< =Rc< =105%.
Sec. 53.63 Wind Tunnel Liquid VOAG produced Relative Aspiration:
Inlet Aspiration Test. aerosol at 2 km/hr 95% < =A< =105%.
and 24 km/hr.
Sec. 53.64 Static Evaluation of the Dp50 = 2.5 [mu]m
Fractionator Test. fractionator under ± 0.2
static conditions. [mu]m
Numerical Analysis
Results: 95%
< =Rc< =105%.
Sec. 53.65 Loading Test... Loading of the clean Acceptance criteria
candidate under as specified in the
laboratory post-loading
conditions. evaluation test
(Sec. 53.62, Sec.
53.63, or Sec.
53.64).
Sec. 53.66 Volatility Test Polydisperse liquid Regression
aerosol producted Parameters
by air nebulization Slope = 1 < plus-
of A.C.S. reagent minus> 0.1,
grade glycerol, Intercept = 0 < plus-
99.5% minimum minus> 0.15 mg r >=
purity. 0.97.
------------------------------------------------------------------------

32. In Figure E-1 to subpart F, the figure number ``E-1'' is
revised to read ``F-1.''

PART 58--[AMENDED]

33. The authority citation for part 58 continues to read as follows:

Authority: 42 U.S.C. 7410, 7601(a), 7613, and 7619.

Subpart A--[Amended]

34. Sections 58.1, 58.2 and 58.3 are revised to read as follows:

Sec. 58.1 Definitions.

As used in this part, all terms not defined herein have the meaning
given them in the Act.
Act means the Clean Air Act as amended (42 U.S.C. 7401, et seq.)
Additive and multiplicative bias means the linear regression
intercept and slope of a linear plot fitted to corresponding candidate
and reference method mean measurement data pairs.
Administrator means the Administrator of the Environmental
Protection Agency (EPA) or his or her authorized representative.
Air Quality System (AQS) means EPA's computerized system for
storing and reporting of information relating to ambient air quality data.
Approved regional method (ARM) means a continuous PM_2.5
method that has been approved specifically within a State or local air
monitoring network for purposes of comparison to the NAAQS and to meet
other monitoring objectives.
AQCR means air quality control region.
CO means carbon monoxide.
Combined statistical area (CSA) is defined by the U.S. Office of
Management and Budget as a geographical area consisting of two or more
adjacent Core Based Statistical Areas (CBSA) with employment
interchange of at least 15 percent. Combination is automatic if the
employment interchange is 25 percent and determined by local opinion if
more than 15 but less than 25 percent
(http://www.census.gov/population/estimates/metro-city/List6.txt).
Community monitoring zone (CMZ) means an optional averaging area
with established, well defined boundaries, such as county or census
block, within an MPA that has relatively uniform concentrations of
annual PM_2.5 as defined by appendix N of part 50 of this
chapter. Two or more community-oriented SLAMS monitors within a CMZ
that meet certain requirements as set forth in appendix N of part 50 of
this chapter may be averaged for making comparisons to the annual
PM_2.5 NAAQS.
Core-based statistical area (CBSA) is defined by the U.S. Office of
Management and Budget, as a statistical geographic entity consisting of
the county or counties associated with at least one urbanized area/
urban cluster of at least 10,000 population, plus adjacent counties
having a high degree of social and economic integration. Metropolitan
and micropolitan statistical areas (MSA) are the two categories of CBSA
(metropolitan areas have populations greater than 50,000; and
micropolitan areas have populations between 10,000 and 50,000). In the
case of very large cities where two or more CBSA are combined, these
larger areas are referred to as combined statistical areas
(http://www.census.gov/population/estimates/metro-city/List1.txt).
Corrected concentration pertains to the result of an accuracy or
precision assessment test of an open path analyzer in which a high-
concentration test or audit standard gas contained in a short test cell
is inserted into the optical measurement beam of the instrument. When
the pollutant concentration measured by the analyzer in such a test
includes both the pollutant concentration in the test cell and the
concentration in the atmosphere, the atmospheric pollutant
concentration must be subtracted from the test measurement to obtain
the corrected concentration test result. The corrected concentration is
equal to the measured concentration minus the average of the
atmospheric pollutant concentrations measured (without the test cell)
immediately before and immediately after the test.
Design value means the calculated concentration according to the
applicable appendix of part 50 of this chapter for the highest site in
an attainment or nonattainment area.
EDO means environmental data operations.
Effective concentration pertains to testing an open path analyzer
with a high-concentration calibration or audit standard gas contained
in a short test cell inserted into the optical measurement beam of the
instrument. Effective concentration is the equivalent ambient-level
concentration that would produce the same spectral absorbance over the
actual atmospheric monitoring path length as produced by the high-
concentration gas in the short test cell. Quantitatively, effective
concentration is equal to the actual concentration of the gas standard
in the test cell multiplied by the ratio of the path length of the test
cell to the actual atmospheric monitoring path length.
Equivalent method means a method of sampling and analyzing the
ambient air

