[Federal Register Volume 71, Number 200 (Tuesday, October 17, 2006)]
[Rules and Regulations]
[Pages 61236-61328]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-8478]



[[Page 61235]]

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Part III





Environmental Protection Agency





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40 CFR Parts 53 and 58



Revisions to Ambient Air Monitoring Regulations; Final Rule

Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / 
Rules and Regulations

[[Page 61236]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 53 and 58

[EPA-HQ-OAR-2004-0018; FRL-8227-2]
RIN 2060-AJ25


Revisions to Ambient Air Monitoring Regulations

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The EPA is issuing final amendments to the ambient air 
monitoring requirements for criteria pollutants. The purpose of the 
amendments is to enhance ambient air quality monitoring to better serve 
current and future air quality management and research needs. The final 
amendments establish limited ambient air monitoring requirements for 
thoracic coarse particles in the size range of PM<INF>10-2.5</INF> to 
support continued research into these particles' distribution, sources, 
and health effects. The ambient air monitoring amendments also require 
each State to operate one to three monitoring stations that take an 
integrated, multipollutant approach to ambient air monitoring. In 
addition, the final amendments modify the general monitoring network 
design requirements for minimum numbers of ambient air monitors to 
focus on populated areas with air quality problems and to reduce 
significantly the requirements for criteria pollutant monitors that 
have measured ambient air concentrations well below the applicable 
National Ambient Air Quality Standards. These amendments also revise 
certain provisions regarding monitoring network descriptions and 
periodic assessments, quality assurance, and data certifications. A 
number of the amendments relate specifically to PM<INF>2.5</INF>, 
revising the requirements for reference and equivalent method 
determinations (including specifications and test procedures) for fine 
particle monitors.

DATES: This final rule is effective on December 18, 2006.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-HQ-OAR-2004-0018. 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., confidential 
business information 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.


    Note: The EPA Docket Center suffered damage due to flooding 
during the last week of June 2006. The Docket Center is continuing 
to operate. However, during the cleanup, there will be temporary 
changes to Docket Center telephone numbers, addresses, and hours of 
operation for people who wish to visit the Public Reading Room to 
view documents. Consult EPA's Federal Register notice at 71 FR 38147 
(July 5, 2006) or the EPA Web site at http://www.epa.gov/epahome/dockets.htm for current information on docket status, locations, and 
telephone numbers.


FOR FURTHER INFORMATION CONTACT: For general questions concerning the 
final amendments, please contact Mr. Lewis Weinstock, U.S. EPA, Office 
of Air Quality Planning and Standards, Air Quality Assessment Division, 
Ambient Air Monitoring Group (C304-06), Research Triangle Park, North 
Carolina 27711; telephone number: (919) 541-3661; fax number: (919) 
541-1903; e-mail address: <a href="/cdn-cgi/l/email-protection#fa8d9f9394898e959991d4969f8d9389ba9f8a9bd49d958c"><span class="__cf_email__" data-cfemail="a6d1c3cfc8d5d2c9c5cd88cac3d1cfd5e6c3d6c788c1c9d0">[email protected]</span></a>. For technical 
questions, please contact Mr. Tim Hanley, U.S. EPA, Office of Air 
Quality Planning and Standards, Air Quality Assessment Division, 
Ambient Air Monitoring Group (C304-06), Research Triangle Park, North 
Carolina 27711; telephone number: (919) 541-4417; fax number: (919) 
541-1903; e-mail address: <a href="/cdn-cgi/l/email-protection#88e0e9e6e4edf1a6fce1e5c8edf8e9a6efe7fe"><span class="__cf_email__" data-cfemail="8ae2ebe4e6eff3a4fee3e7caeffaeba4ede5fc">[email protected]</span></a>.

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                     NAICS code \1\            Examples of regulated entities
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Industry.....................................    334513, 541380  Manufacturer, supplier, 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.
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/territorial/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 or for an approved
                                                                  regional method approved under 40 CFR part 58
                                                                  appendix C. 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. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in the table could also be regulated. To determine whether 
your facility or Federal, State, local, or territorial agency is 
regulated by this action, you should carefully examine the requirements 
for reference or equivalent method determinations in 40 CFR part 53, 
subpart A (General

[[Page 61237]]

Provisions) and the applicability criteria in 40 CFR 51.1 of EPA's 
requirements for State implementation plans. If you have questions 
regarding the applicability of this action to a particular entity, 
consult the person listed in the preceding FOR FURTHER INFORMATION 
CONTACT section.

B. Where can I obtain a copy of this action?

    In addition to being available in the docket, an electronic copy of 
this final action will also be available on the Worldwide Web (WWW) 
through the Technology Transfer Network (TTN). Following the 
Administrator's signature, a copy of the final 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.

C. Public Comments on Proposed Amendments

    EPA received approximately 20,000 public comments on the proposed 
amendments to the ambient air monitoring regulations during the 90-day 
comment period. These comments were submitted to the rulemaking docket 
and also during public hearings held in Chicago, Illinois; 
Philadelphia, Pennsylvania; and San Francisco, California (71 FR 8228, 
February 16, 2006). Public comments on the proposed amendments were 
submitted by States, local governments, Tribes, and related 
associations; energy, mining, ranching, and agricultural interests and 
related associations; vendors, laboratories, and technical consultants; 
health, environmental, and public interest organizations; and private 
citizens. The EPA has carefully considered these comments in developing 
the final amendments. Summaries of these comments and EPA's detailed 
responses are contained in the Response to Comments document included 
in the docket.

D. Judicial Review

    Under section 307(b)(1) of the Clean Air Act (CAA), judicial review 
of the final amendments is available only by filing a petition for 
review in the U.S. Court of Appeals for the District of Columbia 
Circuit by December 18, 2006. Under section 307(d)(7)(B) of the CAA, 
only an objection to the final amendments that was raised with 
reasonable specificity during the period for public comment can be 
raised during judicial review. Moreover, under section 307(b)(2) of the 
CAA, the requirements established by the final amendments may not be 
challenged separately in any civil or criminal proceedings brought by 
EPA to enforce these requirements.

E. Peer Review

    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 formed 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 1-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; configuration 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 final rulemaking. When there is a difference 
(which will be apparent from context), ``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. Where can I obtain a copy of this action?
    C. Public Comments on Proposed Amendments
    D. Judicial Review
    E. Peer Review
    F. How is this document organized?
II. Authority
III. Overview
    A. Summary of Concurrent Final Action on Revisions to the 
National Ambient Air Quality Standards for Particulate Matter
    B. Summary of Changes to Ambient Air Monitoring Regulations
    C. Significant Dates for States, Local Governments, Tribes, and 
Other Stakeholders
    D. Implementation of the Revised Monitoring Requirements
    E. Federal Funding for Ambient Air Monitoring
IV. Discussion of Regulatory Revisions and Major Comments on 
Proposed Amendments to 40 CFR Part 53
    A. Overview of Part 53 Regulatory Requirements
    B. Requirements for Candidate Reference Methods for 
PM<INF>10-2.5</INF>
    C. Requirements for Candidate Equivalent Methods 
PM<INF>2.5</INF> and PM<INF>10-2.5</INF>
    D. Other Changes
V. Discussion of Regulatory Revisions and Major Comments on Proposed 
Amendments to 40 CFR Part 58
    A. Overview of Part 58 Regulatory Requirements
    B. General Monitoring Requirements
    1. Definitions and Terminology
    2. Annual Monitoring Network Plan and Periodic Network 
Assessment
    3. Operating Schedules
    4. Monitoring Network Completion for PM<INF>10-2.5</INF> and 
NCore Sites
    5. System Modifications
    6. Annual Air Monitoring Data Certification
    7. Data Submittal
    8. Special Purpose Monitors
    9. Special Considerations for Data Comparisons to the National 
Ambient Air Quality Standards
    C. Appendix A--Quality Assurance Requirements for State and 
Local Air Monitoring Stations and Prevention of Significant 
Deterioration Air Monitoring
    1. General Quality Assurance Requirements
    2. Specific Requirements for PM<INF>10-2.5</INF>, 
PM<INF>2.5</INF>, PM<INF>10</INF>, and Total Suspended Particulates
    3. Particulate Matter Performance Evaluation Program and 
National Performance Audit Programs
    4. Revisions to Precision and Bias Statistics
    5. Other Program Updates
    D. Appendix C--Ambient Air Quality Monitoring Methodology
    1. Applicability of Federal Reference Methods and Federal 
Equivalent Methods
    2. Approved Regional Methods for PM<INF>2.5</INF>
    E. Appendix D--Network Design Criteria for Ambient Air Quality 
Monitoring
    1. Requirements for Operation of Multipollutant NCore Stations

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    2. Requirements for Operation of PM<INF>10-2.5</INF> Stations
    3. Requirements for Operation of PM<INF>2.5</INF> Stations
    4. Requirements for Operation of PM<INF>10</INF> Stations
    5. Requirements for Operation of Carbon Monoxide, Sulfur 
Dioxide, Nitrogen Dioxide, and Lead Monitoring Sites
    6. Requirements for Operation of Ozone Stations
    7. Requirements for Operation of Photochemical Assessment 
Monitoring Stations
    F. Appendix E--Probe and Monitoring Path Siting Criteria for 
Ambient Air Monitoring
    1. Vertical Placement of PM<INF>10-2.5</INF> Samplers
    2. Ozone Monitor Setback Requirement from Roads
    G. Sample Retention Requirements
    H. Deletion of Appendices B and F
VI. 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 12898: Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    I. Executive Order 13211: Actions That Significantly Affect 
Energy Supply, Distribution, or Use
    J. National Technology Transfer Advancement Act
    K. Congressional Review Act

II. 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 103 authorizes, among others, research and investigations 
relating to the causes, effects, extent, prevention and control of air 
pollution. Section 301(a) of the CAA authorizes EPA to develop 
regulations needed to carry out EPA'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.

III. Overview

A. Summary of Concurrent Final Action on Revisions to the National 
Ambient Air Quality Standards for Particulate Matter

    Elsewhere in this Federal Register, EPA is finalizing revisions to 
the National Ambient Air Quality Standards (NAAQS) for particulate 
matter (PM). These revisions were proposed on January 17, 2006 (71 FR 
2620). For a detailed explanation of these revisions, see that preamble 
elsewhere in this Federal Register.
    The EPA is finalizing the PM<INF>2.5</INF> NAAQS revisions as 
proposed. With regard to the primary standards for fine particles 
(generally referring to particles less than or equal to 2.5 micrometers 
([mu]m) in diameter, PM<INF>2.5</INF>), EPA is revising the level of 
the 24-hour PM<INF>2.5</INF> standard to 35 micrograms per cubic meter 
([mu]g/m\3\), providing increased protection against health effects 
associated with short-term exposure (including premature mortality and 
increased hospital admissions and emergency room visits). The EPA is 
retaining the level of the annual PM<INF>2.5</INF> standard at 15 
[mu]g/m\3\, continuing protection against health effects associated 
with long-term exposure (including premature mortality and development 
of chronic respiratory disease). The EPA is also finalizing the 
proposed revisions in the conditions under which spatial averaging of 
the annual primary PM<INF>2.5</INF> NAAQS is permitted, and placing 
these conditions in appendix N of 40 CFR part 50 rather than in 
appendix D of 40 CFR part 58.
    With regard to secondary PM standards, EPA is revising the current 
24-hour PM<INF>2.5</INF> secondary standard by making it identical to 
the revised 24-hour PM<INF>2.5</INF> primary standard, retaining the 
annual PM<INF>2.5</INF> and 24-hour PM<INF>10</INF> secondary 
standards, and revoking the annual PM<INF>10</INF> secondary standard. 
This suite of secondary PM standards is intended to provide protection 
against PM-related public welfare effects, including visibility 
impairment, effects on vegetation and ecosystems, and materials damage 
and soiling.
    The EPA is finalizing the proposed Federal reference method (FRM) 
for PM<INF>2.5</INF>. This action in essence codifies certain desirable 
features that have already been in widespread use as elements of 
approved equivalent methods or national user modifications.
    The EPA is not finalizing the proposed NAAQS for 
PM<INF>10-2.5</INF>, for reasons explained in the accompanying preamble 
to the revisions to the NAAQS. As a result, EPA is not finalizing a 
number of related provisions (notably those which would have prescribed 
which monitors could have been used for comparison with that proposed 
NAAQS) proposed as amendments to 40 CFR part 58. The EPA is, however, 
finalizing the proposed FRM for PM<INF>10-2.5</INF> (see appendix O to 
40 CFR part 50). This FRM is based on paired filter-based samplers for 
PM<INF>2.5</INF> and PM<INF>10</INF> and it will serve as the standard 
of reference for measurements of PM<INF>10-2.5</INF> concentrations in 
ambient air. This should provide a basis for approving Federal 
Equivalent Methods (FEMs) and promote the gathering of scientific data 
to support future reviews of the PM NAAQS. Because it is a filter based 
system, this method can itself be used to provide speciated data. The 
reference measurement from the PM<INF>10-2.5</INF> FRM is also 
important in the development of alternative PM<INF>10-2.5</INF> 
speciation samplers such as dichotomous samplers. The EPA will be 
issuing guidance to ensure the use of a consistent national approach 
for speciated coarse particle monitors as soon as possible.
    In conjunction with the above NAAQS revisions and FRM provisions, 
as part of this final monitoring rule, as described below EPA is 
finalizing certain provisions which support collection of additional 
high quality data on ambient concentrations of PM<INF>10-2.5</INF>. 
These data should be useful in improving the understanding of 
PM<INF>10-2.5</INF> air quality and in conducting future reviews of the 
PM NAAQS.
    As explained in the preamble to the NAAQS revisions, EPA is 
revoking the annual NAAQS for particles generally less than or equal to 
10 [mu]m in diameter (PM<INF>10</INF>). However, EPA is retaining the 
24-hour PM<INF>10</INF> NAAQS as a standard for short-term exposure to 
thoracic coarse particles, rather than revoking that standard in all 
but 15 areas as proposed. This change from the NAAQS revision proposal 
necessitates that the final monitoring rule restore certain 
PM<INF>10</INF> monitoring provisions that were proposed for removal.

B. Summary of Changes to Ambient Air Monitoring Regulations

    This rule, in most respects, finalizes the proposals put forth in 
the January 17, 2006, notice of proposed rulemaking (71 FR 2710). This 
final rule will facilitate monitoring program changes envisioned in the 
draft National Ambient Air Monitoring Strategy which was fully 
described in the proposal. These final changes, which apply to the 
monitoring program for all of the criteria pollutants, will reduce the 
required scale of monitoring for pollutants for which most areas have 
reached

[[Page 61239]]

attainment. The changes are intended to better focus monitoring 
resources on current air quality challenges. The changes will also 
allow States and local monitoring agencies more flexibility to design 
their monitoring programs to reflect local conditions.
    In amendments to 40 CFR part 53 (Reference and Equivalent Methods), 
this final rule incorporates the proposed criteria for approval of 
Federal equivalent methods (FEM) for PM<INF>2.5</INF>, with some 
modifications to the method testing requirements and approval criteria 
in response to persuasive public comments. The modifications will 
require a more robust set of testing conditions and closer performance 
matching of candidate FEMs to FRMs. The EPA is also finalizing the rule 
with some strengthening revisions to the proposed criteria for approved 
regional methods (ARMs) for PM<INF>2.5</INF>. The new criteria for 
PM<INF>2.5</INF> FEMs and ARMs will facilitate the commercialization 
and EPA approval of continuous PM<INF>2.5</INF> mass monitors, allowing 
them to be substituted for many of the currently operating filter-based 
FRMs, which will support additional monitoring objectives and reduce 
annual monitoring costs.
    In other amendments to 40 CFR part 53, EPA is adopting FEM approval 
criteria for PM<INF>10-2.5</INF>, with some revisions from the proposal 
that will provide for approval and use of methods that can meet 
multiple monitoring objectives. The new FEM performance criteria for 
PM<INF>10-2.5</INF> will facilitate approval of filter-based methods 
for direct sampling of PM<INF>10-2.5</INF> concentrations that can be 
chemically speciated using post-sampling laboratory analysis. The FEM 
criteria are also expected to encourage commercialization of highly 
time-resolved continuous methods. The EPA is hopeful that the 
PM<INF>2.5</INF> and PM<INF>10-2.5</INF> FEM criteria together will 
result in the approval and commercialization of methods that provide 
equivalent measurements of PM<INF>2.5</INF>, PM<INF>10</INF>, and 
PM<INF>10-2.5</INF> from a single instrument.
    In amendments to 40 CFR part 58 (Ambient Air Quality Surveillance), 
this final rule, as proposed, requires States to establish and operate 
a network of NCore multipollutant monitoring stations. The EPA intends 
the NCore network to consist of approximately 75 stations, of which the 
rule requires between 62 and 71 such stations. These stations must be 
operational by 2011. Most States, as well as the District of Columbia, 
Puerto Rico, and the Virgin Islands, will be required to operate a 
single station. California, Florida, Illinois, Michigan, New York, 
North Carolina, Ohio, Pennsylvania, and Texas will be required to 
operate two or three NCore stations. For these States, the selection 
between two or three stations will be part of the development and 
approval of the NCore monitoring plan that is due by July 1, 2009. The 
EPA also plans to negotiate with a number of States, local agencies, 
and/or Tribes to operate additional NCore stations on a voluntary 
basis, bringing the total number of stations to about 75. By approving 
some required stations to be in rural areas and by negotiating for 
additional voluntary sites in rural areas, EPA expects that about 55 
NCore sites will be in urbanized areas and about 20 in rural areas. The 
rural sites are intended to be sited away from any large local emission 
sources, so that they represent ambient concentrations over an 
extensive area. The NCore stations must perform the types of pollutant 
measurements that were proposed, with three exceptions. 
PM<INF>10-2.5</INF> measurements may be made on a 1-in-3 day schedule 
rather than the proposed every day schedule, NO<INF>y</INF> \2\ 
measurements may be waived by the EPA Administrator based on certain 
criteria, and as explained later in this section, PM<INF>10-2.5</INF> 
chemical speciation will be required in addition to PM<INF>10-2.5</INF> 
mass concentration measurements.
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    \2\ NO<INF>y</INF> refers to a broad class of nitrogen-
containing reactive compounds in ambient air, explained in more 
detail in sections V.E.1 and V.E.7 of this preamble.
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    The EPA estimated that the proposed rule would have required States 
to operate about 225 PM<INF>10-2.5</INF> monitors based on the 
population and estimated PM<INF>10-2.5</INF> concentrations of 
metropolitan statistical areas (MSAs) with populations of 100,000 or 
more. In addition, PM<INF>10-2.5</INF> monitors were proposed to be 
required at NCore stations; some monitors likely would have satisfied 
both of these requirements. Because EPA is not adopting a NAAQS for 
PM<INF>10-2.5</INF>, the final monitoring rule does not include the 
proposed requirement for the broad network of PM<INF>10-2.5</INF> 
monitoring stations in MSAs over 100,000 population. However, the final 
monitoring rule does require PM<INF>10-2.5</INF> monitors at the 
required NCore multipollutant monitoring stations. The data gathered 
from these stations should be useful in improving understanding of 
PM<INF>10-2.5</INF> air quality and in conducting future reviews of the 
PM NAAQS. The EPA anticipates that due to natural variations among the 
cities and rural areas where the NCore stations will be sited, the 
NCore PM<INF>10-2.5</INF> monitors will represent a range of 
concentrations and nearby emission source types, and that many but not 
all will be in well populated locations.
    The EPA is not adopting the proposed population-based and 
population density-based siting requirements for PM<INF>10-2.5</INF> 
monitors, or any part of the proposed five-part suitability test for 
PM<INF>10-2.5</INF> monitoring sites, which as proposed would have 
controlled whether PM<INF>10-2.5</INF> data from a monitoring site 
could be compared to the proposed PM<INF>10-2.5</INF> NAAQS. These 
proposed requirements were tied to the establishment of a 
PM<INF>10-2.5</INF> NAAQS with a qualified PM<INF>10-2.5</INF> 
indicator based on a determination of whether ambient mixes of coarse 
particles are or are not dominated by coarse particle emissions from 
enumerated types of sources. Since EPA is not adopting this part of the 
proposal, these issues are now moot. In the absence of a 
PM<INF>10-2.5</INF> NAAQS, our goal nevertheless will be to locate 
PM<INF>10-2.5</INF> monitors in a manner that satisfies an objective of 
the proposed rule, which was to focus most monitoring resources on 
population centers.
    This final rule contains a requirement for PM<INF>10-2.5</INF> 
speciation to be conducted at NCore multipollutant monitoring stations. 
The EPA had proposed a requirement for PM<INF>10-2.5</INF> speciation 
in 25 areas, with the areas required to have this monitoring selected 
based on having a Metropolitan Statistical Area (MSA) population over 
500,000 and having an estimated design value of greater than 80 percent 
of the proposed PM<INF>10-2.5</INF> NAAQS. This would have concentrated 
the PM<INF>10-2.5</INF> speciation monitoring in areas that have high 
populations and high exposures to PM<INF>10-2.5</INF>. Since EPA is 
requiring PM<INF>10-2.5</INF> monitoring at NCore primarily for 
scientific purposes, it is more appropriate to have monitoring in a 
variety of urban and rural locations to increase the diversity of areas 
for which chemical species data will be available to use in scientific 
studies. The EPA had already proposed to require chemical speciation 
for PM<INF>2.5</INF> at NCore stations. The collocation of both 
PM<INF>10-2.5</INF> and PM<INF>2.5</INF> speciation monitoring at NCore 
stations is consistent with the multipollutant objectives of the NCore 
network and will support further research in understanding the chemical 
composition and sources of PM<INF>10</INF>, PM<INF>10-2.5</INF>, and 
PM<INF>2.5</INF> at a variety of urban and rural locations. The EPA 
will work with States to ensure that PM<INF>10-2.5</INF> speciation 
monitors employ the latest in speciation technology to advance the 
science so that future regulation will provide more targeted protection 
against the effects only of those coarse particles

[[Page 61240]]

and related source emissions that prove to be of concern to public 
health.
    Because the 24-hour PM<INF>10</INF> NAAQS is being retained in all 
parts of the country, this final rule retains the existing minimum 
monitoring network design requirements for PM<INF>10</INF>. These 
longstanding requirements are based on the population of a MSA and its 
historical PM<INF>10</INF> air quality. For any given combination of 
these two parameters, a range of required monitors is prescribed, with 
the required number to be determined as part of the annual monitoring 
plan. The EPA estimates that once States and Regional Administrators 
have considered how current population data and recent PM<INF>10</INF> 
air quality affect the required number of PM<INF>10</INF> monitors in 
each area, between 200 and 500 FRM/FEM monitors will be required, 
compared to about 1,200 in operation now. While States may of course 
choose to continue to operate monitors in excess of the minimum 
requirements, EPA notes that many PM<INF>10</INF> monitors have been 
recording concentrations well below the PM<INF>10</INF> NAAQS and are 
candidates for discontinuation at a State's initiative. States may 
choose to retain PM<INF>10</INF> monitors that are recording 
concentrations below the PM<INF>10</INF> NAAQS level to support 
monitoring objectives other than attainment/nonattainment 
determinations, such as baseline monitoring for prevention of 
significant deterioration permitting or public information.
    This final rule changes the requirements for the minimum number of 
monitors for PM<INF>2.5</INF> and ozone (O<INF>3</INF>) monitoring 
networks. In response to comments, the final requirements require more 
O<INF>3</INF> and PM<INF>2.5</INF> monitoring in more polluted areas 
and more monitors in CSAs than was proposed. While this final rule 
requires fewer monitors than are now operating for O<INF>3</INF> and 
PM<INF>2.5</INF>, as did the pre-existing monitoring rule, EPA does not 
intend to encourage net reductions in the number of O<INF>3</INF> and 
PM<INF>2.5</INF> monitoring sites in the U.S. as a whole. The surplus 
in the existing networks relative to minimum requirements gives States 
more flexibility to choose where to apply monitoring resources for 
O<INF>3</INF> and PM<INF>2.5</INF>. For PM<INF>2.5</INF>, this final 
rule requires that sampling be conducted on a daily basis for monitors 
that have recently been recording the highest concentrations in their 
area and have been recording concentrations very near the 24-hour 
NAAQS, to avoid a bias in attainment/nonattainment designations that 
can occur with less frequent sampling. Pursuant to this provision, EPA 
estimates that about 50 sites now sampling less frequently will be 
required to change to daily sampling.
    As proposed, minimum monitoring requirements for carbon monoxide 
(CO), sulfur dioxide (SO<INF>2</INF>), and nitrogen dioxide 
(NO<INF>2</INF>) are eliminated in this final rule. Minimum 
requirements for lead (Pb) monitoring stations and Photochemical 
Assessment Monitoring Stations (PAMS) are reduced to those that were 
proposed. For all five criteria pollutants, however, existing 
monitoring sites (except those already designated as special purpose 
monitors) cannot be discontinued without EPA Administrator (for PAMS or 
NCore stations) or Regional Administrator (for all other types of 
monitoring) approval. Regional Administrator approval is also required 
for discontinuation of O<INF>3</INF>, PM<INF>2.5</INF>, and 
PM<INF>10</INF> sites even if they are in excess of minimum network 
design requirements. While the rule requires EPA approval, such 
approvals should be facilitated where appropriate by rule provisions 
which clearly establish certain criteria under which discontinuation 
will be approved. These criteria are the same as those proposed with 
four minor changes explained in detail in section V.B.5, System 
Modifications. These criteria are not exclusive, and monitors not 
meeting any of the listed criteria may still be approved for 
discontinuation on a case-by-case basis if discontinuation does not 
compromise data collection needed for implementation of a NAAQS. 
Specific monitoring for these pollutants may currently be required in 
individual SIPs; this monitoring rule does not affect any SIP 
requirements for such specific monitoring.
    Appendix A to this final rule includes most of the proposed 
revisions to the quality system for ambient air monitoring. In 
particular, the proposed requirement for States to ensure a program of 
adequate and independent audits of their monitoring stations is 
included in this final rule. One way, but not the only way, a State can 
satisfy this requirement is to agree that EPA will conduct these audits 
using funds that otherwise would have been awarded to the State as part 
of its annual air quality management grant. A small number of changes 
to the proposed quality system requirements reflect public comments on 
details of the proposed revisions. Also, because the objective of 
PM<INF>10-2.5</INF> monitoring is to better understand 
PM<INF>10-2.5</INF> air quality and to support health effects studies, 
rather than to provide data for use in nonattainment designations, and 
because there consequently will be a much smaller network of required 
PM<INF>10-2.5</INF> monitors than proposed, the quality system for 
PM<INF>10-2.5</INF> in this final rule differs from the proposed system 
in that it aims to quantify data quality at the national level of 
aggregation rather than at the level of individual monitoring 
organizations as had been proposed. Another change from the proposal is 
that a provision has been added allowing the EPA Regional Administrator 
to waive the usual quality system requirements for special purpose 
monitors when those requirements are logistically infeasible due to 
unusual site conditions and are not essential to the monitoring 
objectives.
    The EPA is finalizing the proposed provisions regarding when data 
from special purpose monitors (SPMs) can be compared to a NAAQS, with 
minor clarifications. In summary, the final rule provides that if an 
ozone or PM<INF>2.5</INF> SPM operates for only two years or less, EPA 
will not use data from that monitor to make attainment/nonattainment 
determinations. This limitation is inherent in the form of these NAAQS, 
which require three years of data for a determination to be made. For 
the other NAAQS pollutants, as a policy matter, EPA will not use only 
two years of data from a SPM to voluntarily redesignate an area to 
nonattainment. This limitation is possible because as established in 
Section 107(d)(1) of the Act, the only time EPA is obligated to 
redesignate areas as attainment or nonattainment is after it 
promulgates or revises a NAAQS. Under an existing standard, voluntary 
redesignations are at the Administrator's discretion: EPA has no legal 
obligation to redesignate an area even if a monitor should register a 
violation of that standard (see CAA Section 107(d)(3)). In particular, 
in the case of PM<INF>10,</INF> EPA stated in section VII.B of the 
preamble to the NAAQS rule (printed in today's Federal Register) that 
because EPA is retaining the current 24-hour PM<INF>10</INF> standards, 
new nonattainment designations for PM<INF>10</INF> will not be required 
under the provisions of the Clean Air Act. The same is true for CO, 
NO<INF>2</INF>, SO<INF>2</INF>, and Pb. However, all valid data from a 
SPM will be considered in determining if a previously designated 
nonattainment area has subsequently attained the NAAQS. See also 
section V.B.8 below.
    This final rule advances, to May 1, the date each year by which 
monitoring organizations must certify that their submitted data is 
accurate to the best of their knowledge. However, this requirement will 
take effect one year later than proposed, in 2010 for data collected in 
2009.
    This final rule retains the current requirement for an annual 
monitoring plan and finalizes most of the new

[[Page 61241]]

substantive and procedural requirements that were proposed for these 
plans. One change is that some required new elements proposed for the 
annual plan have instead been shifted to the 5-year network assessment, 
to reduce the annual plan preparation burden and to allow these 
elements to be prepared more carefully. The first 5-year network 
assessment has been postponed by one year, to July 1, 2010.
    The proposed requirements regarding probe heights for 
PM<INF>10-2.5</INF> monitors, increased O<INF>3</INF> monitor distance 
from roadways (for newly established O<INF>3</INF> stations), data 
elements to be reported, and PM filter retention are included in this 
final rule.
    This final rule also removes and reserves the pre-existing appendix 
B, Quality Assurance Requirements for Prevention of Significant 
Deterioration (PSD) Air Monitoring, and appendix F, Annual SLAMS Air 
Quality Information, of 40 CFR part 58 because they are no longer 
needed.

C. Significant Dates for States, Local Governments, Tribes, and Other 
Stakeholders

    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.\3\ The 
following summary of applicable requirements is presented in 
chronological order, as an aid for States in planning their activities 
to comply with the rule. States are required to comply with pre-
existing requirements in 40 CFR part 58, until the compliance date for 
each new requirement is reached.
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    \3\ 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. This preamble also uses ``monitoring organization'' to refer 
to States, local agencies, and/or Tribes conducting monitoring under 
or guided by the provisions of 40 CFR part 58. This final rule 
applies the same requirements to the District of Columbia, Puerto 
Rico, and the Virgin Islands as apply to the 50 States. Other U.S. 
territories are not subject to this final rule.
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    The following provisions in 40 CFR part 53 and part 58 are 
effective on December 18, 2006:
    <bullet> The criteria and process for EPA Administrator approval of 
FRMs, FEMs, and ARMs or where applicable Regional Administrator 
approval of ARMs. Manufacturers of continuous PM<INF>2.5</INF> and 
PM<INF>10-2.5</INF> instruments may apply for designation of their 
instruments as FRMs or FEMs starting today. The EPA is eager to receive 
such applications as soon as manufacturers can collect and analyze the 
necessary supporting data. State, local, and Tribal monitoring agencies 
may seek approval of their PM<INF>2.5</INF> continuous monitor as ARMs 
beginning today, either independently or in cooperation with instrument 
manufactures.
    <bullet> The revised quality system requirements, except that full 
quality assurance practices, if not waived, are not required until 
January 1, 2009 for SPMs which use FRM, FEM, or ARM monitors.
    <bullet> The new minimum requirements (or absence of minimum 
requirements) for the number of monitors for specific NAAQS pollutants 
and for PAMS stations, if the new minimum allows a State to discontinue 
a previously required monitor. See below for the compliance date of the 
new minimum requirements in situations in which the final requirement 
is greater than the currently operating network.
    <bullet> The criteria for EPA Regional Administrator approval for 
removal of monitors that are in excess of minimum required, if a State 
seeks such removal.
    <bullet> The criteria for use of data from SPMs in determinations 
of attainment/nonattainment.
    <bullet> The elimination of the requirement for reporting of 
certain PM<INF>2.5</INF> monitor operating parameters.
    <bullet> The revised requirement for separation between roadways 
and O<INF>3</INF> monitors, for new O<INF>3</INF> monitors whose 
placement has not already been approved as of December 18, 2006.
    <bullet> The new specification for probe heights for 
PM<INF>10-2.5</INF> monitors.
    The new requirement to archive all PM<INF>10c</INF> and 
PM<INF>10-2.5</INF> filters for 1 year begins with filters collected on 
or after January 1, 2007. However, EPA expects few if any monitoring 
agencies to be operating PM<INF>10c</INF> or PM<INF>10-2.5</INF> 
filters this early, so most will be affected later.\4\
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    \4\ As explained in section IV.B of this preamble, the term 
``PM<INF>10c</INF>'' refers to a PM<INF>10</INF> Federal reference 
method (FRM) that is designated as a PM<INF>10c</INF> FRM under the 
final NAAQS rule appearing elsewhere in today's Federal Register. In 
essence, it would be a PM<INF>2.5</INF> FRM with the inertial 
fractionator used to separate out particles larger than 2.5 microns 
removed so that all PM<INF>10</INF> is collected. Unlike other 
PM<INF>10</INF> instruments, a PM<INF>10c</INF> instrument must 
control flow to a specified flow rate of 16.67 liters/minute at 
local conditions of temperature and pressure. A PM<INF>10-2.5</INF> 
FRM consists of a PM<INF>2.5</INF> FRM and a PM<INF>10c</INF> FRM of 
the same model. See also 71 FR 2720.
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    The requirement to submit mass data on blank PM<INF>2.5</INF> 
filters begins on January 1, 2007.
    The required date to begin daily PM<INF>2.5</INF> sampling at 
certain PM<INF>2.5</INF> monitoring sites is January 1, 2007. The EPA 
believes this will affect about 50 PM<INF>2.5</INF> monitoring sites. 
The EPA will notify the affected States directly.
    This final rule does not change the schedule for reporting ambient 
air quality data to the Administrator, via the Air Quality System 
(AQS). However the rule now explicitly requires that associated quality 
assurance data be submitted along with ambient concentration data. The 
first submission affected will be the one due on June 30, 2007 for data 
collected in January through March of 2007.
    As presently is the case, States must submit an annual network plan 
by July 1 of each year. The next plan is due July 1, 2007.
    States whose PM<INF>2.5</INF>, PM<INF>10</INF>, or O<INF>3</INF> 
networks do not meet the revised requirements of this final rule 
regarding the number of monitors in a given MSA or CSA are required to 
submit a plan for adding the necessary additional monitors by July 1, 
2007 and to begin operating the new monitors by January 1, 2008. The 
EPA believes that this will only affect O<INF>3</INF> and 
PM<INF>2.5</INF> monitoring in fewer than ten locations each. The EPA 
will notify these States directly.
    A plan for the implementation of the required NCore multipollutant 
monitoring stations, including site selection, is due by July 1, 2009. 
States must implement the required NCore multipollutant stations by 
January 1, 2011, including PM<INF>10-2.5</INF> monitoring.
    States will be required to submit earlier certification letters 
regarding the completeness and accuracy of the ambient concentration 
and quality assurance data they have submitted to the Air Quality 
System (AQS) operated by EPA, starting May 1, 2010 for data collected 
during 2009. Until then, States are required to submit these letters by 
July 1 of each year.
    Network assessments are required from States every 5 years starting 
July 1, 2010.
    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, 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 is any Tribe 
required to monitor ambient air. 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

[[Page 61242]]

will work with the Tribe to develop an appropriate schedule for making 
any appropriate monitoring system changes which meet 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 will be required by EPA 
regions to institute quality assurance programs that comply with 40 CFR 
part 58 appendix A, utilize FRM, FEM, or ARM monitors when comparing 
their data to the NAAQS, and to insure that the data collected is 
representative of their respective airsheds. For FRM, FEM, or ARM 
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.

D. Implementation of the Revised Monitoring Requirements

    After promulgation, EPA will assist States in implementing the 
amended requirements using several mechanisms. The EPA will work with 
each State to develop approvable monitoring plans for its new NCore 
multipollutant monitoring stations, including PM<INF>10-2.5</INF> 
monitoring. For example, EPA will 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 are 
no longer needed. The EPA will negotiate with each State its annual 
grant for air quality management activities, including ambient 
monitoring work. Once States have established a new monitoring 
infrastructure to meet the new requirements, EPA will 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 this final monitoring rule. The EPA 
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. The EPA may also work 
with the States, and possibly with some Tribes, to establish and 
operate PM<INF>10-2.5</INF> speciation sites inaddition to those 
required by this final rule. The EPA also plans to work with the 
States, and possibly with some Tribes, to establish and operate sites 
that will measure only PM<INF>10-2.5</INF> concentrations in rural and 
less urbanized locations, in addition to the PM<INF>10-2.5</INF> 
monitors required at NCore sites.
    An important element of implementing the new requirements will be 
EPA's role in encouraging the development and application of FEMs, and 
the development of a sampler or samplers that can provide a direct 
measurement of PM<INF>10-2.5</INF> for collection of filters used in 
chemical speciation and for continuous methods that measure both 
PM<INF>2.5</INF> and PM<INF>10-2.5.</INF> The EPA has determined that 
continuous monitoring of PM<INF>2.5</INF> has many advantages over the 
filter-based FRM. This final rule makes it more practical for 
manufacturers and users of continuous PM<INF>2.5</INF> instruments to 
obtain designation for them as FEMs or ARMs. To ensure objectivity and 
a sound scientific basis for decisions, EPA's Office of Research and 
Development will review applications for FEM and ARM designations based 
on the criteria in this final rule and will recommend approval or 
disapproval to the Administrator. For agencies seeking use of an ARM 
already approved in another monitoring network, the applicable Regional 
Office will conduct a review, most often as part of the EPA approval of 
an annual monitoring plan, based on the criteria in this final 
monitoring rule.
    The EPA 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. The EPA has already distributed a technical assistance 
document on the precursor gas monitors \5\ that will be part of the 
NCore multipollutant sites and EPA has conducted multiple 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, discontinuation of sites, quality assurance, network 
assessment, and other topics. While Tribes are not subject to the 
monitoring requirements of this final rule, 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.
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    \5\ Technical Assistance Document (TAD) for Precursor Gas 
Measurments 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.
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    The EPA will also continue to support the National Park Service's 
operation of the IMPROVE monitoring network, which provides important 
data for implementing both regional haze and PM<INF>2.5</INF> 
attainment programs.\6\ The number of sites in the IMPROVE program may 
vary, depending on EPA's enacted budget and the data needs of the 
regional haze and PM<INF>2.5</INF> attainment programs.
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    \6\ 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.
---------------------------------------------------------------------------

    The EPA will also continue to operate the Clean Air Status and 
Trends Network (CASTNET), which monitors for O<INF>3</INF>, PM, and 
chemical components of PM in rural areas across the nation.\7\ EPA is 
in the process of revising CASTNET to upgrade its monitoring 
capabilities to allow it to provide even more useful data to multiple 
data users. The EPA expects that about 20 CASTNET sites will have new 
capabilities similar to some of the capabilities required at NCore 
multipollutant sites.
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    \7\ Additional information on CASTNET is available at: http://www.epa.gov/castnet/.
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    This final rule includes a requirement that States must ensure a 
program of adequate and independent audits of their monitoring 
stations. One way, but not the only way, a State can satisfy this 
requirement is to agree that EPA will conduct these audits using funds 
that otherwise would have been awarded to the State as part of its 
annual air quality management grant. In anticipation of the possible 
inclusion of this requirement in this final rule, EPA has been working 
with monitoring organizations to determine which of these organizations 
prefer this approach. The EPA expects that, for 2007, nearly all 
monitoring organizations will request that EPA conduct these audits. 
For those that chose another acceptable approach, EPA will conduct 
limited cross-checks of equipment, calibration standards, auditor 
preparation, and audit procedures to ensure that their audit programs 
are adequate.
    The EPA recognizes that characterizing and managing some air 
quality problems requires ambient concentration and deposition data 
that cannot be provided by the types of monitoring required by the 
monitoring activities addressed in today's final rule. These problems 
include near-roadway exposures to emissions from motor

[[Page 61243]]

vehicles and mercury deposition. The EPA is actively researching these 
issues and developing concepts for monitoring programs to address them, 
but these issues are outside the scope of this final rule.
    The Air Quality System (AQS) is the data system EPA uses to receive 
ambient air monitoring data from State, local, Tribal, and other types 
of monitoring organizations and to make those data available to all 
interested users. AQS is based on a particular data structure and uses 
particular data input formats including data elements and defined 
values for categorical data. The existing AQS data structure and input 
formats are for the most part consistent with a number of changes made 
in this final rule to pre-existing terminology and requirements, but 
some changes will be needed in AQS to re-establish full consistency 
with requirements in the monitoring rule. The changes to AQS will 
likely, in turn, require some modifications to data preparation tools 
and practices at monitoring agencies. The EPA will prepare and 
implement a plan for making these changes, and will advise AQS users of 
the ramifications while doing so. Generally, the compliance deadlines 
in the rule are such that monitoring agencies are not required to 
immediately comply with any changes in rule provisions that would 
affect data transfer formats and procedures. Monitoring agencies, for 
the present, should continue to follow pre-existing AQS formats and 
procedures until notified.

E. Federal Funding for Ambient Air Monitoring

    EPA has historically funded part of the cost to State, local, and 
Tribal governments of installation and operation of monitors to meet 
Federal monitoring requirements. Sections 105 and 103 of the CAA allow 
EPA to provide grant funding for programs for preventing and 
controlling air pollution and for some research and development efforts 
respectively. Eligible entities must apply for section 103 grants. 
Eligible entities must provide nonfederal matching funds for section 
105 grants. The EPA's enacted budget specifies overall how much State 
and Tribal Air Grant (STAG) funding is available for these grants.
    In recent years, EPA has received special authority through 
appropriations acts to use section 103 grant funding for establishing 
and operating PM<INF>2.5</INF>-related monitoring stations. Funding for 
other types of monitoring has been included in the grants awarded under 
section 105. Grants to Tribes for air quality management work, 
including ambient monitoring, have been awarded under section 103 with 
the overall amount for these funds established by the enacted budget.
    During the public comment period for this rulemaking EPA received a 
large number of comments addressing funding issues. Most of these 
comments expressed opposition to the Administration's proposed EPA 
budget for fiscal year 2007, which included a proposal to provide 
PM<INF>2.5</INF> monitoring support through section 105 grant funding, 
as is done for all other criteria pollutants. (As of today, the 
Congress has not enacted a 2007 budget for EPA.) Commenters stated that 
if funding for monitoring were reduced as proposed, State and local 
agencies would have less flexibility than desired in designing and 
operating their monitoring programs, and that the proposed requirements 
for new PM<INF>10-2.5</INF> and NCore networks and for adequate and 
independent audits of monitoring stations would be burdensome. Some 
commenters requested that the proposed new requirements not be included 
in this final rule for this reason.
    The EPA understands these concerns. However, the CAA requirements 
from which this final rule derives \8\ are not contingent on EPA 
providing funding to States to assist in meeting those requirements. 
Accordingly, the comments regarding funding are not directly relevant 
to the content of this final rule. Nevertheless, EPA recognizes that 
resources always have been and will remain a practical consideration 
for establishing and operating monitoring programs. The EPA will 
continue to work with States in this regard, in particular as EPA 
determines how to allocate enacted funding among States and among types 
of monitoring so as to achieve the best possible environmental 
outcomes. Several provisions of this final rule reduce minimum 
requirements, which will provide flexibility for States to reduce some 
of their pre-existing costs.
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    \8\ Section 103(c)(2) of the Clean Air Act [42 U.S.C.A. 7403(c)] 
provides that the Administrator shall conduct a program for sampling 
air pollution that includes the establishment of a national network 
to monitor air quality and to ensure the comparability of air 
quality data collected in different states. Section 110(a)(2)(B) [42 
U.S.C.A 7410(a)] provides that each State implementation plan shall 
provide for establishment and operation of appropriate devices, 
methods, systems, and procedures necessary to monitor, compile, and 
analyze data on ambient air quality and upon request make such data 
available to the Administrator. Section 182(c)(1) [42 U.S.C.A. 
7511a(c)(1)] states that the Administrator will promulgate rules for 
enhanced monitoring for ozone, oxides of nitrogen, and volatile 
organic compounds in serious ozone areas.
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    Several commenters stated that EPA should not use STAG funds for 
the improvement or operation of Federal monitoring networks such as 
CASTNET. The EPA does not intend to use STAG funds from fiscal year 
2007 or beyond in this way.

IV. Discussion of Regulatory Revisions and Major Comments on Proposed 
Amendments to 40 CFR Part 53

A. Overview of Part 53 Regulatory Requirements

    Various appendices to 40 CFR part 50 define certain ambient air 
monitoring methods as Federal reference methods which may be used to 
determine attainment of the National Ambient Air Quality Standards 
(NAAQS), and which form the benchmark for determining equivalency of 
other methods which may also be used to determine attainment. Under 40 
CFR part 53, EPA designates specific commercial instruments or other 
versions of methods as Federal reference methods (FRMs). To be so 
designated, a particular FRM must be shown, according to the procedures 
and requirements of part 53, to meet all specifications of both the 
applicable appendix of part 50 as well as applicable specifications and 
requirements of part 53.
    To foster development of improved alternative air monitoring 
methods, EPA also designates--as Federal equivalent methods (FEMs)--
alternative methods that are shown to have measurement performance 
comparable to the corresponding FRM. Part 53 contains explicit 
performance tests, performance standards, and other requirements for 
designation of both FRMs and FEMs for each of the criteria pollutants. 
In addition, States' air surveillance monitoring networks are required, 
under 40 CFR part 58, appendix C, to use only EPA-designated FRMs, 
FEMs, or ARMs at SLAMS sites. A list of all methods that EPA has 
designated as either FRMs or FEMs for all criteria pollutants is 
available at http://www.epa.gov/ttn/amtic/criteria.html.
    Elsewhere in today's Federal Register, EPA is promulgating a new 
Federal reference method for measurement of mass concentrations of 
thoracic coarse particles (PM<INF>10-2.5</INF>) in the atmosphere, to 
be codified as appendix O to 40 CFR part 50. Although, as explained 
earlier, EPA is not at this time adopting any NAAQS for 
PM<INF>10-2.5</INF>, EPA believes an FRM for PM<INF>10-2.5</INF> is 
still highly desirable to aid in a variety of needed

[[Page 61244]]

research studies.\9\ This new FRM is defined as the standard of 
reference for measurement of PM<INF>10-2.5</INF> concentrations in 
ambient air. It will be an acceptable and readily available 
PM<INF>10-2.5</INF> measurement method for new NCore multipollutant 
monitoring sites to be located at approximately 75 urban and rural 
locations. Availability of an approved FRM for PM<INF>10-2.5</INF> will 
also help provide consistency among PM<INF>10-2.5</INF> measurements 
used in future health studies of the adverse health effects associated 
with exposure to thoracic coarse particles. Lastly, the 
PM<INF>10-2.5</INF> reference method will provide the basis for 
development of speciation samplers capable of providing an improved 
understanding of the compositions of different ambient mixes of 
thoracic coarse particles, so that this composition can be related to 
both health effects and to particle sources. Associated with this new 
reference method, EPA is also establishing related amendments to 40 CFR 
part 53 to extend the designation provisions of FRMs and FEMs to 
methods for PM<INF>10-2.5</INF>. These amendments set forth explicit 
tests, performance standards, and other requirements for designation of 
specific commercial samplers, sampler configurations, or analyzers as 
either FRMs or FEMs for PM<INF>10-2.5</INF>, as appropriate.
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    \9\ Henderson, R. Clean Air Scientific Advisory Committee 
(CASAC) Review of the EPA Staff Recommendations Concerning a 
Potential Thoracic Coarse PM Standard in the Review of the National 
Ambient Air Quality Standards for Particulate Matter: Policy 
Assessment of Scientific and Technical Information (Final PM OAQPS 
Staff Paper, EPA-452/R-05-005). September 15, 2005. http://www.epa.gov/sab/panels/casacpmpanel.html.
    Henderson, R. Letter from Dr. Rogene Henderson, Chair, Clean Air 
Scientific Advisory Committee to the Honorable Stephen L. Johnson, 
Administrator, U.S. EPA. Clean Air Scientific Advisory Committee 
Recommendations Concerning the Proposed National Ambient Air Quality 
Standards for Particulate Matter. March 21, 2006. http://www.epa.gov/sab/pdf/casac-ltr-06-002.pdf.
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    As noted in section VI.A of the preamble to the NAAQS revisions 
published elsewhere in this Federal Register, EPA recognizes that the 
FRM, while providing a good standard of performance for comparison to 
other methods, is not itself optimal for routine use in 
PM<INF>10-2.5</INF> monitoring networks. Alternative methods are needed 
that provide a more direct measurement of ambient PM<INF>10-2.5</INF> 
concentrations. Methods are also needed that collect samples of 
PM<INF>10-2.5</INF> that are more physically separated for analysis of 
chemical species. Also, automated, continuous-type methods provide many 
operational advantages to ease monitoring burdens, reduce on-site 
service requirements, and eliminate off-site sample filter support 
services, as well as to provide measurement resolution of 1 hour or 
less and near real-time reporting of monitoring data. Therefore, EPA is 
interested in encouraging the development of alternative monitoring 
methods for PM<INF>10-2.5</INF> by focusing on the explicit test and 
qualification requirements necessary for designation of such types of 
methods as FEMs for PM<INF>10-2.5</INF>. In fact, EPA anticipates that 
alternative FEMs will eventually provide most of the 
PM<INF>10-2.5</INF> monitoring data obtained in the States' monitoring 
networks.
    Further, EPA recognizes that the potential benefits of automated/
continuous monitoring methods apply as well to FEMs for 
PM<INF>2.5</INF>. Accordingly, as proposed, EPA is also establishing 
new requirements in part 53 for designation of continuous FEMs for 
PM<INF>2.5</INF>. See 71 FR 2721. The PM<INF>2.5</INF> and 
PM<INF>10-2.5</INF> FEM provisions parallel each other in many respects 
so inclusion now is both appropriate and conforming.
    The new requirements for approval of automated/continuous FEMs can 
accommodate a wide range of potential PM<INF>10-2.5</INF> or 
PM<INF>2.5</INF> continuous measurement technologies. Ambient air 
testing of a candidate technology at diverse monitoring sites is 
required in order to demonstrate that the level of comparability to 
collocated Federal reference method measurements is adequate to meet 
established data quality objectives (DQOs).
    This final rule also modifies somewhat certain existing 
requirements for designation of alternative, non-continuous methods for 
PM<INF>2.5</INF>. As explained in section IV.B of this preamble, the 
modified requirements will be fully consistent with the more advanced 
new requirements for both continuous and non-continuous FEMs for 
PM<INF>10-2.5</INF>.