[[Page 2778]]

for an air pollutant that has been designated as an equivalent method
in accordance with part 53 of this chapter; it does not include a
method for which an equivalent method designation has been canceled in
accordance with Sec. 53.11 or Sec. 53.16 of this chapter.
HNO₃ means nitric acid.
Local agency means any local government agency, other than the
State agency, which is charged by a State with the responsibility for
carrying out a portion of the plan.
Meteorological measurements means measurements of wind speed, wind
direction, barometric pressure, temperature, relative humidity, solar
radiation, ultraviolet radiation, and precipitation.
Metropolitan Statistical Area (MSA) means a CBSA associated with at
least one urbanized area of at least 50,000 population. The central
county plus adjacent counties with a high degree of integration
comprise the area.
Monitor means an instrument, sampler, analyzer, or other device
that measures or assists in the measurement of atmospheric air
pollutants and which is acceptable for use in ambient air surveillance
under the applicable provisions of appendix C to this part.
Monitoring agency means a State or local agency responsible for
meeting the requirements of this part.
Monitoring organization means a State, local, or other monitoring
organization responsible for operating a monitoring site for which the
quality assurance regulations apply.
Monitoring path for an open path analyzer means the actual path in
space between two geographical locations over which the pollutant
concentration is measured and averaged.
Monitoring path length of an open path analyzer means the length of
the monitoring path in the atmosphere over which the average pollutant
concentration measurement (path-averaged concentration) is determined.
See also, optical measurement path length.
Monitoring planning area (MPA) means a contiguous geographic area
with established, well defined boundaries, such as a CBSA, county or
State, having a common area that is used for planning monitoring
locations for PM_2.5. An MPA may cross State boundaries, such
as the Philadelphia PA-NJ MSA, and be further subdivided into community
monitoring zones. MPA are generally oriented toward CBSA or CSA with
populations greater than 200,000, but for convenience, those portions
of a State that are not associated with CBSA can be considered as a
single MPA.
NATTS means the national air toxics trends stations. This network
provides hazardous air pollution ambient data.
NCore means the National Core multipollutant monitoring stations.
Monitors at these sites are required to measure particles
(PM_2.5, speciated PM_2.5, PM_10-2.5),
O₃, SO₂, CO, nitrogen oxides (NO/NO₂/
NO_Y), and basic meteorology.
Network means all stations of a given type or types.
NH3 means ammonia.
NO2 means nitrogen dioxide. NO means nitrogen oxide. NO_X
means oxides of nitrogen and is defined as the sum of the
concentrations of NO₂ and NO.
NOy means the sum of all total reactive nitrogen oxides, including
NO, NO₂, and other nitrogen oxides referred to as
NO_Z.
O3 means ozone.
Open path analyzer means an automated analytical method that
measures the average atmospheric pollutant concentration in situ along
one or more monitoring paths having a monitoring path length of 5
meters or more and that has been designated as a reference or
equivalent method under the provisions of part 53 of this chapter.
Optical measurement path length means the actual length of the
optical beam over which measurement of the pollutant is determined. The
path-integrated pollutant concentration measured by the analyzer is
divided by the optical measurement path length to determine the path-
averaged concentration. Generally, the optical measurement path length is:
(1) Equal to the monitoring path length for a (bistatic) system
having a transmitter and a receiver at opposite ends of the monitoring path;
(2) Equal to twice the monitoring path length for a (monostatic)
system having a transmitter and receiver at one end of the monitoring
path and a mirror or retroreflector at the other end; or
(3) Equal to some multiple of the monitoring path length for more
complex systems having multiple passes of the measurement beam through
the monitoring path.
PAMS means photochemical assessment monitoring stations.
Pb means lead.
Plan means a implementation plan approved or promulgated pursuant
to section 110 of the Act.
PM2.5 means particulate matter with an aerodynamic diameter less
than or equal to a nominal 2.5 micrometers as measured by a reference
method based on appendix L of part 50 of this chapter and designated in
accordance with part 53 of this chapter, by an equivalent method
designated in accordance with part 53 of this chapter, or by an
approved regional method designated in accordance with appendix C to
this part.
PM10 means particulate matter with an aerodynamic diameter less
than or equal to a nominal 10 micrometers as measured by a reference
method based on appendix J of part 50 of this chapter and designated in
accordance with part 53 of this chapter or by an equivalent method
designated in accordance with part 53 of this chapter.
PM10C means particulate matter with an aerodynamic diameter less
than or equal to a nominal 10 micrometers as measured by a reference
method based on appendix O of part 50 of this chapter and designated in
accordance with part 53 of this chapter or by an equivalent method
designated in accordance with part 53 of this chapter.
PM10-2.5 means particulate matter with an aerodynamic diameter less
than or equal to a nominal 10 micrometers and greater than a nominal
2.5 micrometers as measured by a reference method based on appendix O
to part 50 of this chapter and designated in accordance with part 53 of
this chapter or by an equivalent method designated in accordance with
part 53 of this chapter.
Point analyzer means an automated analytical method that measures
pollutant concentration in an ambient air sample extracted from the
atmosphere at a specific inlet probe point and that has been designated
as a reference or equivalent method in accordance with part 53 of this
chapter.
Population-oriented monitoring (or sites) means residential areas,
commercial areas, recreational areas, industrial areas where workers
from more than one company are located, and other areas where a
substantial number of people may spend a significant fraction of their day.
Primary quality assurance organization means a monitoring
organization or other organization that is responsible for a set of
stations that monitors the same pollutant and for which data quality
assessments can be pooled. Each criteria pollutant sampler/monitor at a
monitoring station in the SLAMS and SPM networks must be associated
with one, and only one, primary quality assurance organization.
Probe means the actual inlet where an air sample is extracted from
the atmosphere for delivery to a sampler or point analyzer for
pollutant analysis.
PSD station means any station operated for the purpose of
establishing the effect on air quality of the emissions from a proposed
source for purposes of prevention of significant deterioration as
required by Sec. 51.24(n) of this chapter.