B. Requirements for Candidate Reference Methods for PM10-2.5

    No comments were received related specifically to the 
PM<INF>10-2.5</INF> FRM designation requirements. These provisions are 
adopted as proposed. Because of the nearly complete similarity between 
the specifications for the new PM<INF>10-2.5</INF> reference method and 
for the existing PM<INF>2.5</INF> reference method, the designation 
requirements for PM<INF>10-2.5</INF> reference methods are essentially 
the same as those for PM<INF>2.5</INF> reference methods. As set forth 
in the new appendix O to 40 CFR part 50, the PM<INF>10-2.5</INF> 
reference method specifies a pair of samplers consisting of a 
conventional PM<INF>2.5</INF> sampler and a special PM<INF>10</INF> 
sampler. The PM<INF>2.5</INF> sampler must meet all requirements for a 
PM<INF>2.5</INF> reference method in 40 CFR part 50, appendix L, as 
well as additional requirements in part 53. However, the 
PM<INF>10</INF> sampler required by the method is not a conventional 
PM<INF>10</INF> sampler as described in 40 CFR part 50, appendix J; 
rather, it is a sampler specified to be identical to the 
PM<INF>2.5</INF> sampler of the pair, except that the PM<INF>2.5</INF> 
particle size separator is removed. This special PM<INF>10</INF> 
sampler is identified as a ``PM<INF>10c</INF>'' sampler to 
differentiate it from conventional PM<INF>10</INF> samplers that meet 
the less exacting requirements of 40 CFR part 50, appendix J. In view 
of the similarity of the PM<INF>10-2.5</INF> FRM requirements to those 
of the PM<INF>2.5</INF> FRM, the new requirements will allow a 
PM<INF>10-2.5</INF> sampler pair consisting of samplers that have 
already been shown to meet the PM<INF>2.5</INF> FRM requirements 
(except for the PM<INF>2.5</INF> particle size separator in the case of 
the PM<INF>10c</INF> sampler) to be designated as a PM<INF>10-2.5</INF> 
reference method without further testing.

C. Requirements for Candidate Equivalent Methods for PM<INF>2.5</INF> 
and PM10-2.5

    As pointed out in the preamble to the proposed rule (71 FR 2721), 
EPA believes very strongly that provisions to allow designation of 
Federal equivalent methods provide an important incentive to encourage 
the commercial development of innovative new and advantageous 
alternative methods for monitoring air pollutants. However, it is also 
important to show conclusively that any new candidate method will 
produce measurements comparable to those of the FRM and will have 
performance characteristics that are adequate to meet DQOs. At the same 
time, the testing that is necessary to show comparable and adequate 
performance must not be so burdensome that it undermines incentives for 
new method development.
    Because of the complex nature of particulate matter, it is also 
complex to test the performance of PM monitoring methods. For methods 
for PM<INF>2.5</INF>, EPA defined three classes of candidate FEMs 
(Classes I, II, and III) based on the extent to which the method 
differs from the FRM, so that the nature and extent of the performance 
and comparability testing necessary can be more closely matched to the 
nature of the candidate method. See 40 CFR 53.3(a)(2)-(4). In this 
final rule, as proposed, EPA is extending these same class definitions 
and tiered testing requirements to apply to PM<INF>10-2.5</INF> 
candidate FEMs as well.
    Class I methods are limited to minor deviations from the FRM; Class 
II covers

[[Page 61245]]

integrated-sample, filter-based, gravimetric methods deviating more 
significantly from the FRM; and Class III methods (originally) included 
all other methods not categorized as Class I or II. The three classes 
are described in more detail in the proposal preamble (71 FR 2721). As 
proposed, the definition of Class III FEMs is narrowed to include only 
continuous or semi-continuous analyzer methods having 1-hour or less 
measurement resolution, which are the Class III methods that by far 
hold the most potential for monitoring applications and FEM 
designation. The EPA has thus avoided the restrictions and complexity 
that would be necessary to accommodate the wide variety of other types 
of non-Class I or II methods that are unlikely to be economically and 
commercially practical. Also, the continuous operational nature of such 
Class III methods gives rise to a statistical advantage that allows 
more tolerant limits of adequate comparability, relative to a method 
that is not operated continuously, to achieve a similar limit of 
uncertainty in the monitoring data.
    Class III continuous methods appear to offer many potential 
benefits for use in routine field monitoring networks. These automated 
analyzers eliminate most, if not all, of the pre- and post-weighing of 
sample filters, require less frequent on-site service, may be less 
costly to operate, and offer near real-time, electronic reporting of 
hourly (or less) mass concentration measurements (similar to data 
reporting that is common for gaseous pollutant monitors). The EPA is 
accordingly adopting the proposed Class III FEM provisions for 
PM<INF>10-2.5</INF> and PM<INF>2.5</INF> in today's rule, with some 
changes in response to comments.
    Continuous methods, by nature, tend to have somewhat different 
performance characteristics from those of the corresponding filter-
based FRMs, so the comparability and performance testing requirements 
must be adequately comprehensive and discriminating without being 
excessively burdensome. The Class III FEM requirements being 
promulgated today are based predominantly on demonstrating an adequate 
degree of comparability between candidate method measurements and 
concurrent, collocated Federal reference method measurements under a 
representative variety of site conditions. Many issues and much 
technical input were carefully considered during the development of the 
requirements, including peer review by the Ambient Air Monitoring and 
Methods Subcommittee of the Clean Air Scientific Advisory Committee. 
The salient Class III FEM requirements were summarized in the proposal 
preamble (71 FR 2722-2724). Not unexpectedly, a considerable number of 
comments were received in connection with the specifics of the proposed 
Class II and Class III requirements. The more significant of these 
comments are addressed below, after a summary of the proposal regarding 
requirements for Class II and Class III methods. Remaining comments are 
addressed in the Response to Comments document.
    Class II candidate FEMs, although not offering the operational 
advantages of continuous Class III methods, are nevertheless important 
as well. Class II methods encompass the dichotomous and virtual 
impactor types of methods that can provide a more direct, gravimetric, 
filter-based measurement of PM<INF>10-2.5</INF> than available with the 
FRM. These methods are also most likely to fulfill the substantial need 
for collecting PM<INF>10-2.5</INF> samples that are physically 
separated from other particle sizes, or nearly so, for chemical species 
analysis. New requirements for Class II FEMs for PM<INF>10-2.5</INF> 
are being established in this final rule, and some of the previously 
established requirements for Class II FEMs for PM<INF>2.5</INF> are 
being changed somewhat to make them more consistent with the 
corresponding new requirements for PM<INF>10-2.5</INF> Class II FEMs 
and to incorporate some minor technical improvements.
    The proposed Class II FEM requirements, as outlined in the proposal 
preamble (71 FR 2721-2725), were based on daily sampling; therefore, 
Class II equivalent methods used for determining compliance with the 
PM<INF>2.5</INF> NAAQS would generally have been restricted to daily 
sampling. However, in response to concerns about method performance in 
relatively clean areas, EPA has strengthened the additive bias 
(intercept) requirement. With this tighter performance criteria and 
considering that Class II methods are filter-based samplers, a minimum 
of a one-in-three day sample frequency will be appropriate to meet the 
network data quality objectives. Class II methods are also expected to 
be used for collecting samples used in chemical species analysis, which 
would not require daily operation. The character of the test sites 
specified for Classes II and III tests for both PM<INF>2.5</INF> and 
PM<INF>10-2.5</INF> are similar, so concurrent testing for 
PM<INF>2.5</INF> and PM<INF>10-2.5</INF> methods of both classes can be 
carried out, substantially reducing the testing burden for candidate 
FEMs that measure both PM<INF>2.5</INF> and PM<INF>10-2.5</INF> or for 
testing multiple candidate methods simultaneously.
    Of particular note to instrument manufacturers, this final rule 
allows applications for Class II candidate FEMs for both 
PM<INF>10-2.5</INF> and PM<INF>2.5</INF> to optionally substitute the 
more extensive Class III comparability field tests in subpart C for 
some or all of the rather extensive and arduous laboratory wind tunnel 
tests, loading test, and volatility test of subpart F to which a Class 
II candidate FEM sampler may otherwise be subject. Such a substitution 
of test results may be particularly important when the special 
facilities necessary for the wind tunnel tests or other tests are not 
available. Concurrent testing of multiple methods under the Class III 
requirements may also help to reduce overall testing costs.
    In regard to the proposed testing requirements for Class III 
(continuous) FEMs for PM<INF>2.5</INF> and PM<INF>10-2.5</INF>, EPA 
specifically solicited comments related to the adequacy of the number 
and location of the test sites required for the field tests to 
determine comparability of a candidate method to the respective FRM. 
See 71 FR 2722. By definition, a designated FEM is generally qualified 
for use at any monitoring site in the U.S. (with the possible exception 
of some areas with extreme conditions), so the test requirements for 
comparability need to represent a wide variety of possible site 
conditions. The EPA proposed that candidate methods be tested within 
three general geographical areas: (1) The Los Angeles area in winter 
and summer seasons, (2) eastern U.S. in winter and summer, and (3) 
western U.S. in winter only (for a total of five 30-day test 
campaigns). Each proposed test site area was selected for representing 
particular and diverse typical site conditions.
    In response to several comments addressing this issue, a fourth 
test site--in the U.S. Midwest, with tests required in the winter 
season only--has been added to the requirements to further increase the 
geographical diversity. However, the requirement for a winter test 
campaign in the eastern U.S. has been withdrawn while the requirement 
for a summer test campaign in the eastern U.S. has been retained, so 
the total number of required test campaigns (five) is unchanged. 
Comparability testing of a candidate method is costly, rendering it 
impractical to test a candidate method under all possible combinations 
of site and seasonal conditions that might be encountered in national 
PM monitoring networks. The EPA considers the specified complement of 
five test campaigns in the four specified geographical areas and two 
seasons to be reasonable to conduct and adequately representative of 
the diversity of site and seasonal PM

[[Page 61246]]

monitoring conditions across the U.S. As noted above, the two test site 
areas specified for testing candidate Class II FEMs are compatible with 
the test sites for candidate Class III methods, which will 
significantly reduce testing costs by allowing Class II and III 
candidate methods to be tested simultaneously at the same test site. 
Also, the test sites have been relabeled for ease of referencing east 
and west sites.
    Some commenters expressed concern that the Class III comparability 
test standards might be inadequate because a candidate method that had 
an unacceptable seasonal bias (such as has been noted for some 
continuous methods) could be found acceptable, because in pooling test 
data from summer and winter seasons the biases would compensate. The 
EPA finds that the associated minimum correlation requirement of the 
regression test should adequately avoid that situation. Further, in the 
revised test requirements, summer and winter tests at the same site, 
where the data are pooled, are required at only one of the four 
required tests sites.
    Another issue concerning the proposed testing requirements for 
Class III (continuous), as well as Class II candidate equivalent 
methods for PM<INF>2.5</INF> and PM<INF>10-2.5</INF>, was the specific 
acceptance criteria for the regression analysis statistics--
particularly the additive bias (intercept) parameter--of the comparison 
between collocated measurements obtained with the candidate and FRM 
methods. As proposed, the upper and lower limits for the regression 
intercept were specified as functions of the corresponding slope, with 
the acceptable combinations of slope and intercept represented by the 
area inside a trapezoid or a hexagon shape plotted on a slope-intercept 
coordinate system (Figures C-2 and C-3 in proposed revised subpart C of 
part 53 at 71 FR 2768-2769). These acceptance limits were based on 
statistical considerations related to the uncertainty allowable in 
making correct NAAQS attainment decisions for PM<INF>2.5</INF> (or 
similar comparisons of PM<INF>10-2.5</INF> concentrations to non-
regulatory benchmarks). Several commenters were concerned that the 
range of acceptable intercepts proposed for Class II and III FEMs, 
although appropriate for DQOs related to attainment (or similar) 
decisions, may allow excessive measurement bias for FEMs used for other 
PM monitoring applications--especially those applications that require 
measurements of concentrations well below the level of the NAAQS.
    In response to these comments and in deference to potential use of 
FEMs for a variety of applications, EPA has somewhat strengthened the 
range of allowable intercepts for those candidate FEMs. For Class III 
FEMs, new fixed limits of <plus-minus>2.0 [mu]g/m<SUP>3</SUP> for 
PM<INF>2.5</INF> methods and <plus-minus>7.0 [mu]g/m<SUP>3</SUP> for 
PM<INF>10-2.5</INF> methods have been added. For Class II FEMs for 
PM<INF>10-2.5</INF>, the fixed intercept limit has been reduced from 
<plus-minus>7.0 to <plus-minus>3.5 [mu]g/m<SUP>3</SUP>. (The intercept 
requirements proposed for candidate Class II PM<INF>2.5</INF> methods 
were re-examined and found to be appropriate as proposed.) The more 
restrictive intercept limits will reduce the maximum allowable 
measurement bias and are represented by smaller hexagonal acceptance 
areas, as specified in 40 CFR part 53, subpart C revised Table C-4 and 
as illustrated in revised Figures C-2 and C-3 of this final rule.
    Nevertheless, EPA wishes to point out that, because of the design 
of the equivalent method comparability tests (which require no low-
level test concentrations) and the nature of the regression analysis, a 
seemingly high positive or negative intercept resulting from the 
regression analysis of the test data is not necessarily indicative or 
likely to be characteristic of the actual measurement errors or bias of 
the candidate method relative to the FRM at low or very low 
concentrations. This situation may be particularly true when the 
concentration coefficient of variation (CCV) for the FEM test data (see 
40 CFR 53.35(h)) is relatively low, resulting in greater uncertainty in 
the predicted additive bias (and in the multiplicative bias (slope) as 
well).
    Class III FEMs will generally provide 1-hour concentration 
measurements (in addition to the required 24-hour measurements), and 
EPA asked for comments on whether the FEM provisions should include any 
specific requirements for 1-hour precision, and if so, whether a 
specific standard of performance should be specified and how it should 
affect FEM designation. See 71 FR 2723. Of the few comments received on 
this issue, most agreed with EPA that 1-hour precision is an important 
descriptor associated with a Class III candidate method and that 1-hour 
FEM test data should be submitted in a Class III FEM application so 
that the short-term precision can be determined, but no specific 
standard should be set for the precision parameter in connection with 
the FEM designation qualifications. A few commenters suggested that a 
precision performance parameter based on a running average of a few 
(e.g., 3 to 5) hours should be established and regulated, however, to 
preserve flexibility, EPA believes that precision estimates are better 
included in method-specific quality assurance guidance (to be used by 
instrument operators as they believe appropriate) rather than as a 
formal part of the FEM provisions. Therefore, no changes were made to 
the proposed requirement that FEM applicants submit the 1-hour FEM test 
data, and there is no designation requirement based on 1-hour precision 
or any other particular 1-hour based performance statistic.
    The EPA also asked for comments on the adequacy and appropriateness 
of the proposed test requirements for Class II FEMs. See 71 FR 2724. 
Some commenters suggested that the proposed Class II tests were 
inadequate because there was more variation in the PM at different 
sites than could be represented in the tests--particularly in regard to 
chemical compositions--and suggested that continued FEM designation 
should be conditioned on a mandatory periodic reassessment of local-
agency comparisons to FRM measurements. The EPA recognizes that data 
produced by all FEMs operated in monitoring networks under 40 CFR part 
58 should meet the data quality objectives (DQOs) of 40 CFR part 58, 
appendix A, section 2.3.1 on a continuing basis. The operational 
requirements of appendix A will help ensure this. Moreover, EPA can 
invoke designation cancellation procedures for the method designation 
under 40 CFR 53.11 (Cancellation of reference or equivalent method 
designation) if EPA observes that DQOs are not being maintained for a 
particular designated Class II equivalent method (or for any FEM or 
FRM). However, EPA believes that designation cancellation should be 
initiated by EPA when necessary, rather than have designations 
conditioned on specific periodic reassessments as commenters suggested. 
Other commenters suggested that the test sites be approved by both EPA 
and the STAPPA/ALAPCO Monitoring Committee, but EPA believes that would 
be cumbersome and unnecessary.

D. Other Changes

    EPA proposed several other relatively minor changes to various 
provisions of subparts A, C, E, and F of part 53. See 71 FR 2724-2725. 
Organizational changes in subpart C consolidate the provisions for 
various types of methods, making them easier to understand. Other 
changes clarify or simplify some existing provisions for 
PM<INF>10</INF> and PM<INF>2.5</INF> Class I and II FEM testing and 
implement minor technical improvements to test protocols, with little, 
if any, impact on the nature or efficacy of the tests. Minor changes 
are made to subparts A, E, and F to incorporate the new 
PM<INF>10-2.5</INF> provisions and some new definitions,

[[Page 61247]]

make a few administrative adjustments, and incorporate a few minor 
technical changes. These changes are described more completely in the 
proposal preamble (71 FR 2724), and they are being adopted as proposed, 
as no comments were received pertinent to these minor changes.
    After considering all comments carefully, EPA determined that no 
further changes should be made to the proposed new or revised FRM and 
FEM requirements. The EPA is thus adopting the proposed new or revised 
requirements and provisions for Federal reference and Federal 
equivalent methods for PM<INF>2.5</INF> and PM<INF>10-2.5</INF>, 
modified to incorporate the changes described above.

V. Discussion of Regulatory Revisions and Major Comments on Proposed 
Amendments to 40 CFR Part 58

A. Overview of Part 58 Regulatory Requirements

    Part 58 of 40 CFR, Ambient Air Quality Surveillance, contains 
requirements for ambient air monitoring programs operated by States (or 
designated local agencies). As proposed, the structure of part 58 
remains much the same as the 1997 version. Proposed subparts A through 
G, containing 40 CFR 50.1 through 50.61, provide definitions of terms; 
require the operation of certain numbers and types of monitors by 
certain dates; require the use of certain monitoring methods, quality 
system practices, and sampling schedules and frequencies; require 
annual plans describing a State's monitoring network and planned 
changes to it; provide criteria for EPA approval of planned changes; 
require data submission and certification that submitted data is 
accurate to the best of the knowledge of responsible State official; 
address special rules regarding special purpose monitors; provide rules 
for comparing monitoring data to applicable National Ambient Air 
Quality Standards (NAAQS); require reporting of the Air Quality Index 
(AQI) to the public in some areas; and provide for monitoring directly 
by EPA if a State fails to operate required monitors. As proposed, part 
58 also includes appendices A, C, D, E, and G which were referenced by 
various numbered sections in subparts A through G. These appendices 
contain many detailed requirements, as well as considerable explanatory 
or background material and non-binding advice. Appendix A addresses 
quality system requirements, appendix C addresses monitoring methods 
and equipment, appendix D mostly addresses the number of required 
monitors and their placement within a metropolitan or other area, 
appendix E addresses the details of monitoring station layout, and 
appendix G addresses AQI reporting. (Subpart B of the 1997 version was 
proposed to be removed. Subpart F was already reserved in the 1997 
version. No amendments were proposed to the part 58 requirements for 
reporting of the AQI and the associated appendix G.)
    To aid in understanding the provisions of the final part 58 and 
their relationship to the 1997 and proposed provisions, the following 
discussion for the most part follows the order of the final part 58, 
addressing each affected numbered section and then the appendices.

B. General Monitoring Requirements

1. Definitions and Terminology
    The EPA proposed to discontinue the use of the term ``National air 
monitoring stations (NAMS)''. See 71 FR 2720. Previously, this term was 
used to designate Federal reference method (FRM) and Federal equivalent 
method (FEM) monitors which were operated to meet set requirements for 
the number (and, for some pollutants the type of location) of monitors 
and which required EPA Administrator approval for changes, as 
distinguished from ``State and local air monitoring stations (SLAMS)'' 
which referred to additional FRM and FEM monitors for which generally 
there was no minimum number, for which siting was more at the State's 
discretion, and for which changes were approved by the Regional 
Administrator.
    The EPA proposed a new definition for ``National Core (NCore)'' 
stations.
    The definition of ``State or local air monitoring stations 
(SLAMS)'' was proposed to be modified to include NCore, Photochemical 
Air Monitoring Systems (PAMS), and all other State or locally operated 
stations (such as PM<INF>2.5</INF> speciation stations) that have not 
been designated as a special purpose monitor or monitoring station 
(SPM). This change was proposed for convenience in referencing these 
types of monitors together because some provisions in the rule apply to 
all of them but not to SPMs. See 71 FR 2720. Previously, ``SLAMS'' 
referred only to FRM and FEM monitors.
    The term, ``Approved regional methods'' (ARMs), proposed at 71 FR 
2720, is added to refer to alternative PM<INF>2.5</INF> 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 FEM for nationwide use.
    The EPA proposed to adopt a new term, ``Primary quality assurance 
organization'' to clarify the working definition of the term 
``Reporting organization'' currently utilized in section 3.0.3. of 40 
CFR part 58, appendix A, Quality Assurance Requirements, and to avoid 
confusion with the different way ``reporting organization'' has come to 
be used in a related but distinct context (final uploading of data to 
the Air Quality System). See 71 FR 2778.
    The EPA also proposed additional definitions to be consistent with 
terminology used in 40 CFR part 50, appendix O, the FRM for 
PM<INF>10-2.5</INF>. See 71 FR 2777. Modifications to the definitions 
of key geographical terms were proposed, as needed, to reflect changes 
in U.S. Census Bureau usage since the last revision to monitoring 
regulations.
    The EPA received some questions seeking clarification of the new 
term ``Primary quality assurance organization,'' which are addressed in 
the Response to Comments document available in the docket. No other 
adverse comments were received on these proposed definitions, and this 
final rule includes all of them.
2. Annual Monitoring Network Plan and Periodic Network Assessment
    The EPA proposed to consolidate current requirements for the SLAMS 
air quality surveillance plan and NAMS network description into 
elements of the annual monitoring network plan described in 40 CFR 
58.10 of the proposed rule. See 71 FR 2725. The annual monitoring 
network plan would provide a statement of purpose for each monitor in a 
monitoring agency network and provide evidence that siting and 
operation of each monitor meet the requirements of appendices A, C, D, 
and E of part 58, as applicable. The EPA also proposed the addition of 
some required elements to the annual monitoring network plan and 
proposed to add a new requirement for a periodic network assessment.
    The EPA received comments on a number of specific elements within 
the annual monitoring network plan and with regard to the network 
assessment requirement. The comments that were the basis for 
modifications to the proposed rule are discussed briefly here. Detailed 
responses to all comments are provided in the Response to Comments 
document available in the docket.
    Comments were received on the proposed requirement for a 30-day

[[Page 61248]]

public inspection period before State submittal of a draft annual 
monitoring network plan to the Regional Administrator as well as on the 
proposed requirement for Regional Administrator approval of annual 
monitoring network plans seeking SLAMS network modifications including 
new monitoring sites. Some commenters requested clarification regarding 
what methods would be considered acceptable for making documents 
available for public inspection. Commenters also expressed concern that 
the 120 days proposed for Regional Administrator review and approval/
disapproval would result in unnecessary delays.
    The EPA notes the general support in the comments for the public 
inspection requirement. Commenters also supported the flexibility in 
the proposed rule which would allow monitoring agencies to design and 
implement appropriate ways of allowing this inspection. The EPA 
supports use of monitoring agency Web sites for such postings, along 
with other means of providing public notice including hard-copy posting 
in libraries and public offices. Although the public inspection 
requirement does not specifically require States to obtain and respond 
to received comments, such a process is encouraged with the subsequent 
transmission of comments to the appropriate EPA Regional Office for 
review. Therefore, EPA has modified this final rule from the proposal 
to specify that where the State has provided for a public comment 
process and provided any comments received to EPA, and the posted plan 
has not been substantially altered as a result of the public comments, 
the requirement for the Regional Administrator to obtain public comment 
by a separate process can be waived. The 120 days allowed for Regional 
Administrator review of an annual plan is a feature of the current 
monitoring rule, and has been kept in this final rule.
    The EPA received many comments on the proposed requirement for the 
annual monitoring network plan to contain cost information. See 71 FR 
2780. Commenters were concerned that no details were provided regarding 
what information would be required and how the information would be 
used. The accounting difficulty in calculating such cost information 
was also noted along with concerns regarding the administrative burden 
of preparing and documenting the cost estimates.
    The EPA has considered the proposed requirement for cost 
information in the annual monitoring network plan and agrees that 
considerable effort would be needed to develop guidance to standardize 
the development of financial information and for States to collect and 
summarize the information for submittal. Without such standardization, 
cost information would be difficult to interpret. In view of these 
comments, EPA has deleted this element from the list of required 
information to be contained in the annual monitoring network plan.
    The EPA proposed a new requirement that the annual monitoring 
network plan consider the ability of existing and proposed sites to 
support air quality characterization for areas with relatively high 
populations of susceptible individuals (e.g., children with asthma), 
and, for any sites that are being proposed for discontinuance, the 
effect on data users other than the agency itself, such as nearby 
States and Tribes or health effects studies. See 71 FR 2780. Several 
commenters noted that this requirement would be challenging to 
implement and involves knowledge of public health that may not be 
readily available to monitoring organizations. In addition, it was 
noted that, absent the availability of a centralized information 
clearinghouse, it would be difficult for States to be aware of all 
possible users of data for health studies or other types of research.
    This new element of the annual monitoring network plan highlights 
the importance that EPA places on the consideration of sensitive 
populations when evaluating the relative value and representativeness 
of monitoring sites, particularly for areas where one or more NAAQS may 
be approached or exceeded.\10\ The EPA acknowledges the potential 
challenge in obtaining information about the distribution of 
susceptible individuals in specific geographic areas around existing 
and proposed sites, and has purposely defined the requirement as a 
``consideration'' to provide significant latitude for monitoring 
organizations to determine the complexity and depth of their response. 
In recognition of the potential complexity of preparing assessments of 
susceptible populations on a sub-county sized spatial scale as 
represented by typical monitoring sites, in this final rule EPA has 
moved this requirement to become a required element of the 5-year 
network assessment rather than the annual monitoring network plan.
---------------------------------------------------------------------------

    \10\ See S. Rep. No. 91-1196. 91st Cong. 2d Sess. 10 (1970) 
(NAAQS is to be set to protect sensitive, at-risk population 
groups).
---------------------------------------------------------------------------

    With regard to the proposed provision requiring States to consider 
the effect on data users of proposed actions to discontinue sites, EPA 
notes that States are already required to make their annual network 
monitoring plans available for public inspection and that process 
provides the basic framework for disseminating information about 
anticipated site discontinuations. The EPA recognizes that there are 
many potential users of air quality information and that States cannot 
be aware of all such users. However, to the extent that information 
about site shutdowns can be disseminated more widely, there are 
benefits to be gained by protecting key monitors that (for example) 
support ongoing health studies or that are the basis for long-term 
trend analyses, or otherwise provide information that is used by 
stakeholders other than the operating agency. As such, EPA has retained 
this provision in this final rule. The EPA will work with States and 
health organizations to explore options for tracking the status of key 
air quality sites.
    The EPA received many comments in response to the proposed 
requirement for a network assessment to be completed every 5 years and 
to be submitted with the required annual network monitoring plan. 
Commenters acknowledged the overall value of a more complete evaluation 
of monitoring programs but expressed concern about the resource burden 
in meeting the requirement.
    Network assessments are a key tool to help ensure that the right 
parameters are being measured in the right locations, and that 
monitoring resources are used in the most effective and efficient 
manner to meet the needs of multiple stakeholders. Network assessments 
can help identify new data needs and associated technologies, find 
opportunities for consolidation of individual sites into multi-
pollutant sites, and identify geographic areas where network coverage 
should be increased or decreased based on changes in population and/or 
emissions. The EPA has already issued draft guidance to describe the 
possible techniques that States can use in developing their 
assessments, and has purposely limited the required elements to provide 
flexibility in the amount of resources that would be required. After 
consideration of the comments, EPA has retained the network assessment 
requirement in this final rule. In light of the concerns raised about 
the resource requirements needed to complete network assessments, the 
deadline for the first required assessment under this final rule has 
been delayed an additional year to July 1, 2010.
    The EPA is not adopting the proposed requirement for a separate 
plan

[[Page 61249]]

establishing a network of PM<INF>10-2.5</INF> stations as an addendum 
to the annual monitoring network plan (see 71 FR 2740, 2779) since the 
only required PM<INF>10-2.5</INF> monitoring will take place as part of 
the NCore multi-pollutant stations, already covered by the proposed 
plan due July 1, 2009. The EPA has added clarifying language to this 
final rule requiring Administrator approval for the NCore plan due July 
1, 2009 and subsequent annual monitoring network plan elements 
proposing modifications, consistent with the requirement for 
Administrator approval of NCore stations in section 3(a) of appendix D.
    The proposed plan element supporting PM<INF>10-2.5</INF> 
suitability tests for NAAQS comparisons likewise is not being adopted 
since EPA is not finalizing the proposed PM<INF>10-2.5</INF> NAAQS.
    The proposed prescriptive wording with reference to public hearings 
in the context of reviews of changes to violating PM<INF>2.5</INF> 
monitors and/or community monitoring zones (71 FR 2780) has been 
modified to specify that draft plans containing such proposed changes 
to PM<INF>2.5</INF> networks must be made available for public 
inspection and comment by States prior to submission to the EPA 
Regional Administrator but that States can design the process for 
achieving such goals.
3. Operating Schedules
    The EPA proposed that manual PM<INF>2.5</INF> monitors at SLAMS be 
required to operate on a 1-in-3 day sampling frequency, except under 
certain conditions and when approved by the Regional Administrator. See 
71 FR 2780. As discussed in section II.E.1 of the preamble to the final 
revisions to the PM NAAQS, published elsewhere in this Federal 
Register, commenters pointed out a potential bias in the method used to 
calculate the 98th percentile form of the 24-hour PM<INF>2.5</INF> 
NAAQS. As explained there, to avoid this potential bias, EPA is 
requiring daily sampling at design value sites that are within 5 
percent of the 24-hour NAAQS for PM<INF>2.5.</INF>
    The EPA proposed that manual PM<INF>10-2.5</INF> samplers at SLAMS 
stations must operate on a daily schedule, without a requirement for 
any collocated continuously operated FEM PM<INF>10-2.5</INF> samplers. 
See 71 FR 2780. Numerous commenters noted that a 1-in-3 day sampling 
frequency was acceptable for PM<INF>2.5</INF> sites and said that the 
same sampling frequency for PM<INF>10-2.5</INF> would produce 
sufficient data for comparison to the proposed 24-hour 
PM<INF>10-2.5</INF> NAAQS averaged over 3 years. Commenters also noted 
the lack of currently available continuous FEM PM<INF>10-2.5</INF> 
instruments and the burdensome resource requirements associated with 
daily sampling requirements using the proposed filter-based FRM.
    The proposed requirement for daily PM<INF>10-2.5</INF> sampling was 
based on a data quality objective system analysis that identified such 
a frequency as being a key factor in reducing statistical uncertainty 
at concentrations near the level of the proposed 24-hour 
PM<INF>10-2.5</INF> NAAQS. Since EPA is not finalizing a 
PM<INF>10-2.5</INF> NAAQS but instead is requiring a more limited set 
of PM<INF>10-2.5</INF> monitors at NCore sites to support objectives 
other than and (obviously) not including NAAQS compliance, additional 
flexibility in sampling frequency requirements is appropriate. Although 
daily sampling of PM<INF>10-2.5</INF> at NCore sites remains a 
desirable outcome, and will become a more practical goal with the 
advent of continuous FEM monitors in several years, EPA has reduced the 
PM<INF>10-2.5</INF> sampling frequency requirement in this final rule 
to 1-in-3 days.
    The EPA proposed reducing the sample frequency requirement for 
PM<INF>10</INF> manual methods. Reducing the sample frequency for 
PM<INF>10</INF> was possible since EPA had proposed to have daily 
sampling of PM<INF>10-2.5</INF> to support protection from thoracic 
coarse particles. As published elsewhere in today's Federal Register, 
EPA is retaining the 24-hour PM<INF>10</INF> standard and not 
finalizing a PM<INF>10-2.5</INF> standard. The EPA is also only 
finalizing a limited network of PM<INF>10-2.5</INF> monitors at multi-
pollutant NCore stations for scientific purposes. Therefore, since the 
existing requirement for PM<INF>10</INF> sample frequency is for daily 
sampling for the site with the expected maximum concentration in each 
area, and previous assessments of the 24-hour standard demonstrates 
that maximizing sample frequency will minimize decision errors, EPA is 
retaining the existing daily sample frequency requirement for the site 
with expected maximum concentration in each area. This existing 
requirement also allows for other sites in the same area to operate on 
a 1-in-6 day sample frequency. Sample frequency relief is possible for 
expected maximum concentration sites that are significantly away from 
the 24-hour PM<INF>10</INF> NAAQS and in seasons exempted by the 
Regional Administrator.
4. Monitoring Network Completion for PM<INF>10-2.5</INF> and NCore 
Sites
    The proposed requirement for specified numbers of 
PM<INF>10-2.5</INF> sites to be physically established no later than 
January 1, 2009 is not included in this final rule. However, by January 
1, 2011, States must implement the less extensive monitoring for 
PM<INF>10-2.5,</INF> including speciation sampling, as part of the 
generally-applicable requirement to operate NCore multipollutant 
monitoring stations by that date. A plan for the implementation of the 
required NCore multipollutant monitoring stations, including site 
selection, is due July 1, 2009.
    Little comment was received on the requirement for the NCore 
multipollutant sites to be physically established no later than January 
1, 2011, and that requirement remains unchanged in this final rule as 
EPA continues to believe that this is practical and desirable.
5. System Modifications
    In part, EPA started this rulemaking based on the recognition by 
EPA and leaders of State and local monitoring agencies that State/local 
monitoring networks should be modified to reduce some types of 
monitoring activity in some areas and to begin new types of monitoring. 
The EPA proposed rule changes to revise the minimum required number of 
monitors for ozone (O<INF>3</INF>), PM<INF>2.5</INF>, lead (Pb), and 
PAMS pollutants and to eliminate altogether the minimum number of 
required monitors for carbon monoxide (CO), sulfur dioxide 
(SO<INF>2</INF>) and nitrogen dioxide (NO<INF>2</INF>) in order to 
utilize scarce resources more productively by allowing for reductions 
in the number of monitoring sites where appropriate. See 71 FR 2729.
    The EPA stated in the proposal that the remaining requirements for 
the minimum number of monitors for Pb, PM<INF>2.5,</INF> and 
O<INF>3</INF> were intended to be necessary but not always sufficient 
to meet the requirements in section 110(a)(2)(B) of the Clean Air Act 
(CAA) that State implementation plans (SIPs) provide for operation of 
appropriate systems to monitor, compile, and analyze data on ambient 
air quality. Similarly, although EPA believes that one-size-fits-all 
rules for the number of CO, SO<INF>2</INF>, and NO<INF>2</INF> monitors 
are no longer appropriate in light of the rarity of NAAQS violations 
for those pollutants, EPA believes that some monitoring should be 
continued in many areas for these pollutants. Accordingly, EPA proposed 
to continue to require States to propose changes in their monitoring 
networks, including discontinuation of monitors, and obtain EPA 
approval before making changes, even when the remaining minimum 
requirements, if any, for number of monitors would still be met after 
the

[[Page 61250]]

changes. The EPA approval would be given by the Regional Administrator, 
usually through approval of the annual monitoring network plan, except 
for changes involving NCore sites, PAMS sites, and PM<INF>2.5</INF> 
speciation trends sites which would require Administrator approval.
    While local situations need to be considered individually, EPA 
proposed six criteria for approval of requests to discontinue monitors. 
See 71 FR 2749. To summarize, the six criteria addressed: (1) Any 
monitor which could be shown to have a low probability of future 
violations; (2) a CO, PM<INF>10</INF>, SO<INF>2</INF>, or 
NO<INF>2</INF> monitor that has been reading consistently lower than 
another monitor in the same area; (3) any highest reading monitor that 
has not indicated any NAAQS violation in the previous 5 years and for 
which the approved SIP provides for an alternative to continued 
monitoring; (4) any monitor which cannot be compared to a NAAQS because 
of siting considerations; (5) any monitor designed only to measure 
transport from upwind areas if another transport monitor were replacing 
it; and (6) any monitor for which logistical problems make continued 
operation at the current site impossible. Situations not addressed by 
these criteria would be considered on a case-by-case basis.
    The EPA received a number of comments on the proposed removal of 
the minimum monitoring requirements for some of the criteria 
pollutants, on the revision of the minimum numbers of monitors for 
other criteria pollutants, on the six proposed criteria for 
discontinuing monitors, and on the issue of discontinuing monitors more 
generally, mostly from State and local monitoring agency officials. 
This final rule provisions on minimum numbers of monitors for 
O<INF>3</INF>, PM<INF>2.5</INF>, PM<INF>10</INF>, and Pb are discussed 
in section V.E of this preamble. Comments on the other parts of the 
proposal are addressed here. A few commenters specifically endorsed all 
or part of these proposals, or at least the intention to facilitate 
reductions in unnecessary or duplicative monitoring activities. Most 
commenters expressed concern over the proposals.
    A number of commenters appear to have interpreted the proposals as 
indicators of network reductions EPA intended to require monitoring 
agencies to make, and expressed opposition to such reductions. The EPA 
clarifies here that EPA believes that proposals for network 
modifications should generally be initiated by the monitoring agency; 
EPA does not intend to compel any agency to remove any monitor. The 
proposals related to network modifications, and the provisions in this 
final rule, govern only EPA's consideration of changes which monitoring 
agencies seek to adopt. The EPA recognizes that funding constraints may 
require agencies to discontinue monitors that they otherwise would 
operate, but this reinforces the need for EPA review and the usefulness 
of having criteria for discontinuance to govern that review.
    A few commenters suggested that EPA include in the rule or provide 
via guidance specific formulas or calculation procedures regarding the 
estimation of the probability of a future NAAQS exceedance, which is 
the basis of the first of the six proposed adjudicative criteria. The 
EPA intends to provide guidance on this matter in the future, but we 
believe that binding formulas or procedures in rule form would preclude 
development of better general procedures and the sort of case-specific 
analysis of unique factors that is likely to be appropriate in some 
situations.
    A number of commenters stated that the six proposed criteria were 
overly focused on whether a monitor is providing data for use in making 
comparisons to the NAAQS for purposes of attainment/nonattainment 
findings, and that decisions to remove or retain a monitor should also 
recognize the utility of the monitor in satisfying other required 
monitoring objectives. Section 1 of the proposed appendix D of 40 CFR 
part 58 stated that air monitoring networks must be designed to meet 
three monitoring objectives: (1) Providing air pollution data to the 
public; (2) supporting compliance with ambient air quality standards 
and emission strategy development; and (3) supporting air pollution 
research studies. Some commenters pointed out that EPA has articulated 
in the draft National Ambient Air Monitoring Strategy \11\ seven 
objectives for the NCore multipollutant monitoring stations 
(overlapping in part with the three objectives in section 1 of appendix 
D) and stated that single-pollutant stations should be considered to be 
part of an overall network to meet these objectives. The EPA agrees 
that these two sets of overlapping objectives are important and that 
monitors should not be discontinued without regard to whether these 
objectives will continue to be met, but EPA believes the proposed 
criteria, along with other provisions regarding approval of annual 
monitoring network plans and periodic network assessments, protect the 
required monitoring objectives. The paragraphs below address two 
objectives that were most often mentioned by commenters.
---------------------------------------------------------------------------

    \11\ ``Draft National Ambient Air Monitoring Strategy,'' 
December 2005.
---------------------------------------------------------------------------

    Several commenters stated that ambient monitoring can serve as a 
continuing check on the compliance of a specific source, or sources in 
the aggregate, with applicable emissions limits. The EPA believes that 
given that factors such as wind direction, dispersion conditions, and 
atmospheric reactivity conditions can greatly influence the 
relationship between emissions and ambient concentrations, situations 
are infrequent in which ambient monitoring is a critical, or the most 
important, element of source compliance monitoring. Other EPA rules 
address requirements for direct emissions and compliance monitoring for 
many types of sources. Ambient monitoring agencies will have the option 
of continuing to operate ambient monitors they feel are useful for this 
objective.
    Some commenters stated that the ability to track trends in air 
quality and assess whether those trends are consistent with trends 
expected from the emission control program in general or from specific 
control measures (i.e., accountability) could be impaired if too many 
existing monitors are removed. The EPA believes that tracking trends is 
most important for O<INF>3</INF>, PM<INF>2.5</INF>, and PM<INF>10</INF> 
because these are the NAAQS with more than a few remaining 
nonattainment areas. For these pollutants the revised requirements in 
this final rule for minimum number of monitors, the new requirement for 
NCore multipollutant monitoring stations, and the interest of 
monitoring agencies in continuing these types of monitoring as 
indicated by the comments themselves will, in EPA's opinion, result in 
networks that are appropriately robust for tracking trends and 
assessing causal factors. The EPA believes that the availability of 
multiple collocated and time resolved measurements at NCore sites will 
be a major advantage in this work.
    The Response to Comments document available in the docket explains 
in more detail how the other objectives mentioned by commenters are 
consistent with the six proposed criteria.
    Accordingly, this final rule mirrors the proposals, with the 
following four exceptions:
    (1) In the first criterion, which as proposed would have allowed 
the removal of a monitor for any criteria pollutant if it has shown 
attainment over the last five years and has less than a 10 percent 
probability of exceeding 80 percent of the NAAQS over the next three 
years and if it is not specifically

[[Page 61251]]

required by the attainment plan or maintenance plan, this final rule 
also conditions the removal of the last remaining SLAMS monitor in a 
nonattainment or maintenance area on the attainment plan or maintenance 
plan not having any contingency measure triggered by air quality 
concentrations. If a plan does have such a trigger, a plan revision to 
remove that trigger would have to be adopted by the State and approved 
by EPA. The EPA will address the requirements for such a revision at a 
future date.
    (2) While the preamble described a sixth criterion for approval of 
State proposals to discontinue a monitor, having to do with logistical 
problems at a current site, the proposed rule text inadvertently 
omitted this criterion. This final rule includes it.
    (3) The second and third criteria have been slightly revised to 
make them applicable also to the lower reading monitor of a pair that 
are in the same attainment area and county, and not just to the lowest 
reading monitor of a pair that are in the same nonattainment area or 
maintenance area. A commenter pointed out the need for this revision to 
achieve the obvious intention of the proposal.
    (4) The third proposed criterion, worded to apply only to ``the 
highest reading monitor * * * in a county,'' required that a described 
monitor could be removed only if the approved SIP provided for a 
specific, reproducible approach to representing the air quality of the 
affected county in the absence of actual monitoring data. While EPA 
intended the highest reading monitor to be addressed in this third 
criterion, EPA did not intend to preclude the possibility that a lower 
reading monitor ineligible for removal under the first two criteria 
could be addressed also. This final rule revises the criterion to 
encompass any monitor not eligible for removal under the first two 
criteria where applicable.
6. Annual Air Monitoring Data Certification
    The EPA proposed a shorter timeframe for States to submit the 
annual letter certifying ambient concentration and quality assurance 
data to the Administrator. See 71 FR 2749. Under current requirements, 
States have until July 1 to certify data from January 1 to December 31 
of the previous year. For data collected in 2006, for example, the 
annual certification letter is due no later than July 1, 2007. Under 
the proposed requirement, the schedule for certification would be moved 
up 60 days, with the data certification letter required under the 
accelerated deadline to be due by May 1, 2009, for data collected in 
2008. The EPA proposed this change to provide opportunity for an 
earlier start and completion for nationwide designation actions, to 
provide States and the public with earlier design values in time for 
most ozone seasons, and to support other data uses that could benefit 
from earlier data certification.
    In response, some commenters expressed reservations about the 
accelerated schedule as it applies to all submitted data, while others 
supported the proposal for continuous instruments that collect and 
report hourly data but not for data requiring lab analysis for samples 
collected in the field. These commenters were concerned about the 
feasibility and cost of meeting an accelerated schedule. The EPA notes 
that some States have recently provided certifications for filter-based 
data ahead not only of the July 1 deadline, but also of the proposed 
May 1 deadline, when such certifications were deemed advantageous by 
the States for data uses such as PM<INF>2.5</INF> nonattainment 
designations. This suggests that all States could be capable of 
certifying data by the proposed May 1 deadline, if not earlier, if they 
invest in needed improvements in information technology or efficiencies 
in administrative procedures. Therefore, this final rule includes the 
proposed May 1 deadline. In recognition of the time necessary for 
States to adjust to the accelerated certification requirement, the 
implementation date has been delayed 1 year, until May 1, 2010, for 
data collected in 2009.
    One commenter questioned the types of annual summary reports that 
would required to be submitted with the data certification letter, 
finding the proposed requirements of 40 CFR 58.15(b) unclear. The EPA 
notes that different reports were mentioned in the proposal to clarify 
the difference between SLAMS and SPM monitors (only FRM, FEM, and ARM 
SPM monitors are required to be certified) and to ensure that annual 
summary reports are provided for both types of monitors. Providing one 
annual summary report for certification of both SLAMS and SPM data is 
appropriate. An additional report providing a summary of precision and 
accuracy data is necessary to demonstrate that applicable monitors meet 
appendix A criteria.
7. Data Submittal
    The EPA proposed to reduce the data reporting requirements 
associated with PM<INF>2.5</INF> FRMs to ease the data management 
burden for monitoring agencies. See 71 FR 2748. The following Air 
Quality System (AQS) reporting requirements were proposed for 
elimination: Maximum and minimum ambient temperature, maximum and 
minimum ambient pressure, flow rate coefficient of variation, total 
sample volume, and elapsed sample time. AQS reporting requirements were 
retained for average ambient temperature and average ambient pressure, 
and any applicable sampler flags.
    The EPA also proposed a requirement for the submission of data on 
PM<INF>2.5</INF> field blank mass in addition to PM<INF>2.5</INF> 
filter-based measurements. See 71 FR 2749. 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. This requirement only applies to 
field blanks which States are already taking into the field and 
weighing through their laboratory procedures.
    Commenters supported the proposed changes to data submittal 
requirements and they are being finalized without modification. The 
requirement for reporting of field blank mass data begins with filters 
collected on or after January 1, 2007.
8. Special Purpose Monitors
    The January 17, 2006 proposal included a background explanation of 
the historical distinctions between regular air monitors and special 
purpose monitors (SPMs) with respect to monitoring objectives, siting 
actions, quality assurance, and use of data. See 71 FR 2745. The EPA 
proposed a revision of the definition of SPM, to the effect that any 
SPM must be in excess of the required minimum number of monitors and 
that designation of a monitor as an SPM be made by the State. The EPA 
also proposed that States would continue to be able to choose to start 
and stop SPMs at will, without needing EPA approval and that States be 
required to submit all data from SPMs to the AQS operated by EPA. In 
addition, EPA proposed that States follow 40 CFR part 58 appendix A 
quality assurance requirements for any SPM that utilizes a FRM, FEM, or 
ARM instrument and which is sited consistently with the requirements of 
appendix E (which does not apply to SPMs on a mandatory basis). The 
existing rule provides that States follow these requirements only if 
the data from the SPM are intended by the State for use in attainment/
nonattainment determinations.
    The EPA also proposed that data from the first 2 years of operation 
of a SPM (even if using a FRM, FEM, or ARM

[[Page 61252]]

instrument and meeting appendix A and E requirements) would not be used 
by EPA in attainment/nonattainment findings for PM<INF>2.5</INF> or 
O<INF>3</INF> if the monitor stopped operating by the end of those 2 
years. See 71 FR 2745. For CO, SO<INF>2</INF>, NO<INF>2</INF>, Pb, and 
the 24-hour PM<INF>10</INF> NAAQS, EPA proposed that data from the 
first 2 years of operation of a SPM would not be used by EPA for 
nonattainment redesignations but that such data would be considered 
when determining whether a nonattainment area had attained the NAAQS. 
The reasons for this distinction by pollutant had to do with 
differences in the form of the respective NAAQS and whether the EPA 
action in question is mandatory or discretionary. These reasons were 
explained in detail in the preamble to the proposal. Finally, EPA 
proposed that currently operating monitors not already designated as 
SPMs could not be designated as SPMs after January 1, 2007.
    The EPA received many comments on these issues, mostly from State 
and local air monitoring officials but also from two industry groups. 
No commenter objected to the flexibility States have to start and stop 
SPMs. That flexibility is retained in this final rule.
    Some commenters pointed out an ambiguity in the proposed 
requirement that data from SPMs be submitted to AQS. The EPA intended, 
but did not clearly state in the proposal, that this requirement apply 
only to SPMs that are FRMs, FEMs, or ARMs and that are operated 
consistently with the requirements of 40 CFR 58.11 (network technical 
requirements), 40 CFR 58.12 (operating schedule), and part 58, appendix 
A (quality assurance requirements). These would be the SPMs that 
produce data that will be of most interest to EPA and the public, 
because except for possible inconsistencies with the siting 
requirements of appendix E to part 58, these are the type of data which 
can be compared to the respective NAAQS. This final rule provides this 
clarification.
    One commenter suggested that the specific reference to the AQS data 
system be made more general, to provide for the development and use of 
other suitable data submission systems in the future. This comment is 
relevant to all monitoring data, not just data from SPMs. This final 
rule retains references to AQS. If AQS is replaced or supplemented with 
approved alternatives in the future, terminology can be updated at that 
time.
    One State official supported the proposal that SPMs be subject to 
the regular quality requirements of appendix A, if the SPM is a FRM, 
FEM, or ARM. All other commenters on this issue contended that States 
should be allowed more flexibility. Most of these commenters agreed 
that regular quality assurance practices were desirable generally, but 
stated that practical difficulties can arise at a specific SPM site, 
such that requiring regular quality assurance practices would 
effectively mean that the SPM could not be legally operated at all and 
the useful data it could have provided would be lost to users.
    After considering these comments, EPA continues to believe that 
regular quality assurance practices are practical and of reasonable 
cost and feasibility in nearly all situations, as shown by successful 
adherence to these practices at thousands of regular monitoring 
stations. They are appropriate in most cases and should be the 
presumptive requirement. As proposed, this final rule provides for a 
transition period by delaying this requirement until January 1, 2009. 
However, EPA recognizes that unusual situations may exist in which 
exceptions should be allowed. For example, a State, perhaps with EPA 
encouragement, might operate an automated O<INF>3</INF> monitor year-
round but have difficulty getting personnel and equipment to the site 
regularly in winter due to road conditions. This final rule allows the 
Regional Administrator to approve other appropriate quality assurance 
practices if the requirements of 40 CFR part 58 appendix A would be 
physically and/or financially impractical due to physical conditions at 
the monitoring site and the quality assurance practices are not 
essential to achieving the intended data objectives. This approval can 
be given separately, or as part of the approval of the annual 
monitoring plan. Approval of alternative quality assurance practices 
for all or part of the year does not qualify the affected data from an 
affected SPM for comparison to the relevant NAAQS.
    Most of the comments received on the SPM proposals addressed the 
application of SPM data to attainment/nonattainment findings and 
designations. One citizen supported the proposal. About 20 commenters 
argued for a general, indefinitely long prohibition on the use of data 
from SPMs for nonattainment findings and designations, for States to 
have a way of blocking EPA from using particular SPM data indefinitely, 
or for States to be able to negotiate in advance with EPA for 
particular SPM data to not be used. Those commenters who explained 
their position generally stated that the risk of a nonattainment 
finding would discourage voluntary special purpose monitoring that 
could benefit air quality management.
    In the proposal preamble (71 FR 2745, January 17, 2006), EPA stated 
that it understood and to some degree sympathized with the thrust of 
very similar input EPA had received during the development of the 
proposed rule, but that EPA believed that under the CAA EPA may not 
legally ignore technically valid data from FRM and FEM (and by 
implication and logical extension ARM) monitors when making attainment 
or nonattainment determinations. The comments have not provided EPA 
with any reason to change this view of our legal obligation. There are 
only two situations where EPA would not have to consider such data. One 
situation is when the data would be insufficient for making a finding 
because it is of insufficient duration given the averaging period or 
form of the relevant NAAQS. This was the basis for the proposal 
concerning PM<INF>2.5</INF> and O<INF>3</INF> for which the form of the 
NAAQS requires 3 years of data.
    The other situation is when EPA has the discretion to simply not 
make a finding or to take an action, for example by taking no action to 
redesignate an area to nonattainment even though a SPM indicates a new 
violation of a NAAQS subsequent to the area's initial designation as 
attainment. This was the basis for the proposal concerning the CO, 
SO<INF>2</INF>, NO<INF>2</INF>, Pb, and PM<INF>10</INF> NAAQS. Unlike 
the PM<INF>2.5</INF> and O<INF>3</INF> NAAQS, the NAAQS for these 
pollutants have forms that allow a nonattainment finding based on only 
1 or 2 years of data, either because the NAAQS is explicitly based on 
only one year of data or because a single year of data may include so 
many exceedances that it is certain that the average number of expected 
exceedances over three years will be greater than one. However, for 
these other NAAQS, EPA does not have a mandatory duty to make 
nonattainment redesignations until such time as the NAAQS are revised. 
In the absence of either a NAAQS revision or a State request for 
redesignation, the Administrator has discretion in determining whether 
to redesignate an area based on data from a SPM which has operated for 
two years or less. The EPA does regard air quality violations 
seriously, and does expect States to take actions to reduce air quality 
to healthy levels in any areas that are experiencing violations. 
However, EPA recognizes that there are other ways to address such 
violations besides redesignating an area as nonattainment. For example, 
EPA can work directly with a State and nearby industries to take 
appropriate actions to reduce emissions that are

[[Page 61253]]

contributing to the violation. The EPA has worked in this way with 
States in the past. In the case of PM<INF>10</INF>, EPA stated in 
section VII.B of the preamble to the NAAQS rule (printed in today's 
Federal Register) that because EPA is retaining the current 24-hour 
PM<INF>10</INF> standards, new nonattainment designations for 
PM<INF>10</INF> will not be required under the provisions of the Clean 
Air Act.
    With respect to the second situation, applicable to the CO, 
SO<INF>2</INF>, NO<INF>2</INF>, Pb, and 24-hour PM<INF>10</INF> NAAQS, 
EPA believes it could have extended the proposed 2-year exclusion from 
use of SPM data in making nonattainment findings to a longer period. 
However, such a provision could exclude more data than appropriate and 
could prevent consideration of violations in making nonattainment 
decisions even when a SPM monitor has shown violations over 3 or more 
years. The EPA believes that in some and perhaps many situations like 
this, it would be good policy to avoid a nonattainment designation and 
to find other less prescriptive approaches to reducing risk to public 
health. EPA also believes, however, that it could be appropriate to 
base a nonattainment designation on such data in some other cases, 
where a nonattainment designation is the appropriate way to deal with a 
long-term nonattainment problem. Since under the final rule EPA still 
has the discretion not to make nonattainment redesignations based on 
three more years of data if EPA so chooses, EPA concludes the 
appropriate approach is not to universally extend the exclusion and 
rather rely on the Administrator's discretion to redesignate areas only 
in appropriate cases.
    This final rule follows the proposed approach for use of data from 
SPMs. The EPA would like to emphasize, however, that States and other 
parties will have practical ways of obtaining useful information using 
SPMs without risk of a nonattainment redesignation. In many situations, 
the potential problem to be investigated, or the place under 
investigation, is such that a FRM, FEM, or ARM instrument meeting the 
siting requirements of 40 CFR part 58, appendix E is not the only 
suitable measurement system, and may not even be a preferred way to 
measure. For example, there are many commercially available 
PM<INF>2.5</INF> monitors that lack FRM, FEM, or ARM status that 
nevertheless would be suitable for an initial study of PM<INF>2.5</INF> 
concentrations in an unmonitored area of interest. In some other cases, 
2 years may be sufficient to achieve the study objectives. Finally, 
under the 1997 rule (see statement at 71 FR 2719 and section 2.8.1.2.3 
of appendix D to part 58 of the 1997 rule), \12\ a SPM that is not 
population-oriented may not be used in comparisons to the 
PM<INF>2.5</INF> NAAQS; this may be the situation in some studies 
focusing on near-source impacts as well as in some studies of transport 
of air pollution from rural upwind areas. If the Regional Administrator 
has approved alternative quality assurance practices in place of the 
requirements of appendix A, the data from the affected SPM are not 
eligible for comparison to the relevant NAAQS.
---------------------------------------------------------------------------

    \12\ EPA is recodifying this provision in section 58.30 of the 
final monitoring rule, but is not reconsidering or otherwise 
reevaluating it.
---------------------------------------------------------------------------

    In reviewing comments about SPMs, EPA noticed that the proposed 
rule text for 40 CFR 58.11(d) implied that all SPMs using FRM, FEM, or 
ARM methods must meet appendix E siting requirements. This was not our 
intention, as the study objective for a SPM may require it to be 
located inconsistently with appendix E requirements. The implied 
restriction in 40 CFR 58.11(d) as proposed conflicted with an explicit 
statement to the contrary in 40 CFR 58.20(b) as proposed. Removing this 
implication is certainly in keeping with the sense of most SPM-related 
comments, which supported flexibility for States to operate SPMs as 
they choose. The promulgated version of 40 CFR 58.11(d) is drafted so 
as to remove this implied restriction. Data from a SPM not sited 
consistently with appendix E are not eligible for comparison to the 
respective NAAQS, unless the State has requested and EPA has approved a 
waiver of these criteria.
    In the course of considering all the public comments on SPMs, EPA 
realized that the proposed restriction on designating pre-existing 
SLAMS monitors as SPMs after January 1, 2007 would have the effect of 
preventing a State from switching a monitor to SPM status even if EPA 
had approved the outright removal of that monitor under other 
provisions. This could be counter-productive. This final rule provides 
that if EPA has approved the discontinuation of a SLAMS monitor, the 
State may choose to retain the monitor and redesignate it to be a SPM. 
Such a monitor could be removed later without further EPA approval.

9. Special Considerations for Data Comparisons to the National Ambient 
Air Quality Standards

    By way of background, the preamble to the proposed monitoring rule 
provided an explanation of when and how monitoring data are considered 
comparable to the respective NAAQS under existing rules and EPA 
policies. See 71 FR 2719-20. The EPA also proposed to relocate one of 
the provisions mentioned in the discussion, proposing to move pre-
existing PM<INF>2.5</INF> rule language currently found in section 
2.8.1.2.3 of appendix D to 40 CFR 58.30 of subpart D without 
substantive change. This relocation would provide a more prominent rule 
location for monitoring requirements detailing the comparability of 
ambient data to the PM<INF>2.5</INF> NAAQS. See 71 FR 2782. One 
commenter objected, not to this proposed rearrangement of rule 
language, but rather to the underlying existing (1997) requirement that 
PM<INF>2.5</INF> sites must be population-oriented to be comparable to 
the PM<INF>2.5</INF> NAAQS. This commenter stated that EPA had failed 
to justify any benchmark for defining an area as population-oriented. 
Another commenter challenged whether EPA had provided an adequate 
public health basis for this provision.
    The EPA considers these comments to be outside the scope of the 
proposal. EPA noted in the preamble to the monitoring proposal that 
some existing regulatory language was being reprinted without change 
and that such reprinting was done solely for the readers' convenience 
to aid in viewing the proposal in a single context (71 FR 2712). EPA 
also stated that all of the background description of existing 
regulatory provisions--including the provision the commenters 
challenged--was presented not to reexamine any of the background 
provisions but rather ``to facilitate informed public comment'' on 
certain aspects of the proposal other than these background provisions. 
These other provisions were ``requirements for the proposed 
PM<INF>10-2.5</INF> NAAQS'', ``provisions for special purpose 
monitors'', provisions ``related to the required spacing between ozone 
monitors and roadways'', and ``certain quality assurance requirements'' 
(71 FR at 2719). EPA thus did not seek comment on, reconsider, or 
otherwise reopen the pre-existing provision regarding population-
oriented PM<INF>2.5</INF> monitors (or any of the other provisions 
recited in the background section). The EPA notes, however, that the 
pre-existing rule and this final rule do provide the same definition of 
population-oriented, in 40 CFR 58.1 Definitions, which while not 
quantified in terms of population affected has served to guide 
PM<INF>2.5</INF> monitor placement and interpretation of monitoring 
data since 1997.
    The most controversial portion of this part of the proposal dealt 
with issues pertaining to the proposed NAAQS for

[[Page 61254]]

PM<INF>10-2.5</INF>. The EPA proposed a new five-part suitability test 
for the comparison of PM<INF>10-2.5</INF> data to the proposed 
qualified PM<INF>10-2.5</INF> indicator. This test included an 
urbanized area population criterion, a block group population density 
criterion, a requirement for sites to be population oriented, an 
exclusion for source-influenced microscale sites, and a site-specific 
assessment to insure that data were dominated by certain sources of 
concern. See 71 FR 2736-2738. The EPA received extensive comment on the 
proposed PM<INF>10-2.5</INF> qualified indicator and on the proposed 
PM<INF>10-2.5</INF> NAAQS five-part site-suitability test. These issues 
are now moot since EPA is not adopting a NAAQS using a 
PM<INF>10-2.5</INF> indicator. See also section III.C of the preamble 
to the final rule adopting revisions to the PM NAAQS which explains why 
EPA did not adopt the proposed qualified indicator for thoracic coarse 
particles and why the proposed monitoring suitability criteria proved 
to be inappropriate.

C. Appendix A--Quality Assurance Requirements for State and Local Air 
Monitoring Stations and Prevention of Significant Deterioration Air 
Monitoring

    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 were intended to 
provide the requirements necessary to develop quality systems for 
monitoring the pollutants of SO<INF>2</INF>, NO<INF>2</INF>, 
O<INF>3</INF>, CO, PM<INF>2.5</INF>, PM<INF>10</INF> and 
PM<INF>10-2.5</INF> at SLAMS stations including NCore stations, PAMS, 
and Prevention of Significant Deterioration (PSD) networks, and SPM 
stations using FRM, FEM, or ARM monitors. The proposed revisions 
addressed responsibilities for implementing the quality system for EPA 
and monitoring organizations. They also addressed adherence to EPA's QA 
policy, DQOs, 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 described 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 DQOs. The proposed amendments also 
addressed required auditing programs to help determine and ensure data 
quality comparability across individual monitoring programs.
    The EPA received some comments expressing concerns about the 
funding of the quality system. Funding issues are addressed in section 
III.E of this preamble. Substantive and procedural issues are addressed 
here.
1. General Quality Assurance Requirements
    The EPA proposed to revise or include a number of general QA 
provisions that would serve to consolidate information and to ensure 
conformance to the QA requirements specified in EPA Order 5360.1 A2.
    The EPA proposed to consolidate the QA requirements for SLAMS and 
PSD stations from two separate appendices, 40 CFR part 58, appendices A 
and B, into one single appendix A because both programs have similar QA 
requirements. See 71 FR 2725. The EPA received only endorsements on the 
proposed consolidation and therefore this final rule consolidates these 
appendices.
    The EPA proposed to revise the part 58 appendix A to conform to the 
current EPA Quality Assurance Policies in EPA Order 5360.1 A2 which 
requires agencies that accept Federal grant funding for their air 
monitoring programs to have a QA program with certain elements 
including quality management plans (QMPs), quality assurance project 
plans (QAPPs), and the identification of a QA management function. EPA 
received three sets of comments endorsing the revision and received one 
comment expressing concern about the identification of the QA manager 
function. See 71 FR 2725. The proposed regulation would not have 
required that monitoring organizations identify a QA manager but would 
have required that they provide for a QA management function, which 
provides for independent oversight of the ambient air monitoring 
quality system. The EPA feels that the proposed language captures the 
essence of the requirements in EPA Order 5360.1A2, while accommodating 
the diverse nature of the ambient air monitoring community which is 
made up of large and small (local and Tribal) organizations. Consistent 
with the majority of positive feedback, and the need for conformance to 
the EPA Order, this final rule matches the proposed rule on this point.
    The EPA proposed to revise the QA program by emphasizing the DQO 
process. See 71 FR 2725. 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 NAAQS. 
The DQOs help to establish the requirements for the data quality 
indicators of precision, bias, completeness, and detectability and the 
rationale for the acceptance criteria for these indicators. The EPA 
received a number of endorsements on this approach and did not receive 
negative comments. This final rule matches the proposed rule.
2. Specific Requirements for PM<INF>10-2.5,</INF> PM<INF>2.5</INF>, 
PM<INF>10</INF> and Total Suspended Particulates
    The EPA proposed to revise some of the PM<INF>2.5</INF> and 
PM<INF>10</INF> QA requirements in an attempt to provide consistency in 
implementation and assessment. Since PM<INF>10-2.5</INF> monitoring was 
proposed to be required, EPA included similar QA requirements for this 
monitoring. These requirements included the implementation of flow rate 
audits conducted by the monitoring organization, collocated monitoring, 
and performance evaluations.
    The EPA proposed to make all the requirements for flow rate 
verifications and audits consistent among the PM<INF>10-2.5</INF>, 
PM<INF>2.5</INF>, and PM<INF>10</INF> methods. See 71 FR 2728. This 
requirement would have increased the audit frequency for 
PM<INF>10</INF> monitoring and decreased the audit frequency for 
PM<INF>2.5</INF> monitoring. Most commenters endorsed the proposed 
approach but a few commenters voiced concerns regarding the increased 
frequency for high-volume samplers for PM<INF>10</INF> and total 
suspended particulates (TSP) which operate somewhat differently and are 
not as easy to audit. The EPA reviewed the comments and revised the 
flowrate verification requirement from monthly to quarterly for the hi-
volume manual instruments sampling for PM<INF>10</INF> and TSP only.
    The EPA proposed to revise the sampling frequency for the 
implementation of the PM<INF>2.5</INF> Performance Evaluation Program 
(PEP). See 71 FR 2726. This proposed approach, based on historical 
PM<INF>2.5</INF> precision and bias data, identified 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 a suitable sampling frequency of five valid 
audits a year for organizations with less than or equal to five 
monitoring sites and eight valid

[[Page 61255]]

audits a year for those organizations with greater than five monitoring 
sites. The majority of commenters approved of the PEP reduction 
frequency. A few commenters suggested that some primary quality 
assurance organizations do not need to be audited and said PEP audits 
should only focus on those producing inferior results. The EPA 
disagrees with this comment and believes that because the PEP program 
needs to provide a periodic estimate of bias for each primary quality 
assurance organization, the program must be implemented at each primary 
quality assurance organization.
    There was also a comment suggesting further reductions to the 
auditing frequency or requiring the same number of audits over a longer 
period of time. The proposed audit cycle is based on 3 years since that 
is how many years of data are collected for comparison the 
PM<INF>2.5</INF> NAAQS. Therefore, the audit cycle frequency was based 
on the number of audit values needed to provide EPA the confidence in 
our bias estimates at the primary quality assurance organization over a 
3 year period. Therefore, this final rule matches the proposed rule.
    The EPA proposed to reduce the lower ends of concentration limits 
for which collocated data can be used to provide precision estimates. 
See 71 FR 2727. The lower ends of concentration limits would be reduced 
from 6 micrograms per cubic meter ([mu]/m<SUP>3</SUP>) to 3 [mu]/
m<SUP>3</SUP> for PM<INF>2.5</INF> and PM<INF>10c</INF> (low-volume 
samplers) and from 20 [mu]/m<SUP>3</SUP> to 15 [mu]/m<SUP>3</SUP> for 
PM<INF>10</INF> (high-volume samplers). Statistical evaluation of 3 
years of PM<INF>2.5</INF> and PM<INF>10</INF> data revealed comparable 
estimates of precision using data from both of these reduced 
concentration ranges, and also revealed that the addition of the data 
at these lower ranges will increase the level of confidence in the 
precision estimates. The majority of commenters endorsed the approach 
but there were a few commenters who were concerned that the lower 
concentrations, based on the statistics used to estimate precision, 
might lead to greater imprecision estimates. The evaluation that EPA 
made with the data from these lower concentrations included did not 
show any major increase in imprecision compared to omitting those 
data.\13\ Since EPA has proposed the use of target upper confidence 
limits for statistical assessments and an upper confidence limit is 
influenced by sample size, lowering the concentration values tends to 
tighten or lower the confidence limits because more data points are 
available in the sample and therefore offsets any greater variability 
that might be associated with lower concentrations. Therefore this 
final rule matches the proposed rule.
---------------------------------------------------------------------------

    \13\ ``Proposal to Change PM<INF>2.5</INF> and PM<INF>10</INF> 
Collocation Sampling Frequency Requriements,'' Mike Papp and Louise 
Camalier; November 2005. http://www.epa.gov/ttn/amtic/pmgainf.html.
---------------------------------------------------------------------------

    Based upon the decision that there is no need to implement a 
PM<INF>10-2.5</INF> monitoring program broad enough to systematically 
determine attainment/nonattainment with a PM<INF>10-2.5</INF> NAAQS, 
EPA has modified the proposed PM<INF>10-2.5</INF> collocation precision 
requirement and the Performance Evaluation Program (PEP) requirements 
in this final rule. See 71 FR 2726. The proposed quality system for 
PM<INF>10-2.5</INF> was developed for NAAQS comparison purposes and 
would have provided reliable precision and bias estimates at the 
primary quality assurance organization level of aggregation. However, 
EPA is not adopting a NAAQS using a PM<INF>10-2.5</INF> indicator at 
this time, so EPA is now requiring a network of PM<INF>10-2.5</INF> 
monitors only at NCore stations. The goal of these monitors will be to 
improve our understanding of PM<INF>10-2.5</INF>, support health 
studies for future reviews of the NAAQS, and promote improvements in 
the monitoring technology. States may choose to operate additional 
PM<INF>10-2.5</INF> monitors. With this in mind, the quality system 
need not be focused on the data quality assessments at the primary 
quality assurance organization level of aggregation but rather can and 
should be focused on understanding and controlling the data quality of 
each of the methods used to collect PM<INF>10-2.5</INF>. Also, since it 
is now anticipated that a primary quality assurance organization would 
have very few PM<INF>10-2.5</INF> sites, the proposal, if adopted 
without change, would have required almost every NCore site to have a 
collocated second PM<INF>10-2.5</INF> monitor, and the proposal would 
not provide for assessment of FEM precision even if FEMs are approved 
and deployed in place of some or most FRMs since as proposed the first 
collocation requirement of an FEM in a primary quality assurance 
organization would always be with a FRM. To avoid these undesirable 
outcomes, this final rule requires fewer collocated samplers than the 
proposal would have. Under this final rule, EPA will ensure that 
collocated sampling for estimating precision be implemented at 15 
percent of FRMs (all FRMs aggregated) and 15 percent of the FEMs of 
each method designation. The number of collocated sites would thus be 
based on the size of the final PM<INF>10-2.5</INF> network. In order to 
provide a distribution of collocation across the United States, EPA 
will require, at a minimum, one collocated site in each EPA Region. The 
Regional Administrator shall select the sites for collocation. The site 
selection process will also consider selecting States with more than 
one PM<INF>10-2.5</INF> site to have one or two of the required 
collocations and will aim for an appropriate distribution among rural 
and urban sites.
    For the PEP, this final rule departs from the proposal by requiring 
only one PEP audit at one PM<INF>10-2.5</INF> site in each primary 
quality assurance organization each year. The proposed rule would have 
required five or eight PEP audits for PM<INF>10-2.5</INF> in each 
organization. See 71 FR 2787, 2788. Since the PEP is already being run, 
at present, for the PM<INF>2.5</INF> network and it is expected that 
the PM<INF>10-2.5</INF> FRMs will utilize the same FRMs as the 
PM<INF>2.5</INF> samplers, the PEP audit for the PM<INF>10-2.5</INF> 
site can count towards the required number of PEP audits for 
PM<INF>2.5</INF> sites. It will be necessary to place a 
PM<INF>10c</INF> PEP sampler at the NCore site also but, this 
incremental requirement will not be a significant additional resource 
burden. When and if FEMs are implemented at some PM<INF>10-2.5</INF> 
sites, the PEP audit will be an additional audit at those particular 
sites and will require additional resources for auditing.
    The incremental cost of placing and operating PM<INF>10-2.5</INF> 
samplers for purposes of tracking precision will also be minor in most 
cases. Many of the primary quality assurance organizations that will 
implement the PM<INF>10-2.5</INF> monitor at NCore sites are required 
to implement PM<INF>2.5</INF> and PM<INF>10</INF> networks. Some or 
most of the initial PM<INF>10-2.5</INF> deployments will be with manual 
FRM instruments, similar to the instruments used in the 
PM<INF>2.5</INF> networks and to some of the instruments used in the 
PM<INF>10</INF> networks. The EPA will allow collocated 
PM<INF>10-2.5</INF> monitors to be included in the primary quality 
assurance organization's count for required PM<INF>2.5</INF> and 
PM<INF>10</INF> collocation. In most cases, the primary quality 
assurance organization's collocation requirements for FRMs will not 
increase overall, since it is not anticipated that any one primary 
quality assurance organization will have many additional 
PM<INF>10-2.5</INF> sites that are not already both PM<INF>2.5</INF> 
and PM<INF>10</INF> sites. The only restriction to this aggregated 
collocation count will be for monitoring organizations that are 
operating high-volume PM<INF>10</INF> samplers. Since the 
PM<INF>10c</INF> monitor in a PM<INF>10-2.5</INF> FRM will be a low-
volume sampler, PM<INF>10</INF> high-volume and PM<INF>10</INF> low-
volume samplers cannot be aggregated together in the collocation

[[Page 61256]]

count and at least one collocated monitor must be identified for each 
type within primary quality assurance organization. Therefore, it is 
expected that the 15 percent collocation requirement for 
PM<INF>10-2.5</INF> FRMs will not actually increase the overall 
collocation burden at the majority of the primary quality assurance 
organizations beyond what they would have been required to implement 
for their PM<INF>10</INF> and PM<INF>2.5</INF> networks.
    For any FEMs that might be used at PM<INF>10-2.5</INF> sites, EPA 
will require 15 percent collocation of each method designation or at 
least two collocations within each method designation. The EPA will 
require two collocations in order to collocate one FEM instrument with 
the same method designation to provide estimates of within method 
precision and collocate a second with an FRM to provide for an estimate 
of bias. These collocations would not necessarily need to be at 
separate monitoring sites.
3. Particulate Matter Performance Evaluation Program and National 
Performance Audit Programs
    The EPA proposed to revise the current regulatory requirements 
dealing with responsibilities for independent assessments of monitoring 
system performance. See 71 FR 2726. These evaluations are the subject 
of sections 2.4 and 3.5.3.1 of the existing (1997) appendix A to 40 CFR 
part 58. Section 2.4 of appendix A to 40 CFR part 58 applied to all 
NAAQS pollutants and section 3.5.3.1 applied only to PM<INF>2.5</INF>.
    The EPA proposed to revise the text of 40 CFR part 58, appendix A 
to cover PM<INF>10-2.5</INF> and also to clarify 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 FEM criteria 
pollutant monitors. The proposed language also clearly indicates that 
it is the monitoring organization's choice whether to obtain its 
independent performance evaluations through EPA's National Performance 
Audit Program (NPAP) and PM<INF>2.5</INF> 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 performance evaluation auditing. The proposed 
approach would ensure that adequate and independent audits are 
performed and 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<INF>2.5</INF>, 
PM<INF>10-2.5</INF>, and/or other NAAQS pollutants, would be required 
to agree that EPA hold back part of the grant funds they would 
otherwise receive directly. These funds would be used by EPA to hire 
contractors to perform the audits and to purchase expendable supplies. 
To ensure national consistency and effective audits, EPA included 
provisions to ensure 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.
    The EPA received a broad range of comments on this proposed 
revision. The EPA received a few comments in support of these programs 
and one commenter felt that the PEP audits should be increased. In 
general, the comments expressing concern with the proposed language did 
not suggest that these programs were not necessary but were concerned 
about some technical aspects of the programs or with funding 
implications. Funding issues are addressed in section III.E of this 
preamble.
    The EPA received a number of comments expressing concerns that 
allowing the monitoring agencies to implement the audit programs 
themselves or through third parties would increase the variability in 
the performance evaluation data. Since one of the major goals in the 
historically centralized and federally implemented PEP and NPAP 
programs has been the evaluation of data comparability, EPA is also 
concerned about any additional variability and its effect on data 
comparability. It has been EPA's practice with regard to any State 
which already performs these audits to perform side-by-side comparisons 
of EPA's equipment and procedures and the State's procedures to ensure 
both are producing results of acceptable quality. The EPA has 
successfully performed these comparisons with the California Air 
Resources Board's audit system. These comparisons will be expanded to 
include any additional States which choose to perform audits themselves 
or through third parties, rather than ask EPA to do so. During the 
comment period, EPA asked the monitoring organizations whether or not, 
assuming finalization of the proposed rule changes, they would continue 
to use the federally implemented program or perform the audits itself. 
For 2007, only three monitoring organizations (besides the one already 
implementing NPAP) opted to implement the NPAP and three monitoring 
organizations (besides the two already implementing PEP) opted to 
implement the PEP. The EPA believes it has the capability to ensure 
these State will implement programs will produce data of a quality 
comparable to the Federally implemented program.
    The EPA also received comments stating concerns about the 
stringency of the definition of adequate and independent. Adequacy 
refers to the number of audits administered at any primary quality 
assurance organization and the technical procedures used in the audits. 
This final rule does not require any additional adequacy requirements 
above and beyond what EPA currently implements for the federally 
implemented program. The EPA evaluates data quality at the aggregation 
called ``reporting organization'' (which was changed to ``primary 
quality assurance organization'' in the proposal). The EPA feels that 
it needs to collect enough data to be able to judge data quality within 
each primary quality assurance organization over the same period that 
it uses the data for comparison to the NAAQS (3 years).
    In the case of the PEP for PM<INF>2.5</INF>, today's action 
requires five audits per year for organizations with five or fewer 
sites and eight audits for those organizations with greater than five 
sites, the same as proposed. The number of audits aggregated over three 
years provides a reasonable estimate of bias at a primary quality 
assurance organization within an acceptable level of confidence. For 
the NPAP program addressing NAAQS for CO, SO<INF>2</INF>, Pb, and 
NO<INF>2</INF>, the goal is to perform audits on about 20 percent of 
the sites each year, but since there may be a number of high priority 
sites within a primary quality assurance organization that should be 
audited more often, it is anticipated that NPAP might audit each site 
within a primary quality assurance organization over about 7 to 8 
years. This 20 percent goal is the current EPA practice, but was not 
proposed to be required by rule and, therefore, does not appear in this 
final rule.
    There were a few comments suggesting that some primary quality 
assurance organizations do not need to be audited and that EPA 
mandatory audits for CO, SO<INF>2</INF>, Pb, and NO<INF>2</INF> should 
only focus on those organizations producing inferior results. The EPA 
continues to believe that it is important to develop an estimate of 
bias for each primary quality assurance organization. To do this, the 
audit program must be

[[Page 61257]]

implemented at each primary quality assurance organization. The NPAP 
audits using a through-the-probe approach, which is generally not how 
audits are performed by the primary quality assurance organizations 
themselves. By auditing some stations within a primary quality 
assurance organization each year using the through-the-probe approach, 
the NPAP can identify problems which the organization may not be aware 
of on its own. Also, EPA continues to believe that it is necessary to 
provide an adequate assessment of data comparability of all primary 
quality assurance organizations every year.
    There were also comments concerning the requirement to use 
independent filter weighing laboratories for the implementation of the 
PEP. When EPA first implemented the PEP program, EPA established two 
independent laboratories to weigh filters for the PEP audits. Due to 
program efficiencies, EPA is now using one filter weighing laboratory. 
If primary quality assurance organizations implement the PEP 
themselves, they should not be able to utilize the same laboratory in 
which they weigh their routine sampler filters since any bias or 
contamination that might occur at the routine lab will also be ``passed 
on'' to the PEP filter. Because the PEP provides an estimate of bias 
(systematic error), it is necessary to avoid having a systematic bias 
occurring in the routine filter weighing lab affect both the PEP 
filters and the routine filters. Primary quality assurance 
organizations interested in implementing the PEP themselves have the 
option to make arrangements with other State labs, contractor labs, or 
utilize the PEP national lab.
    The EPA believes that both the NPAP and PEP programs serve as an 
integral part of the overall ambient air monitoring program quality 
system and provide EPA and the public with independent and objective 
assessments of data quality and data comparability. Both programs 
provide the only quantitative independent assessments of data quality 
at a national level. Therefore, the proposed language was not changed 
and this final rule matches the proposed rule.
4. Revisions to Precision and Bias Statistics
    The EPA proposed to change the statistics for assessment of 
precision and bias for criteria pollutants. See 71 FR 2727. Two 
important data quality indicators that are needed to assess the 
achievement of DQOs are bias and precision. Statistics in the current 
requirements of 40 CFR part 58, appendix A (with the exception of 
PM<INF>2.5</INF>) combine precision and bias together into a 
probability limit at the primary quality assurance organization level 
of aggregation. Since the standard EPA DQO process uses separate 
estimates of precision and bias, EPA examined separated assessment 
methods that were statistically reasonable and simple.
    For SO<INF>2</INF>, NO<INF>2</INF>, CO, and O<INF>3</INF>, EPA 
proposed 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 SO<INF>2</INF>, NO<INF>2</INF>, CO, and 
O<INF>3</INF> because there is sufficient QC information collected at 
the site level to perform adequate assessments.
    The precision and bias statistics for PM measurements 
(PM<INF>10</INF>, PM<INF>10-2.5</INF> and PM<INF>2.5</INF>) are 
generated at a primary quality assurance organization level because, 
unlike the gaseous pollutants, due to costs only a percentage of the 
sites have precision and bias checks performed in any year and only a 
few times per year. As with the gaseous pollutants, the statistics 
would use the confidence limit approach. Using a consistent set of 
statistics simplifies the procedures.
    The EPA also proposed to change the precision and bias statistics 
for Pb to provide a framework for developing and assessing a DQO. See 
71 FR 2727. The QC checks for Pb come in three forms: Flow rate audits, 
Pb audit strips, and collocation. The EPA proposed 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 for SO<INF>2</INF>, 
NO<INF>2</INF>, CO, and O<INF>3</INF>.
    The EPA received only positive comments on the proposed statistics 
and some typographical corrections. This final rule matches the 
proposed rule.
5. Other Program Updates
    The EPA proposed several QA program changes to update the existing 
requirements in 40 CFR part 58 to reflect current program needs and 
terminology.
    The EPA proposed to remove SO<INF>2</INF> and NO<INF>2</INF> manual 
audit checks. A review of all SLAMS/NAMS/PAMS sites by monitor type 
revealed that no monitoring organizations are using manual 
SO<INF>2</INF> or NO<INF>2</INF> methods, nor are any monitoring 
organizations expected to use these older technologies. The EPA 
received only comments endorsing the removal of the manual audit 
checks. Therefore, this final rule matches the proposed rule.
    The EPA proposed to change the concentration ranges for QC checks 
and annual audit concentrations. The one-point QC check concentration 
ranges for the gaseous pollutants SO<INF>2</INF>, NO<INF>2</INF>, 
O<INF>3</INF>, and CO were expanded to include lower concentrations. 
Lower audit ranges were added to concentration ranges for the annual 
audits. Adding or expanding the required range to lower concentration 
ranges was 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 
proposed that 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. The majority of the 
comments EPA received on this proposal were positive but EPA received 
comments that asked for more guidance on how a monitoring organization 
would choose the appropriate audit ranges. The EPA would like to 
provide as much flexibility as possible for the monitoring organization 
to use their local knowledge of their monitoring sites to choose their 
audit concentration ranges. Accordingly, in this final rule, section 
3.2.2.1 of appendix A to part 58 establishes a non-binding goal that 
the primary quality assurance organization select the three audit 
concentration ranges which bracket 80 percent of the routine monitoring 
concentrations at the site. So in general, with some minor modification 
to address comments, this final rule matches the proposed rule.
    The EPA proposed to revise the PM<INF>10</INF> collocation 
requirement. See 71 FR 2726. Fifteen percent of all PM<INF>2.5</INF> 
sites are required to maintain collocated samplers. For 
PM<INF>10</INF>, the collocated requirements in the existing (1997) 
regulation were three alternative values based on the number of routine 
monitors within a primary quality assurance organization. For 
consistency, the proposed amendments would have changed the 
PM<INF>10</INF> collocation requirement to match the PM<INF>2.5</INF> 
requirement. This proposed change would make the collocation 
requirement consistent for PM<INF>2.5</INF> and PM<INF>10</INF>. The 
EPA did not receive any comments on this proposed change. Therefore, 
this final rule matches the proposed rule.
    The EPA proposed to revise the requirements for PM<INF>2.5</INF> 
flow rate audits.

[[Page 61258]]

See 71 FR 2728. Based on an evaluation of flow rate data and 
discussions within the QA Strategy Workgroup,\14\ EPA proposed to 
reduce the frequency of flow rate audits from quarterly to semiannually 
and to 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 an external transfer standard to be the preferred method 
and believed that the quarterly audit data demonstrated the instruments 
were sufficiently stable to reduce the audit frequency. The EPA did not 
receive any comments on this proposal; therefore, this final rule 
matches the proposed rule.
---------------------------------------------------------------------------

    \14\ The QA Strategy Workgroup consists of EPA, State, and local 
staff responsible for monitoring quality assurance activities who 
meet informally to exchange information on current monitoring 
issues.
---------------------------------------------------------------------------

D. Appendix C--Ambient Air Quality Monitoring Methodology

1. Applicability of Federal Reference Methods and Federal Equivalent 
Methods
    The EPA proposed that monitoring methods used in the multipollutant 
NCore, SLAMS, and PAMS networks were required to be FRMs, FEMs, ARMs, 
or where appropriate, other methods designed to meet the DQOs of the 
network being deployed. See 71 FR 2731. Specifics on the monitoring 
methods proposed for use at each type of site are described below.
    The EPA proposed that NCore multipollutant stations must use FRMs 
or FEMs for criteria pollutants when the expected concentration of the 
pollutants was at or near the level of the NAAQS. For criteria 
pollutant measurements of CO and SO<INF>2</INF>, where the level of the 
pollutant is well below the NAAQS, EPA observed that it may be more 
appropriate to operate higher sensitivity monitors than typical FRM or 
FEM instruments. See 71 FR 2728. In these cases, higher sensitivity 
methods were expected to support additional monitoring objectives that 
conventional FRMs or FEMs cannot. In some 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, SO<INF>2</INF>, and total reactive nitrogen (NO<INF>y</INF>) are 
described in the report, ``Technical Assistance Document for Precursor 
Gas Measurements in the NCore Multipollutant Monitoring Network.'' 
Comments regarding monitoring methods used at NCore stations are 
addressed in section V.E.1 of this preamble.
    The EPA proposed that SLAMS use FRMs or FEMs for criteria 
pollutants. See 71 FR 2728. The EPA also proposed that these sites have 
the additional option of using ARMs for PM<INF>2.5</INF>. Approved 
regional methods are described in section V.D.2 of this preamble.
    Photochemical assessment monitoring stations (PAMS) were proposed 
to be required to use FRM or FEM monitors for O<INF>3</INF>, with most 
expected to use the O<INF>3</INF> ultraviolet photometry FEM and the 
nitric oxide (NO) and NO<INF>2</INF> chemiluminescence FRM for criteria 
pollutant measurements. See 71 FR 2728. Methods for volatile organic 
compounds (VOC) including carbonyls, additional measurements of gaseous 
nitrogen, such as NO<INF>y</INF>, and meteorological measurements are 
routinely operated at PAMS. Because these measurements are not of 
criteria pollutants, the methods were not subject to the requirements 
for reference or equivalent methods. However, these methods were 
described in detail in the report, ``Technical Assistance Document 
(TAD) for Sampling and Analysis of Ozone Precursors.'' \15\
---------------------------------------------------------------------------

    \15\ 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.
---------------------------------------------------------------------------

    The EPA proposed that 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 the SPM provision was designed 
to encourage monitoring, agencies could design SPM sites with methods 
to meet monitoring objectives that may not be achievable with FRMs or 
FEMs. Additional information on SPMs is included in section V.E.8 of 
this preamble.
    The EPA received several comments on its proposed approach for 
ambient air monitoring methodology. Some of these comments expressed 
concern that requiring only designated reference or equivalent methods 
takes away flexibility and the drive for improvements to air quality 
instrumentation. The EPA agrees that some flexibility is desirable for 
agencies to use innovative methods that can support other objectives 
beyond NAAQS decision making. However, CAA section 319 requires ``* * * 
an air quality monitoring system throughout the U.S. which utilizes 
uniform air quality monitoring criteria and methodology * * *''. The 
EPA recognizes that there may be occasions when a unique method is 
better suited to meet a specific monitoring objective that is different 
from NAAQS decision making. In these cases, EPA will allow for these 
innovative methods, so long as the monitoring agency is not attempting 
to use them to meet minimum requirements for the number of monitors for 
a given criteria pollutant. For example, a low cost method might be 
applied as a SPM to provide short term data for validation of an air 
quality model.
2. Approved Regional Methods for PM<INF>2.5</INF>
    The EPA proposed amendments that expanded the allowed use of 
alternative PM<INF>2.5</INF> measurement methods through ARMs. See 71 
FR 2729. The EPA also proposed to extend the existing provisions for 
approval of a nondesignated PM<INF>2.5</INF> 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<INF>2.5</INF> 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 would have 
required 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 was envisioned to address monitoring 
objectives beyond just determining compliance with NAAQS. The hybrid 
network was expected to lead to a reduced number of existing FRM 
samplers and an increase in continuous ARM samplers that would all be 
approved for direct comparison with the applicable forms of the 
PM<INF>2.5</INF> NAAQS.
    Many comments were received on EPA's proposal regarding ARMs for 
PM<INF>2.5</INF>. Several commenters suggested requiring on-going 
collocation with an FRM. Commenters also raised concerns about ensuring 
data quality, especially in light of the lower level of the 24-hour 
PM<INF>2.5</INF> NAAQS and therefore the perceived need to ensure that 
the statistical criteria are met in each season. One commenter was so 
concerned about the data quality issues that the commenter recommended 
dropping the ARM provision. Other commenters voiced strong support for 
the ARM provision, but also recommended that EPA allow for less 
collocation with FRMs than the 30

[[Page 61259]]

percent that was proposed. Several commenters recommended that EPA 
allow non-linear data adjustment factors as are used for AIRNow and 
mapping purposes.
    In reviewing comments on the provision for ARMs, EPA agrees that 
data quality issues need to be appropriately addressed. Since ARMs will 
be used for several monitoring objectives, including NAAQS attainment/
nonattainment determinations, they must meet the Class III FEM 
performance criteria set out in part 53. However, as proposed, these 
performance criteria left open the possibility that in cleaner 
environments where concentration data approached background levels of 
PM<INF>2.5</INF> that approved methods may have unacceptable levels of 
bias to meet other monitoring objectives. Therefore, the Class III 
equivalency criteria, which are the same criteria used for 
PM<INF>2.5</INF> ARMs, has been strengthened to address concerns about 
additive bias in cleaner environments. The EPA performed an extensive 
investigation into developing equivalency criteria for PM<INF>2.5</INF> 
continuous methods. One of the conclusions from that process was that 
continuous methods, by virtue of being able to provide a sample every 
day, generate data with more certainty in decision making than methods 
used with lower sample frequencies (i.e., a 1-in-3 day sample 
schedule), with all other factors being equal. Although biases can be 
seasonal, correlation combined with the other performance criteria will 
guard against high biases in one season cancelling out low biases in 
another. Together, the performance criteria and the daily sample 
schedule will ensure that data quality objectives are met when making 
NAAQS decisions with data from ARMs.
    With respect to requiring on-going collocation with FRMs at 30 
percent of the sites with continuous PM<INF>2.5</INF> monitors, EPA has 
considered how this would affect agencies with many continuous monitors 
and finds it unnecessary to require such a large absolute number of 
collocated sites, although the number of collocated FRM under a 30 
percent collocation requirement makes sense for smaller networks. 
Therefore, this final rule states that monitoring agencies are only 
required to have 30 percent collocation of the ARMs they count towards 
the applicable minimum number of required FRM/FEM/ARM sites--rounded 
up, rather than 30 percent of their full networks of ARMs.
    For the issue of non-linear data transformations, this final rule 
specifically allows data transformations when using an ARM, including 
non-linear ones, so long as the transformations are described in both 
the ARM application and the monitoring agency's quality assurance 
project plan (or addendum to the QAPP), the transformations are 
prospective, and the ARM application provides for details on how often 
or under what circumstances they will be recalculated, based on what 
data, and which analytical method.
    Since participation in seeking approval of ARMs is voluntary and 
approval of an ARM applies only in the territory of the agency seeking 
approval, no monitoring agency having concerns will be required to 
utilize the ARM provisions. However, for many agencies this approach 
will offer an opportunity to improve their monitoring network's 
utility, by using methods that can serve multiple objectives, while 
having lower costs. Therefore, EPA is finalizing the ARM provisions as 
proposed, with the exceptions of the additive bias requirement being 
strengthened; changes to the required collocation requirement; and 
clarifying use of data transformations, including non-linear ones.
    Today's final action thus allows State, local, and Tribal 
monitoring agencies to independently, or in cooperation with instrument 
manufacturers, seek approval of ARMs where PM<INF>2.5</INF> continuous 
monitor data quality is sufficiently comparable to FRMs for integration 
into the agency's PM<INF>2.5</INF> network used in NAAQS attainment 
findings. The performance criteria for approval of candidate ARMs are 
the same criteria for precision, correlation, and additive and 
multiplicative bias that have been finalized for approval of continuous 
PM<INF>2.5</INF> Class III equivalent methods, described in section 
IV.C of this preamble. These performance criteria are to 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 is 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 will be validated periodically in 
recognition of changing aerosol composition and instrument performance. 
These validations will 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 V.B.2 of this preamble.
    The testing criteria EPA will use for approval of PM<INF>2.5</INF> 
continuous methods as ARMs are intended to be robust but not overly 
burdensome. The two main features of testing that are different than 
FEMs are the duration and locations of testing. The duration is 
expected to be 1 year to provide an 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<INF>2.5</INF> continuous monitor to be approved as an ARM. Testing 
will 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 are required to be tested.
    To ensure that approvals of new methods are made consistently on a 
national basis, the procedures for approval of methods are similar to 
the requirements specified in 40 CFR part 53, i.e., the EPA 
Administrator (or delegated official) will approve the application. 
However, to optimize flexibility in the approval process, all other 
monitoring agencies seeking approval of an ARM that is already approved 
in another agency's monitoring network can seek approval through their 
EPA Regional Administrator. This approach will provide a streamlined 
approval process, as well as an incentive for consistency in selection 
and operation of PM<INF>2.5</INF> continuous monitors across various 
monitoring agency networks.
    The QA requirements for approval of continuous PM<INF>2.5</INF> ARM 
at a network of sites are the same as for FEM in 40 CFR part 58, 
appendix A, except that 30 percent--rounded up--of the required sites 
that utilize a PM<INF>2.5</INF> ARM would be collocated with an FRM and 
required to operate at a sample frequency of at least a 1-in-6 day 
schedule. The higher collocation requirement would support the main 
goal of the particulate matter continuous monitoring implementation 
plan, which was to have an optimized FRM and PM<INF>2.5</INF> 
continuous monitoring network that can serve several monitoring 
objectives. This collocation requirement 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 AQS. The collocated sites are 
to be located at the highest concentration sites, starting

[[Page 61260]]

with one site in each of the largest population MSA in the network and 
working to the next highest-population MSA with the second site and so 
forth.
    Finally, EPA reiterates that ARMs may be used to measure compliance 
with the PM<INF>2.5</INF> NAAQS. See section 50.13(b) and (c) (as 
published elsewhere in today's Federal Register) (annual and 24-hour 
primary and secondary standards are met when designated concentrations 
``as determined in accordance with Appendix N'' are met), and Part 50 
Appendix N section 1.a (for purposes of section 50.13, PM<INF>2.5</INF> 
can be measured by FRM, FEM, ``or by an Approved Regional Method (ARM) 
designated in accordance with part 58 of this chapter'').