[[Page 2779]]

Reference method means a method of sampling and analyzing the
ambient air for an air pollutant that is specified as a reference
method in an appendix to part 50 of this chapter, or a method that has
been designated as a reference method in accordance with this part; it
does not include a method for which a reference method designation has
been canceled in accordance with Sec. 53.11 or Sec. 53.16 of this chapter.
Regional Administrator means the Administrator of one of the ten
EPA Regional Offices or his or her authorized representative.
Reporting organization means an entity, such as a State, local, or
Tribal monitoring agency, that collects and reports air quality data to EPA.
Site means a geographic location. One or more stations may be at
the same site.
SLAMS means State or local air monitoring stations. The SLAMS make
up the ambient air quality monitoring sites that are primarily needed
for NAAQS comparisons, but may serve other data purposes. SLAMS exclude
special purpose monitor (SPM) stations and include NCore, PAMS, and all
other State or locally operated stations that have not been designated
as SPM stations.
SO2 means sulfur dioxide.
Special purpose monitor (SPM) station means a monitor included in
an agency's monitoring network that the agency has designated as a
special purpose monitor station in its monitoring network plan and in
the Air Quality System, and which the agency does not count when
showing compliance with the minimum requirements of this subpart for
the number and siting of monitors of various types.
State agency means the air pollution control agency primarily
responsible for development and implementation of a plan under the Act.
State speciation site means a supplemental PM_2.5
speciation station that is not part of the speciation trends network.
Station means a single monitor, or a group of monitors with a
shared objective, located at a particular site.
STN station means a PM_2.5 speciation station designated
to be part of the speciation trends network. This network provides
chemical species data of fine particulate.
Traceable means that a local standard has been compared and
certified, either directly or via not more than one intermediate
standard, to a National Institute of Standards and Technology (NIST)-
certified primary standard such as a NIST-traceable Reference Material
(NTRM) or a NIST-certified Gas Manufacturer's Internal Standard (GMIS).
TSP (total suspended particulates) means particulate matter as
measured by the method described in appendix B of part 50 of this chapter.
Urbanized area means an area with a minimum residential population
of at least 50,000 people and which generally includes core census
block groups or blocks that have a population density of at least 1,000
people per square mile and surrounding census blocks that have an
overall density of at least 500 people per square mile