E. Appendix D--Network Design Criteria for Ambient Air Quality 
Monitoring

1. Requirements for Operation of Multipollutant NCore Stations
    The EPA proposed requirements for NCore stations applicable to 
States individually that would, in the aggregate, result in the 
deployment of a new network of multipollutant monitoring stations in 
approximately 60 mostly urban areas. See 71 FR 2730. In the proposal, 
most States would have been required to operate one urban station; 
however, rural stations could be substituted in States that have 
limited dense urban exposures. Such substitution would not change the 
goal of having about 20 rural NCore sites. California, Florida, 
Illinois, Michigan, New York, North Carolina, Ohio, Pennsylvania, and 
Texas would be required to operate one to two additional NCore stations 
in order to account for their unique situations. These stations, 
combined with about 20 multipollutant rural stations, which were not 
proposed to be required of specific States, would form the new NCore 
multipollutant network. The rural NCore stations would 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.\16\
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    \16\ To clarify, under the proposed rule, and this final rule, 
41 States, the District of Columbia, the Virgin Islands, and Puerto 
Rico will be required to operate one NCore site. The other nine 
States will be required to operate two or three sites, for a 
national total of 62 to 71 required sites. Some of these required 
sites might be waived by EPA. The EPA anticipates, but the rule does 
not require that some of these sites will be rural. Counting non-
required sites, the goal is a total of about 75 sites, about 20 of 
which will be rural.
---------------------------------------------------------------------------

    These NCore multipollutant 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<INF>2.5</INF>, 
PM<INF>10</INF>, O<INF>3</INF>, and other NAAQS pollutant sites would 
also provide data for use in attainment and nonattainment designations 
and for public reporting and forecasting of the AQI.
    The EPA proposed that these NCore multipollutant stations be 
required to measure O<INF>2</INF>; CO, SO<INF>2</INF>, and total 
reactive nitrogen (NO<INF>y</INF>) (using high-sensitivity methods, 
where appropriate); PM<INF>2.5</INF> (with both a FRM and a continuous 
monitor); PM<INF>2.5</INF> chemical speciation; PM<INF>10-2.5</INF> 
(with a continuous FEM); and meteorological parameters including 
temperature, wind speed, wind direction, and relative humidity. See 71 
FR 2730. High-sensitivity measurements are necessary for CO, 
SO<INF>2</INF>, and NO<INF>y</INF> to adequately measure these 
pollutants in most air sheds for data purposes beyond NAAQS attainment 
determinations. For the other criteria pollutants, EPA proposed use of 
conventional ambient air monitoring methods.
    At least one NCore station was proposed to 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 could propose 
modifications to these requirements for approval by the Administrator. 
While the proposed amendments did not specify the cities in which the 
States would have to place their NCore multipollutant monitoring 
stations, EPA anticipated that the overall result would 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<INF>2.5</INF> and PM<INF>10-2.5</INF>, allowing air 
quality models to be evaluated under a range of conditions.
    The EPA received several comments on the proposed requirements for 
operating the NCore multipollutant monitoring stations. Some commenters 
recommended requiring additional NCore monitoring stations for better 
spatial coverage and to capture gradients, including specifically 
requiring additional rural sites. Regarding methods, a few commenters 
recommended not requiring the total reactive NO<INF>y</INF> 
measurement, since this measurement in some but not all cases is little 
different from the existing NO<INF>2</INF> measurement by 
chemiluminescence, which uses the same measurement principle as 
NO<INF>y</INF>.
    In reviewing the comments, EPA notes that more NCore sites can be 
deployed than required by regulation. For example, in our proposal EPA 
stated that it would develop a design of the network for rural sites--
not specifically required of any individual State--that leveraged 
existing rural networks such as IMPROVE, CASTNET and, in some cases, 
State-operated rural sites. In some cases it may be appropriate to have 
enough NCore multipollutant sites to assess gradients; however, in 
other areas having enough sites to develop gradients with all the 
parameters required of an NCore station may not be needed and would 
therefore present an unnecessary burden to the States. Therefore, EPA 
is finalizing the NCore network design requirements as proposed.
    For required methods, EPA agrees that in areas where the existing 
NO<INF>X</INF> method provides comparable data to the NO<INF>y</INF> 
method, monitoring agencies should be allowed to operate NO<INF>X</INF> 
instead of the more challenging measurement of NO<INF>y</INF>. However, 
EPA notes much of the reason for NO<INF>y</INF> and NO<INF>X</INF> 
reading being so close may be a positive bias with current typical 
NO<INF>X</INF> (NO + NO<INF>2</INF>) instruments which may over report 
NO<INF>2</INF>. Since further development of the NO<INF>X</INF> method 
is underway, monitoring agencies which seek waivers for the 
NO<INF>y</INF> method are encouraged to utilize high sensitivity 
versions of the chemiluminescence method so that they are capable of 
switching from high sensitivity NO<INF>X</INF> to high sensitivity 
NO<INF>y</INF> in performing gaseous nitrogen measurements. The EPA is 
therefore finalizing the required measurements at NCore multipollutant 
sites as proposed; however, EPA will allow for waivers of the 
NO<INF>y</INF> method in areas where measured NO<INF>X</INF> is 
expected to provide virtually the same data as NO<INF>y</INF>. This is 
largely expected to be in urban environments until such time as the 
NO<INF>2</INF> method (and hence the NO<INF>X</INF>) is sufficiently 
improved that having separate measurements of NO<INF>y</INF> and 
NO<INF>X</INF> provides more useful information than the existing 
technology. See also section V.E.7.
    The NCore stations are to be deployed at sites representing as 
large an area of relatively uniform land use and ambient air 
concentrations as possible (i.e., out

[[Page 61261]]

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 NCore multipollutant 
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 this 
siting scheme. The State or local agency may propose utilizing these 
kinds of sites as the NCore multipollutant 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 NCore 
multipollutant stations should be collocated, when appropriate, with 
other multipollutant air monitoring stations including PAMS, National 
Air Toxic Trends Station sites, and the PM<INF>2.5</INF> chemical 
Speciation Trends Network sites. Collocation will allow use of the same 
monitoring platform and equipment to meet the objectives of multiple 
programs where possible and advantageous. Of the approximately 60 
required NCore stations, up to 35 existing State-operated multi-monitor 
stations are already also operating or preparing to also operate the 
high-sensitivity monitors for CO, SO<INF>2</INF>, and NO<INF>y</INF> 
that are part of the NCore requirement.
    Although EPA is retaining the 24-hour PM<INF>10</INF> NAAQS for 
requisite protection against short-term exposure to thoracic coarse 
particles and is not promulgating a PM<INF>10-2.5</INF> NAAQS, the 
NCore stations are also being required to deploy a PM<INF>10-2.5</INF> 
FRM or FEM to build a dataset for scientific research purposes, 
including supporting health studies and future reviews of the PM NAAQS. 
Separate PM<INF>10</INF> monitoring will not be required at NCore 
stations. For many PM<INF>10-2.5</INF> methods, including the FRM, 
PM<INF>10</INF> data will be readily available as part of the 
calculated PM<INF>10-2.5</INF> measurement. Even if a 
PM<INF>10-2.5</INF> method that does not report PM<INF>10</INF> is 
approved as an FEM and is deployed to one or more NCore sites, 
PM<INF>10</INF> will still be available by virtue of the independent 
measurements of PM<INF>2.5</INF> and PM<INF>10-2.5</INF> (which could 
appropriately be summed). Therefore, EPA is not making measurements of 
PM<INF>10</INF> a requirement of the NCore network. Also, since the 
NCore network of PM<INF>10-2.5</INF> FRM/FEM is not being used for 
attainment/nonattainment determinations, agencies may operate filter 
methods on as infrequent a schedule as a 1-in-3 day sampling.
    This final rule contains a requirement for PM<INF>10-2.5</INF> 
speciation to be conducted at NCore multipollutant monitoring stations. 
The EPA had proposed a requirement for PM<INF>10-2.5</INF> speciation 
in 25 areas, with the areas required to have this monitoring selected 
based on having an MSA population over 500,000 and having an estimated 
design value of greater than 80 percent of the proposed 
PM<INF>10-2.5</INF> NAAQS. This would have concentrated the 
PM<INF>10-2.5</INF> speciation monitoring in areas that have high 
populations and high exposures to PM<INF>10-2.5.</INF> Since EPA is 
requiring PM<INF>10-2.5</INF> monitoring at NCore primarily for 
scientific purposes, it is more appropriate to have monitoring in a 
variety of urban and rural locations so as to increase the diversity of 
areas that have available chemical species data to use in scientific 
studies. The EPA had already proposed to have chemical speciation for 
PM<INF>2.5</INF> at NCore stations. The collocation of both 
PM<INF>10-2.5</INF> and PM<INF>2.5</INF> speciation monitoring at NCore 
stations is consistent with the multipollutant objectives of the NCore 
network and will support further research in understanding the chemical 
composition and sources of PM<INF>10</INF> and PM<INF>10-2.5</INF>, and 
PM<INF>2.5</INF> at a variety of urban and rural locations.
    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 accessibility to the sites proposed for NCore monitoring 
stations. Relocating these stations will require EPA approval, which 
will be based on the data needs of the host State and other clients of 
the information.
    The EPA may negotiate with some States, and possibly with some 
Tribes, for the establishment and operation of additional rural NCore 
multipollutant monitoring stations to complement the stations required 
by today's action.
    The EPA is in the process of upgrading the CASTNET monitoring 
capabilities to allow stations to provide even more useful data to 
multiple users. The EPA expects that about 20 CASTNET sites, operated 
at EPA expense, will have new capabilities equivalent to some of the 
capabilities envisioned for NCore multipollutant sites. After 
consultations with State air quality planners and other data users, EPA 
may adjust the goal of having 20 rural State-operated NCore stations, 
if some of these CASTNET stations can achieve the same data objectives. 
This would preserve State/local funding resources for other types of 
monitoring. Alternatively, the CASTNET stations will contribute to a 
more robust rural network with multipollutant capabilities.
2. Requirements for Operation of PM<INF>10-2.5</INF> Stations
    For PM<INF>10-2.5</INF>, EPA proposed a new minimum network 
requirement based on metropolitan statistical area (MSA) population and 
estimated PM<INF>10-2.5</INF> design value. See 71 FR 2732-2736. Under 
that proposal, only those MSAs that contained an urbanized area of at 
least 100,000 persons were required to have one or more monitors. The 
minimum network design requirements would not have included separate 
requirements for multiple urbanized areas of 100,000 persons or more 
within a single MSA. Where more than one MSA was part of a CSA, each 
MSA was treated separately and was subject to individual requirements.
    The EPA proposed that the actual or estimated PM<INF>10-2.5</INF> 
design value (3-year average of 98th percentile 24-hour concentrations) 
of a MSA, where one could be calculated, be used as a second factor to 
increase the minimum number of monitors in MSAs with higher estimated 
ambient coarse particle levels and to reduce requirements in MSAs with 
lower estimated concentrations. The EPA developed an initial database 
of estimated PM<INF>10-2.5</INF> design values by analyzing 
concentrations from existing collocated or nearly collocated 
PM<INF>10</INF> and PM<INF>2.5</INF> monitors in each MSA and 
identifying which pairs met the proposed siting criteria which 
specified when a monitor was suitable for comparison to the proposed 
PM<INF>10-2.5</INF> NAAQS. Monitoring agencies were given the option of 
proposing other procedures for calculating estimated 
PM<INF>10-2.5</INF> design values as a substitute for EPA-calculated 
values.
    The EPA's proposal would have required as many as five 
PM<INF>10-2.5</INF> monitors in MSAs with total population of more than 
5 million with actual or estimated design values of greater than 80 
percent of the proposed PM<INF>10-2.5</INF> NAAQS, and no monitors in 
MSAs under 1 million people with actual or estimated design values less 
than 50 percent of that proposed NAAQS. The EPA estimated that the size 
of the minimum required PM<INF>10-2.5</INF> network would be 
approximately 250 monitors based on these proposed requirements and the 
most recent estimates of PM<INF>10-2.5</INF> design values available at 
the time of proposal. An additional review of urbanized area population 
counts and estimated design values completed after proposal 
subsequently reduced the

[[Page 61262]]

estimated size of the required PM<INF>10-2.5</INF> network to 
approximately 225 monitors (not counting PM<INF>10-2.5</INF> monitors 
at NCore stations) through the elimination of some MSAs where the 
population of the urbanized area was found to be fewer than 100,000 
persons, or where updated estimated design values decreased 
sufficiently for monitoring requirements to drop into an adjoining 
design value category with lower requirements.
    As noted earlier, in addition to the minimum monitoring 
requirements, EPA proposed a five-part test that would be used to 
determine whether potential PM<INF>10-2.5</INF> monitoring sites were 
suitable for comparison to the proposed NAAQS. All five parts of the 
site-suitability test were required to be met for data from required 
monitors or non-required monitors to be compared to the proposed 
PM<INF>10-2.5</INF> NAAQS.
    The EPA received extensive comments on all aspects of the 
PM<INF>10-2.5</INF> network design proposal including the minimum 
monitoring requirements, five-part suitability test for 
PM<INF>10-2.5</INF> NAAQS comparability, and monitor placement 
criteria. As summarized in section III.C.2 of the preamble for the 
NAAQS revisions published elsewhere in this Federal Register, EPA is 
not adopting a proposed PM<INF>10-2.5</INF> NAAQS but instead will be 
retaining the current 24-hour PM<INF>10</INF> standard. Therefore, the 
elements of the PM<INF>10-2.5</INF> monitoring network design that were 
proposed to implement an ambient network for the primary purpose of 
determining NAAQS compliance are no longer required and are not 
included in this final rule.
    As described elsewhere in this notice, EPA is requiring 
PM<INF>10-2.5</INF> mass concentration and speciation monitoring as 
part of the NCore network of multipollutant sites. These sites 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.
3. Requirements for Operation of PM<INF>2.5</INF> Stations
    The PM<INF>2.5</INF> 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. More than 500 
continuous PM<INF>2.5</INF> monitors are operated to support public 
reporting and forecasting of the AQI.
    The EPA proposed to modify the network minimum requirements for 
PM<INF>2.5</INF> monitoring so that multiple urban monitors in the same 
MSA or CSA are not required if they are redundant or are measuring 
concentrations well below the NAAQS. See 71 FR 2741. EPA proposed to 
base minimum monitoring requirements on PM<INF>2.5</INF> concentrations 
as represented by the design value of the area, and on the census 
population of the CSA, or in cases where there is no CSA, the MSA. 
Overall, this was expected to result in a lower number of required 
sites (to satisfy minimum network design requirements); however, EPA 
recommended 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 the sites.\17\ Id.
---------------------------------------------------------------------------

    \17\ As explained earlier, an approved regional method (ARM) is 
a PM<INF>2.5</INF> 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 V.D.2 of this preamble.
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    The EPA proposed to require that all sites counted by a State 
towards meeting the minimum requirement for the number of 
PM<INF>2.5</INF> sites have an FRM, FEM, or ARM monitor. The EPA also 
proposed that at least one-half of all the required PM<INF>2.5</INF> 
sites be required to operate PM<INF>2.5</INF> continuous monitors of 
some type even if not an FEM or ARM.
    As noted, EPA proposed to use design value and population as inputs 
in deciding the minimum required number of PM<INF>2.5</INF> monitoring 
sites in each CSA/MSA. The EPA proposed these inputs so that monitoring 
resources would be 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 have been required to continue 
to perform any PM<INF>2.5</INF> monitoring.
    The proposed amendments also would have required fewer sites when 
design values are well above (rather than near) the level of the NAAQS 
to allow more flexibility in the use of monitoring resources in areas 
where States and EPA are already confident of the severity and extent 
of the PM<INF>2.5</INF> problem and possibly in more need of other 
types of data to address it.
    We proposed to retain the current siting criteria for 
PM<INF>2.5</INF>, which have an emphasis on population-oriented sites 
at neighborhood scale and larger. See 71 FR 2741. In the proposal, EPA 
stated that these current design criteria appeared to remain 
appropriate for implementation of the proposed primary PM<INF>2.5</INF> 
NAAQS. See 71 FR 2742. The proposal stated that 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 (and now final) lowering of the 24-hour NAAQS.
    The EPA further proposed that background and transport sites remain 
a required part of each State's network to support characterization of 
regional transport and regional scale episodes of PM<INF>2.5</INF>. To 
meet these requirements, IMPROVE samplers could be used even though 
they would not be eligible for comparison to the PM<INF>2.5</INF> 
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 could also fulfill these minimum siting 
requirements.
    The preamble to the proposal also pointed out that in most MSAs, 
the PM<INF>2.5</INF> monitor recording the maximum annual 
PM<INF>2.5</INF> concentrations is the same as the monitor showing the 
maximum 24-hour PM<INF>2.5</INF> concentrations, suggesting that 
generally it will be these common high-reading monitors that will 
determine attainment/nonattainment for both the annual and 24-hour 
PM<INF>2.5</INF> NAAQS. 71 FR 2742. The preamble further noted that 
where this is the case, supplemental monitors, such as continuous 
PM<INF>2.5</INF> monitors and PM<INF>2.5</INF> speciation monitors, 
should already be well located to help in understanding the causes of 
the high PM<INF>2.5</INF> concentrations. In a relatively small number 
of cases, certain microscale PM<INF>2.5</INF> monitors that have not 
been eligible for comparison to the annual PM<INF>2.5</INF> NAAQS and 
that have been complying with the pre-existing 24-hour PM<INF>2.5</INF> 
NAAQS of 65 [mu]g/m<SUP>3</SUP>, and therefore have no impact on 
attainment status, may become more influential to attainment status 
under the more stringent level of the then-proposed, now adopted 24-
hour PM<INF>2.5</INF> standard. In these cases, EPA noted that States 
may choose to move accompanying speciation and continuous monitors to

[[Page 61263]]

the new site of particular interest to get a better characterization of 
PM<INF>2.5</INF> at that location.
    The EPA received a number of comments regarding the 
PM<INF>2.5</INF> network design. Several commenters expressed concern 
regarding the provision to allow fewer required sites when monitored 
PM<INF>2.5</INF> concentrations are significantly above the 
PM<INF>2.5</INF> NAAQS. Commenters stated that allowing fewer sites 
would be inadequate to demonstrate actual ambient air conditions. One 
commenter stated that the provision had merit for long-term NAAQS such 
as the annual average but not for short term standards. The commenter 
pointed out that long term standards, where concentrations are averaged 
out over a multiple year period, tend to provide relatively uniform 
results even over a large geographical area; however, daily 
observations are going to be more variable at a given site and from 
site to site. Other commenters expressed concern that while they 
appreciated the flexibility to redirect resources to speciation 
sampling in areas with significantly high NAAQS design values, there 
would still be a need for both speciation and FRM data. In these cases, 
while the flexibility may be available, in practice it would be 
difficult to shut down a monitor in an area that is significantly above 
the NAAQS.
    The EPA also received comments on using CSA as the definition for a 
metropolitan area in which to apply the minimally required 
PM<INF>2.5</INF> monitoring network criteria. Commenters expressed 
concern that the CSA was too large an area to apply minimum monitoring 
requirements and that it may result in the loss of essential monitors 
necessary to characterize the extent of nonattainment areas. In 
addition, EPA received comments on the proposed requirement for the 
PM<INF>2.5</INF> monitoring network to provide for one-half the 
required sites, rounded-up, to operate PM<INF>2.5</INF> continuous 
monitors. Commenters expressed concern that requiring PM<INF>2.5</INF> 
continuous monitors, none of which at present meet FEM and/or ARM 
performance criteria, may result in minimizing the impetus for 
equipment manufacturers to further develop versions of these 
technologies that would meet the FEM/ARM performance criteria. Some 
commenters expressed concern that although PM<INF>2.5</INF> continuous 
monitors serve multiple monitoring objectives, which underscores the 
need for their operation, requiring collocation with FRMs should not be 
a requirement of all the sites since it places an unnecessary burden on 
the States.
    The EPA also received several comments regarding the location of 
required PM<INF>2.5</INF> monitoring sites, questioning EPA's proposal 
to keep the siting requirements for PM<INF>2.5</INF> monitors the same 
despite the revision of the 24-hour NAAQS to a level at which 
commenters asserted that violations of the 24-hour NAAQS may occur in 
many middle scale or microscale locations not presently experiencing 
violations of the current 24-hour NAAQS. The gist of the comments was 
that more monitors should be deployed in middle and/or microscale 
locations to find such violations. One commenter recommended that EPA 
specifically require a monitoring organization to have at least one 
microscale site in any area that is nonattainment or marginally 
nonattainment for the 24-hour NAAQS.
    In response to concerns about requiring fewer PM<INF>2.5</INF> 
monitoring sites when monitored PM<INF>2.5</INF> concentrations are 
significantly above the NAAQS, EPA is not adopting the provision and 
will instead provide two ranges of minimum monitoring requirements 
depending on design value. As proposed, agencies with areas that are 
significantly below the PM<INF>2.5</INF> NAAQS (less than or equal to 
85 percent of the annual and 24-hour PM<INF>2.5</INF> NAAQS) will have 
a lower minimum monitoring requirement. Areas that are within 15 
percent of the NAAQS or above it will be required to operate more 
PM<INF>2.5</INF> monitoring sites (i.e., be required to deploy a 
greater minimum number of monitors), relative to those at less than 85 
percent of the NAAQS.
    To address the comments concerning the most appropriate Census 
Bureau definition in which to apply the PM<INF>2.5</INF> minimum 
monitoring requirements, EPA compared the current network to the number 
of monitors that would be required using either CSA or MSA as the unit 
for applying monitoring requirements. The results demonstrated that 
using MSA ensures a few more required sites in areas that have multiple 
MSAs making up a large CSA with high populations and large geographical 
areas, without requiring new sites of less obvious priority in MSAs 
that have smaller geographic coverage and population. Since the overall 
goal of reducing redundant required sites in large metropolitan areas 
can be met by using MSA as the unit for monitoring requirements, and 
using MSA as the unit will also result in multiple MSAs with high 
design values in the same CSA each having minimum monitoring 
requirements to address spatial gradients in large areas, EPA is 
adopting the MSA in as the geographic unit for applying the minimum 
PM<INF>2.5</INF> monitoring requirements. In a CSA, each MSA must meet 
the MSA requirements separately.
    In considering the comments on requiring one-half the required 
PM<INF>2.5</INF> sites to have continuous monitors, EPA notes that the 
existing network of monitors is providing invaluable data for reporting 
and forecasting of the AQI and in support of emergency situations such 
as wildfires and natural disasters (e.g., Hurricane Katrina). Ensuring 
a minimum network of these monitors is essential to informing the 
public and policy makers on the quality of the air during air pollution 
episodes. The technology utilized in the network continues to evolve as 
agencies adopt the most suitable methods for use in their own network. 
The EPA believes that as agencies continue to purchase the most optimal 
equipment for their networks and as instrument manufacturers now will 
have the opportunity to receive FEM or ARM approval for their 
method(s), manufacturers will continue to develop better continuous 
instruments. The EPA is therefore adopting the proposed requirement for 
one-half the required PM<INF>2.5</INF> sites to have continuous 
monitors as proposed. However, to address the concern about whether 
required continuous monitors need to be collocated with a matching 
second continuous monitor, this final rule states that only one of all 
the required PM<INF>2.5</INF> continuous monitors in each MSA needs to 
have such a collocated match. This will allow a minimal level of 
performance characterization of the continuous monitors in each area 
that they are operated. Additional PM<INF>2.5</INF> continuous 
monitors, when required, can either be collocated with FRMs or set up 
at non-collocated sites to provide better spatial coverage of the MSA.
    With regard to concerns expressed in comments about monitor siting 
in light of the revised 24-hour PM<INF>2.5</INF> NAAQS, EPA agrees that 
the proposed change in the level of the primary 24-hour 
PM<INF>2.5</INF> NAAQS from 65 [mu]g/m<SUP>3</SUP> to 35 [mu]g/
m<SUP>3</SUP> raised the issue of whether any commensurate changes 
would be needed in these requirements. The EPA has considered the 
original requirements for PM<INF>2.5</INF> network design promulgated 
in 1997 and their rationale, how the PM<INF>2.5</INF> network is 
currently configured, what if any changes need to be made to this 
network to make it consistent with the intended level of protection of 
the lower 24-hour PM<INF>2.5</INF> NAAQS in combination with the annual 
PM<INF>2.5</INF> NAAQS, and whether these or any changes should be 
required by a general rule or developed on a case-by-case basis.

[[Page 61264]]

    In specifying monitor siting criteria for the original 
PM<INF>2.5</INF> monitoring network in 1997, EPA noted that the annual 
standard had been set based on epidemiology studies in which monitors 
generally were representative of community-average exposures. The EPA 
stated its expectations that the annual standard would generally be the 
controlling standard in designating nonattainment areas and that 
controlling emissions to reduce annual averages would lower both annual 
and 24-hour PM<INF>2.5</INF> concentrations across each annual NAAQS 
nonattainment area. Accordingly, the PM<INF>2.5</INF> network design 
provisions in that final rule (62 FR 38833, July 18, 1997) and EPA's 
subsequent negotiations with State/local monitoring agencies over 
monitoring plans were largely but not solely directed at obtaining air 
quality data reflecting community-wide exposures by placing monitors in 
neighborhood and larger scales of representation.
    Section 2.8 of appendix D of 40 CFR part 58 as promulgated in 1997 
had only a few definite requirements regarding the siting of 
PM<INF>2.5</INF> monitors. Section 2.8.1.3 specified how many ``core'' 
monitors representing community-wide air quality were required based on 
MSA population. For areas with populations of 500,000 or more, section 
2.8.1.3.1(a) required that at least one core monitoring station must be 
placed in a ``population-oriented'' area of expected maximum 
concentration and (unless waived under section 2.8.1.3.4) at least one 
core station in an area of poor air quality. Areas with populations 
between 200,000 and 500,000 were required to operate at least one core 
monitor. Section 2.8.1.3.4 strongly encouraged any State with an MSA 
with only one required monitor (due to being fewer than 500,000 in 
population or due to a waiver) to site it so it represented community-
oriented concentrations in areas of high average PM<INF>2.5</INF> 
concentrations. Section 2.8.1.3.7 required core monitoring sites to 
represent neighborhood or larger spatial scales. States could at their 
initiative place additional monitors anywhere, but monitors in 
relatively unique microscale, localized hot spot, or unique middle-
scale locations cannot be compared to the annual NAAQS, and any 
monitoring site must be population-oriented to be compared to either 
NAAQS. Part 58 App. D section 2.8.1.2.3.
    In practice, the majority of PM<INF>2.5</INF> monitors are deployed 
at neighborhood scale and larger, meaning that they are located far 
enough from large emission sources that they represent the fairly 
uniform air quality across an area with dimensions of at least a few 
kilometers and thus can be considered community-oriented. The existing 
PM<INF>2.5</INF> monitoring network continues to mostly be made up of 
these population-oriented, community-oriented, neighborhood scale 
monitoring sites. The EPA is presently aware of fewer than ten 
PM<INF>2.5</INF> monitors that are sited in relatively unique 
population-oriented microscale areas, localized hot spots, or unique 
population-oriented middle-scale areas. Such sites may have higher 
concentrations than neighborhood scale sites on at least some days 
because they may be close to and downwind of large emission sources, 
but the number of people exposed to such concentrations is not large 
relative to the surrounding communities.
    The EPA believes the PM<INF>2.5</INF> networks that were deployed 
were, and the networks that are now operating currently are, consistent 
with the intended level of protection of the annual PM<INF>2.5</INF> 
NAAQS. Consistency or inconsistency with regard to the 24-hour 
PM<INF>2.5</INF> NAAQS has not been of practical significance until now 
due to the near absence of violations of that standard. In the January 
17, 2006, proposal notice, EPA said that it believed that the 1997 
rule's design criteria remained appropriate for implementation of the 
proposed primary PM<INF>2.5</INF> NAAQS, including the lower 24-hour 
NAAQS, because these requirements effectively ensured that monitors are 
placed in locations that appropriately reflect the community-oriented 
areawide concentration levels used in the epidemiological studies that 
support the proposed lowering of the 24-hour PM<INF>2.5</INF> NAAQS. 71 
FR 2742. The EPA continues to believe this, noting that the monitors 
used in the epidemiology studies underlying the 24-hour 
PM<INF>2.5</INF> NAAQS were sited similar to the majority of monitors 
in the existing State/local networks.
    No comments directly contradicted this assessment. While an 
implication of the final monitoring rule provisions regarding siting of 
PM<INF>2.5</INF> monitors is that States may choose not to monitor 
microenvironment or middle scale locations where some people are 
exposed to 24-hour concentrations above the level of the 24-hour NAAQS, 
such a result remains consistent with the community-oriented area-wide 
level of protection on which the 24-hour PM<INF>2.5</INF> NAAQS is 
premised. Thus, EPA believes it is not appropriate to specifically 
require any number of monitors to be placed in microenvironment or hot 
spot locations as one commenter suggested.
    On the other hand, States and EPA may agree as part of the annual 
monitoring plan submission by the State and approval by the Regional 
Administrator that in specific cases placement of new or relocated 
monitors into microenvironment or middle scale locations is warranted 
and consistent with the intended level of protection of the 24-hour 
PM<INF>2.5</INF> NAAQS. States may also propose, and EPA would be 
inclined to approve, the placement of PM<INF>2.5</INF> monitors in 
populated areas too small to be subject to the requirements regarding 
minimum numbers of monitors, if there is reason to believe 
PM<INF>2.5</INF> concentrations are of concern. Of particular interest 
may be smaller cities and towns which presently lack any 
PM<INF>2.5</INF> monitor but which experience emission patterns such as 
use of wood stoves and/or weather conditions such as inversions which 
can create high short-term concentrations of PM<INF>2.5</INF>. States 
also remain free to place SPM at any location, without need for EPA 
review or approval.\18\
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    \18\ The possible additional monitoring discussed in the text 
above could be compared solely to the 24-hour PM<INF>2.5</INF> 
NAAQS. As mentioned earlier, the 1997 rules provide that monitors 
that are sited in relatively unique population-oriented microscale 
areas, localized hot spots, or unique population-oriented middle-
scale areas, may not be compared to the annual PM<INF>2.5</INF> 
NAAQS.
---------------------------------------------------------------------------

    The proposed rule text for 40 CFR 58, appendix D inadvertently 
failed to include rule text on PM<INF>2.5</INF> monitoring network 
design criteria, found in existing appendix D section 2.8.1.2.3, 
setting forth the requirements that: (1) The required monitors are 
sited to represent community-wide air quality, (2) at least one 
monitoring site is placed in a ``population-oriented'' area of expected 
maximum concentration, and (3) at least one station is placed in an 
area of poor air quality. Therefore, this final rule restores these 
pre-existing requirements to appendix D. This final rule sets out these 
criteria (in substantively identical but slightly redrafted form) in 
appendix D section 4.7.1(b).
    Also, as noted in the proposal and again above, some monitors that 
have not measured high concentrations relative to the 1997 24-hour 
NAAQS may become more influential to attainment status under the just 
adopted, more stringent 24-hour NAAQS. In these cases, EPA encourages 
States to consider adding or moving speciation and continuous monitors 
to the newly influential site to get a better characterization of 
PM<INF>2.5</INF> concentrations and their causes at that location.
    Finally, this final rule clarifies that IMPROVE monitors operated 
by an

[[Page 61265]]

organization other than the State may be counted as satisfying the 
State's obligation to operate background and transport monitoring sites 
for PM<INF>2.5</INF>.
4. Requirements for Operation of PM<INF>10</INF> Stations
    PM<INF>10</INF> monitors currently are deployed throughout the 
country at about 1,200 sites, with most metropolitan areas already 
operating more PM<INF>10</INF> monitors than are required by current 
monitoring requirements.
    In the January 17, 2006, proposal notice, EPA proposed changes to 
the PM<INF>10</INF> requirements in coordination with new minimum 
requirements for a PM<INF>10-2.5</INF> monitoring network in support of 
the proposed 24-hour PM<INF>10-2.5</INF> NAAQS which would have 
eventually replaced the PM<INF>10</INF> NAAQS entirely. See 71 FR 2742. 
As already explained, EPA is not finalizing the proposed NAAQS for 
PM<INF>10-2.5</INF> and instead is retaining the 24-hour 
PM<INF>10</INF> NAAQS for all parts of the U.S. This change has 
necessitated a different approach for PM<INF>10</INF> minimum 
monitoring requirements from the one proposed.
    Rather than revoking PM<INF>10</INF> monitoring requirements, as 
proposed, EPA believes that a robust nationwide monitoring network is 
required to provide compliance data for the 24-hour PM<INF>10</INF> 
NAAQS and to support other objectives including the assessment of long-
term trends, evaluations of the effectiveness of State and local coarse 
particle control programs, and health effects research. The EPA has 
therefore considered whether the existing National Air Monitoring 
Station Criteria in Table 4 of appendix D of 40 CFR part 58, last 
revisited in 1997, are still appropriate for these purposes. Because 
these criteria have an urban focus by being based on MSAs, allow for 
local considerations to be a factor in determining the actual required 
number of stations, require more stations in larger MSAs and MSAs with 
more evidence of poor PM<INF>10</INF> air quality while also requiring 
some stations even in clean MSAs of a certain size, and in the 
aggregate will result in a required number of PM<INF>10</INF> monitors 
that is similar to the required numbers of ozone and PM<INF>2.5</INF> 
monitors, EPA believes these criteria are appropriate. With regard to 
the comparison to the required numbers of ozone and PM<INF>2.5</INF> 
monitors, EPA has considered two directionally opposite factors. 
PM<INF>10</INF> is less spatially uniform than O<INF>3</INF> or 
PM<INF>2.5</INF>, suggesting the need for relatively more intensive 
monitoring in areas with PM<INF>10</INF> problems, but PM<INF>10</INF> 
concentrations in most areas are below the PM<INF>10</INF> NAAQS 
(unlike for O<INF>3</INF> and PM<INF>2.5</INF>) suggesting that fewer 
monitors should be required overall for PM<INF>10</INF>. This final 
rule therefore retains the current PM<INF>10</INF> minimum network 
requirements, except that these will no longer be called ``NAMS'' 
requirements.
    The current PM<INF>10</INF> minimum monitoring requirements in 
section 3.7.7 of part 58 appendix D are based on MSA population and 
three different ranges of ambient PM<INF>10</INF> concentrations as 
compared to the PM<INF>10</INF> NAAQS. For MSAs in the lowest category 
of ambient PM<INF>10</INF> concentrations, those for which ambient 
PM<INF>10</INF> data show concentrations less than 80 percent of the 
NAAQS, at least one monitor is required if the population of the MSA is 
500,000 or greater. For MSAs in the highest category of ambient 
PM<INF>10</INF> concentrations, those for which ambient PM<INF>10</INF> 
data show concentrations exceeding the NAAQS by 20 percent or more, at 
least one monitor is required if the population of the MSAs is 100,000 
persons or greater. These requirements list ranges of required 
monitors, with the actual number of monitors to be determined by EPA 
and States.
    Based on PM<INF>10</INF> ambient data for 2003-2005 and current 
census population statistics, a minimum of between 200 and 500 
PM<INF>10</INF> FRM/FEM monitors will be required across all affected 
MSAs. Over 800 PM<INF>10</INF> monitors are in fact currently deployed 
in these MSAs. About 400 other PM<INF>10</INF> monitors currently 
operate outside the boundary of any MSA. As stated in section III.B of 
this preamble, EPA believes a reduction in the size of the existing 
monitoring networks for certain pollutants, including PM<INF>10</INF>, 
for which the large majority of monitors record no NAAQS violations, is 
an appropriate way to free up resources for higher priority monitoring 
objectives. These higher priority objectives could include meeting both 
the new requirements in this final rule such as the NCore 
multipollutant measurements and objectives defined by the local air 
quality management program. The EPA notes that many PM<INF>10</INF> 
monitors have been recording concentrations well below the 24-hour 
PM<INF>10</INF> NAAQS and thus are candidates for discontinuation at a 
State's initiative. States may also choose to continue to operate 
monitors in excess of the minimum requirements. To the extent that 
States and Tribes are considering reducing the total number of 
PM<INF>10</INF> monitors deployed, EPA believes, consistent with the 
basis for retaining the 24-hour PM<INF>10</INF> standard, priority 
should be given to maintaining monitors sited in urban and industrial 
\19\ areas. States may of course choose to retain PM<INF>10</INF> 
monitors that are recording concentrations below the PM<INF>10</INF> 
NAAQS level to support monitoring objectives other than attainment/
nonattainment determinations, such as baseline monitoring for 
prevention of significant deterioration permitting or public 
information. The EPA expects to work with States to assess their 
PM<INF>10</INF> networks and help determine which of these monitors are 
delivering valuable data and which monitors present disinvestment 
opportunities. As should be evident, however, States may not reduce 
their PM<INF>10</INF> networks below the minimum requirements for 
monitoring within MSAs given in 40 CFR part 58 appendix D.
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    \19\ As used in the Staff Paper, the term ``mining sources'' is 
intended to include all activities that encompass extraction and/or 
mechanical handling of natural geologic crustal materials. In the 
context of this rule making, neither mining nor agricultural sources 
are included in the more general category of ``industrial sources.''
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    In addition, if States and Tribes are considering deploying new 
PM<INF>10</INF> monitors, EPA recommends, again consistent with the 
basis for retaining the 24-hour PM<INF>10</INF> standard, that those 
monitors be placed in areas where there are urban and/or industrial 
sources of thoracic coarse particles. Furthermore, consistent with the 
monitors used in studies that informed our decision on the level of the 
standard (see section III.D of the final rule on the PM NAAQS published 
elsewhere in today's Federal Register), EPA recommends that any new 
PM<INF>10</INF> monitors be placed in locations that are reflective of 
community exposures at middle and neighborhood scales of 
representation, and not in source-oriented hotspots that are not 
population oriented.
    The final rule omits two passages in section 4.6 (Particulate 
Matter (PM<INF>10</INF>) Design Criteria) of 40 CFR 58, appendix D that 
were included for providing context for the proposed rule. The omitted 
passages are 4.6(b)(4) (Urban scale) and 4.6(b)(5) (Regional scale). As 
explained below, these two passages are not consistent with EPA's 
intention to preserve the substance of the 1997 monitoring rule 
regarding scales of representativeness, while restructuring appendix D 
to eliminate SLAMS versus NAMS distinctions and to make clearer which 
requirements (and explanatory background and guidance) applied to each 
individual pollutant. In appendix D of the 1997 monitoring rule, 
section 2.8 (Particulate Matter Design Criteria for SLAMS) addressed 
both PM<INF>2.5</INF> and PM<INF>10</INF>, in some sentences referring 
explicitly to PM<INF>2.5</INF>, PM<INF>10</INF>, or both, and in some 
sentences referring only in general to particulate matter. In this 
final rule, section 4.6 (Particulate Matter (PM<INF>10</INF>)

[[Page 61266]]

Design Criteria) addresses this subject matter for PM<INF>10</INF>, 
while section 4.7 (Fine Particulate Matter (PM<INF>2.5</INF>) Design 
Criteria) does so for PM<INF>2.5</INF>. In the proposed rule, for the 
purpose of providing context, EPA included paragraphs on microscale, 
middle scale, neighborhood scale, urban scale, and regional monitoring 
scales in both section 4.6 and 4.7. However, EPA upon closer 
consideration has determined that omitting the paragraphs on urban 
scale and regional scale from section 4.6 is appropriate for 
PM<INF>10</INF>, in terms of clarifying and preserving the effective 
substance of the 1997 rule for PM<INF>10</INF>. The bases for reaching 
this conclusion include the following: (1) The paragraphs concerning 
these scales of representation in the 1997 appendix D (section 2.8.0.7 
and 2.8.0.8) mention PM<INF>2.5</INF> specifically but not 
PM<INF>10</INF>, (2) the paragraph which precedes the five paragraphs 
on the five scales (2.8.0.2) states that middle and neighborhood scales 
are the most important scales for PM<INF>10</INF>, (3) section 2.8 in 
the 1997 rule was titled as applying to SLAMS in particular but no 
SLAMS monitors were specifically required at any spatial scale or 
scales, (4) under section 3.7 (Particulate Matter Design Criteria for 
NAMS) specific numbers of PM<INF>10</INF> monitors were required but 
without specification as to spatial scale, and (5) Table 6 of appendix 
D in the 1997 rule indicates that only the micro, middle, and 
neighborhood scales are ``required for NAMS.'' The EPA notes that in 
the final rule, the same numbers of PM<INF>10</INF> monitors are 
required as in the 1997 rule, but they are not referred to as NAMS 
monitors. The EPA notes that urban scale and regional scale are of 
little, if any, relevance to PM<INF>10</INF> monitoring, because of the 
short transport distances for PM<INF>10</INF>, especially when emitted 
near ground level. In contrast, because PM<INF>2.5</INF> is a secondary 
pollutant, large spatial scales are relevant because monitors in such 
locations will reflect regional emissions trends and transport 
patterns.
5. Requirements for Operation of Carbon Monoxide, Sulfur Dioxide, 
Nitrogen Dioxide, and Lead Monitoring Stations
    Criteria pollutant monitoring networks for the measurement of CO, 
SO<INF>2</INF>, NO<INF>2</INF>, and Pb are primarily operated to 
determine compliance with the NAAQS and to track trends and 
accountability of emission control 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.
    The EPA proposed to revoke all minimum requirements for CO, 
SO<INF>2</INF>, and NO<INF>2</INF> monitoring networks, and reduce the 
requirements for Pb. See 71 FR 27423. The proposal allowed for 
reductions in ambient air monitoring for CO, SO<INF>2</INF>, 
NO<INF>2</INF>, 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. The EPA stated it would work with 
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, SO<INF>2</INF>, and NO<INF>y</INF> were also 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. Under 40 CFR 58.11 of this final 
rule, States must consider the effect of monitoring site closures on 
data users other than the State itself, such as health effects studies. 
The EPA expects State and local agencies to seek input on which 
monitors are being used for health effects studies so they can give 
this consideration. See also section IV.E.8 of this preamble.
6. Requirements for Operation of Ozone Stations
    Ozone (O<INF>3</INF>) monitors currently are deployed throughout 
the country at about 1,200 sites, with most metropolitan areas already 
operating more O<INF>3</INF> monitors than would be required by today's 
action. The EPA does not anticipate or recommend significant changes to 
the size of this network because O<INF>3</INF> remains a pollutant with 
measured levels near or above the NAAQS in many areas throughout the 
country. However, this final rule should help to better prioritize 
monitoring resources depending on the population and levels of 
O<INF>3</INF> in an area.
    For O<INF>3</INF>, EPA proposed changing 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 to O<INF>3</INF>, as indicated by the design value, 
and the census population of a metropolitan area. See 71 FR 2742. The 
proposal stated that a CSA, or MSA if there is no CSA, with a 
population of 10 million or more and a design value near the 
O<INF>3</INF> NAAQS would be required to operate at least four sites. 
Smaller CSAs and MSAs as low as 350,000 people in population would be 
required to operate as few as one site. An even smaller area would have 
no required monitor, provided its design values (for example, from a 
previously required monitor or a SPM) were sufficiently low. Taking the 
same approach used in the proposed minimum requirements for 
PM<INF>2.5</INF> sites, EPA proposed that high-population areas with 
measured ambient concentrations significantly above the NAAQS be 
allowed to operate one less site than areas with measured ambient 
concentrations near the NAAQS to allow flexibility of monitoring 
resources in those areas.
    The EPA received a number of comments on the proposed minimum 
network requirements for O<INF>3</INF>. Similar to the comments 
received on PM<INF>2.5</INF>, many commenters had concerns with 
requiring only one site when an area is significantly above the NAAQS 
and with defining the minimum monitoring requirements by CSA instead of 
by a smaller level of a metropolitan area. For instance, several 
commenters noted that by applying the minimum monitoring requirements 
by CSA, agencies may not be required to deploy enough monitors to 
characterize the within-MSA gradient needed to adequately characterize 
O<INF>3</INF> across a metropolitan area.
    In response to concerns about allowing one less O<INF>3</INF> 
monitoring site when a high-population area is significantly above the 
NAAQS, EPA is not adopting this provision. This final rule instead 
provides two values for the minimum required number of monitors 
according to design value. Agencies with areas that are significantly 
below the O<INF>3</INF> NAAQS (less than or equal to 85 percent of the 
O<INF>3</INF> NAAQS) have the lower minimum monitoring requirement. 
Areas that are within 15 percent of the NAAQS or above it have will be 
required to operate more O<INF>3</INF> monitoring sites.
    To address the comments concerning the most appropriate Census 
Bureau-defined area for which to apply the O<INF>3</INF> minimum 
monitoring requirements, EPA investigated the current network compared 
with using either CSA or MSA as the basis for applying the minimum 
network requirements. The results demonstrate that using MSA ensures a 
few more sites in the small number of large CSAs that have high 
populations and large geographical areas without unnecessarily 
requiring new sites in the many areas that have smaller geographic 
coverage and population. Since using MSA does not impose a significant 
new burden on the States and makes it more likely that within-MSA 
gradient characterization of

[[Page 61267]]

O<INF>3</INF> will be characterized in high concentration areas, EPA is 
adopting MSA as the appropriate unit of a metropolitan area to apply 
the minimum O<INF>3</INF> monitoring requirements. All other monitoring 
requirements for O<INF>3</INF> are adopted as proposed.
7. Requirements for Operation of Photochemical Assessment Monitoring 
Stations
    Section 182(c)(1) of the CAA required EPA to promulgate rules 
requiring enhanced monitoring of O<INF>3</INF>, NO, and VOC in ozone 
nonattainment areas classified as serious, severe, or extreme. On 
February 12, 1993, EPA promulgated requirements for State and local 
monitoring agencies to establish PAMS as part of their SIP monitoring 
networks in ozone nonattainment areas classified as serious, severe, or 
extreme. During 2001, EPA 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.
    The EPA proposed changes to the minimum PAMS monitoring 
requirements in 40 CFR part 58 to implement the recommendations of the 
PAMS workgroup. See 71 FR 2743. Specifically, EPA proposed 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; and 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 O<INF>3</INF> 
standard. Conventional NO<INF>2</INF>/NO<INF>X</INF> monitors would 
only be required at Type 2 sites. High sensitivity NO<INF>y</INF> 
monitors would be required at one site per PAMS area (either Type 1 or 
Type 3). High sensitivity CO monitors would be required at Type 2 
sites.
    The EPA received comments on the proposed amended PAMS 
requirements. Overall, the commenters supported the reduction in 
minimum PAMS requirements which will allow for more individualized PAMS 
networks and alternative enhanced O<INF>3</INF> monitoring initiatives. 
However, some commenters were concerned with the proposed requirement 
for NO<INF>y</INF> monitoring at one Type 1 or one Type 3 site. Several 
commenters stated that the PAMS NO<INF>y</INF> requirement is not 
likely to be beneficial. They argued that NO<INF>y</INF> data in urban 
areas are likely to be indistinguishable from NO<INF>X</INF> data, the 
commercial NO<INF>y</INF> instrumentation is not yet fully developed, 
NO<INF>y</INF> monitors are difficult to site properly, and that few 
States have the modeling capability to employ NO<INF>y</INF> data.
    The EPA disagrees with the commenters' statements that PAMS 
NO<INF>y</INF> measurements will not be beneficial. As compared to 
NO<INF>X</INF> measurements, NO<INF>y</INF> measurements provide a more 
complete measurement of the available reactive nitrogen species 
involved in the photochemical reactions that lead to O<INF>3</INF> 
formation. One of the primary uses of NO<INF>y</INF> data is for 
O<INF>3</INF> modeling. However, O<INF>3</INF> modeling is not the only 
use for NO<INF>y</INF> data. Long-term measurements of NO<INF>y</INF> 
provide the best indicator of the effectiveness of NO<INF>X</INF> 
controls at reducing the reactive nitrogen compounds involved in 
O<INF>3</INF> formation. In addition, a relatively simple analysis of 
the O<INF>3</INF>-to-NO<INF>y</INF> ratio, or VOC-to-NO<INF>y</INF> 
ratio can be performed to identify if an area is ``NO<INF>X</INF> 
limited'' or ``VOC limited'' which would indicate if additional 
NO<INF>X</INF> controls would be more beneficial than additional VOC 
controls.
    Ideally, the NO<INF>X</INF> method should measure NO and 
NO<INF>2</INF>, whereas NO<INF>y</INF> measurements include NO, 
NO<INF>2</INF>, and other important reactive nitrogen species (referred 
to here as NO<INF>z</INF>) which includes nitrous acids [nitric acid 
(HNO<INF>3</INF>), and nitrous acid (HONO)], organic nitrates [peroxyl 
acetyl nitrate (PAN), methyl peroxyl acetyl nitrate (MPAN), and peroxyl 
propionyl nitrate, (PPN)], and particulate nitrates. However, recent 
studies have shown that existing NO<INF>X</INF> monitors also measure 
(and misreport as NO<INF>2</INF>) some NOz species. The NO<INF>y</INF> 
method was developed as an extension of the NO<INF>X</INF> method to 
accurately measure all reactive nitrogen compounds. Nonetheless, EPA 
will allow for waivers of the NO<INF>y</INF> method (via an alternative 
plan provided for under paragraph 5.3 of appendix D to part 53) in 
areas where measured NO<INF>X</INF> is expected to provide virtually 
the same data as NO<INF>y</INF>. This is largely expected to be in 
areas with fresh oxides of nitrogen emissions until such time as the 
NO<INF>2</INF> method (and hence the NO<INF>X</INF> method) is 
sufficiently improved that having separate measurements of 
NO<INF>y</INF> and NO<INF>X</INF> provides more useful information than 
the existing technology. The EPA has evaluated a number of commercially 
available NO<INF>y</INF> monitors and has found them accurate and 
reliable. As with many methods, EPA continues to evaluate improvements 
to the method, but at this time EPA believes that the current method 
(and commercially available instrumentation) provides data of 
sufficient quality to meet the PAMS program objectives.
    While proper siting of an NO<INF>y</INF> monitor (installing a 10 
meter tower and meeting proper fetch characteristics) may be difficult 
in some urban settings, EPA believes that NO<INF>y</INF> monitors can 
be adequately sited at most PAMS areas. Nonetheless, if siting a 
NO<INF>y</INF> monitor is not practicable in a given PAMS area, a State 
may request an alternative plan, as allowed for under paragraph 5.3 of 
appendix D to part 53, to allow monitoring of NO<INF>X</INF> instead of 
monitoring for NO<INF>y</INF>.
    After review and consideration of the comments received, EPA has 
decided to finalize the revisions to the PAMS requirements as proposed.

F. Appendix E--Probe and Monitoring Path Siting Criteria for Ambient 
Air Monitoring

    The proposed revisions to this appendix consisted of minor 
organizational changes and two technical changes to the siting criteria 
affecting PM<INF>10-2.5</INF> and O<INF>3</INF> monitoring sites. See 
71 FR 2748.
1. Vertical Placement of PM<INF>10-2.5</INF> Samplers
    Specific probe siting criteria were required to support the 
proposed PM<INF>10-2.5</INF> network. The EPA proposed vertical probe 
placement requirements that limited microscale PM<INF>10-2.5</INF> 
sites to an allowable height range of 2 to 7 meters and neighborhood 
and large scale PM<INF>10-2.5</INF> sites to a range of 2 to 15 meters. 
These ranges were identical to the existing requirements for 
PM<INF>10</INF>. The range for middle-scale PM<INF>10-2.5</INF> sites 
was limited to 2 to 7 meters which represented a change from 
PM<INF>10</INF> where 2 to 15 meters was the allowed vertical placement 
range for middle-scale sites.
    Several commenters supported the proposed PM<INF>10-2.5</INF> 
middle-scale vertical requirement as being consistent with the 
expectation that coarse particle concentrations nearest the breathing 
zone would be important to measure in the assessment of exposure risk, 
and that monitoring sites with more elevated inlets would be more 
likely to miss localized concentrations where the public is exposed. By 
contrast, other commenters raised concerns that the requirement would 
result in the measurement of localized (microscale) near-ground 
conditions not representative of a middle-scale sized area. Commenters 
also noted the

[[Page 61268]]

importance of keeping identical inlet requirements for 
PM<INF>10-2.5</INF> and PM<INF>2.5</INF> to maximize the benefits of 
having collocated measurements at the same site.
    Based on review of the comments, EPA is retaining the 2 to 7 meter 
vertical requirement for middle-scale PM<INF>10-2.5</INF> sites. This 
requirement is consistent with current requirements for microscale PM 
monitors but would require modifications for existing PM<INF>2.5</INF> 
and PM<INF>10</INF> monitors located between 8 and 15 meters above 
ground that were intended for middle-scale PM<INF>10-2.5</INF> 
measurement. The EPA does not expect this requirement to have a major 
impact on monitoring networks since this final rule requires 
PM<INF>10-2.5</INF> monitoring only at NCore sites, and these sites 
will typically represent neighborhood or larger scales. This final rule 
retains the existing rule language that has the option for the Regional 
Administrator to grant a waiver of siting criteria, providing 
flexibility for States to document situations where useful data could 
still be produced by monitors not meeting applicable requirements.
2. Ozone Monitor Setback Requirement From Roads
    The EPA proposed an increase to the minimum permitted distance 
between roadways and the inlet probes of neighborhood and urban scale 
ozone and oxides of nitrogen sites to reduce the scavenging effects of 
motor vehicle-related nitric oxide emissions. See 71 FR 2748.
    Many commenters believed that the scavenging effects of oxides of 
nitrogen on O<INF>3</INF> levels in urban, populated areas was more of 
an area-wide phenomena and would not be changed by moving a site a few 
meters farther from the nearest roadway. The relative value of the 
proposed change on the basis of the resource requirements necessary to 
relocate sites not meeting the increased road setback requirements was 
also questioned. Some support was noted for the application of the 
increased roadway setback requirement to new sites as long as existing 
ozone sites were ``grandfathered.''
    The EPA acknowledges the logistical difficulty and expense of 
moving existing sites to meet the increased setback requirement. To 
achieve a balance between the goal of minimizing the interference of 
roadway emissions on O<INF>3</INF> and oxides of nitrogen monitor data 
and to reduce the burden on affected monitoring organizations, EPA has 
modified the increased roadway setback requirement to apply only to 
newly established sites.

G. Sample Retention Requirements

    During the regulatory development process, various governmental 
agencies and health scientists indicated that archiving particulate 
matter filters for FRM and FEM would be useful for later chemical 
speciation analyses, mass analyses, or other analyses.
    Current sample retention requirements apply specifically to 
PM<INF>2.5</INF> filters and require a minimum storage requirement of 1 
year. The EPA proposed that retention requirements be expanded to 
require archival of PM<INF>2.5</INF>, PM<INF>10-2.5</INF>, and 
PM<INF>10c</INF> (low volume) filters for a period of 1 year after 
collection. See 71 FR 2749.
    Commenters were supportive of the proposed requirement. Some 
commenters stated that the required filter retention period should be 
longer than 1 year, with a range in suggested storage periods of 
between 3 to 7 years. States provided examples of how filters archived 
for longer than 1 year were subsequently analyzed to provide data 
useful in the support of health studies, SIP work, or analysis of 
exceptional events. Several commenters, while supportive of the 
rationale for filter archival, preferred that the requirement not be 
included in the regulation and instead left for voluntary monitoring 
agency compliance. One commenter suggested that the requirement be 
clarified to explicitly include retention of blank filters in addition 
to exposed filters.
    The EPA notes the support for the proposed sample retention 
requirement and did not change that requirement in this final rule. As 
stated in this final rule, States have the discretion to retain their 
samples for longer than one year. The EPA supports such procedures, 
recognizing that States will have different logistical constraints that 
control the maximum length of time for which filters can be stored. The 
EPA has clarified that the requirement applies to all such filters 
referenced in 40 CFR 58.16(f), including exposed filters and blanks.
    The EPA acknowledges the concern among some commenters that States 
retain the right to determine the best use of archived filters. These 
commenters stated that national considerations for filter analysis 
should be considered a secondary priority to State needs. The EPA is 
respectful of this issue, and expects to negotiate with States on the 
scope of any request for archived filters intended for potentially 
destructive analyses so that the request if compatible with other State 
uses for the same type of filters.
    The EPA did not propose a specific effective date for this 
requirement in the monitoring rule and no commenters expressed 
implementation concerns. Accordingly, this final rule includes an 
effective date of January 1, 2007 for the sample retention requirement.
    In the proposal, rule requirements regarding sample retention were 
located in section 4.9 of appendix D, a section devoted to network 
design criteria. The EPA believes that sample retention requirements 
are more logically located in subpart B of part 58, which contains 
provisions on data submittal. Accordingly, the title of 40 CFR 58.16 
(``Data submittal'') has been renamed ``Data submittal and archiving 
requirements'' and corresponding rule requirements on sample retention 
have been moved to 40 CFR 58.16(f) of this final rule.

H. Deletion of Appendices B and F

    This final rule removes and reserves appendix B of 40 CFR 58, 
Quality Assurance Requirements for Prevention of Significant 
Deterioration (PSD) Air Monitoring, and appendix F of 40 CFR part 58, 
Annual SLAMS Air Quality Information, because both are obsolete.
    The preamble to the proposed rule explicitly proposed to remove 
appendix B because the quality assurance requirements for PSD 
monitoring were proposed to be moved to appendix A, which this final 
rule does. See 71 FR 2725. (The amendatory language at the end of the 
January 17, 2006 proposal notice inadvertently did not list this 
change.) No adverse comments were received on this change.
    The January 17, 2006 notice did not explicitly address the 
preservation or removal of appendix F, but its effective removal was 
inherent in the proposed rule because no section of the proposed part 
58 would continue to refer to appendix F. Similarly, the final part 58 
does not refer to appendix F. Appendix F previously was referenced by 
40 CFR 58.26 in subpart C, Annual state air monitoring report, now 
deleted. Appendix F specified the required content, which was 
extensive, of the annual report of summarized monitoring data. An 
extensive annual report of summarized monitoring data is no longer 
required in this final rule. New section, 40 CFR 58.16, Data submittal, 
instead requires submission of individual data values. Summary 
information on monitoring data is still required by 40 CFR 58.15, 
Annual air monitoring data certification, for the sole purpose of 
making it clear what data is within the scope of the required 
certification letter. This final rule does not specify the exact 
content of the

[[Page 61269]]

summary information required by 40 CFR 58.15 in order to provide more 
flexibility and to accommodate possible evolution of the standardized 
AQS reports which are the most convenient way for monitoring 
organizations to provide this information.

VI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), this 
action is a ``significant regulatory action'' because it may raise 
novel legal policy issues arising out of legal mandates, the 
President's priorities, or the principles set forth in the Executive 
Order. Accordingly, EPA submitted this action to the Office of 
Management and Budget (OMB) for review under Executive Order 12866 and 
any changes made in response to OMB recommendations have been 
documented in the docket for this action.

B. Paperwork Reduction Act

    The information collection requirements in this 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., OMB control 
number 2060-0084. The information collection requirements are not 
enforceable until OMB approves them.
    The monitoring, recordkeeping, and reporting requirements in 40 CFR 
parts 53 and 58 are specifically authorized by sections 110, 301(a), 
and 319 of the Clean Air Act (CAA). All information submitted to EPA 
pursuant to the monitoring, recordkeeping, 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 final 
amendments add requirements for PM<INF>10-2.5</INF> FEM and FRM 
determinations, Class II equivalent methods for PM<INF>10-2.5</INF> and 
Class III equivalent methods for PM<INF>2.5</INF> and 
PM<INF>10-2.5</INF>; reduce certain monitoring and data collection 
requirements; and streamline EPA administrative requirements.
    The incremental annual reporting and recordkeeping 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 amendments revise the technical requirements for 
certain types of sites, add provisions for monitoring of 
PM10<INF>10-2.5</INF>, and reduce certain monitoring requirements for 
criteria pollutants. Monitoring agencies are required to submit annual 
monitoring network plans, conduct network assessments every 5 years, 
perform quality assurance activities, and, in certain instances, 
establish NCore sites by January 1, 2011.
    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 48,546 labor hours 
per year with a decrease in costs of $6,151,494. State, local, and 
Tribal entities are eligible for State assistance grants provided by 
the Federal government under the CAA which can be used 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. When 
these ICR are approved by OMB, EPA will publish a technical amendment 
to 40 CFR part 9 in the Federal Register to display the OMB control 
number for the approved information collection requirements contained 
in this final rule.

C. Regulatory Flexibility Act

    The EPA has determined that it is not necessary to prepare a 
regulatory flexibility analysis in connection with these final rule 
amendments.
    For the purposes of assessing the impacts of the final amendments 
on small entities, small entity is defined as: (1) A small business as 
defined by the Small Business Administration's regulations at 13 CFR 
121.201; (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 this final rule 
amendments on small entities, EPA has concluded that this action will 
not have a significant economic impact on a substantial number of small 
entities. The final requirements in 40 CFR part 53 for an FEM 
application are voluntary actions on the part of equipment 
manufacturers to seek EPA approval for their candidate sampling 
methods. The applications are evaluated according to the requirements 
in 40 CFR part 53 and test data submitted by the manufacturers to EPA 
to ensure that the candidate equivalent methods meet the same technical 
standards as the FRM. The final amendments to 40 CFR part 58 will 
reduce annual ambient air monitoring costs for State and local agencies 
by approximately $6.2 million and 48,546 labor hours from present 
levels. State and Tribal assistance grant funding provided by the 
Federal government can be used to defray the costs of new or upgraded 
monitors for the NCore networks.

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

[[Page 61270]]

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 this 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 proposals with significant 
Federal intergovernmental mandates, and informing, educating, and 
advising small governments on compliance with the regulatory 
requirements.
    The EPA has determined that this final 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 final amendments to 40 CFR part 58 
will reduce annual ambient air monitoring costs for State and local 
agencies by approximately $6.2 million and 48,546 labor hours from 
present levels. Thus, these final amendments are not subject to the 
requirements of sections 202 and 205 of the UMRA.
    The EPA has determined that this final rule contains no regulatory 
requirements that might significantly or uniquely affect small 
governments. Small governments that may be affected by the final 
amendments are already meeting similar requirements under the existing 
rules, and the final amendments will substantially reduce the costs of 
the existing rules. Therefore, this final 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 final rule does not have federalism implications because 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. Thus, Executive 
Order 13132 does not apply to this final rule.
    Although section 6 of the Executive Order does not apply to this 
final 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 
from 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 develop specific 
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. The EPA also met with State, local, and Tribal government 
representatives to discuss their comments on the proposed amendments 
and suggestions for resolving issues.

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

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, 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 final rule does not have 
tribal implications, as specified in Executive Order 13175. The final 
amendments will 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 and after proposal to 
discuss their comments and concerns. As discussed in section VI.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.

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, EPA 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 EPA.
    The 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. This final rule is not subject 
to Executive Order 13045 because, while it is based on the need for 
monitoring data to characterize risk,

[[Page 61271]]

this final monitoring rule itself does not establish an environmental 
standard intended to mitigate health or safety risks.

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

    Executive Order 12898 (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 (RIA) for the 
final revisions to the NAAQS for particulate matter.

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

    This final 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 quality measurements will not increase above 
present levels. Further, EPA has concluded that this final rule is not 
likely to have any adverse energy effects.

J. 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 EPA decides not to use 
available and applicable voluntary consensus standards.
    The final amendments involve environmental monitoring and 
measurement. Ambient air concentrations of PM<INF>2.5</INF> 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<INF>2.5</INF> in the Atmosphere) or by FRM or FEM that meet the 
requirements in 40 CFR part 53. Ambient air concentrations of 
PM<INF>10-2.5</INF> will be measured by the final FRM in 40 CFR part 
50, appendix O (Reference Method for the Determination of Coarse 
Particulate Matter as PM<INF>10-2.5</INF> in the Atmosphere) published 
elsewhere in this Federal Register or by an FRM or FEM that meets the 
requirements in 40 CFR part 53. As discussed in section IV.B of this 
preamble, the final FRM for PM<INF>10-2.5</INF> is similar to the 
existing methods for PM<INF>2.5</INF> and PM<INF>10</INF>.
    Procedures are included in this final rule that allow for approval 
of an FEM for PM<INF>10-2.5</INF> that is similar to the final FRM. Any 
method that meets the performance criteria for a candidate equivalent 
method may be approved for use as an FRM or FEM.
    This approach is consistent with EPA'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. The 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.

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801, et seq., as added by 
the Small Business Regulatory Enforcement Fairness Act of 1996, 
generally provides that before a rule may take effect, the agency 
promulgating the rule must submit a rule report, which includes a copy 
of the rule, to each House of Congress and to the Comptroller General 
of the United States. The EPA will submit a report containing the final 
amendments and other required information to the U.S. Senate, the U.S. 
House of Representatives, and the Comptroller General of the United 
States prior to publication of the final amendments in the Federal 
Register. A major rule cannot take effect until 60 days after it is 
published in the Federal Register. This action is not a ``major rule'' 
as defined by 5 U.S.C. 804(2). This final rule will not have an annual 
effect on the economy of $100 million or more, will not result in a 
major increase in costs or prices for State or local agencies, and will 
not affect competition with foreign-based enterprises in domestic and 
export markets. The final amendments will be effective on December 18, 
2006. The final amendments will be effective 60 days after publication 
in the Federal Register to be consistent with the effective date of the 
revised NAAQS for PM published elsewhere in this Federal Register. 
Revisions to Ambient Air Monitoring Regulations.

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: September 27, 2006.
Stephen L. Johnson,
Administrator.

0
For the reasons set out in the preamble, title 40, chapter I, parts 53 
and 58 of the Code of Federal Regulations are amended as follows:

PART 53--[AMENDED]

0
1. The authority citation for part 53 continues to read as follows:

    Authority: Section 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]

0
2. Sections 53.1 through 53.5 are revised 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 
Federal reference method or Federal 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),

[[Page 61272]]

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 
Federal reference method determination or a Federal 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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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<INF>2.5</INF> or PM<INF>10-2.5</INF> that utilizes a 
PM<INF>2.5</INF> sampler or PM<INF>10-2.5</INF> sampler in which 
integrated PM<INF>2.5</INF> samples or PM<INF>10-2.5</INF> 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 
applicable) of part 50 of this chapter, as determined by EPA.
    Class III equivalent method means an equivalent method for 
PM<INF>2.5</INF> or PM<INF>10-2.5</INF> that is an analyzer capable of 
providing PM<INF>2.5</INF> or PM<INF>10-2.5</INF> ambient air 
measurements representative of one-hour or less integrated 
PM<INF>2.5</INF> or PM<INF>10-2.5</INF> concentrations as well as 24-
hour measurements determined as, or equivalent to, the mean of 24 one-
hour consecutive measurements.
    CO means carbon monoxide.
    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.
    Federal equivalent method (FEM) 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.
    Federal reference method (FRM) 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.
    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; or
    (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 
Federal reference method and Federal 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 PM<INF>10</INF> or PM<INF>2.5</INF> 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.
    NOX means oxides of nitrogen and is defined as the sum of the 
concentrations of NO<INF>2</INF> 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 PM<INF>10</INF>, PM<INF>10C</INF>, PM<INF>2.5</INF>, 
PM<INF>10-2.5</INF>, or particulate matter of unspecified size range.
    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 this part or by an equivalent method designated in 
accordance with this part.
    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 this part or by an equivalent method designated in 
accordance with this part.
    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 this part 
or by an equivalent method designated in accordance with this part.
    PM2.5 sampler means a device, associated with a manual method for 
measuring PM<INF>2.5</INF>, designed to collect PM<INF>2.5</INF> from 
an ambient air sample, but lacking the ability to automatically analyze 
or measure the collected sample to determine the mass concentrations of 
PM<INF>2.5</INF> in the sampled air.
    PM10 sampler means a device, associated with a manual method for 
measuring PM<INF>10</INF>, designed to collect PM<INF>10</INF> from an 
ambient air sample, but lacking the ability to automatically analyze or 
measure the collected sample to determine the mass concentrations of 
PM<INF>10</INF> in the sampled air.
    PM10C sampler means a PM<INF>10</INF> sampler that meets the 
special requirements for a PM<INF>10C</INF> sampler that is part of a 
PM<INF>10-2.5</INF> reference method sampler, as specified in appendix 
O to part 50 of this chapter, or a PM<INF>10</INF> sampler that is part 
of a PM<INF>10-2.5</INF> sampler that has been designated as an 
equivalent method for PM<INF>10-2.5</INF>.

[[Page 61273]]

    PM10-2.5 sampler means a sampler, or a collocated pair of samplers, 
associated with a manual method for measuring PM<INF>10-2.5</INF> and 
designed to collect either PM<INF>10-2.5</INF> directly or 
PM<INF>10C</INF> and PM<INF>2.5</INF> 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<INF>10-2.5</INF> in the sampled air.
    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 PM<INF>10</INF> sampler, PM<INF>2.5</INF> 
sampler, or PM<INF>10-2.5</INF> 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 
Federal reference method or a Federal equivalent method for purposes 
other than resale.


Sec.  53.2  General requirements for a reference method determination.

    The following general requirements for a Federal reference method 
(FRM) determination are summarized in table A-1 of this subpart.
    (a) Manual methods--(1) Sulfur dioxide (SO2) and lead. For 
measuring SO<INF>2</INF> and lead, appendices A and G of part 50 of 
this chapter specify unique manual FRM for measuring these pollutants. 
Except as provided in Sec.  53.16, other manual methods for 
SO<INF>2</INF> and lead will not be considered for FRM determinations 
under this part.
    (2) PM10. A FRM for measuring PM<INF>10</INF> must be a manual 
method that meets all requirements specified in appendix J of part 50 
of this chapter and must include a PM<INF>10</INF> 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) PM2.5. A FRM for measuring PM<INF>2.5</INF> must be a manual 
method that meets all requirements specified in appendix L of part 50 
of this chapter and must include a PM<INF>2.5</INF> 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, FRM 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) PM10-2.5. A FRM for measuring PM<INF>10-2.5</INF> must be a 
manual method that meets all requirements specified in appendix O of 
part 50 of this chapter and must include PM<INF>10C</INF> and 
PM<INF>2.5</INF> 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<INF>10-2.5</INF> FRM 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 FRM for measuring CO, 
O<INF>3</INF>, or NO<INF>2</INF> 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 Federal equivalent method (FEM) 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 method for 
PM<INF>10</INF>, PM<INF>2.5</INF>, or PM<INF>10-2.5</INF> must have 
been shown in accordance with this part to satisfy the following 
additional requirements, as applicable:
    (1) PM10. A PM<INF>10</INF> sampler associated with a manual method 
for PM<INF>10</INF> must satisfy the requirements of subpart D of this 
part.
    (2) PM2.5 Class I. A PM<INF>2.5</INF> Class I FEM 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 FRM sampler specifications does not significantly alter the 
performance of the sampler.
    (3) PM2.5 Class II. (i) A PM<INF>2.5</INF> Class II FEM 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<INF>2.5</INF> methods in subparts C and F of this part, a Class II 
PM<INF>2.5</INF> FEM 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<INF>2.5</INF> in subpart C of this 
part.
    (4) PM10-2.5 Class I. A PM<INF>10-2.5</INF> Class I FEM sampler 
must also satisfy the applicable requirements of subpart E of this part 
(there are no additional requirements specifically for Class I 
PM<INF>10-2.5</INF> methods in subpart C of this part).
    (5) PM10-2.5 Class II. (i) A PM<INF>10-2.5</INF> Class II FEM 
sampler 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<INF>10-2.5</INF> methods in subpart C of this part and in paragraph 
(b)(3)(iii) of this section, a Class II PM<INF>10-2.5</INF> FEM 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 FEMs for 
PM<INF>10-2.5</INF> in subpart C of this part.
    (6) ISO 9001. All designated FEMs for PM<INF>2.5</INF> or 
PM<INF>10-2.5</INF> 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 FEMs 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 FEM must have been shown in accordance with this 
part to satisfy the following additional requirements, as applicable:
    (1) An automated FEM 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 FEM for PM<INF>10</INF> must be shown in 
accordance with this part to satisfy the applicable requirements of 
subpart D of this part.
    (3) A Class III automated FEM for PM<INF>2.5</INF> or 
PM<INF>10-2.5</INF> 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

[[Page 61274]]

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 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 FEM for PM<INF>2.5</INF> or PM<INF>10-2.5</INF> 
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 FRM or FEM 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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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

[[Page 61275]]

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 PM<INF>10</INF>, PM<INF>2.5</INF>, and PM<INF>10-2.5</INF> 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 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<INF>2.5</INF> and PM<INF>10-2.5</INF> 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<INF>2.5</INF> and PM<INF>10-2.5</INF> 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<INF>2.5</INF> and Class II or Class III equivalent methods for 
PM<INF>10-2.5</INF>, 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. The 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 FRM or FEM 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

[[Page 61276]]

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).
    3. Sections 53.8 and 53.9 are revised 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 FRM 
or FEM (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 FRM or FEM shall be sent to the applicant.
    (c) The Administrator will maintain a current list of methods 
designated as FRM or FEM 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 FRM or FEM 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 cancellation of the designation in accordance 
with Sec.  53.11.
    (a) Any method offered for sale as a FRM or FEM 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 FRM or FEM shall generate no 
unreasonable hazard to operators or to the environment during normal 
use or when malfunctioning.
    (c) Any analyzer, PM<INF>10</INF> sampler, PM<INF>2.5</INF> 
sampler, or PM<INF>10-2.5</INF> sampler offered for sale as part of a 
FRM or FEM 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, PM<INF>10</INF> sampler, PM<INF>2.5</INF> 
sampler, or PM<INF>10-2.5</INF> sampler offered for sale as a FRM or 
FEM shall bear a prominent, permanently affixed label or sticker 
indicating that the analyzer or sampler has been designated by EPA as a 
FRM or FEM (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 FRM or FEM 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 FRM or FEM.
    (f) An applicant who offers analyzers, PM<INF>10</INF> samplers, 
PM<INF>2.5</INF> samplers, or PM<INF>10-2.5</INF> samplers for sale as 
FRM or FEMs 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 FRM or FEM 
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, PM<INF>10</INF> sampler, 
PM<INF>2.5</INF> sampler, or PM<INF>10-2.5</INF> sampler that has been 
designated as a FRM or FEM, 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 FRM or FEM determination 
for the modified analyzer or sampler.
    (h) An applicant who has offered PM<INF>2.5</INF> or 
PM<INF>10-2.5</INF> samplers or analyzers for sale as part of a FRM or 
FEM 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 FRM or FEM 
designation under Sec.  53.11.
    (i) An applicant who has offered PM<INF>2.5</INF> or 
PM<INF>10-2.5</INF> samplers or analyzers for sale as part of a FRM or 
FEM 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.
    4. 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO2.................  Reference..........  Manual.............  A...................
                      Equivalent.........  Manual.............  ....................  [check]     ..........  [check]

[[Page 61277]]

 
                                           Automated..........  ....................  [check]     [check]     [check]
CO..................  Reference..........  Automated..........  C...................  [check]     [check]
                      Equivalent.........  Manual.............  ....................  [check]     ..........  [check]
                                           Automated..........  ....................  [check]     [check]     [check]
O3..................  Reference..........  Automated..........  D...................  [check]     [check]
                      Equivalent.........  Manual.............  ....................  [check]     ..........  [check]
                                           Automated..........  ....................  [check]     [check]     [check]
NO2.................  Reference..........  Automated..........  F...................  [check]     [check]
                      Equivalent.........  Manual.............  ....................  [check]     ..........  [check]
                                           Automated..........  ....................  [check]     [check]     [check]
Pb..................  Reference..........  Manual.............  G...................  ..........
                      Equivalent.........  Manual.............  ....................  [check]     ..........  [check]
PM10................  Reference..........  Manual.............  J...................  [check]     ..........  .........  [check]
                      Equivalent.........  Manual.............  ....................  [check]     ..........  [check]    [check]
                                           Automated..........  ....................  [check]     ..........  [check]    [check]
PM2.5...............  Reference..........  Manual.............  L...................  [check]     ..........  .........  .........  [check]
                      Equivalent Class I.  Manual.............  L...................  [check]     ..........  [check]    .........  [check]
                      Equivalent Class II  Manual.............  L1..................  [check]     ..........  [check]2   .........  [check]    [check]1,
                                                                                                                                                2
                      Equivalent Class     Automated..........  L1..................  [check]     ..........  [check]    .........  [check]1   [check]1
                       III.
PM10	2.5............  Reference..........  Manual.............  O2..................  [check]     ..........  .........  .........  [check]
                      Equivalent Class I.  Manual.............  O2..................  [check]     ..........  .........  .........  [check]
                      Equivalent Class II  Manual.............  O2..................  [check]     ..........  [check]2   .........  [check]1   [check]1,
                                                                                                                                                2
                      Equivalent Class     Automated..........  L1,O1, 2............  [check]     ..........  [check]    .........  [check]1   [check]1
                       III.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.


[[Page 61278]]


0
5. Paragraphs (1), (2), and (6) of appendix A to subpart A of part 53 
are revised to read as follows:

Appendix A to Subpart A of Part 53--References

    (1) American National Standard Quality Systems--Model for 
Quality Assurance in Design, Development, Production, Installation, 
and Servicing, ANSI/ISO/ASQC Q9001-1994. Available from American 
Society for Quality, P.O. Box 3005, Milwaukee, WI 53202 (http://qualitypress.asq.org).
    (2) American National Standard Quality Systems for Environmental 
Data and Technology Programs--Requirements with guidance for use, 
ANSI/ASQC E4-2004. Available from American Society for Quality P.O. 
Box 3005, Milwaukee, WI 53202 (http://qualitypress.asq.org).
* * * * *
    (6) Quality Assurance Guidance Document 2.12. Monitoring 
PM<INF>2.5</INF> 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.

0
6. Subpart C is revised to read as follows:

Sec.
Subpart C--Procedures for Determining Comparability Between Candidate 
Methods and Reference Methods
53.30 General provisions.
53.31 [Reserved]
53.32 Test procedures for methods for SO<INF>2</INF>, CO, 
O<INF>3</INF>, and NO<INF>2</INF>.
53.33 Test procedure for methods for Pb.
53.34 Test procedures for methods for PM<INF>10</INF> and Class I 
methods for PM<INF>2.5.</INF>
53.35 Test procedures for Class II and Class III methods for 
PM<INF>2.5</INF> and PM<INF>10-2.5.</INF>

Tables to Subpart C of Part 53

Table C-1 to Subpart C of Part 53--Test Concentration Ranges, Number of 
Measurements Required, and Maximum Discrepancy Specification
Table C-2 to Subpart C of Part 53--Sequence of Test Measurements
Table C-3 to Subpart C of Part 53--Test Specifications for Pb Methods
Table C-4 to Subpart C of Part 53--Test Specifications for 
PM<INF>10</INF>, PM<INF>2.5</INF>, and PM<INF>10-2.5</INF> Candidate 
Equivalent Methods
Table C-5 to Subpart C of Part 53--Summary of Comparability Field 
Testing Campaign Site and Seasonal Requirements for Class II and III 
FEMs for PM<INF>10-2.5</INF> and PM<INF>2.5</INF>

Figures to Subpart C of Part 53

Figure C-1 to Subpart C of Part 53--Suggested Format for Reporting Test 
Results for Methods for SO<INF>2</INF>, CO, O<INF>3</INF>, 
NO<INF>2</INF>
Figure C-2 to Subpart C of Part 53--Illustration of the Slope and 
Intercept Limits for Class II and Class III PM<INF>2.5</INF> Candidate 
Equivalent Methods
Figure C-3 to Subpart C of Part 53--Illustration of the Slope and 
Intercept Limits for Class II and Class III PM<INF>10-2.5</INF> 
Candidate Equivalent Methods
Figure C-4 to Subpart C of Part 53--Illustration of the Minimum Limits 
for Correlation Coefficient for PM<INF>2.5</INF> and 
PM<INF>10-2.5</INF> Class II and III Methods

Appendix to Subpart C of Part 53

Appendix A to Subpart C of Part 53--References

Subpart C--Procedures for Determining Comparability Between 
Candidate Methods and Reference Methods


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

[[Page 61279]]

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<INF>2.5</INF> and PM<INF>10-2.5</INF>, all submitted information 
must meet the requirements of the ANSI/ASQC E4 Standard, sections 6 
(reference 1 of appendix A of this subpart).


Sec.  53.31  [Reserved]


Sec.  53.32  Test procedures for methods for SO<INF>2</INF>, CO, 
O<INF>3</INF>, and NO<INF>2</INF>.

    (a) Comparability. Comparability is shown for SO<INF>2</INF>, CO, 
O<INF>3</INF>, and NO<INF>2</INF> 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 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 SO<INF>2</INF> 
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.

[[Page 61280]]

    (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 SO<INF>2</INF>, 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 of twenty-four (24) sequential 1-hour measurements.
    (6) For O<INF>3</INF> and CO, no more than six 1-hour measurements 
shall be made per day. For SO<INF>2</INF>, 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.


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<SUP>3</SUP>) 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<INF>1A</INF>, R<INF>1B</INF>, R<INF>1C</INF>, 
R<INF>2A</INF>, R<INF>2B</INF>, * * *, Q<INF>1A</INF>, Q<INF>1B</INF>, 
Q<INF>1C</INF>, * * *, 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<SUP>3</SUP> 
for each analysis of each filter. Label these test results as 
C<INF>1A</INF>, C<INF>1B</INF>, C<INF>2C</INF>, * * *, where C denotes 
results from the candidate method. For candidate methods which provide 
a direct measurement of Pb concentrations without a separable 
procedure, C<INF>1A</INF>=C<INF>1B</INF>=C<INF>1C</INF>, 
C<INF>2A</INF>=C<INF>2B</INF>=C<INF>2C</INF>, 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] TR17OC06.015

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] TR17OC06.016

Where, i is audit sample number.

    (ii) Calculate the percent difference (D<INF>q</INF>) between the 
indicated Pb concentration for each audit sample and the true Pb 
concentration (T<INF>q</INF>) using equation 3 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.017

    (2) If any difference value (D<INF>qi</INF>) exceeds <plus-minus>5 
percent, the accuracy of the

[[Page 61281]]

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<SUP>3</SUP>. 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<SUP>3</SUP> 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] TR17OC06.018


 or
[GRAPHIC] [TIFF OMITTED] TR17OC06.019

 where, i indicates the filter number.

    (2) If any reference method precision value (P<INF>Ri</INF>) 
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<INF>Ci</INF>) 
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<INF>Ri</INF>'s and all P<INF>Ci</INF>'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] TR17OC06.020

 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 <plus-minus>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.


Sec.  53.34  Test procedure for methods for PM10 and Class I methods 
for PM2.5.

    (a) Comparability. Comparability is shown for PM<INF>10</INF> 
methods and for Class I methods for PM<INF>2.5</INF> 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 PM<INF>10</INF> 
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 PM<INF>10</INF> 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 PM<INF>10</INF> 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<INF>2.5</INF> 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<INF>2.5</INF> ambient concentration levels required by 
table C-4 of this subpart and the requirements of Sec.  53.30(b) 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 
PM<INF>10</INF> or PM<INF>2.5</INF> 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 PM<INF>10</INF> method measurements shall be nominal 
24-hour (<plus-minus>1 hour) integrated measurements or shall be 
averaged to obtain the mean concentration for a nominal 24-hour period. 
PM<INF>2.5</INF> 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 PM<INF>10</INF> or 
PM<INF>2.5</INF> concentration in [mu]g/m<SUP>3</SUP>. If the 
conditions of paragraph (c) of this section apply, collect sample sets 
only

[[Page 61282]]

with the three reference method samplers. Guidance for quality 
assurance procedures for PM<INF>2.5</INF> 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 PM<INF>10</INF> 
or PM<INF>2.5</INF> concentration obtained with the reference method 
samplers, using equation 7 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.021

Where:
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 PM<INF>10</INF> or PM<INF>2.5</INF> measurements 
as the standard deviation, P<INF>Rj</INF>, using equation 8 of this 
section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.022

    (3) For each measurement set, also calculate the precision of the 
reference method PM<INF>10</INF> or PM<INF>2.5</INF> measurements as 
the relative standard deviation, RP<INF>Rj</INF>, in percent, using 
equation 9 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.023

    (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<INF>j</INF> falls within the acceptable concentration range specified 
in table C-4 of this subpart, and either P<INF>Rj</INF> or 
RP<INF>Rj</INF> 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<INF>j</INF> 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 PM<INF>10</INF> 
or PM<INF>2.5</INF> concentration measurements obtained with the 
candidate method samplers, using equation 10 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.024

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 PM<INF>10</INF> or PM<INF>2.5</INF> measurements obtained with 
the candidate method (C<INF>j</INF>) against the corresponding average 
PM<INF>10</INF> or PM<INF>2.5</INF> measurements obtained with the 
reference method (R<INF>j</INF>. 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.


Sec.  53.35  Test procedure for Class II and Class III methods for 
PM<INF>2.5</INF> and PM<INF>10-2.5.</INF>

    (a) Overview. Class II and Class III candidate equivalent methods 
shall be tested for comparability of PM<INF>2.5</INF> or 
PM<INF>10-2.5</INF> measurements to corresponding collocated 
PM<INF>2.5</INF> or PM<INF>10-2.5</INF> 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. A summary of the test site and seasonal 
testing requirements is presented in table C-5 of this subpart.
    (1) Test sites. Comparability testing is required at each of the 
applicable U.S. 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 temperature, humidity, wind, and elevation. For 
Class III methods, one test site shall be selected in each of the 
following four general locations (A, B, C, and D). For Class II 
methods, two test sites, one western site (A or B) and one midwestern 
or eastern site (C or D), shall be selected from these locations.
    (A) Test site A shall be in the Los Angeles basin or California 
Central Valley area in a location that is characterized by relatively 
high PM<INF>2.5</INF>, nitrates, and semi-volatile organic pollutants.
    (B) Test site B shall be in a western city such as Denver, Salt 
Lake City, or Albuquerque in an area characterized by cold weather, 
higher elevation, winds, and dust.
    (C) Test site C shall be in a midwestern city characterized by 
substantial temperature variation, high nitrates, and wintertime 
conditions.
    (D) Test site D shall be in a northeastern or mid-Atlantic city 
that is seasonally characterized by high sulfate concentrations and 
high relative humidity.
    (ii) PM10-2.5 Class II and Class III candidate methods. Test sites 
shall be chosen to provide modest to high levels of PM<INF>10-2.5</INF> 
representative of locations in proximity to urban sources of 
PM<INF>10-2.5</INF> 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 four following general 
locations (A, B, C, and D), and 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 western site (A or B) and one 
midwestern or eastern site (C or D), shall be selected from these 
locations.
    (A) Test site A shall be in the Los Angeles basin or the California 
Central Valley area in a location that is characterized by relatively 
high PM<INF>2.5</INF>, nitrates, and semi-volatile organic pollutants.

[[Page 61283]]

    (B) Test site B shall be in a western city characterized by a high 
ratio of PM<INF>10-2.5</INF> to PM<INF>2.5</INF>, with exposure to 
windblown dust, such as Las Vegas or Phoenix.
    (C) Test site C shall be in a midwestern city characterized by 
substantial temperature variation, high nitrates, and wintertime 
conditions.
    (D) Test site D shall be in a large city east of the Mississippi 
River, having characteristically high sulfate concentrations and high 
humidity levels.
    (2) Test seasons. (i) For PM<INF>2.5</INF> and PM<INF>10-2.5</INF> 
Class III candidate methods, test campaigns are required in both summer 
and winter seasons at test site A, in the winter season only at test 
sites B and C, and in the summer season only at test site D. (A total 
of five test campaigns is required.) The summer season shall be defined 
as the typically warmest three or four months of the year at the site; 
the winter season shall be defined as the typically coolest three or 
four months of the year at the site.
    (ii) For Class II PM<INF>2.5</INF> and PM<INF>10-2.5</INF> 
candidate methods, one test campaign is required at test site A or B 
and a second test campaign at test site C or D (total of two 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).
    (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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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<INF>2.5</INF> or PM<INF>10-2.5</INF> measured concentration in 
[mu]g/m\3\. Guidance and quality assurance procedures applicable to 
PM<INF>2.5</INF> or PM<INF>10-2.5</INF> 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<INF>i,j</INF> 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<INF>1,j</INF>/(R<INF>1,j</INF> + 
R<INF>2,j</INF>) and 2 x R<INF>1,j</INF>/(R<INF>1,j</INF> + 
R<INF>3,j</INF>). If both quantities fall outside of the interval, 
(0.93, 1.07), then R<INF>1,j</INF> is an outlier.
    (ii) Calculate the quantities 2 x R<INF>2,j</INF>/(R<INF>2,j</INF> 
+ R<INF>1,j</INF>) and 2 x R<INF>2,j</INF>/(R<INF>2,j</INF> + 
R<INF>3,j</INF>). If both quantities fall outside of the interval, 
(0.93, 1.07), then R<INF>2,j</INF> is an outlier.
    (iii) Calculate the quantities 2 x R<INF>3,j</INF>/(R<INF>3,j</INF> 
+ R<INF>1,j</INF>) and 2 x R<INF>3,j</INF>/(R<INF>3,j</INF> + 
R<INF>2,j</INF>). If both quantities fall outside of the

[[Page 61284]]

interval, (0.93, 1.07), then R<INF>3,j</INF> 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] TR17OC06.025

Where:

R<INF>j</INF> = The mean concentration measured by the reference 
method for the measurement set;
R<INF>i,j</INF> = 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<INF>j</INF> 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.
    (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] TR17OC06.026

Where:

C<INF>j</INF> = The mean concentration measured by the candidate 
method for the measurement set;
C<INF>i,j</INF> = The measurement of the candidate method sampler or 
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<INF>j</INF>, using 
equation 13 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.027

    (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] TR17OC06.028

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<INF>j,</INF> using 
equation 15 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.029

    (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] TR17OC06.030

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] TR17OC06.031

    (2) For each test site, calculate the mean concentration measured 
by the candidate method, C, using equation 18 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.032

    (3) For each test site, calculate the linear regression slope and 
intercept of the mean candidate method measurements (C<INF>j</INF>) 
against the mean reference method measurements (R<INF>j</INF>), using 
equations 19 and 20 of this section, respectively:
[GRAPHIC] [TIFF OMITTED] TR17OC06.033

[GRAPHIC] [TIFF OMITTED] TR17OC06.034

    (4) To pass this test, at each test site:
    (i) The slope (calculated to at least 2 decimal places) must be in 
the interval specified for regression slope in table C-4 of this 
subpart; and
    (ii) The intercept (calculated to at least 2 decimal places) 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] TR17OC06.035


[[Page 61285]]


    (2) For each test site, calculate the concentration coefficient of 
variation, CCV, using equation 22 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.036

    (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.

Tables to Subpart C of Part 53

   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            1-hr                  24-hr           discrepancy
            Pollutant              range, parts per  -------------------------------------------- specification,
                                        million         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/m3..............................      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 of Part 53.--Test Specifications for PM10, PM2.5 and PMR10-2.5 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................  4................  2................  4
Minimum number of candidate      3......................  3.................  3\1\.............  3\1\.............  3\1\.............  3\1\
 method samplers or analyzers
 per site.

[[Page 61286]]

 
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-   .......................  3
     hr or Rj < 20 [mu]g/m\3\
     for 48-hr samples.
    Rj > 30 [mu]g/m\3\ for 24-   .......................  3
     hr or Rj > 20 [mu]g/m\3\
     for 48-hr samples.
    Each season................  .......................  10................  23...............  23...............  23...............  23
    Total, each site...........  .......................  10................  23...............  23 (46 for two-    23...............  23 (46 for two-
                                                                                                  season sites).                        season sites)
Precision of replicate           5 [mu]g/m\3\ or 7%.....  2 [mu]g/m\3\ or 5%  10%\2\...........  10%\2\...........  10%\2\...........  10%\2\
 reference 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              1<plus-minus>0.10......  1<plus-minus>0.05.  1<plus-minus>0.10  1<plus-minus>0.10  1<plus-minus>0.10  1<plus-minus>0.12
 relationship.
Intercept of regression          0<plus-minus>5.........  0<plus-minus>1....  Between: 13.55-    Between: 15.05-    Between: 62.05-    Between: 70.50-
 relationship, [mu]g/m\3\.                                                     (15.05 x slope),   (17.32 x slope),   (70.5 x slope),    (82.93 x slope),
                                                                               but not less       but not less       but not less       but not less
                                                                               than -1.5; and     than -2.0; and     than -3.5; and     than -7.0; and
                                                                               16.56-(15.05 x     15.05-(13.20 x     78.95-(70.5 x      70.50-(61.16 x
                                                                               slope), but not    slope), but not    slope), but not    slope), but not
                                                                               more than + 1.5.   more than + 2.0.   more than + 3.5.   more than + 7.0
Correlation of reference method  [gteqt]0.97............  [gteqt]0.97.......   [gteqt]0.93 . . . . . . . CCV[lteqt]0.4; [gteqt]0.85 + 0.2 x CCV . . for
 and candidate method                                                             0.4[lteqt]CCV[lteqt]0.5; [gteqt]0.95 . . . . . . . for CCV[gteqt]0.5
 measurements.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Some missing daily measurement values may be permitted; see test procedure.
\2\ Calculated as the root mean square over all measurement sets


Table C-5 to Subpart C of Part 53--Summary of Comparability Field Testing Campaign Site and Seasonal Requirements for Class II and III FEMs for PM10-2.5
                                                                        and PM2.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
          Candidate method                  Test site                   A                      B                      C                      D
--------------------------------------------------------------------------------------------------------------------------------------------------------
PM2.5..............................  Test site location      Los Angeles basin or    Western city such as   Midwestern city......  Northeastern or mid-
                                      area.                   California Central      Denver, Salt Lake                             Atlantic city.
                                                              Valley.                 City, or Albuquerque.
                                     Test site               Relatively high PM2.5,  Cold weather, higher   Substantial            High sulfate and high
                                      characteristics.        nitrates, and semi-     elevation, winds,      temperature            relative humidity.
                                                              volatile organic        and dust.              variation, high
                                                              pollutants.                                    nitrates, wintertime
                                                                                                             conditions.
                                     Class III Field test    Winter and summer.....  Winter only..........  Winter only..........  Summer only.
                                      campaigns (Total: 5).
                                                            --------------------------------------------------------------------------------------------
                                     Class II Field test                Site A or B, any season
                                      campaigns (Total: 2).
                                                Site C or D, any season.
                                                            --------------------------------------------------------------------------------------------

[[Page 61287]]

 
PM10-2.5...........................  Test site location      Los Angeles basin or    Western city such as   Midwestern city......  Large city east of
                                      area.                   California Central      Las Vegas or Phoenix.                         the Mississippi
                                                              Valley.                                                               River.
                                                            --------------------------------------------------------------------------------------------
                                     Test site               Relatively high PM2.5,  High PM10-2.5 to       Substantial            High sulfate and high
                                      characteristics.        nitrates, and semi-     PM2.5 ratio,           temperature            relative humidity.
                                                              volatile organic        windblown dust.        variation, high
                                                              pollutants.                                    nitrates, wintertime
                                                                                                             conditions.
                                     Class III Field test    Winter and summer.....  Winter only..........  Winter only..........  Summer only.
                                      campaigns (Total: 5).
                                                            --------------------------------------------------------------------------------------------
                                     Class II Field test                Site A or B, any season
                                      campaigns (Total: 2).
                                                Site C or D, any season.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Figures to Subpart C of Part 53

Figure C-1 to Subpart C of Part 53--Suggested Format for Reporting Test 
Results for Methods for SO<INF>2</INF>, CO, O<INF>3</INF>, 
NO<INF>2</INF>
Candidate Method-------------------------------------------------------

Reference Method-------------------------------------------------------

Applicant--------------------------------------------------------------

[ballot] First Set [ballot] Second Set [ballot] Type
[ballot] 1 Hour [ballot] 24 Hour


--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Concentration, ppm
      Concentration range                      Date            Time      --------------------------------   Difference       Table C-1     Pass or fail
                                                                             Candidate       Reference                         spec.
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Low                1
                                ------------------------------------------------------------------------------------------------------------------------
-------- ppm                     2
                                ------------------------------------------------------------------------------------------------------------------------
to -------- ppm                  3
                                ------------------------------------------------------------------------------------------------------------------------
                                 4
                                ------------------------------------------------------------------------------------------------------------------------
                                 5
                                ------------------------------------------------------------------------------------------------------------------------
                                 6
--------------------------------------------------------------------------------------------------------------------------------------------------------
             Medium              1
                                ------------------------------------------------------------------------------------------------------------------------
-------- ppm                     2
                                ------------------------------------------------------------------------------------------------------------------------
to -------- ppm                  3
                                ------------------------------------------------------------------------------------------------------------------------
                                 4
                                ------------------------------------------------------------------------------------------------------------------------
                                 5
                                ------------------------------------------------------------------------------------------------------------------------
                                 6
--------------------------------------------------------------------------------------------------------------------------------------------------------
              High               1
                                ------------------------------------------------------------------------------------------------------------------------
-------- ppm                     2
                                ------------------------------------------------------------------------------------------------------------------------
to -------- ppm                  3
                                ------------------------------------------------------------------------------------------------------------------------
                                 4
                                ------------------------------------------------------------------------------------------------------------------------
                                 5
                                ------------------------------------------------------------------------------------------------------------------------
                                 6
                                ------------------------------------------------------------------------------------------------------------------------
                                 7
                                ------------------------------------------------------------------------------------------------------------------------
                                 8
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                   Total
                                                                                                                               Failures:
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 61288]]

[GRAPHIC] [TIFF OMITTED] TR17OC06.057

[GRAPHIC] [TIFF OMITTED] TR17OC06.058


[[Page 61289]]

[GRAPHIC] [TIFF OMITTED] TR17OC06.059

Appendix to Subpart C of Part 53

Appendix A to Subpart C of Part 53--References

    (1) American National Standard Quality Systems for Environmental 
Data and Technology Programs--Requirements with guidance for use, 
ANSI/ASQC E4-2004. Available from American Society for Quality, P.O. 
Box 3005, Milwaukee, WI 53202 (http://qualitypress.asq.org).
    (2) Quality Assurance Guidance Document 2.12. Monitoring 
PM<INF>2.5</INF> 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) and Performance 
Characteristics of Reference Methods and Class I and Class II 
Equivalent Methods for PM2.5 or PM<INF>10-2.5</INF>

0
7. The heading for subpart E is revised as set out above.

0
8. Section 53.50 is revised to read as follows:


Sec.  53.50  General provisions.

    (a) A candidate method for PM<INF>2.5</INF> or PM<INF>10-2.5</INF> 
described in an application for a FRM or FEM determination submitted 
under Sec.  53.4 shall be determined by the EPA to be a FRM or a Class 
I, II, or III FEM 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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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<INF>2.5</INF> 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<INF>2.5</INF> 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<INF>2.5</INF> 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) PM<INF>10-2.5</INF> methods--(1) Reference method. A sampler 
associated with a reference method for PM<INF>10-2.5</INF>, 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<INF>2.5</INF> sampler of the PM<INF>10-2.5</INF> sampler 
pair shall be verified to be either currently designated under this 
part 53 as a FRM for PM<INF>2.5</INF>, or shown to meet all 
requirements for designation as a FRM for PM<INF>2.5</INF>, in 
accordance with this part 53.
    (ii) The PM<INF>10C</INF> sampler of the PM<INF>10-2.5</INF> 
sampler pair shall be verified to be of like manufacturer, design, 
configuration, and fabrication to the PM<INF>2.5</INF> sampler of the 
PM<INF>10-2.5</INF> sampler pair, 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)(1)(i) 
and (ii) of this section, the candidate PM<INF>10-2.5</INF> reference 
method may be determined to be a FRM without further testing.
    (2) Class I method. A sampler associated with a Class I candidate 
equivalent method for PM<INF>10-2.5</INF> shall meet the requirements 
in this paragraph (c)(2).
    (i) The PM<INF>2.5</INF> sampler of the PM<INF>10-2.5</INF> sampler 
pair shall be verified to be either currently designated under this 
part 53 as a FRM or Class I FEM for PM<INF>2.5</INF>, or shown to meet 
all requirements for designation as a FRM or Class I FEM for 
PM<INF>2.5</INF>, in accordance with this part 53.
    (ii) The PM<INF>10c</INF> sampler of the PM<INF>10-2.5</INF> 
sampler pair shall be verified to be of similar design to the 
PM<INF>10-2.5</INF> sampler and to meet all requirements for 
designation as a FRM or Class I FRM for PM<INF>2.5</INF>, in accordance 
with this part 53, except for replacement of the particle size 
separator specified in section 7.3.4

[[Page 61290]]

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<INF>10-2.5</INF> method may 
be determined to be a Class I FEM without further testing.
    (3) Class II method. A sampler associated with a Class II candidate 
equivalent method for PM<INF>10-2.5</INF> 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<INF>2.5</INF> or PM<INF>10-2.5</INF> that have a sample air flow 
path configuration upstream of the sample filter that is modified from 
that specified for the FRM 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 FRM and Class I FEM samplers for 
PM<INF>2.5</INF>. This test requires collocated operation of three 
candidate method samplers at a field test site. For candidate FEM 
samplers, this test may be combined and carried out concurrently with 
the test for comparability to the FRM specified under Sec.  53.34, 
which requires collocated operation of three FRM samplers and three 
candidate FEM 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 6) and Part C, (section 7) 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.

0
9. 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) Paragraphs (a) through (f) of this section 
specify certain documentation that must be submitted and tests that are 
required to demonstrate that samplers associated with a designated FRM 
or FEM for PM<INF>2.5</INF> or PM<INF>10-2.5</INF> 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<INF>2.5</INF> 
or PM<INF>10-2.5</INF> 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 FRM 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<INF>2.5</INF> or PM<INF>10-2.5</INF> FRM or FEM 
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 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<INF>2.5</INF> 
or PM<INF>10-2.5</INF> samplers to be sold as part of a FRM or FEM 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

[[Page 61291]]

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<INF>2.5</INF> (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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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 
VSCC<SUP>TM</SUP> 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 FRM or FEM 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 FRM or FEM devices. The completed 
checklist shall be submitted with the application for FRM or FEM 
determination.

0
10. 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.
* * * * *

0
11. 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 systems shall 
all be calibrated per the sampler's operation or instruction manual 
within 7 days prior to this test.
* * * * *

0
12. 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.
* * * * *

0
13. Section 53.33 is amended by:
0
a. Revising paragraphs (a)(1) introductory text and (a)(2).
0
b. Revising paragraph (e)(1).
0
c. Revising paragraph (g)(5)(i) to read as follows.


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

[[Page 61292]]

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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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] TR17OC06.037

Where:
T<INF>ind,ave</INF> = The mean ambient air temperature indicated by 
the test sampler, [deg]C; and
T<INF>ref,ave</INF> = The mean ambient air temperature measured by 
the reference temperature instrument, [deg]C.
* * * * *

0
14. 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<INF>2.5</INF> or PM<INF>10-2.5</INF> 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.
* * * * *

0
15. 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.
* * * * *
    (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 five additional filters for magazine-type 
sequential samplers) as directed by the sampler's operation or 
instruction manual.
* * * * *

0
16. 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

[[Page 61293]]

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<INF>2.5</INF> (or 
PM<INF>10-2.5</INF>, 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 
five 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, and 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<INF>i,j,</INF> 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<INF>ave,j</INF> where j is 
the test period using equation 26 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.038

    (ii) If C<INF>ave,j</INF> < 3 [mu]g/m<SUP>3</SUP> 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] TR17OC06.039

    (ii) For each of the 10 test periods, also calculate and record the 
precision as the relative standard deviation, in percent, using 
equation 28 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.040

    (h) Test results. (1) The candidate method passes the precision 
test if either P<INF>j</INF> or RP<INF>j</INF> 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.

0
17. 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

[[Page 61294]]

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.
* * * * *

0
18. Table E-1 to subpart E is revised to read as follows:

  Table E-1 to Subpart E of Part 53.--Summary of Test Requirements for Reference and Class I Equivalent Methods
                                             for PM2.5 and PM10	2.5
----------------------------------------------------------------------------------------------------------------
                                                          Performance                          Part 50, appendix
       Subpart E procedure         Performance test      specification      Test conditions       L reference
----------------------------------------------------------------------------------------------------------------
Sec.   53.52 Sample leak check    Sampler leak check  External leakage:   Controlled leak     Sec. 7.4.6.
 test.                             facility.           80 mL/min, max.     flow rate of 80
                                                      Internal leakage:    mL/min.
                                                       80 mL/min, max.
Sec.   53.53 Base flow rate test  Sample flow rate..  1. 16.67 ? 5% L/    (a) 6-hour normal   Sec. 7.4.1,
                                  1. Mean...........   min.                operational test   Sec. 7.4.2
                                  2. Regulation.....  2. 2%, max........   plus flow rate     Sec. 7.4.3
                                  3. Meas accuracy..  3. 2%, max........   cut-off test.      Sec. 7.4.4
                                  4. CV accuracy....  4. 0.3%, max......  (b) Normal          Sec. 7.4.5.
                                  5. Cut-off........  5. Flow rate cut-    conditions.
                                                       off if flow rate   (c) Additional 55
                                                       deviates more       mm Hg pressure
                                                       than 10% from       drop to simulate
                                                       design flow rate    loaded filter.
                                                       for >60 <plus-     (d) Variable flow
                                                       minus> ?30          restriction used
                                                       seconds.            for cut-off test.
Sec.   53.54 Power interruption   Sample flow rate:.  1. 16.67 ?<plus-    (a) 6-hour normal   Sec. 7.4.1,
 test.                            1. Mean...........   minus> 5% L/Min.    operational test.  Sec. 7.4.2
                                  2. Regulation.....  2. 2%, max........  (b) Nominal         Sec. 7.4.3
                                  3. Meas. accuracy.  3. 2%, max........   conditions.        Sec. 7.4.5
                                  4. CV accuracy....  4. 0.3% max.......  (c) Additional 55   Sec. 7.4.12
                                  5. Occurrence time  5. ? <plus-minus>    mm Hg pressure     Sec. 7.4.13
                                   of power            2 min if >60        drop to simulate   Sec. 7.4.15.4
                                   interruptions.      seconds.            loaded filter.     Sec. 7.4.15.5.
                                  6. Elapsed sample   6. ? <plus-minus>   (d) 6 power
                                   time.               20 seconds.         interruptions of
                                  7. Sample volume..  7. <plus-minus>      various durations.
                                                       ?2%, max.
Sec.   53.55 Temperature and      Sample flow rate..  1. 16.6 <plus-      (a) 6-hour normal   Sec. 7.4.1,
 line voltage test.               1. Mean...........   minus>? 5% L/min.   operational test.  Sec. 7.4.2
                                  2. Regulation.....  2. 2%, max........  (b) Normal          Sec. 7.4.3
                                  3. Meas. accuracy.  3. 2%, max........   conditions.        Sec. 7.4.5
                                  4. CV accuracy....  4. 0.3% max.......  (c) Additional 55   Sec. 7.4.8
                                  5. Temperature      5. 2 [deg]C.......   mm Hg pressure     Sec. 7.4.15.1.
                                   meas. accuracy.                         drop to simulate
                                  6. Proper                                loaded filter.
                                   operation.                             (d) Ambient
                                                                           temperature at -
                                                                           20 and +40 [deg]C.
                                                                          (e) Line voltage:
                                                                           105 Vac to 125
                                                                           Vac.
Sec.   53.56 Barometric pressure  Sample flow rate..  1. 16.67 ?<plus-    (a) 6-hour normal   Sec. 7.4.1,
 effect test.                     1. Mean...........   minus> ? 5% L/min.  operational test.  Sec. 7.4.2
                                  2. Regulation.....  2. 2%, max........  (b) Normal          Sec. 7.4.3
                                  3. Meas. accuracy.  3. 2%, max........   conditions.        Sec. 7.4.5
                                  4. CV accuracy....  3. 2%, max........  (c) Additional 55   Sec. 7.4.9.
                                  5. Pressure meas.   4. 0.3%, max......   mm Hg pressure
                                   accuracy.          5. 10 mm Hg.......   drop to simulate
                                  6. Proper                                loaded filter.
                                   operation.                             (d) Barometric
                                                                           pressure at 600
                                                                           and 800 mm Hg.
    Sec.   53.57 Filter           1. Filter temp      1. 2 [deg]C.......  (a) 4-hour          Sec. 7.4.8
     temperature control test.     meas. accuracy.    2. 2 [deg]C.......   simulated solar    Sec. 7.4.10
                                  2. Ambient temp.    3. Not more than 5   radiation,         Sec. 7.4.11.
                                   meas. accuracy.     [deg]C above        sampling.
                                  3. Filter temp.      ambient temp. for  (b) 4-hour
                                   control accuracy,   more than 30 min..  simulated solar
                                   sampling and non-                       radiation, non-
                                   sampling.                               sampling.
                                                                          (c) Solar flux of
                                                                           1000 ?50 W/m2.
Sec.   53.58 Field precision      1. Measurement      1. Pj < 2 [mu]g/m3  (a) 3 collocated    Sec. 5.1
 test.                             precision.          or RPj < 5%.        samplers at 1      Sec. 7.3.5
                                  2. Storage          2. 50 [mu]g max.     site for at least  Sec. 8
                                   deposition test     average weight      10 days;.          Sec. 9
                                   for sequential      gain/blank filter. (b) PM2.5 conc. >   Sec. 10.
                                   samplers.                               3 [mu]g/m3.
                                                                          (c) 24- or 48-hour
                                                                           samples.
                                                                          (d) 5- or 10-day
                                                                           storage period
                                                                           for inactive
                                                                           stored filters.
----------------------------------------------------------------------------------------------------------------

[[Page 61295]]

 
              The Following Requirement Is Applicable to Class I Candidate Equivalent Methods Only
----------------------------------------------------------------------------------------------------------------
Sec.   53.59 Aerosol transport    Aerosol transport.  97%, min. for all   Determine aerosol   ..................
 test.                                                 channels.           transport through
                                                                           any new or
                                                                           modified
                                                                           components with
                                                                           respect to the
                                                                           reference method
                                                                           sampler before
                                                                           the filter for
                                                                           each channel.
----------------------------------------------------------------------------------------------------------------


0
19. References (1), (2), (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

    (1) American National Standard Quality Systems--Model for 
Quality Assurance in Design, Development, Production, Installation, 
and Servicing, ANSI/ISO/ASQC Q9001-1994. Available from American 
Society for Quality, P.O. Box 3005, Milwaukee, WI 53202 (http://qualitypress.asq.org).
    (2) American National Standard Quality Systems for Environmental 
Data and Technology Programs--Requirements with guidance for use, 
ANSI/ASQC E4-2004. Available from American Society for Quality, P.O. 
Box 3005, Milwaukee, WI 53202 (http://qualitypress.asq.org).
    (3) Quality Assurance Guidance Document 2.12. Monitoring 
PM<INF>2.5</INF> 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.
* * * * *
    (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]

0
20. Section 53.60 is amended by:
0
a. Revising paragraph (b);
0
b. Revising paragraph (c);
0
c. Revising paragraph (d) introductory text; and
0
d. Revising paragraph (f)(4) to read as follows:


Sec.  53.60  General provisions.

* * * * *
    (b) A candidate method described in an application for a FRM or FEM 
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 FEM in Sec.  53.1.
    (c) Any sampler associated with a Class II candidate equivalent 
method (Class II sampler) must meet all applicable requirements for FRM 
samplers or Class I FEM samplers specified in subpart E of this part, 
as appropriate. Except as provided in Sec.  53.3(a)(3), a Class II 
PM<INF>2.5</INF> 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.
* * * * *

0
21. The section heading of Sec.  53.61 is revised to read as follows:


Sec.  53.61  Test conditions.

* * * * *

0
22. Section 53.66 is amended by revising paragraph (e)(2)(iii) to read 
as follows:


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.
* * * * *

0
23. Table F-1 to subpart F is revised to read as follows:

[[Page 61296]]



Table F-1 to Subpart F of Part 53.--Performance Specifications for PM2.5
                      Class II Equivalent Samplers
------------------------------------------------------------------------
      Performance test           Specifications      Acceptance criteria
------------------------------------------------------------------------
Sec.   53.62 Full Tunnel      Solid VOAG produced   Dp50 2.5 [mu]m <plus-
 Evaluation.                   aerosol at 2 km/hr    minus> 0.2 [mu]m
                               and 24 km/hr.         Numerical Analysis
                                                     Results: 95% <= ?
                                                     Rc <= ? 105%
Sec.   53.63 Wind Tunnel      Liquid VOAG produced  Relative Aspiration:
 Inlet Aspriation Test.        aerosol at 2 km/hr    95% <= ? A <= ?
                               and 24 km/hr.         105%
Sec.   53.64 Static           Evaluation of the     Dp50 = 2.5 [mu]m ?
 Fractionator Test.            fractionator under    0.2 [mu]m Numerical
                               static conditions.    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 produced by   Parameters Slope =
                               air nebulization of   1 <plus-minus> 0.1,
                               A.C.S. reagent        Intercept = 0 <plus-
                               grade glycerol,       minus> ? 0.15mg r
                               99.5% minimum         >= 0.97.
                               purity.
------------------------------------------------------------------------


0
24. In Figure E-1 to subpart F, the figure number ``E-1'' is revised to 
read ``F-1.''

PART 58--[AMENDED]

0
25. The authority citation for part 58 is revised to read as follows:

    Authority: 42 U.S.C. 7403, 7410, 7601(a), 7611, and 7619.


0
26. Subpart A is revised to read as follows:
Subpart A--General Provisions
Sec.
58.1 Definitions.
58.2 Purpose.
58.3 Applicability.

Subpart A--General Provisions


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<INF>2.5</INF> 
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<INF>2.5</INF> 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<INF>2.5</INF> 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 
Statistical Areas (MSAs) and micropolitan statistical areas 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 CBSAs are 
combined, these larger areas are referred to as combined statistical 
areas (CSAs) (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.
    Federal equivalent method (FEM) 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 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.
    Federal reference method (FRM) means a method of sampling and

[[Page 61297]]

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.
    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/or precipitation.
    Metropolitan Statistical Area (MSA) means a CBSA associated with at 
least one urbanized area of 50,000 population or greater. 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<INF>2.5.</INF> An MPA may cross State boundaries, such 
as the Philadelphia PA-NJ MSA, and be further subdivided into community 
monitoring zones. MPAs are generally oriented toward CBSAs or CSAs with 
populations greater than 200,000, but for convenience, those portions 
of a State that are not associated with CBSAs 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<INF>2.5</INF>, speciated PM<INF>2.5</INF>, PM<INF>10-2.5</INF>), 
O<INF>3</INF>, SO<INF>2</INF>, CO, nitrogen oxides (NO/NO<INF>2</INF>/
NO<INF>y</INF>), Pb, 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<INF>X</INF> 
means oxides of nitrogen and is defined as the sum of the 
concentrations of NO<INF>2</INF> and NO.
    NOy means the sum of all total reactive nitrogen oxides, including 
NO, NO<INF>2</INF>, and other nitrogen oxides referred to as 
NO<INF>Z.</INF>
    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 an implementation plan approved or promulgated pursuant 
to section 110 of the Act.
    PM means PM<INF>10</INF>, PM1<INF>10C</INF>, PM<INF>2.5</INF>, 
PM<INF>10-2.5</INF>, or particulate matter of unspecified size range.
    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.
    PM<INF>10-2.5</INF> 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 monitor 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.

[[Page 61298]]

    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.
    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.
    SO<INF>2</INF> 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<INF>2.5</INF> 
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<INF>2.5</INF> 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. The Census 
Bureau notes that under certain conditions, less densely settled 
territory may be part of each Urbanized Area.
    VOC means volatile organic compounds.


Sec.  58.2  Purpose.

    (a) This part contains requirements for measuring ambient air 
quality and for reporting ambient air quality data and related 
information. The monitoring criteria pertain to the following areas:
    (1) Quality assurance procedures for monitor operation and data 
handling.
    (2) Methodology used in monitoring stations.
    (3) Operating schedule.
    (4) Siting parameters for instruments or instrument probes.
    (5) Minimum ambient air quality monitoring network requirements 
used to provide support to the State implementation plans (SIP), 
national air quality assessments, and policy decisions. These minimums 
are described as part of the network design requirements, including 
minimum numbers and placement of monitors of each type.
    (6) Air quality data reporting, and requirements for the daily 
reporting of an index of ambient air quality.
    (b) The requirements pertaining to provisions for an air quality 
surveillance system in the SIP are contained in this part.
    (c) This part also acts to establish a national ambient air quality 
monitoring network for the purpose of providing timely air quality data 
upon which to base national assessments and policy decisions.


Sec.  58.3  Applicability.

    This part applies to:
    (a) State air pollution control agencies.
    (b) Any local air pollution control agency to which the State has 
delegated authority to operate a portion of the State's SLAMS network.
    (c) Owners or operators of proposed sources.

0
27. Subpart B is revised to read as follows:
Subpart B--Monitoring Network
Sec.
58.10 Annual monitoring network plan and periodic network 
assessment.
58.11 Network technical requirements.
58.12 Operating schedules.
58.13 Monitoring network completion.
58.14 System modification.
58.15 Annual air monitoring data certification.
58.16 Data submittal and archiving requirements.

Subpart B--Monitoring Network


Sec.  58.10  Annual monitoring network plan and periodic network 
assessment.

    (a)(1) Beginning July 1, 2007, the State, or where applicable 
local, agency shall adopt and submit to the Regional Administrator an 
annual monitoring network plan which shall provide for the 
establishment and maintenance of an air quality surveillance system 
that consists of a network of SLAMS monitoring stations including FRM, 
FEM, and ARM monitors that are part of SLAMS, NCore stations, STN 
stations, State speciation stations, SPM stations, and/or, in serious, 
severe and extreme ozone nonattainment areas, PAMS stations, and SPM 
monitoring stations. The plan shall include a statement of purposes for 
each monitor and evidence that siting and operation of each monitor 
meets the requirements of appendices A, C, D, and E of this part, where 
applicable. The annual monitoring network plan must be made available 
for public inspection for at least 30 days prior to submission to EPA.
    (2) Any annual monitoring network plan that proposes SLAMS network 
modifications including new monitoring sites is subject to the approval 
of the EPA Regional Administrator, who shall provide opportunity for 
public comment and shall approve or disapprove the plan and schedule 
within 120 days. If the State or local agency has already provided a 
public comment opportunity on its plan and has made no changes 
subsequent to that comment opportunity, the Regional Administrator is 
not required to provide a separate opportunity for comment.
    (3) The plan for establishing required NCore multipollutant 
stations shall be submitted to the Administrator not later than July 1, 
2009. The plan shall provide for all required stations to be 
operational by January 1, 2011.
    (b) The annual monitoring network plan must contain the following 
information for each existing and proposed site:
    (1) The AQS site identification number.
    (2) The location, including street address and geographical 
coordinates.

[[Page 61299]]

    (3) The sampling and analysis method(s) for each measured 
parameter.
    (4) The operating schedules for each monitor.
    (5) Any proposals to remove or move a monitoring station within a 
period of 18 months following plan submittal.
    (6) The monitoring objective and spatial scale of 
representativeness for each monitor as defined in appendix D to this 
part.
    (7) The identification of any sites that are suitable and sites 
that are not suitable for comparison against the annual 
PM<INF>2.5</INF> NAAQS as described in Sec.  58.30.
    (8) The MSA, CBSA, CSA or other area represented by the monitor.
    (c) The annual monitoring network plan must document how States and 
local agencies provide for the review of changes to a PM<INF>2.5</INF> 
monitoring network that impact the location of a violating 
PM<INF>2.5</INF> monitor or the creation/change to a community 
monitoring zone, including a description of the proposed use of spatial 
averaging for purposes of making comparisons to the annual 
PM<INF>2.5</INF> NAAQS as set forth in appendix N to part 50 of this 
chapter. The affected State or local agency must document the process 
for obtaining public comment and include any comments received through 
the public notification process within their submitted plan.
    (d) The State, or where applicable local, agency shall perform and 
submit to the EPA Regional Administrator an assessment of the air 
quality surveillance system every 5 years to determine, at a minimum, 
if the network meets the monitoring objectives defined in appendix D to 
this part, whether new sites are needed, whether existing sites are no 
longer needed and can be terminated, and whether new technologies are 
appropriate for incorporation into the ambient air monitoring network. 
The network assessment must consider the ability of existing and 
proposed sites to support air quality characterization for areas with 
relatively high populations of susceptible individuals (e.g., children 
with asthma), and, for any sites that are being proposed for 
discontinuance, the effect on data users other than the agency itself, 
such as nearby States and Tribes or health effects studies. For 
PM<INF>2.5</INF>, the assessment also must identify needed changes to 
population-oriented sites. The State, or where applicable local, agency 
must submit a copy of this 5-year assessment, along with a revised 
annual network plan, to the Regional Administrator. The first 
assessment is due July 1, 2010.
    (e) All proposed additions and discontinuations of SLAMS monitors 
in annual monitoring network plans and periodic network assessments are 
subject to approval according to Sec.  58.14.


Sec.  58.11  Network technical requirements.

    (a)(1) State and local governments shall follow the applicable 
quality assurance criteria contained in appendix A to this part when 
operating the SLAMS networks.
    (2) Beginning January 1, 2009, State and local governments shall 
follow the quality assurance criteria contained in appendix A to this 
part that apply to SPM sites when operating any SPM site which uses a 
FRM, FEM, or ARM and meets the requirements of appendix E to this part, 
unless the Regional Administrator approves an alternative to the 
requirements of appendix A with respect to such SPM sites because 
meeting those requirements would be physically and/or financially 
impractical due to physical conditions at the monitoring site and the 
requirements are not essential to achieving the intended data 
objectives of the SPM site. Alternatives to the requirements of 
appendix A may be approved for an SPM site as part of the approval of 
the annual monitoring plan, or separately.
    (3) The owner or operator of an existing or a proposed source shall 
follow the quality assurance criteria in appendix A to this part that 
apply to PSD monitoring when operating a PSD site.
    (b) State and local governments must follow the criteria in 
appendix C to this part to determine acceptable monitoring methods or 
instruments for use in SLAMS networks. Appendix C criteria are optional 
at SPM stations.
    (c) State and local governments must follow the network design 
criteria contained in appendix D to this part in designing and 
maintaining the SLAMS stations. The final network design and all 
changes in design are subject to approval of the Regional 
Administrator. NCore, STN, and PAMS network design and changes are also 
subject to approval of the Administrator. Changes in SPM stations do 
not require approvals, but a change in the designation of a monitoring 
site from SLAMS to SPM requires approval of the Regional Administrator.
    (d) State and local governments must follow the criteria contained 
in appendix E to this part for siting monitor inlets, paths or probes 
at SLAMS stations. Appendix E adherence is optional for SPM stations.


Sec.  58.12  Operating schedules.

    State and local governments shall collect ambient air quality data 
at any SLAMS station on the following operational schedules:
    (a) For continuous analyzers, consecutive hourly averages must be 
collected except during:
    (1) Periods of routine maintenance,
    (2) Periods of instrument calibration, or
    (3) Periods or monitoring seasons exempted by the Regional 
Administrator.
    (b) For Pb manual methods, at least one 24-hour sample must be 
collected every 6 days except during periods or seasons exempted by the 
Regional Administrator.
    (c) For PAMS VOC samplers, samples must be collected as specified 
in section 5 of appendix D to this part. Area-specific PAMS operating 
schedules must be included as part of the PAMS network description and 
must be approved by the Regional Administrator.
    (d) For manual PM<INF>2.5</INF> samplers:
    (1) Manual PM<INF>2.5</INF> samplers at SLAMS stations other than 
NCore stations must operate on at least a 1-in-3 day schedule at sites 
without a collocated continuously operating PM<INF>2.5</INF> monitor. 
For SLAMS PM<INF>2.5</INF> sites with both manual and continuous 
PM<INF>2.5</INF> monitors operating, the monitoring agency may request 
approval for a reduction to 1-in-6 day PM<INF>2.5</INF> sampling at 
SLAMS stations or for seasonal sampling from the EPA Regional 
Administrator. The EPA Regional Administrator may grant sampling 
frequency reductions after consideration of factors, including but not 
limited to the historical PM<INF>2.5</INF> data quality assessments, 
the location of current PM<INF>2.5</INF> design value sites, and their 
regulatory data needs. Sites that have design values that are within 
plus or minus 10 percent of the NAAQS; and sites where the 24-hour 
values exceed the NAAQS for a period of 3 years are required to 
maintain at least a 1-in-3 day sampling frequency. Sites that have a 
design value within plus or minus 5 percent of the daily 
PM<INF>2.5</INF> NAAQS must have an FRM or FEM operate on a daily 
schedule.
    (2) Manual PM<INF>2.5</INF> samplers at NCore stations and required 
regional background and regional transport sites must operate on at 
least a 1-in-3 day sampling frequency.
    (3) Manual PM<INF>2.5</INF> speciation samplers at STN stations 
must operate on a 1-in-3 day sampling frequency.
    (e) For PM<INF>10</INF> samplers'a 24-hour sample must be taken 
from midnight to midnight (local time) to ensure national consistency. 
The minimum monitoring schedule for the site in the area of expected 
maximum concentration shall be based on the relative level of that

[[Page 61300]]

monitoring site concentration with respect to the 24-hour standard as 
illustrated in Figure 1. If the operating agency demonstrates by 
monitoring data that during certain periods of the year conditions 
preclude violation of the PM<INF>10</INF> 24-hour standard, the 
increased sampling frequency for those periods or seasons may be 
exempted by the Regional Administrator and permitted to revert back to 
once in six days. The minimum sampling schedule for all other sites in 
the area remains once every six days. No less frequently than as part 
of each 5-year network assessment, the most recent year of data must be 
considered to estimate the air quality status at the site near the area 
of maximum concentration. Statistical models such as analysis of 
concentration frequency distributions as described in ``Guideline for 
the Interpretation of Ozone Air Quality Standards,'' EPA-450/479-003, 
U.S. Environmental Protection Agency, Research Triangle Park, NC, 
January 1979, should be used. Adjustments to the monitoring schedule 
must be made on the basis of the 5-year network assessment. The site 
having the highest concentration in the most current year must be given 
first consideration when selecting the site for the more frequent 
sampling schedule. Other factors such as major change in sources of 
PM<INF>10</INF> emissions or in sampling site characteristics could 
influence the location of the expected maximum concentration site. 
Also, the use of the most recent 3 years of data might, in some cases, 
be justified in order to provide a more representative database from 
which to estimate current air quality status and to provide stability 
to the network. This multiyear consideration reduces the possibility of 
an anomalous year biasing a site selected for accelerated sampling. If 
the maximum concentration site based on the most current year is not 
selected for the more frequent operating schedule, documentation of the 
justification for selection of an alternative site must be submitted to 
the Regional Office for approval during the 5-year network assessment 
process. Minimum data completeness criteria, number of years of data 
and sampling frequency for judging attainment of the NAAQS are 
discussed in appendix K of part 50 of this chapter.
[GRAPHIC] [TIFF OMITTED] TR17OC06.060

    (f) For manual PM<INF>10-2.5</INF> samplers:
    (1) Manual PM<INF>10-2.5</INF> samplers at NCore stations must 
operate on at least a 1-in-3 day schedule at sites without a collocated 
continuously operating federal equivalent PM<INF>10-2.5</INF> method 
that has been designated in accordance with part 53 of this chapter.
    (2) Manual PM<INF>10-2.5</INF> speciation samplers at NCore 
stations must operate on at least a 1-in-3 day sampling frequency.


Sec.  58.13  Monitoring network completion.

    (a) The network of NCore multipollutant sites must be physically 
established no later than January 1, 2011, and at that time, operating 
under all of the requirements of this part, including the requirements 
of appendices A, C, D, E, and G to this part.
    (b) Where existing networks are not in conformance with required 
numbers of monitors specified in this part, additional required 
monitors must be operated by January 1, 2008.


Sec.  58.14  System modification.

    (a) The State, or where appropriate local, agency shall develop and 
implement a plan and schedule to modify the ambient air quality 
monitoring network that complies with the findings of the network 
assessments required every 5 years by Sec.  58.10(e). The State or 
local agency shall consult with the EPA Regional Administrator during 
the development of the schedule to modify the monitoring program, and 
shall make the plan and schedule available to the public for 30 days 
prior to submission to the EPA Regional Administrator. The final plan 
and schedule with respect to the SLAMS network are subject to the 
approval of the EPA Regional Administrator. Plans containing 
modifications to NCore Stations or PAMS Stations shall be submitted to 
the Administrator. The Regional Administrator shall provide opportunity 
for public comment and shall approve or disapprove submitted plans and 
schedules within 120 days.
    (b) Nothing in this section shall preclude the State, or where 
appropriate local, agency from making modifications to the SLAMS 
network for reasons other than those resulting from the periodic 
network assessments. These modifications must be reviewed and

[[Page 61301]]

approved by the Regional Administrator. Each monitoring network may 
make or be required to make changes between the 5-year assessment 
periods, including for example, site relocations or the addition of 
PAMS networks in bumped-up ozone nonattainment areas. These 
modifications must address changes invoked by a new census and changes 
due to changing air quality levels. The State, or where appropriate 
local, agency shall provide written communication describing the 
network changes to the Regional Administrator for review and approval 
as these changes are identified.
    (c) State, or where appropriate, local agency requests for SLAMS 
monitor station discontinuation, subject to the review of the Regional 
Administrator, will be approved if any of the following criteria are 
met and if the requirements of appendix D to this part, if any, 
continue to be met. Other requests for discontinuation may also be 
approved on a case-by-case basis if discontinuance does not compromise 
data collection needed for implementation of a NAAQS and if the 
requirements of appendix D to this part, if any, continue to be met.
    (1) Any PM<INF>2.5</INF>, O<INF>3</INF>, CO, PM<INF>10</INF>, 
SO<INF>2</INF>, Pb, or NO<INF>2</INF> SLAMS monitor which has shown 
attainment during the previous five years, that has a probability of 
less than 10 percent of exceeding 80 percent of the applicable NAAQS 
during the next three 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. In a nonattainment 
or maintenance area, if the most recent attainment or maintenance plan 
adopted by the State and approved by EPA contains a contingency measure 
to be triggered by an air quality concentration and the monitor to be 
discontinued is the only SLAMS monitor operating in the nonattainment 
or maintenance area, the monitor may not be discontinued.
    (2) Any SLAMS monitor for CO, PM<INF>10</INF>, SO<INF>2</INF>, or 
NO<INF>2</INF> which has consistently measured lower concentrations 
than another monitor for the same pollutant in the same county (or 
portion of a county within a distinct attainment area, nonattainment 
area, or maintenance area, as applicable) during the previous five 
years, and which is not specifically required by an attainment plan or 
maintenance plan, if control measures scheduled to be implemented or 
discontinued during the next five 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.
    (3) For any pollutant, any SLAMS monitor in a county (or portion of 
a county within a distinct attainment, nonattainment, or maintenance 
area, as applicable) provided the monitor has not measured violations 
of the applicable NAAQS in the previous five years, 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.
    (4) A PM<INF>2.5</INF> SLAMS monitor which EPA has determined 
cannot be compared to the relevant NAAQS because of the siting of the 
monitor, in accordance with Sec.  58.30.
    (5) A SLAMS 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 five years, if discontinuation of the monitor is tied to 
start-up of another station also characterizing transport.
    (6) A SLAMS monitor not eligible for removal under any of the 
criteria in paragraphs (c)(1) through (c)(5) of this section may 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.


Sec.  58.15  Annual air monitoring data certification.

    (a) The State, or where appropriate local, agency shall submit to 
the EPA Regional Administrator an annual air monitoring data 
certification letter to certify data collected at all SLAMS and at all 
FRM, FEM, and ARM SPM stations that meet criteria in appendix A to this 
part from January 1 to December 31 of the previous year. The senior air 
pollution control officer in each agency, or his or her designee, shall 
certify that the previous year of ambient concentration and quality 
assurance data are completely submitted to AQS and that the ambient 
concentration data are accurate to the best of her or his knowledge, 
taking into consideration the quality assurance findings.
    (1) Through 2009, the annual data certification letter is due by 
July 1 of each year.
    (2) Beginning in 2010, the annual data certification letter is due 
by May 1 of each year.
    (b) Along with each certification letter, the State shall submit to 
the Administrator (through the appropriate Regional Office) an annual 
summary report of all the ambient air quality data collected at all 
SLAMS and at SPM stations using FRM, FEM, or ARMs. The annual report(s) 
shall be submitted for data collected from January 1 to December 31 of 
the previous year. The annual summary report(s) must contain all 
information and data required by the State's approved plan and must be 
submitted on the same schedule as the certification letter, unless an 
approved alternative date is included in the plan. The annual summary 
serves as the record of the specific data that is the object of the 
certification letter.
    (c) Along with each certification letter, the State shall submit to 
the Administrator (through the appropriate Regional Office) a summary 
of the precision and accuracy data for all ambient air quality data 
collected at all SLAMS and at SPM stations using FRM, FEM, or ARMs. The 
summary of precision and accuracy shall be submitted for data collected 
from January 1 to December 31 of the previous year. The summary of 
precision and accuracy must be submitted on the same schedule as the 
certification letter, unless an approved alternative date is included 
in the plan.


Sec.  58.16  Data submittal and archiving requirements.

    (a) The State, or where appropriate, local agency, shall report to 
the Administrator, via AQS all ambient air quality data and associated 
quality assurance data for SO<INF>2</INF>; CO; O<INF>3</INF>; 
NO<INF>2</INF>; NO; NO<INF>Y</INF>; NO<INF>X</INF>; Pb; PM<INF>10</INF> 
mass concentration; PM<INF>2.5</INF> mass concentration; for filter-
based PM<INF>2.5</INF> FRM/FEM the field blank mass, sampler-generated 
average daily temperature, and sampler-generated average daily 
pressure; chemically speciated PM<INF>2.5</INF> mass concentration 
data; PM<INF>10-2.5</INF> mass concentration; chemically speciated 
PM<INF>10-2.5</INF> mass concentration data; meteorological data from 
NCore and PAMS sites; and metadata records and information specified by 
the AQS Data Coding Manual (http://www.epa.gov/ttn/airs/airsaqs/manuals/manuals.htm). Such air quality data and information must be 
submitted directly to the AQS via electronic transmission on the 
specified quarterly schedule described in paragraph (b) of this 
section.
    (b) The specific quarterly reporting periods are January 1-March 
31, April 1-June 30, July 1-September 30, and October 1-December 31. 
The data and information reported for each reporting period must 
contain all data and information gathered during the reporting period, 
and be received in the AQS within 90 days after the end of the 
quarterly reporting period. For example,

[[Page 61302]]

the data for the reporting period January 1-March 31 are due on or 
before June 30 of that year.
    (c) Air quality data submitted for each reporting period must be 
edited, validated, and entered into the AQS (within the time limits 
specified in paragraph (b) of this section) pursuant to appropriate AQS 
procedures. The procedures for editing and validating data are 
described in the AQS Data Coding Manual and in each monitoring agency's 
quality assurance project plan.
    (d) The State shall report VOC and if collected, carbonyl, 
NH<INF>3</INF>, and HNO<INF>3</INF> data, from PAMS sites to AQS within 
6 months following the end of each quarterly reporting period listed in 
paragraph (b) of this section.
    (e) The State shall also submit any portion or all of the SLAMS and 
SPM data to the appropriate Regional Administrator upon request.
    (f) The State, or where applicable, local agency shall archive all 
PM<INF>2.5</INF>, PM<INF>10</INF>, and PM<INF>10-2.5</INF> filters from 
manual low-volume samplers (samplers having flow rates less than 200 
liters/minute) from all SLAMS sites for a minimum period of 1 year 
after collection. These filters shall be made available during the 
course of that year for supplemental analyses at the request of EPA or 
to provide information to State and local agencies on particulate 
matter composition. Other Federal agencies may request access to 
filters for purposes of supporting air quality management or community 
health--such as biological assay--through the applicable EPA Regional 
Administrator. The filters shall be archived according to procedures 
approved by the Administrator. The EPA recommends that particulate 
matter filters be archived for longer periods, especially for key sites 
in making NAAQS related decisions or for supporting health-related air 
pollution studies.

0
28. Subpart C is revised to read as follows:

Subpart C--Special Purpose Monitors


Sec.  58.20  Special purpose monitors (SPM).

    (a) An SPM is defined as any monitor included in an agency's 
monitoring network that the agency has designated as a special purpose 
monitor in its annual monitoring network plan and in AQS, 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. Any SPM operated by an air monitoring agency must be 
included in the periodic assessments and annual monitoring network plan 
required by Sec.  58.10. The plan shall include a statement of purposes 
for each SPM monitor and evidence that operation of each monitor meets 
the requirements of appendix A or an approved alternative as provided 
by Sec.  58.11(a)(2) where applicable. The monitoring agency may 
designate a monitor as an SPM after January 1, 2007 only if it is a new 
monitor, i.e., a SLAMS monitor that is not included in the currently 
applicable monitoring plan or, for a monitor included in the monitoring 
plan prior to January 1, 2007, if the Regional Administrator has 
approved the discontinuation of the monitor as a SLAMS site.
    (b) Any SPM data collected by an air monitoring agency using a 
Federal reference method (FRM), Federal equivalent method (FEM), or 
approved regional method (ARM) must meet the requirements of Sec.  
58.11, Sec.  58.12, and appendix A to this part or an approved 
alternative to appendix A to this part. Compliance with appendix E to 
this part is optional but encouraged except when the monitoring 
agency's data objectives are inconsistent with those requirements. Data 
collected at an SPM using a FRM, FEM, or ARM meeting the requirements 
of appendix A must be submitted to AQS according to the requirements of 
Sec.  58.16. Data collected by other SPMs may be submitted. The 
monitoring agency must also submit to AQS an indication of whether each 
SPM reporting data to AQS monitor meets the requirements of appendices 
A and E to this part.
    (c) All data from an SPM using an FRM, FEM, or ARM which has 
operated for more than 24 months is eligible for comparison to the 
relevant NAAQS, subject to the conditions of Sec.  58.30, unless the 
air monitoring agency demonstrates that the data came from a particular 
period during which the requirements of appendix A or an approved 
alternative, appendix C, or appendix E were not met in practice.
    (d) If an SPM using an FRM, FEM, or ARM is discontinued within 24 
months of start-up, the Administrator will not base a NAAQS violation 
determination for the PM<INF>2.5</INF> or ozone NAAQS solely on data 
from the SPM.
    (e) If an SPM using an FRM, FEM, or ARM is discontinued within 24 
months of start-up, the Administrator will not designate an area as 
nonattainment for the CO, SO<INF>2</INF>, NO<INF>2</INF>, Pb, or 24-
hour PM<INF>10</INF> NAAQS solely on the basis of data from the SPM. 
Such data are eligible for use in determinations of whether a 
nonattainment area has attained one of these NAAQS.
    (f) Prior approval from EPA is not required for discontinuance of 
an SPM.

0
29. Subpart D is revised to read as follows:

Subpart D--Comparability of Ambient Data to NAAQS


Sec.  58.30  Special considerations for data comparisons to the NAAQS.

    (a) Comparability of PM2.5 data. (1) There are two forms of the 
PM<INF>2.5</INF> NAAQS described in part 50 of this chapter. The 
PM<INF>2.5</INF> monitoring site characteristics (see appendix D to 
this part, section 4.7.1) impact how the resulting PM<INF>2.5</INF> 
data can be compared to the annual PM<INF>2.5</INF> NAAQS form. 
PM<INF>2.5</INF> data that are representative, not of areawide but 
rather, 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<INF>2.5</INF> 
NAAQS. For example, if the PM<INF>2.5</INF> monitoring site is adjacent 
to a unique dominating local PM<INF>2.5</INF> source or can be shown to 
have average 24-hour concentrations representative of a smaller than 
neighborhood spatial scale, then data from a monitor at the site would 
only be eligible for comparison to the 24-hour PM<INF>2.5</INF> NAAQS.
    (2) There are cases where certain population-oriented microscale or 
middle scale PM<INF>2.5</INF> monitoring sites are determined by the 
Regional Administrator to collectively identify a larger region of 
localized high ambient PM<INF>2.5</INF> concentrations. In those cases, 
data from these population-oriented sites would be eligible for 
comparison to the annual PM<INF>2.5</INF> NAAQS.
    (b) [Reserved]

Subpart E--[Removed and Reserved]

0
30. Subpart E of part 58 is removed and reserved.

Subpart F--[Amended]

0
31. Section 58.50 is revised to read as follows:


Sec.  58.50  Index reporting.

    (a) The State or where applicable, local agency shall report to the 
general public on a daily basis through prominent notice an air quality 
index that complies with the requirements of appendix G to this part.
    (b) Reporting is required for all individual MSA with a population 
exceeding 350,000.
    (c) The population of a MSA for purposes of index reporting is the 
most recent decennial U.S. census population.

[[Page 61303]]

Subpart G--[Amended]

0
32. Sections 58.60 and 58.61 are revised to read as follows:


Sec.  58.60  Federal monitoring.

    The Administrator may locate and operate an ambient air monitoring 
site if the State or local agency fails to locate, or schedule to be 
located, during the initial network design process, or as a result of 
the 5-year network assessments required in Sec.  58.10, a SLAMS station 
at a site which is necessary in the judgment of the Regional 
Administrator to meet the objectives defined in appendix D to this 
part.


Sec.  58.61  Monitoring other pollutants.

    The Administrator may promulgate criteria similar to that 
referenced in subpart B of this part for monitoring a pollutant for 
which an NAAQS does not exist. Such an action would be taken whenever 
the Administrator determines that a nationwide monitoring program is 
necessary to monitor such a pollutant.

0
33. Appendix A to part 58 is revised to read as follows:

Appendix A to Part 58--Quality Assurance Requirements for SLAMS, SPMs 
and PSD Air Monitoring

1. General Information
2. Quality System Requirements
3. Measurement Quality Check Requirements
4. Calculations for Data Quality Assessments
5. Reporting Requirements
6. References

1. General Information

    This appendix specifies the minimum quality system requirements 
applicable to SLAMS air monitoring data and PSD data for the 
pollutants SO<INF>2</INF>, NO<INF>2</INF>, O<INF>3</INF>, CO, 
PM<INF>2.5</INF>, PM<INF>10</INF> and PM<INF>10-2.5</INF> submitted 
to EPA. This appendix also applies to all SPM stations using FRM, 
FEM, or ARM methods which also meet the requirements of Appendix E 
of this part. Monitoring organizations are encouraged to develop and 
maintain quality systems more extensive than the required minimums. 
The permit-granting authority for PSD may require more frequent or 
more stringent requirements. Monitoring organizations may, based on 
their quality objectives, develop and maintain quality systems 
beyond the required minimum. Additional guidance for the 
requirements reflected in this appendix can be found in the 
``Quality Assurance Handbook for Air Pollution Measurement 
Systems'', volume II, part 1 (see reference 10 of this appendix) and 
at a national level in references 1, 2, and 3 of this appendix.
    1.1 Similarities and Differences Between SLAMS and PSD 
Monitoring. In most cases, the quality assurance requirements for 
SLAMS, SPMs if applicable, and PSD are the same. Affected SPMs are 
subject to all the SLAMS requirements, even where not specifically 
stated in each section. Table A-1 of this appendix summarizes the 
major similarities and differences of the requirements for SLAMS and 
PSD. Both programs require:
    (a) The development, documentation, and implementation of an 
approved quality system;
    (b) The assessment of data quality;
    (c) The use of reference, equivalent, or approved methods. The 
requirements of this appendix do not apply to a SPM that does not 
use a FRM, FEM, or ARM;
    (d) The use of calibration standards traceable to NIST or other 
primary standard;
    (e) Performance evaluations and systems.
    1.1.1 The monitoring and quality assurance responsibilities for 
SLAMS are with the State or local agency, hereafter called the 
monitoring organization, whereas for PSD they are with the owner/
operator seeking the permit. The monitoring duration for SLAMS is 
indefinite, whereas for PSD the duration is usually 12 months. 
Whereas the reporting period for precision and accuracy data is on 
an annual or calendar quarter basis for SLAMS, it is on a continuing 
sampler quarter basis for PSD, since the monitoring may not commence 
at the beginning of a calendar quarter.
    1.1.2 The annual performance evaluations (described in section 
3.2.2 of this appendix) for PSD must be conducted by personnel 
different from those who perform routine span checks and 
calibrations, whereas for SLAMS, it is the preferred but not the 
required condition. For PSD, the evaluation rate is 100 percent of 
the sites per reporting quarter whereas for SLAMS it is 25 percent 
of the sites or instruments quarterly. Monitoring for sulfur dioxide 
(SO<INF>2</INF>) and nitrogen dioxide (NO<INF>2</INF>) for PSD must 
be done with automated analyzers--the manual bubbler methods are not 
permitted.
    1.1.3 The requirements for precision assessment for the 
automated methods are the same for both SLAMS and PSD. However, for 
manual methods, only one collocated site is required for PSD.
    1.1.4 The precision, accuracy and bias data for PSD are reported 
separately for each sampler (site), whereas for SLAMS, the report 
may be by sampler (site), by primary quality assurance organization, 
or nationally, depending on the pollutant. SLAMS data are required 
to be reported to the AQS, PSD data are required to be reported to 
the permit-granting authority. Requirements in this appendix, with 
the exception of the differences discussed in this section, and in 
Table A-1 of this appendix will be expected to be followed by both 
SLAMS and PSD networks unless directly specified in a particular 
section.
    1.2 Measurement Uncertainty. Measurement uncertainty is a term 
used to describe deviations from a true concentration or estimate 
that are related to the measurement process and not to spatial or 
temporal population attributes of the air being measured. Monitoring 
organizations must develop quality assurance project plans (QAPP) 
which describe how the organization intends to control measurement 
uncertainty to an appropriate level in order to achieve the 
objectives for which the data are collected. The process by which 
one determines the quality of data needed to meet the monitoring 
objective is sometimes referred to the Data Quality Objectives 
Process. Data quality indicators associated with measurement 
uncertainty include:
    (a) Precision. A measurement of mutual agreement among 
individual measurements of the same property usually under 
prescribed similar conditions, expressed generally in terms of the 
standard deviation.
    (b) Bias. The systematic or persistent distortion of a 
measurement process which causes errors in one direction.
    (c) Accuracy. The degree of agreement between an observed value 
and an accepted reference value. Accuracy includes a combination of 
random error (imprecision) and systematic error (bias) components 
which are due to sampling and analytical operations.
    (d) Completeness. A measure of the amount of valid data obtained 
from a measurement system compared to the amount that was expected 
to be obtained under correct, normal conditions.
    (e) Detectability. The low critical range value of a 
characteristic that a method specific procedure can reliably 
discern.
    1.3 Measurement Quality Checks. The SLAMS measurement quality 
checks described in sections 3.2 and 3.3 of this appendix shall be 
reported to AQS and are included in the data required for 
certification. The PSD network is required to implement the 
measurement quality checks and submit this information quarterly 
along with assessment information to the permit-granting authority.
    1.4 Assessments and Reports. Periodic assessments and 
documentation of data quality are required to be reported to EPA or 
to the permit granting authority (PSD). To provide national 
uniformity in this assessment and reporting of data quality for all 
networks, specific assessment and reporting procedures are 
prescribed in detail in sections 3, 4, and 5 of this appendix. On 
the other hand, the selection and extent of the quality assurance 
and quality control activities used by a monitoring organization 
depend on a number of local factors such as field and laboratory 
conditions, the objectives for monitoring, the level of data quality 
needed, the expertise of assigned personnel, the cost of control 
procedures, pollutant concentration levels, etc. Therefore, quality 
system requirements in section 2 of this appendix are specified in 
general terms to allow each monitoring organization to develop a 
quality system that is most efficient and effective for its own 
circumstances while achieving the data quality objectives required 
for the SLAMS sites.

2. Quality System Requirements

    A quality system is the means by which an organization manages 
the quality of the monitoring information it produces in a 
systematic, organized manner. It provides a framework for planning, 
implementing, assessing and reporting work performed by an 
organization and for carrying out required quality assurance and 
quality control activities.
    2.1 Quality Management Plans and Quality Assurance Project 
Plans. All

[[Page 61304]]

monitoring organizations must develop a quality system that is 
described and approved in quality management plans (QMP) and quality 
assurance project plans (QAPP) to ensure that the monitoring 
results:
    (a) Meet a well-defined need, use, or purpose;
    (b) Provide data of adequate quality for the intended monitoring 
objectives;
    (c) Satisfy stakeholder expectations;
    (d) Comply with applicable standards specifications;
    (e) Comply with statutory (and other) requirements of society; 
and
    (f) Reflect consideration of cost and economics.
    2.1.1 The QMP describes the quality system in terms of the 
organizational structure, functional responsibilities of management 
and staff, lines of authority, and required interfaces for those 
planning, implementing, assessing and reporting activities involving 
environmental data operations (EDO). The QMP must be suitably 
documented in accordance with EPA requirements (reference 2 of this 
appendix), and approved by the appropriate Regional Administrator, 
or his or her representative. The quality system will be reviewed 
during the systems audits described in section 2.5 of this appendix. 
Organizations that implement long-term monitoring programs with EPA 
funds should have a separate QMP document. Smaller organizations or 
organizations that do infrequent work with EPA funds may combine the 
QMP with the QAPP based on negotiations with the funding agency. 
Additional guidance on this process can be found in reference 10 of 
this appendix. Approval of the recipient's QMP by the appropriate 
Regional Administrator or his or her representative, may allow 
delegation of the authority to review and approve the QAPP to the 
recipient, based on adequacy of quality assurance procedures 
described and documented in the QMP. The QAPP will be reviewed by 
EPA during systems audits or circumstances related to data quality.
    2.1.2 The QAPP is a formal document describing, in sufficient 
detail, the quality system that must be implemented to ensure that 
the results of work performed will satisfy the stated objectives. 
The quality assurance policy of the EPA requires every environmental 
data operation (EDO) to have a written and approved QAPP prior to 
the start of the EDO. It is the responsibility of the monitoring 
organization to adhere to this policy. The QAPP must be suitably 
documented in accordance with EPA requirements (reference 3 of this 
appendix).
    2.1.3 The monitoring organization's quality system must have 
adequate resources both in personnel and funding to plan, implement, 
assess and report on the achievement of the requirements of this 
appendix and its approved QAPP.
    2.2 Independence of Quality Assurance. The monitoring 
organization must provide for a quality assurance management 
function- that aspect of the overall management system of the 
organization that determines and implements the quality policy 
defined in a monitoring organization's QMP. Quality management 
includes strategic planning, allocation of resources and other 
systematic planning activities (e.g., planning, implementation, 
assessing and reporting) pertaining to the quality system. The 
quality assurance management function must have sufficient technical 
expertise and management authority to conduct independent oversight 
and assure the implementation of the organization's quality system 
relative to the ambient air quality monitoring program and should be 
organizationally independent of environmental data generation 
activities.
    2.3. Data Quality Performance Requirements.
    2.3.1 Data Quality Objectives. Data quality objectives (DQO) or 
the results of other systematic planning processes are statements 
that define the appropriate type of data to collect and specify the 
tolerable levels of potential decision errors that will be used as a 
basis for establishing the quality and quantity of data needed to 
support the objectives of the SLAMS stations. DQO will be developed 
by EPA to support the primary SLAMS objectives for each criteria 
pollutant. As they are developed they will be added to the 
regulation. DQO or the results of other systematic planning 
processes for PSD or other monitoring will be the responsibility of 
the monitoring organizations. The quality of the conclusions made 
from data interpretation can be affected by population uncertainty 
(spatial or temporal uncertainty) and measurement uncertainty 
(uncertainty associated with collecting, analyzing, reducing and 
reporting concentration data). This appendix focuses on assessing 
and controlling measurement uncertainty.
    2.3.1.1 Measurement Uncertainty for Automated and Manual 
PM<INF>2.5</INF> Methods. The goal for acceptable measurement 
uncertainty is defined as 10 percent coefficient of variation (CV) 
for total precision and plus or minus 10 percent for total bias.
    2.3.1.2 Measurement Uncertainty for Automated Ozone Methods. The 
goal for acceptable measurement uncertainty is defined for precision 
as an upper 90 percent confidence limit for the coefficient 
variation (CV) of 7 percent and for bias as an upper 95 percent 
confidence limit for the absolute bias of 7 percent.
    2.3.1.3 Measurement Uncertainty for PM<INF>10-2.5</INF> Methods. 
The goal for acceptable measurement uncertainty is defined for 
precision as an upper 90 percent confidence limit for the 
coefficient variation (CV) of 15 percent and for bias as an upper 95 
percent confidence limit for the absolute bias of 15 percent.
    2.4 National Performance Evaluation Programs. Monitoring plans 
or the QAPP shall provide for the implementation of a program of 
independent and adequate audits of all monitors providing data for 
SLAMS and PSD including the provision of adequate resources for such 
audit programs. A monitoring plan (or QAPP) which provides for 
monitoring organization participation in EPA's National Performance 
Audit Program (NPAP) and the PM Performance Evaluation Program (PEP) 
program and which indicates the consent of the monitoring 
organization for EPA to apply an appropriate portion of the grant 
funds, which EPA would otherwise award to the monitoring 
organization for monitoring activities, will be deemed by EPA to 
meet this requirement. For clarification and to participate, 
monitoring organizations should contact either the appropriate EPA 
Regional Quality Assurance (QA) Coordinator at the appropriate EPA 
Regional Office location, or the NPAP Coordinator, Emissions 
Monitoring and Analysis Division (D205-02), U.S. Environmental 
Protection Agency, Research Triangle Park, NC 27711.
    2.5 Technical Systems Audit Program. Technical systems audits of 
each ambient air monitoring organization shall be conducted at least 
every 3 years by the appropriate EPA Regional Office and reported to 
the AQS. Systems audit programs are described in reference 10 of 
this appendix. For further instructions, monitoring organizations 
should contact the appropriate EPA Regional QA Coordinator.
    2.6 Gaseous and Flow Rate Audit Standards.
    2.6.1 Gaseous pollutant concentration standards (permeation 
devices or cylinders of compressed gas) used to obtain test 
concentrations for carbon monoxide (CO), sulfur dioxide 
(SO<INF>2</INF>), nitrogen oxide (NO), and nitrogen dioxide 
(NO<INF>2</INF>) must be traceable to either a National Institute of 
Standards and Technology (NIST) Traceable Reference Material (NTRM) 
or a NIST-certified Gas Manufacturer's Internal Standard (GMIS), 
certified in accordance with one of the procedures given in 
reference 4 of this appendix. Vendors advertising certification with 
the procedures provided in reference 4 of this appendix and 
distributing gasses as ``EPA Protocol Gas'' must participate in the 
EPA Protocol Gas Verification Program or not use ``EPA'' in any form 
of advertising.
    2.6.2 Test concentrations for ozone (O<INF>3</INF>) must be 
obtained in accordance with the ultra violet photometric calibration 
procedure specified in appendix D to part 50 of this chapter, or by 
means of a certified O<INF>3</INF> transfer standard. Consult 
references 7 and 8 of this appendix for guidance on primary and 
transfer standards for O<INF>3</INF>.
    2.6.3 Flow rate measurements must be made by a flow measuring 
instrument that is traceable to an authoritative volume or other 
applicable standard. Guidance for certifying some types of 
flowmeters is provided in reference 10 of this appendix.
    2.7 Primary Requirements and Guidance. Requirements and guidance 
documents for developing the quality system are contained in 
references 1 through 10 of this appendix, which also contain many 
suggested procedures, checks, and control specifications. Reference 
10 of this appendix describes specific guidance for the development 
of a quality system for SLAMS. Many specific quality control checks 
and specifications for methods are included in the respective 
reference methods described in part 50 of this chapter or in the 
respective equivalent method descriptions available from EPA 
(reference 6 of this appendix). Similarly, quality control 
procedures related to specifically designated reference and 
equivalent method analyzers are contained in the respective 
operation or instruction manuals associated with those analyzers.

[[Page 61305]]

3. Measurement Quality Check Requirements

    This section provides the requirements for primary quality 
assurance organizations (PQAOs) to perform the measurement quality 
checks that can be used to assess data quality. With the exception 
of the flow rate verifications (sections 3.2.3 and 3.3.2 of this 
appendix), data from these checks are required to be submitted to 
the AQS within the same time frame as routine ambient concentration 
data. Section 3.2 of this appendix describes checks of automated or 
continuous instruments while section 3.3 describe checks associated 
with manual sampling instruments. Other quality control samples are 
identified in the various references described earlier and can be 
used to control certain aspects of the measurement system.
    3.1 Primary Quality Assurance Organization. A primary quality 
assurance organization is defined as a monitoring organization or a 
coordinated aggregation of such organizations that is responsible 
for a set of stations that monitors the same pollutant and for which 
data quality assessments can logically be pooled. Each criteria 
pollutant sampler/monitor at a monitoring station in the SLAMS 
network must be associated with one, and only one, primary quality 
assurance organization.
    3.1.1 Each primary quality assurance organization shall be 
defined such that measurement uncertainty among all stations in the 
organization can be expected to be reasonably homogeneous, as a 
result of common factors. Common factors that should be considered 
by monitoring organizations in defining primary quality assurance 
organizations include:
    (a) Operation by a common team of field operators according to a 
common set of procedures;
    (b) Use of a common QAPP or standard operating procedures;
    (c) Common calibration facilities and standards;
    (d) Oversight by a common quality assurance organization; and
    (e) Support by a common management, laboratory or headquarters.
    3.1.2 Primary quality assurance organizations are not 
necessarily related to the organization reporting data to the AQS. 
Monitoring organizations having difficulty in defining the primary 
quality assurance organizations or in assigning specific sites to 
primary quality assurance organizations should consult with the 
appropriate EPA Regional Office. All definitions of primary quality 
assurance organizations shall be subject to final approval by the 
appropriate EPA Regional Office during scheduled network reviews or 
systems audits.
    3.1.3 Data quality assessment results shall be reported as 
specified in section 5 of this appendix.
    3.2 Measurement Quality Checks of Automated Methods. Table A-2 
of this appendix provides a summary of the types and frequency of 
the measurement quality checks that will be described in this 
section.
    3.2.1 One-Point Quality Control Check for SO<INF>2</INF>, 
NO<INF>2</INF>, O<INF>3</INF>, and CO. A one-point quality control 
(QC) check must be performed at least once every 2 weeks on each 
automated analyzer used to measure SO<INF>2</INF>, NO<INF>2</INF>, 
O<INF>3</INF> and CO. The frequency of QC checks may be reduced 
based upon review, assessment and approval of the EPA Regional 
Administrator. However, with the advent of automated calibration 
systems more frequent checking is encouraged. See Reference 10 of 
this appendix for guidance on the review procedure. The QC check is 
made by challenging the analyzer with a QC check gas of known 
concentration (effective concentration for open path analyzers) 
between 0.01 and 0.10 parts per million (ppm) for SO<INF>2</INF>, 
NO<INF>2</INF>, and O<INF>3</INF>, and between 1 and 10 ppm for CO 
analyzers. The ranges allow for appropriate check gas selection for 
SLAMS sites that may be sampling for different objectives, i.e., 
trace gas monitoring vs. comparison to National Ambient Air Quality 
Standards (NAAQS). The QC check gas concentration selected should be 
related to the routine concentrations normally measured at sites 
within the monitoring network in order to appropriately reflect the 
precision and bias at these routine concentration ranges. To check 
the precision and bias of SLAMS analyzers operating at ranges either 
above or below the levels identified, use check gases of appropriate 
concentrations as approved by the appropriate EPA Regional 
Administrator or their designee. The standards from which check 
concentrations are obtained must meet the specifications of section 
2.6 of this appendix.
    3.2.1.1 Except for certain CO analyzers described below, point 
analyzers must operate in their normal sampling mode during the QC 
check, and the test atmosphere must pass through all filters, 
scrubbers, conditioners and other components used during normal 
ambient sampling and as much of the ambient air inlet system as is 
practicable. If permitted by the associated operation or instruction 
manual, a CO point analyzer may be temporarily modified during the 
QC check to reduce vent or purge flows, or the test atmosphere may 
enter the analyzer at a point other than the normal sample inlet, 
provided that the analyzer's response is not likely to be altered by 
these deviations from the normal operational mode. If a QC check is 
made in conjunction with a zero or span adjustment, it must be made 
prior to such zero or span adjustments.
    3.2.1.2 Open path analyzers are tested by inserting a test cell 
containing a QC check gas concentration into the optical measurement 
beam of the instrument. If possible, the normally used transmitter, 
receiver, and as appropriate, reflecting devices should be used 
during the test and the normal monitoring configuration of the 
instrument should be altered as little as possible to accommodate 
the test cell for the test. However, if permitted by the associated 
operation or instruction manual, an alternate local light source or 
an alternate optical path that does not include the normal 
atmospheric monitoring path may be used. The actual concentration of 
the QC check gas in the test cell must be selected to produce an 
effective concentration in the range specified earlier in this 
section. Generally, the QC test concentration measurement will be 
the sum of the atmospheric pollutant concentration and the QC test 
concentration. If so, the result must be corrected to remove the 
atmospheric concentration contribution. The corrected concentration 
is obtained by subtracting the average of the atmospheric 
concentrations measured by the open path instrument under test 
immediately before and immediately after the QC test from the QC 
check gas concentration measurement. If the difference between these 
before and after measurements is greater than 20 percent of the 
effective concentration of the test gas, discard the test result and 
repeat the test. If possible, open path analyzers should be tested 
during periods when the atmospheric pollutant concentrations are 
relatively low and steady.
    3.2.1.3 Report the audit concentration (effective concentration 
for open path analyzers) of the QC gas and the corresponding 
measured concentration (corrected concentration, if applicable, for 
open path analyzers) indicated by the analyzer. The percent 
differences between these concentrations are used to assess the 
precision and bias of the monitoring data as described in sections 
4.1.2 (precision) and 4.1.3 (bias) of this appendix.
    3.2.2 Annual performance evaluation for SO<INF>2</INF>, 
NO<INF>2</INF>, O<INF>3</INF>, or CO. Each calendar quarter (during 
which analyzers are operated), evaluate at least 25 percent of the 
SLAMS analyzers that monitor for SO<INF>2</INF>, NO<INF>2</INF>, 
O<INF>3</INF>, or CO such that each analyzer is evaluated at least 
once per year. If there are fewer than four analyzers for a 
pollutant within a primary quality assurance organization, it is 
suggested to randomly evaluate one or more analyzers so that at 
least one analyzer for that pollutant is evaluated each calendar 
quarter. The evaluation should be conducted by a trained experienced 
technician other than the routine site operator.
    3.2.2.1 (a) The evaluation is made by challenging the analyzer 
with audit gas standard of known concentration (effective 
concentration for open path analyzers) from at least three 
consecutive audit levels. The audit levels selected should represent 
or bracket 80 percent of ambient concentrations measured by the 
analyzer being evaluated:

----------------------------------------------------------------------------------------------------------------
                                                               Concentration range, ppm
             Audit level             ---------------------------------------------------------------------------
                                              O3                SO2                NO2                 CO
----------------------------------------------------------------------------------------------------------------
1...................................          0.02-0.05       0.0003-0.005       0.0002-0.002          0.08-0.10
2...................................          0.06-0.10         0.006-0.01        0.003-0.005          0.50-1.00

[[Page 61306]]

 
3...................................          0.11-0.20          0.02-0.10         0.006-0.10          1.50-4.00
4...................................          0.21-0.30          0.11-0.40          0.11-0.30               5-15
5...................................          0.31-0.90          0.41-0.90          0.31-0.60              20-50
----------------------------------------------------------------------------------------------------------------

    (b) An additional 4th level is encouraged for those monitors 
that have the potential for exceeding the concentration ranges 
described by the initial three selected.
    3.2.2.2 (a) NO<INF>2</INF> audit gas for chemiluminescence-type 
NO<INF>2</INF> analyzers must also contain at least 0.08 ppm NO. NO 
concentrations substantially higher than 0.08 ppm, as may occur when 
using some gas phase titration (GPT) techniques, may lead to 
evaluation errors in chemiluminescence analyzers due to inevitable 
minor NO-NO<INF>X</INF> channel imbalance. Such errors may be 
atypical of routine monitoring errors to the extent that such NO 
concentrations exceed typical ambient NO concentrations at the site. 
These errors may be minimized by modifying the GPT technique to 
lower the NO concentrations remaining in the NO<INF>2</INF> audit 
gas to levels closer to typical ambient NO concentrations at the 
site.
    (b) To evaluate SLAMS analyzers operating on ranges higher than 
0 to 1.0 ppm for SO<INF>2</INF>, NO<INF>2</INF>, and O<INF>3</INF> 
or 0 to 50 ppm for CO, use audit gases of appropriately higher 
concentration as approved by the appropriate EPA Regional 
Administrator or the Administrator's designee.
    3.2.2.3 The standards from which audit gas test concentrations 
are obtained must meet the specifications of section 2.6 of this 
appendix. The gas standards and equipment used for evaluations must 
not be the same as the standards and equipment used for calibration 
or calibration span adjustments. For SLAMS sites, the auditor should 
not be the operator or analyst who conducts the routine monitoring, 
calibration, and analysis. For PSD sites the auditor must not be the 
operator or analyst who conducts the routine monitoring, 
calibration, and analysis.
    3.2.2.4 For point analyzers, the evaluation shall be carried out 
by allowing the analyzer to analyze the audit gas test atmosphere in 
its normal sampling mode such that the test atmosphere passes 
through all filters, scrubbers, conditioners, and other sample inlet 
components used during normal ambient sampling and as much of the 
ambient air inlet system as is practicable. The exception provided 
in section 3.2.1 of this appendix for certain CO analyzers does not 
apply for evaluations.
    3.2.2.5 Open path analyzers are evaluated by inserting a test 
cell containing the various audit gas concentrations into the 
optical measurement beam of the instrument. If possible, the 
normally used transmitter, receiver, and, as appropriate, reflecting 
devices should be used during the evaluation, and the normal 
monitoring configuration of the instrument should be modified as 
little as possible to accommodate the test cell for the evaluation. 
However, if permitted by the associated operation or instruction 
manual, an alternate local light source or an alternate optical path 
that does not include the normal atmospheric monitoring path may be 
used. The actual concentrations of the audit gas in the test cell 
must be selected to produce effective concentrations in the 
evaluation level ranges specified in this section of this appendix. 
Generally, each evaluation concentration measurement result will be 
the sum of the atmospheric pollutant concentration and the 
evaluation test concentration. If so, the result must be corrected 
to remove the atmospheric concentration contribution. The corrected 
concentration is obtained by subtracting the average of the 
atmospheric concentrations measured by the open path instrument 
under test immediately before and immediately after the evaluation 
test (or preferably before and after each evaluation concentration 
level) from the evaluation concentration measurement. If the 
difference between the before and after measurements is greater than 
20 percent of the effective concentration of the test gas standard, 
discard the test result for that concentration level and repeat the 
test for that level. If possible, open path analyzers should be 
evaluated during periods when the atmospheric pollutant 
concentrations are relatively low and steady. Also, if the open path 
instrument is not installed in a permanent manner, the monitoring 
path length must be reverified to within plus or minus 3 percent to 
validate the evaluation, since the monitoring path length is 
critical to the determination of the effective concentration.
    3.2.2.6 Report both the evaluation concentrations (effective 
concentrations for open path analyzers) of the audit gases and the 
corresponding measured concentration (corrected concentrations, if 
applicable, for open path analyzers) indicated or produced by the 
analyzer being tested. The percent differences between these 
concentrations are used to assess the quality of the monitoring data 
as described in section 4.1.4 of this appendix.
    3.2.3 Flow Rate Verification for Particulate Matter. A one-point 
flow rate verification check must be performed at least once every 
month on each automated analyzer used to measure PM<INF>10</INF>, 
PM<INF>10-2.5</INF> and PM<INF>2.5</INF>. The verification is made 
by checking the operational flow rate of the analyzer. If the 
verification is made in conjunction with a flow rate adjustment, it 
must be made prior to such flow rate adjustment. Randomization of 
the flow rate verification with respect to time of day, day of week, 
and routine service and adjustments is encouraged where possible. 
For the standard procedure, use a flow rate transfer standard 
certified in accordance with section 2.6 of this appendix to check 
the analyzer's normal flow rate. Care should be used in selecting 
and using the flow rate measurement device such that it does not 
alter the normal operating flow rate of the analyzer. Report the 
flow rate of the transfer standard and the corresponding flow rate 
measured (indicated) by the analyzer. The percent differences 
between the audit and measured flow rates are used to assess the 
bias of the monitoring data as described in section 4.2.2 of this 
appendix (using flow rates in lieu of concentrations).
    3.2.4 Semi-Annual Flow Rate Audit for Particulate Matter. Every 
6 months, audit the flow rate of the PM<INF>10</INF>, 
PM<INF>10-2.5</INF> and PM<INF>2.5</INF> particulate analyzers. 
Where possible, EPA strongly encourages more frequent auditing. The 
audit should (preferably) be conducted by a trained experienced 
technician other than the routine site operator. The audit is made 
by measuring the analyzer's normal operating flow rate using a flow 
rate transfer standard certified in accordance with section 2.6 of 
this appendix. The flow rate standard used for auditing must not be 
the same flow rate standard used to calibrate the analyzer. However, 
both the calibration standard and the audit standard may be 
referenced to the same primary flow rate or volume standard. Great 
care must be used in auditing the flow rate to be certain that the 
flow measurement device does not alter the normal operating flow 
rate of the analyzer. Report the audit flow rate of the transfer 
standard and the corresponding flow rate measured (indicated) by the 
analyzer. The percent differences between these flow rates are used 
to validate the one-point flow rate verification checks used to 
estimate bias as described in section 4.2.3 of this appendix.
    3.2.5 Collocated Sampling Procedures for PM<INF>2.5.</INF> For 
each pair of collocated monitors, designate one sampler as the 
primary monitor whose concentrations will be used to report air 
quality for the site, and designate the other as the audit monitor.
    3.2.5.1 Each EPA designated Federal reference method (FRM) or 
Federal equivalent method (FEM) within a primary quality assurance 
organization must:
    (a) Have 15 percent of the monitors collocated (values of 0.5 
and greater round up); and
    (b) Have at least 1 collocated monitor (if the total number of 
monitors is less than 3). The first collocated monitor must be a 
designated FRM monitor.
    3.2.5.2 In addition, monitors selected for collocation must also 
meet the following requirements:
    (a) A primary monitor designated as an EPA FRM shall be 
collocated with an audit monitor having the same EPA FRM method 
designation.
    (b) For each primary monitor model designated as an EPA FEM used 
by the PQAO, 50 percent of the monitors designated for collocation 
shall be collocated with an audit monitor having the same method 
designation and 50 percent of the monitors shall be collocated with 
an FRM audit monitor. If the primary quality assurance

[[Page 61307]]

organization only has one FEM monitor it shall be collocated with an 
FRM audit monitor. If there are an odd number of collocated monitors 
required, the additional monitor shall be an FRM audit monitor. An 
example of this procedure is found in Table A-3 of this appendix.
    3.2.5.3 The collocated monitors should be deployed according to 
the following protocol:
    (a) 80 percent of the collocated audit monitors should be 
deployed at sites with annual average or daily concentrations 
estimated to be within <plus-minus>20 percent of the applicable 
NAAQS and the remainder at what the monitoring organizations 
designate as high value sites;
    (b) If an organization has no sites with annual average or daily 
concentrations within <plus-minus> 20 percent of the annual NAAQS 
(or 24-hour NAAQS if that is affecting the area), 60 percent of the 
collocated audit monitors should be deployed at those sites with the 
annual mean concentrations (or 24-hour NAAQS if that is affecting 
the area) among the highest 25 percent for all sites in the network.
    3.2.5.4 In determining the number of collocated sites required 
for PM<INF>2.5</INF>, monitoring networks for visibility assessments 
should not be treated independently from networks for particulate 
matter, as the separate networks may share one or more common 
samplers. However, for Class I visibility areas, EPA will accept 
visibility aerosol mass measurement instead of a PM<INF>2.5</INF> 
measurement if the latter measurement is unavailable. Any 
PM<INF>2.5</INF> monitoring site which does not have a monitor which 
is an EPA FRM, FEM or ARM is not required to be included in the 
number of sites which are used to determine the number of collocated 
monitors.
    3.2.5.5 For each PSD monitoring network, one site must be 
collocated. A site with the predicted highest 24-hour pollutant 
concentration must be selected.
    3.2.5.6 The two collocated monitors must be within 4 meters of 
each other and at least 2 meters apart for flow rates greater than 
200 liters/min or at least 1 meter apart for samplers having flow 
rates less than 200 liters/min to preclude airflow interference. 
Calibration, sampling, and analysis must be the same for both 
collocated samplers and the same as for all other samplers in the 
network.
    3.2.5.7 Sample the collocated audit monitor for SLAMS sites on a 
12-day schedule; sample PSD sites on a 6-day schedule or every third 
day for PSD daily monitors. If a primary quality assurance 
organization has only one collocated monitor, higher sampling 
frequencies than the 12-day schedule may be needed in order to 
produce about 25 valid sample pairs a year. Report the measurements 
from both primary and collocated audit monitors at each collocated 
sampling site. The calculations for evaluating precision between the 
two collocated monitors are described in section 4.3.1 of this 
appendix.
    3.2.6 Collocated Sampling Procedures for PM<INF>10-2.5.</INF> 
For the PM<INF>10-2.5</INF> network, all automated methods must be 
designated as Federal equivalent methods (FEMs). For each pair of 
collocated monitors, designate one sampler as the primary monitor 
whose concentrations will be used to report air quality for the 
site, and designate the other as the audit monitor.
    3.2.6.1 The EPA shall ensure that each EPA designated FEM within 
the national PM<INF>10-2.5</INF> monitoring network must:
    (a) Have 15 percent of the monitors collocated (values of 0.5 
and greater round up); and
    (b) Have at least 2 collocated monitors (if the total number of 
monitors is less than 10). The first collocated monitor must be a 
designated FRM monitor and the second must be a monitor of the same 
method designation. Both collocated FRM and FEM monitors can be 
located at the same site.
    3.2.6.2 The Regional Administrator for the EPA Regions where the 
FEMs are implemented will select the sites for collocated 
monitoring. The site selection process shall consider giving 
priority to sites at primary quality assurance organizations or 
States with more than one PM<INF>10-2.5</INF> site, sites considered 
important from a regional perspective, and sites needed for an 
appropriate distribution among rural and urban NCore sites. 
Depending on the speed at which the PM<INF>10-2.5</INF> network is 
deployed, the first sites implementing FEMs shall be required to 
perform collocation until there is a larger distribution of FEM 
monitors implemented in the network.
    3.2.6.3 The two collocated monitors must be within 4 meters of 
each other and at least 2 meters apart for flow rates greater than 
200 liters/min or at least 1 meter apart for samplers having flow 
rates less than 200 liters/min to preclude airflow interference. 
Calibration, sampling, and analysis must be the same for both 
collocated samplers and the same as for all other samplers in the 
network.
    3.2.6.4 Sample the collocated audit monitor for SLAMS sites on a 
12-day schedule. Report the measurements from both primary and 
collocated audit monitors at each collocated sampling site. The 
calculations for evaluating precision between the two collocated 
monitors are described in section 4.3.1 of this appendix.
    3.2.7 PM<INF>2.5</INF> Performance Evaluation Program (PEP) 
Procedures. The PEP is an independent assessment used to estimate 
total measurement system bias. These evaluations will be performed 
under the PM Performance Evaluation Program (PEP) (section 2.4 of 
this appendix) or a comparable program. Performance evaluations will 
be performed on the SLAMS monitors annually within each primary 
quality assurance organization. For primary quality assurance 
organizations with less than or equal to five monitoring sites, five 
valid performance evaluation audits must be collected and reported 
each year. For primary quality assurance organizations with greater 
than five monitoring sites, eight valid performance evaluation 
audits must be collected and reported each year. A valid performance 
evaluation audit means that both the primary monitor and PEP audit 
concentrations are valid and above 3 [mu]g/m<SUP>3</SUP>. 
Additionally, each year, every designated FRM or FEM within a 
primary quality assurance organization must:
    (1) Have each method designation evaluated each year; and,
    (2) Have all FRM or FEM samplers subject to a PEP audit at least 
once every six years; which equates to approximately 15 percent of 
the monitoring sites audited each year.
    (b) Additional information concerning the Performance Evaluation 
Program is contained in reference 10 of this appendix. The 
calculations for evaluating bias between the primary monitor and the 
performance evaluation monitor for PM<INF>2.5</INF> are described in 
section 4.3.2 of this appendix.
    3.2.8 PM<INF>10-2.5</INF> Performance Evaluation Program. For 
the PM<INF>10-2.5</INF> network, all automated methods will be 
designated as federal equivalent methods (FEMs). One performance 
evaluation audit, as described in section 3.2.7 must be performed at 
one PM<INF>10-2.5</INF> site in each primary quality assurance 
organization each year. The calculations for evaluating bias between 
the primary monitor(s) and the performance evaluation monitors for 
PM<INF>10-2.5</INF> are described in section 4.1.3 of this appendix.
    3.3 Measurement Quality Checks of Manual Methods. Table A-2 of 
this appendix provides a summary of the types and frequency of the 
measurement quality checks that will be described in this section.
    3.3.1 Collocated Sampling Procedures for PM<INF>10</INF>. For 
each network of manual PM<INF>10</INF> methods, select 15 percent 
(or at least one) of the monitoring sites within the primary quality 
assurance organization for collocated sampling. For purposes of 
precision assessment, networks for measuring total suspended 
particulate (TSP) and PM<INF>10</INF> shall be considered separately 
from one another. However, PM<INF>10</INF> samplers used in the 
PM<INF>10-2.5</INF> network, may be counted along with the 
PM<INF>10</INF> samplers in the PM<INF>10</INF> network as long as 
the PM<INF>10</INF> samplers in both networks are the same method 
designation. PM<INF>10</INF> and TSP sites having annual mean 
particulate matter concentrations among the highest 25 percent of 
the annual mean concentrations for all the sites in the network must 
be selected or, if such sites are impractical, alternative sites 
approved by the EPA Regional Administrator may be selected.
    3.3.1.1 In determining the number of collocated sites required 
for PM<INF>10</INF>, monitoring networks for lead (Pb) should be 
treated independently from networks for particulate matter (PM), 
even though the separate networks may share one or more common 
samplers. However, a single pair of samplers collocated at a common-
sampler monitoring site that meets the requirements for both a 
collocated Pb site and a collocated PM site may serve as a 
collocated site for both networks.
    3.3.1.2 The two collocated monitors must be within 4 meters of 
each other and at least 2 meters apart for flow rates greater than 
200 liters/min or at least 1 meter apart for samplers having flow 
rates less than 200 liters/min to preclude airflow interference. 
Calibration, sampling, analysis and verification/validation 
procedures must be the same for both collocated samplers and the 
same as for all other samplers in the network.
    3.3.1.3 For each pair of collocated samplers, designate one 
sampler as the

[[Page 61308]]

primary sampler whose samples will be used to report air quality for 
the site, and designate the other as the audit sampler. Sample SLAMS 
sites on a 12-day schedule; sample PSD sites on a 6-day schedule or 
every third day for PSD daily samplers. If a primary quality 
assurance organization has only one collocated monitor, higher 
sampling frequencies than the 12-day schedule may be needed in order 
to produce approximately 25 valid sample pairs a year. Report the 
measurements from both samplers at each collocated sampling site. 
The calculations for evaluating precision between the two collocated 
samplers are described in section 4.2.1 of this appendix.
    3.3.2 Flow Rate Verification for Particulate Matter. Follow the 
same procedure as described in section 3.2.3 of this appendix for 
PM<INF>2.5</INF>, PM<INF>10</INF> (low-volume instruments), and 
PM<INF>10-2.5.</INF> High-volume PM<INF>10</INF> and TSP instruments 
can also follow the procedure in section 3.2.3 but the audits are 
required to be conducted quarterly. The percent differences between 
the audit and measured flow rates are used to assess the bias of the 
monitoring data as described in section 4.2.2 of this appendix.
    3.3.3 Semi-Annual Flow Rate Audit for Particulate Matter. Follow 
the same procedure as described in section 3.2.4 of this appendix 
for PM<INF>2.5</INF>, PM<INF>10</INF>, PM<INF>10-2.5</INF> and TSP 
instruments. The percent differences between these flow rates are 
used to validate the one-point flow rate verification checks used to 
estimate bias as described in section 4.2.3 of this appendix. Great 
care must be used in auditing high-volume particulate matter 
samplers having flow regulators because the introduction of 
resistance plates in the audit flow standard device can cause 
abnormal flow patterns at the point of flow sensing. For this 
reason, the flow audit standard should be used with a normal filter 
in place and without resistance plates in auditing flow-regulated 
high-volume samplers, or other steps should be taken to assure that 
flow patterns are not perturbed at the point of flow sensing.
    3.3.4 Pb Methods.
    3.3.4.1 Annual Flow Rate. For the Pb Reference Method (40 CFR 
part 50, appendix G), the flow rates of the high-volume Pb samplers 
shall be verified and audited using the same procedures described in 
sections 3.3.2 and 3.3.3 of this appendix.
    3.3.4.2 Pb Strips. Each calendar quarter or sampling quarter 
(PSD), audit the Pb Reference Method analytical procedure using 
glass fiber filter strips containing a known quantity of Pb. These 
audit sample strips are prepared by depositing a Pb solution on 
unexposed glass fiber filter strips of dimensions 1.9 centimeters 
(cm) by 20.3 cm (\3/4\ inch by 8 inch) and allowing them to dry 
thoroughly. The audit samples must be prepared using batches of 
reagents different from those used to calibrate the Pb analytical 
equipment being audited. Prepare audit samples in the following 
concentration ranges:

------------------------------------------------------------------------
                                                      Equivalent ambient
              Range                Pb concentration,   Pb concentration,
                                      [mu]g/strip         [mu]g/m3 1
------------------------------------------------------------------------
1...............................             100-300             0.5-1.5
2...............................           400-1,000            3.0-5.0
------------------------------------------------------------------------
\1\ Equivalent ambient Pb concentration in [mu]/m3 is based on sampling
  at 1.7 m3/min for 24 hours on a 20.3 cm x 25.4 cm (8 inch x 10 inch)
  glass fiber filter.

    (a) Audit samples must be extracted using the same extraction 
procedure used for exposed filters.
    (b) Analyze three audit samples in each of the two ranges each 
quarter samples are analyzed. The audit sample analyses shall be 
distributed as much as possible over the entire calendar quarter.
    (c) Report the audit concentrations (in [mu]g Pb/strip) and the 
corresponding measured concentrations (in [mu]g Pb/strip) using AQS 
unit code 077. The relative percent differences between the 
concentrations are used to calculate analytical accuracy as 
described in section 4.4.2 of this appendix.
    (d) The audits of an equivalent Pb method are conducted and 
assessed in the same manner as for the reference method. The flow 
auditing device and Pb analysis audit samples must be compatible 
with the specific requirements of the equivalent method.
    3.3.5 Collocated Sampling Procedures for PM<INF>2.5.</INF> 
Follow the same procedure as described in section 3.2.5 of this 
appendix. PM<INF>2.5</INF> samplers used in the PM<INF>10-2.5</INF> 
network, may be counted along with the PM<INF>2.5</INF> samplers in 
the PM<INF>2.5</INF> network as long as the PM<INF>2.5</INF> 
samplers in both networks are the same method designation.
    3.3.6 Collocated Sampling Procedures for PM<INF>10-2.5</INF>. 
All designated FRMs within the PM<INF>10-2.5</INF> monitoring 
network must have 15 percent of the monitors collocated (values of 
0.5 and greater round up) at the PM<INF>10-2.5</INF> sites. All FRM 
method designations can be aggregated.
    3.3.6.1 The EPA shall ensure that each designated FEM within the 
PM<INF>10-2.5</INF> monitoring network must:
    (a) Have 15 percent of the monitors collocated (values of 0.5 
and greater round up); and
    (b) Have at least 2 collocated monitors (if the total number of 
monitors is less than 10). The first collocated monitor must be a 
designated FRM monitor and the second must be a monitor of the same 
method designation. Both collocated FRM and FEM monitors can be 
located at the same site.
    3.3.6.2 The Regional Administrator for the EPA Region where the 
FRM or FEMs are implemented will select the sites for collocated 
monitoring. The collocation site selection process shall consider 
sites at primary quality assurance organizations or States with more 
than one PM<INF>10-2.5</INF> site; primary quality assurance 
organizations already monitoring for PM<INF>10</INF> and 
PM<INF>2.5</INF> using FRMs or FEMs; and an appropriate distribution 
among rural and urban NCore sites. Monitoring organizations 
implementing PM<INF>10</INF> samplers and PM<INF>2.5</INF> FRM 
samplers of the same method designation as the PM<INF>10-2.5</INF> 
FRM can include the PM<INF>10-2.5</INF> monitors in their respective 
PM<INF>10</INF> and PM<INF>2.5</INF> count. Follow the same 
procedures as described in sections 3.2.6.2 and 3.2.6.3 of this 
appendix.
    3.3.7 PM<INF>2.5</INF> Performance Evaluation Program (PEP) 
Procedures. Follow the same procedure as described in section 3.2.7 
of this appendix.
    3.3.8 PM<INF>10-2.5</INF> Performance Evaluation Program (PEP) 
Procedures. One performance evaluation audit, as described in 
section 3.2.7 of this appendix must be performed at one 
PM<INF>10-2.5</INF> site in each primary quality assurance 
organization each year. Monitoring organizations implementing 
PM<INF>2.5</INF> FRM samplers of the same method designation in both 
the PM<INF>2.5</INF> and the PM<INF>10-2.5</INF> networks can 
include the PM<INF>10-2.5</INF> performance evaluation audit in 
their respective PM<INF>2.5</INF> performance evaluation count as 
long as the performance evaluation is conducted at the 
PM<INF>10-2.5</INF> site. The calculations for evaluating bias 
between the primary monitor(s) and the performance evaluation 
monitors for PM<INF>10-2.5</INF> are described in section 4.1.3 of 
this appendix.

4. Calculations for Data Quality Assessment

    (a) Calculations of measurement uncertainty are carried out by 
EPA according to the following procedures. Primary quality assurance 
organizations should report the data for all appropriate measurement 
quality checks as specified in this appendix even though they may 
elect to perform some or all of the calculations in this section on 
their own.
    (b) The EPA will provide annual assessments of data quality 
aggregated by site and primary quality assurance organization for 
SO<INF>2</INF>, NO<INF>2</INF>, O<INF>3</INF> and CO and by primary 
quality assurance organization for PM<INF>10</INF>, 
PM<INF>2.5</INF>, PM<INF>10-2.5</INF> and Pb.
    (c) At low concentrations, agreement between the measurements of 
collocated samplers, expressed as relative percent difference or 
percent difference, may be relatively poor. For this reason, 
collocated measurement pairs are selected for use in the precision 
and bias calculations only when both measurements are equal to or 
above the following limits:
(1) TSP: 20 [mu]g/m<SUP>3</SUP>.
(2) Pb: 0.15 [mu]g/m<SUP>3</SUP>.
(3) PM<INF>10</INF> (Hi-Vol): 15 [mu]g/m<SUP>3</SUP>.
(4) PM<INF>10</INF> (Lo-Vol): 3 [mu]g/m<SUP>3</SUP>.
(5) PM<INF>10-2.5</INF> and PM<INF>2.5</INF>: 3 [mu]g/m<SUP>3</SUP>.

    4.1 Statistics for the Assessment of QC Checks for 
SO<INF>2</INF>, NO<INF>2</INF>, O<INF>3</INF> and CO.
    4.1.1 Percent Difference. All measurement quality checks start 
with a comparison of an audit concentration or value (flowrate) to 
the concentration/value measured by the analyzer and use percent 
difference as the comparison statistic as described in equation 1 of 
this section. For

[[Page 61309]]

each single point check, calculate the percent difference, di, as 
follows:
[GRAPHIC] [TIFF OMITTED] TR17OC06.041

where, meas is the concentration indicated by the monitoring 
organization's instrument and audit is the audit concentration of 
the standard used in the QC check being measured.
    4.1.2 Precision Estimate. The precision estimate is used to 
assess the one-point QC checks for SO<INF>2</INF>, NO<INF>2</INF>, 
O<INF>3</INF>, or CO described in section 3.2.1 of this appendix. 
The precision estimator is the coefficient of variation upper bound 
and is calculated using equation 2 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.042

where, X<SUP>2</SUP><INF>0.1,n-1</INF> is the 10th percentile of a 
chi-squared distribution with n-1 degrees of freedom.
    4.1.3 Bias Estimate. The bias estimate is calculated using the 
one-point QC checks for SO<INF>2</INF>, NO<INF>2</INF>, 
O<INF>3</INF>, or CO described in section 3.2.1 of this appendix and 
the performance evaluation program for PM<INF>10-2.5</INF> described 
in sections 3.2.8 and 3.3.8 of this appendix. The bias estimator is 
an upper bound on the mean absolute value of the percent differences 
as described in equation 3 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.043

where, n is the number of single point checks being aggregated; 
t<INF>0.95,n-1</INF> is the 95th quantile of a t-distribution with 
n-1 degrees of freedom; the quantity AB is the mean of the absolute 
values of the di's and is calculated using equation 4 of this 
section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.044

and the quantity AS is the standard deviation of the absolute value 
of the di's and is calculated using equation 5 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.045

    4.1.3.1 Assigning a sign (positive/negative) to the bias 
estimate. Since the bias statistic as calculated in equation 3 of 
this appendix uses absolute values, it does not have a tendency 
(negative or positive bias) associated with it. A sign will be 
designated by rank ordering the percent differences of the QC check 
samples from a given site for a particular assessment interval.
    4.1.3.2 Calculate the 25th and 75th percentiles of the percent 
differences for each site. The absolute bias upper bound should be 
flagged as positive if both percentiles are positive and negative if 
both percentiles are negative. The absolute bias upper bound would 
not be flagged if the 25th and 75th percentiles are of different 
signs.
    4.1.4 Validation of Bias Using the one-point QC Checks. The 
annual performance evaluations for SO<INF>2</INF>, NO<INF>2</INF>, 
O<INF>3</INF>, or CO described in section 3.2.2 of this appendix are 
used to verify the results obtained from the one-point QC checks and 
to validate those results across a range of concentration levels. To 
quantify this annually at the site level and at the 3-year primary 
quality assurance organization level, probability limits will be 
calculated from the one-point QC checks using equations 6 and 7 of 
this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.064

[GRAPHIC] [TIFF OMITTED] TR17OC06.065

where, m is the mean (equation 8 of this appendix):
[GRAPHIC] [TIFF OMITTED] TR17OC06.046

where, k is the total number of one point QC checks for the interval 
being evaluated and S is the standard deviation of the percent 
differences (equation 9 of this appendix) as follows:
[GRAPHIC] [TIFF OMITTED] TR17OC06.047

    4.1.5 Percent Difference. Percent differences for the 
performance evaluations, calculated using equation 1 of this 
appendix can be compared to the probability intervals for the 
respective site or at the primary quality assurance organization 
level. Ninety-five percent of the individual percent differences 
(all audit concentration levels) for the performance evaluations 
should be captured within the probability intervals for the primary 
quality assurance organization.
    4.2 Statistics for the Assessment of PM<INF>10</INF>.
    4.2.1 Precision Estimate from Collocated Samplers. Precision is 
estimated via duplicate measurements from collocated samplers of the 
same type. It is recommended that the precision be aggregated at the 
primary quality assurance organization level quarterly, annually, 
and at the 3-year level. The data pair would only be considered 
valid if both concentrations are greater than the minimum values 
specified in section 4(c) of this appendix. For each collocated data 
pair, calculate the relative percent difference, di, using equation 
10 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.048

where, Xi is the concentration from the primary sampler and Yi is 
the concentration value from the audit sampler. The coefficient of 
variation upper bound is calculated using the equation 11 of this 
appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.049

where, n is the number of valid data pairs being aggregated, and X 
\2\<INF>0.1.n-1</INF> is the 10th percentile of a chi-squared 
distribution with n1 degrees of freedom. The factor of 2 in the 
denominator adjusts for the fact that each di is calculated from two 
values with error.
4.2.2 Bias Estimate Using One-Point Flow Rate Verifications. For 
each one-point flow rate verification described in sections 3.2.3 
and 3.3.2 of this appendix, calculate the percent difference in 
volume using equation 1 of this appendix where meas is the value 
indicated by the sampler's volume measurement and audit is the 
actual volume indicated by the auditing flow meter. The absolute 
volume bias upper bound is then calculated using equation 3, where n 
is the number of flow rate audits being aggregated; 
t<INF>0.95,n-1</INF> is the 95th quantile of a t-distribution with 
n-1 degrees of freedom, the quantity AB is the mean of the absolute 
values of the di's and is calculated using equation 4 of this 
appendix , and the quantity AS in equation 3 of this appendix is the 
standard deviation of the absolute values if the di's and is 
calculated using equation 5 of this
    4.2.3 Assessment Semi-Annual Flow Rate Audits. The flow rate 
audits described in sections 3.2.4 and 3.3.3 of this appendix are 
used to assess the results obtained from the one-point flow rate 
verifications and to provide an estimate of flow rate acceptability. 
For each flow rate audit, calculate the percent difference in volume 
using equation 1 of this appendix where meas is the value indicated 
by the sampler's volume measurement and audit is the actual volume 
indicated by the auditing flow meter. To quantify this annually and 
at the 3-year primary quality assurance organization level, 
probability limits are calculated from the percent differences using 
equations 6 and 7 of this appendix where m is the mean described in 
equation 8 of this appendix and k is the total number of one-point 
flow rate verifications for the year and S is the standard deviation 
of the percent differences as described in equation 9 of this 
appendix.

[[Page 61310]]

    4.2.4 Percent Difference. Percent differences for the annual 
flow rate audit concentration, calculated using equation 1 of this 
appendix, can be compared to the probability intervals for the one-
point flow rate verifications for the respective primary quality 
assurance organization. Ninety-five percent of the individual 
percent differences (all audit concentration levels) for the 
performance evaluations should be captured within the probability 
intervals for primary quality assurance organization.
    4.3 Statistics for the Assessment of PM<INF>2.5</INF> and 
PM<INF>10-2.5.</INF>
    4.3.1 Precision Estimate. Precision for collocated instruments 
for PM<INF>2.5</INF> and PM<INF>10-2.5</INF> may be estimated where 
both the primary and collocated instruments are the same method 
designation and when the method designations are not similar. Follow 
the procedure described in section 4.2.1 of this appendix. In 
addition, one may want to perform an estimate of bias when the 
primary monitor is an FEM and the collocated monitor is an FRM. 
Follow the procedure described in section 4.1.3 of this appendix in 
order to provide an estimate of bias using the collocated data.
    4.3.2 Bias Estimate. Follow the procedure described in section 
4.1.3 of this appendix for the bias estimate of PM<INF>10-2.5.</INF> 
The PM<INF>2.5</INF> bias estimate is calculated using the paired 
routine and the PEP monitor data described in section 3.2.6 of this 
appendix. Calculate the percent difference, di, using equation 1 of 
this appendix, where meas is the measured concentration from 
agency's primary monitor and audit is the concentration from the PEP 
monitor. The data pair would only be considered valid if both 
concentrations are greater than the minimum values specified in 
section 4(c) of this appendix. Estimates of bias are presented for 
various levels of aggregation, sometimes aggregating over time, 
sometimes aggregating over samplers, and sometimes aggregating over 
both time and samplers. These various levels of aggregation are 
achieved using the same basic statistic.
    4.3.2.1 This statistic averages the individual biases described 
in equation 1 of this appendix to the desired level of aggregation 
using equation 12 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.050

    where, nj is the number of pairs and d<INF>1</INF>, 
d<INF>2</INF>, d<INF>nj</INF> are the biases for each of the pairs 
to be averaged.
    4.3.2.2 Confidence intervals can be constructed for these 
average bias estimates in equation 12 of this appendix using 
equations 13 and 14 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.051

[GRAPHIC] [TIFF OMITTED] TR17OC06.052

    Where, t<INF>0.95,df</INF> is the 95th quantile of a t-
distribution with degrees of freedom df = n<INF>j</INF> - 1 and s is 
an estimate of the variability of the average bias calculated using 
equation 15 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.053

    4.4 Statistics for the Assessment of Pb.
    4.4.1 Precision Estimate. Follow the same procedures as 
described for PM<INF>10</INF> in section 4.2.1 of this appendix 
using the data from the collocated instruments. The data pair would 
only be considered valid if both concentrations are greater than the 
minimum values specified in section 4(c) of this appendix.
    4.4.2 Bias Estimate. In order to estimate bias, the information 
from the flow rate audits and the Pb strip audits needs to be 
combined as described below. To be consistent with the formulas for 
the gases, the recommended procedures are to work with relative 
errors of the lead measurements. The relative error in the 
concentration is related to the relative error in the volume and the 
relative error in the mass measurements using equation 16 of this 
appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.054

    As with the gases, an upper bound for the absolute bias is 
desired. Using equation 16 above, the absolute value of the relative 
(concentration) error is bounded by equation 17 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.055


[[Page 61311]]


    The quality indicator data collected are then used to bound each 
part of equation 17 separately.
    4.4.2.1 Flow rate calculations. For each flow rate audit, 
calculate the percent difference in volume by equation 1 of this 
appendix where meas is the value indicated by the sampler's volume 
measurement and audit is the actual volume indicated by the auditing 
flow meter. The absolute volume bias upper bound is then calculated 
using equation 3 of this appendix where n is the number of flow rate 
audits being aggregated; t<INF>0.95,n-1</INF> is the 95th quantile 
of a t-distribution with n-1 degrees of freedom; the quantity AB is 
the mean of the absolute values of the di's and is calculated using 
equation 4, and the quantity AS in equation 3 of this appendix is 
the standard deviation of the absolute values of the di's and is 
calculated using equation 5 of this appendix.
    4.4.2.2 Lead strip calculations. Similarly for each lead strip 
audit, calculate the percent difference in mass by equation 1 where 
meas is the value indicated by the mass measurement and audit is the 
actual lead mass on the audit strip. The absolute mass bias upper 
bound is then calculated using equation 3 of this appendix where n 
is the number of lead strip audits being aggregated; 
t<INF>0.95,n-1</INF> is the 95th quantile of a t-distribution with 
n-1 degrees of freedom; the quantity AB is the mean of the absolute 
values of the di's and is calculated using equation 4 of this 
appendix and the quantity AS in equation 3 of this appendix is the 
standard deviation of the absolute values of the di's and is 
calculated using equation 5 of this appendix.
    4.4.2.3 Final bias calculation. Finally, the absolute bias upper 
bound is given by combining the absolute bias estimates of the flow 
rate and Pb strips using equation 18 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.056

where, the numerator and denominator have been multiplied by 100 
since everything is expressed as a percentage.
    4.5 Time Period for Audits. The statistics in this section 
assume that the mass and flow rate audits represent the same time 
period. Since the two types of audits are not performed at the same 
time, the audits need to be grouped by common time periods. 
Consequently, the absolute bias estimates should be done on annual 
and 3-year levels. The flow rate audits are site-specific, so the 
absolute bias upper bound estimate can be done and treated as a 
site-level statistic.

5. Reporting Requirements

    5.1 SLAMS Reporting Requirements. For each pollutant, prepare a 
list of all monitoring sites and their AQS site identification codes 
in each primary quality assurance organization and submit the list 
to the appropriate EPA Regional Office, with a copy to AQS. Whenever 
there is a change in this list of monitoring sites in a primary 
quality assurance organization, report this change to the EPA 
Regional Office and to AQS.
    5.1.1 Quarterly Reports. For each quarter, each primary quality 
assurance organization shall report to AQS directly (or via the 
appropriate EPA Regional Office for organizations not direct users 
of AQS) the results of all valid measurement quality checks it has 
carried out during the quarter. The quarterly reports must be 
submitted consistent with the data reporting requirements specified 
for air quality data as set forth in Sec.  58.16. The EPA strongly 
encourages early submission of the quality assurance data in order 
to assist the monitoring organizations control and evaluate the 
quality of the ambient air data.
    5.1.2 Annual Reports.
    5.1.2.1 When the monitoring organization has certified relevant 
data for the calendar year, EPA will calculate and report the 
measurement uncertainty for the entire calendar year.
    5.2 PSD Reporting Requirements. At the end of each sampling 
quarter, the organization must report the appropriate statistical 
assessments in section 4 of this appendix for the pollutants 
measured. All data used to calculate reported estimates of precision 
and bias including span checks, collocated sampler and audit results 
must be made available to the permit granting authority upon 
request.

6.0 References

    (1) American National Standard--Specifications and Guidelines 
for Quality Systems for Environmental Data Collection and 
Environmental Technology Programs. ANSI/ASQC E4-2004. February 2004. 
Available from American Society for Quality Control, 611 East 
Wisconsin Avenue, Milwaukee, WI 53202.
    (2) EPA Requirements for Quality Management Plans. EPA QA/R-2. 
EPA/240/B-01/002. March 2001. Office of Environmental Information, 
Washington DC 20460. http://www.epa.gov/quality/qs-docs/r2-final.pdf.
    (3) EPA Requirements for Quality Assurance Project Plans for 
Environmental Data Operations. EPA QA/R-5. EPA/240/B-01/003. March 
2001. Office of Environmental Information, Washington DC 20460. 
http://www.epa.gov/quality/qs-docs/r5-final.pdf.
    (4) EPA Traceability Protocol for Assay and Certification of 
Gaseous Calibration Standards. EPA-600/R-97/121. September 1997. 
Available from U.S. Environmental Protection Agency, ORD 
Publications Office, Center for Environmental Research Information 
(CERI), 26 W. Martin Luther King Drive, Cincinnati, OH 45268.
    (5) Guidance for the Data Quality Objectives Process. EPA QA/G-
4. EPA/240/B-06/001. February, 2006. Office of Environmental 
Information, Washington DC 20460. http://www.epa.gov/quality/qs-docs/g4-final.pdf.
    (6) List of Designated Reference and Equivalent Methods. 
Available from U.S. Environmental Protection Agency, National 
Exposure Research Laboratory, Human Exposure and Atmospheric 
Sciences Division, MD-D205-03, Research Triangle Park, NC 27711. 
http://www.epa.gov/ttn/amtic/criteria.html.
    (7) McElroy, F.F. Transfer Standards for the Calibration of 
Ambient Air Monitoring Analyzers for Ozone. EPA-600/4-79-056. U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711, 
September, 1979. http://www.epa.gov/ttn/amtic/cpreldoc.html.
    (8) Paur, R.J. and F.F. McElroy. Technical Assistance Document 
for the Calibration of Ambient Ozone Monitors. EPA-600/4-79-057. 
U.S. Environmental Protection Agency, Research Triangle Park, NC 
27711, September, 1979. http://www.epa.gov/ttn/amtic/cpreldoc.html.
    (9) Quality Assurance Handbook for Air Pollution Measurement 
Systems, Volume 1--A Field Guide to Environmental Quality Assurance. 
EPA-600/R-94/038a. April 1994. Available from U.S. Environmental 
Protection Agency, ORD Publications Office, Center for Environmental 
Research Information (CERI), 26 W. Martin Luther King Drive, 
Cincinnati, OH 45268. http://www.epa.gov/ ttn/amtic/qabook.html.
    (10) Quality Assurance Handbook for Air Pollution Measurement 
Systems, Volume II: Part 1--Ambient Air Quality Monitoring Program 
Quality System Development. EPA-454/R-98-004. http://www.epa.gov/ttn/amtic/qabook.html.

[[Page 61312]]



 Table A-1 of Appendix A to Part 58. Difference and Similarities Between
                       SLAMS and PSD Requirements
------------------------------------------------------------------------
              Topic                      SLAMS                PSD
------------------------------------------------------------------------
Requirements....................  1. The
                                   development,
                                   documentation,
                                   and
                                   implementation of
                                   an approved
                                   quality system.
                                  2. The assessment
                                   of data quality.
                                  3. The use of
                                   reference,
                                   equivalent, or
                                   approved methods.
                                  4. The use of
                                   calibration
                                   standards
                                   traceable to NIST
                                   or other primary
                                   standard.
                                  5. The
                                   participation in
                                   EPA performance
                                   evaluations and
                                   the permission
                                   for EPA to
                                   conduct system
                                   audits.
Monitoring and QA Responsibility  State/local agency  Source owner/
                                   via the ``primary   operator.
                                   quality assurance
                                   organization''.
Monitoring Duration.............  Indefinitely......  Usually up to 12
                                                       months.
Annual Performance Evaluation     Standards and       Personnel,
 (PE).                             equipment           standards and
                                   different from      equipment
                                   those used for      different from
                                   spanning,           those used for
                                   calibration, and    spanning,
                                   verifications.      calibration, and
                                   Prefer different    verifications.
                                   personnel.
PE audit rate:
    --Automated.................  100% per year.....  100% per quarter.
    --Manual....................  Varies depending    100% per quarter.
                                   on pollutant. See
                                   Table A-2 of this
                                   appendix.
Precision Assessment:
    --Automated.................  One-point QC check  One point QC check
                                   biweekly but data   biweekly.
                                   quality dependent.
    --Manual....................  Varies depending    One site: 1 every
                                   on pollutant. See   6 days or every
                                   Table A-2 of this   third day for
                                   appendix.           daily monitoring
                                                       (TSP and Pb).
Reporting
    --Automated.................  By site--EPA        By site--source
                                   performs            owner/operator
                                   calculations        performs
                                   annually.           calculations each
                                                       sampling quarter.
    --Manual....................  By reporting        By site--source
                                   organization--EPA   owner/operator
                                   performs            performs
                                   calculations        calculations each
                                   annually.           sampling quarter.
------------------------------------------------------------------------


            Table A-2 of Appendix A to Part 58. Minimum Data Assessment Requirements for SLAMS Sites
----------------------------------------------------------------------------------------------------------------
                                                                                                  Parameters
             Method                Assessment method       Coverage        Minimum frequency       reported
----------------------------------------------------------------------------------------------------------------
                                                Automated Methods
----------------------------------------------------------------------------------------------------------------
1-Point QC for SO2, NO2, O3, CO.  Response check at   Each analyzer.....  Once per 2 weeks..  Audit
                                   concentration                                               concentration \1\
                                   0.01-0.1 ppm SO2,                                           and measured
                                   NO2, O3, and 1-10                                           concentration
                                   ppm CO.                                                     \2\.
Annual performance evaluation     See section 3.2.2   Each analyzer.....  Once per year.....  Audit
 for SO2, NO2, O3, CO.             of this appendix.                                           concentration \1\
                                                                                               and measured
                                                                                               concentration \2\
                                                                                               for each level.
Flow rate verification PM10,      Check of sampler    Each sampler......  Once every month..  Audit flow rate
 PM2.5, PM10	2.5.                  flow rate.                                                  and measured flow
                                                                                               rate indicated by
                                                                                               the sampler.
Semi-annual flow rate audit       Check of sampler    Each sampler......  Once every 6......  Audit flow rate
 PM10, PM2.5, PM10	2.5.            flow rate using                                             and measured flow
                                   independent                                                 rate indicated by
                                   standard.                                                   the sampler.
Collocated sampling PM2.5,        Collocated          15%...............  Every 12 days.....  Primary sampler
 PM10	2.5.                         samplers.                                                   concentration and
                                                                                               duplicate sampler
                                                                                               concentration.
Performance evaluation program    Collocated          1. 5 valid audits   Over all 4          Primary sampler
 PM2.5, PM10	2.5.                  samplers.           for primary QA      quarters.           concentration and
                                                       orgs, with <= 5                         performance
                                                       sites.                                  evaluation
                                                      2. 8 valid audits                        sampler
                                                       for primary QA                          concentration.
                                                       orgs, with > 5
                                                       sites.
                                                      3. All samplers in
                                                       6 years.
----------------------------------------------------------------------------------------------------------------
                                                 Manual Methods
----------------------------------------------------------------------------------------------------------------
Collocated sampling PM10, TSP,    Collocated          15%...............  Every 12 days PSD-- Primary sampler
 PM10	2.5, PM2.5.                  samplers.                               every 6 days.       concentration and
                                                                                               duplicate sampler
                                                                                               concentration.
Flow rate verification PM10 (low  Check of sampler    Each sampler......  Once every month..  Audit flow rate
 Vol), PM10	2.5, PM2.5.            flow rate.                                                  and measured flow
                                                                                               rate indicated by
                                                                                               the sampler.

[[Page 61313]]

 
Flow rate verification PM10       Check of sampler    Each sampler......  Once every quarter  Audit flow rate
 (High-Vol), TSP.                  flow rate.                                                  and measured flow
                                                                                               rate indicated by
                                                                                               the sampler.
Semi-annual flow rate audit       Check of sampler    Each sampler, all   Once every 6        Audit flow rate
 PM10, TSP, PM10	2.5, PM2.5.       flow rate using     locations.          months.             and measured flow
                                   independent                                                 rate indicated by
                                   standard.                                                   the sampler.
Manual Methods Lead.............  1. Check of sample  1. Each sampler...  1. Include with     1. Same as for
                                   flow rate as for   2. Analytical.....   TSP.                TSP.
                                   TSP.                                   2. Each quarter...  2. Actual
                                  2. Check of                                                  concentration.
                                   analytical system
                                   with Pb audit
                                   strips.
Performance evaluation program    Collocated          1. 5 valid audits   Over all 4          Primary sampler
 PM2.5, PM10	2.5.                  samplers.           for primary QA      quarters.           concentration and
                                                       orgs, with <= 5                         performance
                                                       sites.                                  evaluation
                                                      2. 8 valid audits                        sampler
                                                       for primary QA                          concentration.
                                                       orgs, with >= 5
                                                       sites.
                                                      3. All samplers in
                                                       6 years.
----------------------------------------------------------------------------------------------------------------
\1\ Effective concentration for open path analyzers.
\2\ Corrected concentration, if applicable, for open path analyzers.


      Table A-3 of Appendix A to Part 58.--Summary of PM2.5 Number and Type of Collocation (15% Collocation
 Requirement) Needed as an Example of a Primary Quality Assurance Organization That Has 54 Monitors and Procured
                                  FRMs and Three Other Equivalent Method Types
----------------------------------------------------------------------------------------------------------------
                                                                                                      No. of
                                                                                                    collocated
                                                   Total no. of      Total no.        No. of        monitors of
       Primary sampler method designation            monitors       collocated    collocated FRM    same method
                                                                                                  designation as
                                                                                                      primary
----------------------------------------------------------------------------------------------------------------
FRM.............................................              20               3               3             n/a
FEM (A).........................................              20               3               2               1
FEM (C).........................................               2               1               1               0
FEM (D).........................................              12               2               1               1
----------------------------------------------------------------------------------------------------------------

Appendix B--[Removed and Reserved]

34. Appendix B to part 58 is removed and reserved
35. Appendix C to part 58 is revised to read as follows:

Appendix C to Part 58--Ambient Air Quality Monitoring Methodology

1.0 Purpose
2.0 SLAMS Ambient Air Monitoring Stations
3.0 NCore Ambient Air Monitoring Stations
4.0 Photochemical Assessment Monitoring Stations (PAMS)
5.0 Particulate Matter Episode Monitoring
6.0 References

1.0 Purpose

    This appendix specifies the criteria pollutant monitoring 
methods (manual methods or automated analyzers) which must be used 
in SLAMS and NCore stations that are a subset of SLAMS.

2.0 SLAMS Ambient Air Monitoring Network

    2.1 Except as otherwise provided in this appendix, a criteria 
pollutant monitoring method used for making NAAQS decisions at a 
SLAMS site must be a reference or equivalent method as defined in 
Sec.  50.1 of this chapter.
    2.2 Reserved
    2.3 Any manual method or analyzer purchased prior to 
cancellation of its reference or equivalent method designation under 
Sec.  53.11 or Sec.  53.16 of this chapter may be used at a SLAMS 
site following cancellation for a reasonable period of time to be 
determined by the Administrator.
    2.4 Approval of Non-designated Continuous PM<INF>2.5</INF> 
Methods as Approved Regional Methods (ARMs) Operated Within a 
Network of Sites. A method for PM<INF>2.5</INF> that has not been 
designated as an FRM or FEM as defined in Sec.  50.1 of this chapter 
may be approved as an ARM for purposes of section 2.1 of this 
appendix at a particular site or network of sites under the 
following stipulations.
    2.4.1 The candidate ARM must be demonstrated to meet the 
requirements for PM<INF>2.5</INF> Class III equivalent methods as 
defined in subpart C of part 53 of this chapter. Specifically the 
requirements for precision, correlation, and additive and 
multiplicative bias apply. For purposes of this section 2.4, the 
following requirements shall apply:
    2.4.1.1 The candidate ARM shall be tested at the site(s) in 
which it is intended to be used. For a network of sites operated by 
one reporting agency or primary quality assurance organization, the 
testing shall occur at a subset of sites to include one site in each 
MSA/CSA, up to the first 2 highest population MSA/CSA and at least 
one rural area or Micropolitan Statistical Area site. If the 
candidate ARM for a network is already approved for purposes of this 
section in another agency's network, subsequent testing shall 
minimally occur at one site in a MSA/CSA and one rural area or 
Micropolitan Statistical Area. There shall be no requirement for 
tests at any other sites.
    2.4.1.2 For purposes of this section, a full year of testing may 
begin and end in any season, so long as all seasons are covered.
    2.4.1.3 No PM<INF>10</INF> samplers shall be required for the 
test, as determination of the PM<INF>2.5</INF>/PM<INF>10</INF> ratio 
at the test site shall not be required.
    2.4.1.4 The test specification for PM<INF>2.5</INF> Class III 
equivalent method precision defined in subpart C of part 53 of this 
chapter applies; however, there is no specific requirement that 
collocated continuous monitors be operated for purposes of 
generating a statistic for coefficient of variation (CV). To provide 
an estimate of precision that meets the requirement identified in 
subpart C of part 53 of this chapter, agencies may cite peer-
reviewed published data or data in AQS that can be presented 
demonstrating the candidate ARM operated will produce data that 
meets the specification for precision of Class III PM<INF>2.5</INF> 
methods.
    2.4.1.5 A minimum of 90 valid sample pairs per site for the year 
with no less than 20 valid sample pairs per season must be generated 
for use in demonstrating that additive bias, multiplicative bias and 
correlation meet the comparability requirements specified in subpart 
C of part 53 of this chapter. A valid sample pair may be generated 
with as little as one valid FRM and one valid candidate ARM 
measurement per day.

[[Page 61314]]

    2.4.1.6 For purposes of determining bias, FRM data with 
concentrations less than 3 micrograms per cubic meter ([mu]g/m\3\) 
may be excluded. Exclusion of data does not result in failure of 
sample completeness specified in this section.
    2.4.1.7 Data transformations are allowed to be used to 
demonstrate meeting the comparability requirements specified in 
subpart C of part 53 of this chapter. Data transformation may be 
linear or non-linear, but must be applied in the same way to all 
sites used in the testing.
    2.4.2 The monitoring agency wishing to use an ARM must develop 
and implement appropriate quality assurance procedures for the 
method. Additionally, the following procedures are required for the 
method:
    2.4.2.1 The ARM must be consistently operated throughout the 
network. Exceptions to a consistent operation must be approved 
according to section 2.8 of this appendix;
    2.4.2.2 The ARM must be operated on an hourly sampling frequency 
capable of providing data suitable for aggregation into daily 24-
hour average measurements;
    2.4.2.3 The ARM must use an inlet and separation device, as 
needed, that are already approved in either the reference method 
identified in appendix L to part 50 of this chapter or under part 53 
of this chapter as approved for use on a PM<INF>2.5</INF> reference 
or equivalent method. The only exceptions to this requirement are 
those methods that by their inherent measurement principle may not 
need an inlet or separation device that segregates the aerosol; and
    2.4.2.4 The ARM must be capable of providing for flow audits, 
unless by its inherent measurement principle, measured flow is not 
required. These flow audits are to be performed on the frequency 
identified in appendix A to this part.
    2.4.2.5 If data transformations are used, they must be described 
in the monitoring agencies Quality Assurance Project plan (or 
addendum to QAPP). The QAPP shall describe how often (e.g., 
quarterly, yearly) and under what provisions the data transformation 
will be updated. For example, not meeting the data quality 
objectives for a site over a season or year may be cause for 
recalculating a data transformation, but by itself would not be 
cause for invalidating the data. Data transformations must be 
applied prospectively, i.e., in real-time or near real-time, to the 
data output from the PM<INF>2.5</INF> continuous method. See 
reference 7 of this appendix.
    2.4.3 The monitoring agency wishing to use the method must 
develop and implement appropriate procedures for assessing and 
reporting the precision and accuracy of the method comparable to the 
procedures set forth in appendix A of this part for designated 
reference and equivalent methods.
    2.4.4 Assessments of data quality shall follow the same 
frequencies and calculations as required under section 3 of appendix 
A to this part with the following exceptions:
    2.4.4.1 Collocation of ARM with FRM/FEM samplers must be 
maintained at a minimum of 30 percent of the required SLAMS sites 
with a minimum of 1 per network;
    2.4.4.2 All collocated FRM/FEM samplers must maintain a sample 
frequency of at least 1 in 6 sample days;
    2.4.4.3 Collocated FRM/FEM samplers shall be located at the 
design value site, with the required FRM/FEM samplers deployed among 
the largest MSA/CSA in the network, until all required FRM/FEM are 
deployed; and
    2.4.4.4 Data from collocated FRM/FEM are to be substituted for 
any calendar quarter that an ARM method has incomplete data.
    2.4.4.5 Collocation with an ARM under this part for purposes of 
determining the coefficient of variation of the method shall be 
conducted at a minimum of 7.5 percent of the sites with a minimum of 
1 per network. This is consistent with the requirements in appendix 
A to this part for one-half of the required collocation of FRM/FEM 
(15 percent) to be collocated with the same method.
    2.4.4.6 Assessments of bias with an independent audit of the 
total measurement system shall be conducted with the same frequency 
as an FEM as identified in appendix A to this part.
    2.4.5 Request for approval of a candidate ARM, that is not 
already approved in another agency's network under this section, 
must meet the general submittal requirements of section 2.7 of this 
appendix. Requests for approval under this section when an ARM is 
already approved in another agency's network are to be submitted to 
the EPA Regional Administrator. Requests for approval under section 
2.4 of this appendix must include the following requirements:
    2.4.5.1 A clear and unique description of the site(s) at which 
the candidate ARM will be used and tested, and a description of the 
nature or character of the site and the particulate matter that is 
expected to occur there.
    2.4.5.2 A detailed description of the method and the nature of 
the sampler or analyzer upon which it is based.
    2.4.5.3 A brief statement of the reason or rationale for 
requesting the approval.
    2.4.5.4 A detailed description of the quality assurance 
procedures that have been developed and that will be implemented for 
the method.
    2.4.5.5 A detailed description of the procedures for assessing 
the precision and accuracy of the method that will be implemented 
for reporting to AQS.
    2.4.5.6 Test results from the comparability tests as required in 
section 2.4.1 through 2.4.1.4 of this appendix.
    2.4.5.7 Such further supplemental information as may be 
necessary or helpful to support the required statements and test 
results.
    2.4.6 Within 120 days after receiving a request for approval of 
the use of an ARM at a particular site or network of sites under 
section 2.4 of this appendix, the Administrator will approve or 
disapprove the method by letter to the person or agency requesting 
such approval. When appropriate for methods that are already 
approved in another SLAMS network, the EPA Regional Administrator 
has approval/disapproval authority. In either instance, additional 
information may be requested to assist with the decision.
    2.5 [Reserved]
    2.6 Use of Methods With Higher, Nonconforming Ranges in Certain 
Geographical Areas.
    2.6.1 [Reserved]
    2.6.2 An analyzer may be used (indefinitely) on a range which 
extends to concentrations higher than two times the upper limit 
specified in table B-1 of part 53 of this chapter if:
    2.6.2.1 The analyzer has more than one selectable range and has 
been designated as a reference or equivalent method on at least one 
of its ranges, or has been approved for use under section 2.5 (which 
applies to analyzers purchased before February 18, 1975);
    2.6.2.2 The pollutant intended to be measured with the analyzer 
is likely to occur in concentrations more than two times the upper 
range limit specified in table B-1 of part 53 of this chapter in the 
geographical area in which use of the analyzer is proposed; and
    2.6.2.3 The Administrator determines that the resolution of the 
range or ranges for which approval is sought is adequate for its 
intended use. For purposes of this section (2.6), ``resolution'' 
means the ability of the analyzer to detect small changes in 
concentration.
    2.6.3 Requests for approval under section 2.6.2 of this appendix 
must meet the submittal requirements of section 2.7. Except as 
provided in section 2.7.3 of this appendix, each request must 
contain the information specified in section 2.7.2 in addition to 
the following:
    2.6.3.1 The range or ranges proposed to be used;
    2.6.3.2 Test data, records, calculations, and test results as 
specified in section 2.7.2.2 of this appendix for each range 
proposed to be used;
    2.6.3.3 An identification and description of the geographical 
area in which use of the analyzer is proposed;
    2.6.3.4 Data or other information demonstrating that the 
pollutant intended to be measured with the analyzer is likely to 
occur in concentrations more than two times the upper range limit 
specified in table B-1 of part 53 of this chapter in the 
geographical area in which use of the analyzer is proposed; and
    2.6.3.5 Test data or other information demonstrating the 
resolution of each proposed range that is broader than that 
permitted by section 2.5 of this appendix.
    2.6.4 Any person who has obtained approval of a request under 
this section (2.6.2) shall assure that the analyzer for which 
approval was obtained is used only in the geographical area 
identified in the request and only while operated in the range or 
ranges specified in the request.
    2.7 Requests for Approval; Withdrawal of Approval.
    2.7.1 Requests for approval under sections 2.4, 2.6.2, or 2.8 of 
this appendix must be submitted to: Director, National Exposure 
Research Laboratory (MD-D205-03), U.S. Environmental Protection 
Agency, Research Triangle Park, North Carolina 27711. For ARM that 
are already approved in another agency's network, subsequent

[[Page 61315]]

requests for approval under section 2.4 are to be submitted to the 
applicable EPA Regional Administrator.
    2.7.2 Except as provided in section 2.7.3 of this appendix, each 
request must contain:
    2.7.2.1 A statement identifying the analyzer (e.g., by serial 
number) and the method of which the analyzer is representative 
(e.g., by manufacturer and model number); and
    2.7.2.2 Test data, records, calculations, and test results for 
the analyzer (or the method of which the analyzer is representative) 
as specified in subpart B, subpart C, or both (as applicable) of 
part 53 of this chapter.
    2.7.3 A request may concern more than one analyzer or 
geographical area and may incorporate by reference any data or other 
information known to EPA from one or more of the following:
    2.7.3.1 An application for a reference or equivalent method 
determination submitted to EPA for the method of which the analyzer 
is representative, or testing conducted by the applicant or by EPA 
in connection with such an application;
    2.7.3.2 Testing of the method of which the analyzer is 
representative at the initiative of the Administrator under Sec.  
53.7 of this chapter; or
    2.7.3.3 A previous or concurrent request for approval submitted 
to EPA under this section (2.7).
    2.7.4 To the extent that such incorporation by reference 
provides data or information required by this section (2.7) or by 
sections 2.4, 2.5, or 2.6 of this appendix, independent data or 
duplicative information need not be submitted.
    2.7.5 After receiving a request under this section (2.7), the 
Administrator may request such additional testing or information or 
conduct such tests as may be necessary in his judgment for a 
decision on the request.
    2.7.6 If the Administrator determines, on the basis of any 
available information, that any of the determinations or statements 
on which approval of a request under this section was based are 
invalid or no longer valid, or that the requirements of section 2.4, 
2.5, or 2.6, as applicable, have not been met, he/she may withdraw 
the approval after affording the person who obtained the approval an 
opportunity to submit information and arguments opposing such 
action.
    2.8 Modifications of Methods by Users.
    2.8.1 Except as otherwise provided in this section, no reference 
method, equivalent method, or ARM may be used in a SLAMS network if 
it has been modified in a manner that could significantly alter the 
performance characteristics of the method without prior approval by 
the Administrator. For purposes of this section, ``alternative 
method'' means an analyzer, the use of which has been approved under 
section 2.4, 2.5, or 2.6 of this appendix or some combination 
thereof.
    2.8.2 Requests for approval under this section (2.8) must meet 
the submittal requirements of sections 2.7.1 and 2.7.2.1 of this 
appendix.
    2.8.3 Each request submitted under this section (2.8) must 
include:
    2.8.3.1 A description, in such detail as may be appropriate, of 
the desired modification;
    2.8.3.2 A brief statement of the purpose(s) of the modification, 
including any reasons for considering it necessary or advantageous;
    2.8.3.3 A brief statement of belief concerning the extent to 
which the modification will or may affect the performance 
characteristics of the method; and
    2.8.3.4 Such further information as may be necessary to explain 
and support the statements required by sections 2.8.3.2 and 2.8.3.3.
    2.8.4 The Administrator will approve or disapprove the 
modification by letter to the person or agency requesting such 
approval within 75 days after receiving a request for approval under 
this section and any further information that the applicant may be 
asked to provide.
    2.8.5 A temporary modification that could alter the performance 
characteristics of a reference, equivalent, or ARM may be made 
without prior approval under this section if the method is not 
functioning or is malfunctioning, provided that parts necessary for 
repair in accordance with the applicable operation manual cannot be 
obtained within 45 days. Unless such temporary modification is later 
approved under section 2.8.4 of this appendix, the temporarily 
modified method shall be repaired in accordance with the applicable 
operation manual as quickly as practicable but in no event later 
than 4 months after the temporary modification was made, unless an 
extension of time is granted by the Administrator. Unless and until 
the temporary modification is approved, air quality data obtained 
with the method as temporarily modified must be clearly identified 
as such when submitted in accordance with Sec.  58.16 and must be 
accompanied by a report containing the information specified in 
section 2.8.3 of this appendix. A request that the Administrator 
approve a temporary modification may be submitted in accordance with 
sections 2.8.1 through 2.8.4 of this appendix. In such cases the 
request will be considered as if a request for prior approval had 
been made.
    2.9 Use of IMPROVE Samplers at a SLAMS Site. ``IMPROVE'' 
samplers may be used in SLAMS for monitoring of regional background 
and regional transport concentrations of fine particulate matter. 
The IMPROVE samplers were developed for use in the Interagency 
Monitoring of Protected Visual Environments (IMPROVE) network to 
characterize all of the major components and many trace constituents 
of the particulate matter that impair visibility in Federal Class I 
Areas. Descriptions of the IMPROVE samplers and the data they 
collect are available in references 4, 5, and 6 of this appendix.

3.0 NCore Ambient Air Monitoring Stations

    3.1 Methods employed in NCore multipollutant sites used to 
measure SO<INF>2</INF>, CO, NO<INF>2</INF>, O<INF>3</INF>, 
PM<INF>2.5</INF>, or PM<INF>10-2.5</INF> must be reference or 
equivalent methods as defined in Sec.  50.1 of this chapter, or an 
ARM as defined in section 2.4 of this appendix, for any monitors 
intended for comparison with applicable NAAQS.
    3.2 If alternative SO<INF>2</INF>, CO, NO<INF>2</INF>, 
O<INF>3</INF>, PM<INF>2.5</INF>, or PM<INF>10-2.5</INF> monitoring 
methodologies are proposed for monitors not intended for NAAQS 
comparison, such techniques must be detailed in the network 
description required by Sec.  58.10 and subsequently approved by the 
Administrator. Examples of locations that are not intended to be 
compared to the NAAQS may be rural background and transport sites or 
areas where the concentration of the pollutant is so low that it 
would be more useful to operate a higher sensitivity method that is 
not an FRM or FEM.

4.0 Photochemical Assessment Monitoring Stations (PAMS)

    4.1 Methods used for O<INF>3</INF> monitoring at PAMS must be 
automated reference or equivalent methods as defined in Sec.  50.1 
of this chapter.
    4.2 Methods used for NO, NO<INF>2</INF> and NO<INF>X</INF> 
monitoring at PAMS should be automated reference or equivalent 
methods as defined for NO<INF>2</INF> in Sec.  50.1 of this chapter. 
If alternative NO, NO<INF>2</INF> or NO<INF>X</INF> monitoring 
methodologies are proposed, such techniques must be detailed in the 
network description required by Sec.  58.10 and subsequently 
approved by the Administrator.
    4.3 Methods for meteorological measurements and speciated VOC 
monitoring are included in the guidance provided in references 2 and 
3 of this appendix. If alternative VOC monitoring methodology 
(including the use of new or innovative technologies), which is not 
included in the guidance, is proposed, it must be detailed in the 
network description required by Sec.  58.10 and subsequently 
approved by the Administrator.

5.0 Particulate Matter Episode Monitoring

    5.1 For short-term measurements of PM<INF>10</INF> during air 
pollution episodes (see Sec.  51.152 of this chapter) the 
measurement method must be:
    5.1.1 Either the ``Staggered PM<INF>10</INF>'' method or the 
``PM<INF>10</INF> Sampling Over Short Sampling Times'' method, both 
of which are based on the reference method for PM<INF>10</INF> and 
are described in reference 1: or
    5.1.2 Any other method for measuring PM<INF>10</INF>:
    5.1.2.1 Which has a measurement range or ranges appropriate to 
accurately measure air pollution episode concentration of 
PM<INF>10</INF>,
    5.1.2.2 Which has a sample period appropriate for short-term 
PM<INF>10</INF> measurements, and
    5.1.2.3 For which a quantitative relationship to a reference or 
equivalent method for PM<INF>10</INF> has been established at the 
use site. Procedures for establishing a quantitative site-specific 
relationship are contained in reference 1.
    5.2 PM<INF>10</INF> methods other than the reference method are 
not covered under the quality assessment requirements of appendix to 
this part. Therefore, States must develop and implement their own 
quality assessment procedures for those methods allowed under this 
section 4. These quality assessment procedures should be similar or 
analogous to

[[Page 61316]]

those described in section 3 of appendix A to this part for the 
PM<INF>10</INF> reference method.

6.0 References

    1. Pelton, D. J. Guideline for Particulate Episode Monitoring 
Methods, GEOMET Technologies, Inc., Rockville, MD. Prepared for U.S. 
Environmental Protection Agency, Research Triangle Park, NC. EPA 
Contract No. 68-02-3584. EPA 450/4-83-005. February 1983.
    2. Technical Assistance Document For Sampling and Analysis of 
Ozone Precursors. Atmospheric Research and Exposure Assessment 
Laboratory, U.S. Environmental Protection Agency, Research Triangle 
Park, NC 27711. EPA 600/8-91-215. October 1991.
    3. Quality Assurance Handbook for Air Pollution Measurement 
Systems: Volume IV. Meteorological Measurements. Atmospheric 
Research and Exposure Assessment Laboratory, U.S. Environmental 
Protection Agency, Research Triangle Park, NC 27711. EPA 600/4-90-
0003. August 1989.
    4. Eldred, R.A., Cahill, T.A., Wilkenson, L.K., et al., 
Measurements of fine particles and their chemical components in the 
IMPROVE/NPS networks, in Transactions of the International Specialty 
Conference on Visibility and Fine Particles, Air and Waste 
Management Association: Pittsburgh, PA, 1990; pp. 187-196.
    5. Sisler, J.F., Huffman, D., and Latimer, D.A.; Spatial and 
temporal patterns and the chemical composition of the haze in the 
United States: An analysis of data from the IMPROVE network, 1988-
1991, ISSN No. 0737-5253-26, National Park Service, Ft. Collins, CO, 
1993.
    6. Eldred, R.A., Cahill, T.A., Pitchford, M., and Malm, W.C.; 
IMPROVE--a new remote area particulate monitoring system for 
visibility studies, Proceedings of the 81st Annual Meeting of the 
Air Pollution Control Association, Dallas, Paper 88-54.3, 1988.
    7. Data Quality Objectives (DQOs) for Relating Federal Reference 
Method (FRM) and Continuous PM<INF>2.5</INF> Measurements to Report 
an Air Quality Index (AQI). Office of Air Quality Planning and 
Standards, U.S. Environmental Protection Agency, Research Triangle 
Park, NC 27711. EPA 454/B-02-2002. November 2002.

36. Appendix D to part 58 is revised to read as follows:

Appendix D to Part 58--Network Design Criteria for Ambient Air Quality 
Monitoring

1. Monitoring Objectives and Spatial Scales
2. General Monitoring Requirements
3. Design Criteria for NCore Sites
4. Pollutant-Specific Design Criteria for SLAMS Sites
5. Design Criteria for Photochemical Assessment Monitoring Stations 
(PAMS)
6. References

1. Monitoring Objectives and Spatial Scales

    The purpose of this appendix is to describe monitoring 
objectives and general criteria to be applied in establishing the 
required SLAMS ambient air quality monitoring stations and for 
choosing general locations for additional monitoring sites. This 
appendix also describes specific requirements for the number and 
location of FRM, FEM, and ARM sites for specific pollutants, NCore 
multipollutant sites, PM<INF>10</INF> mass sites, PM<INF>2.5</INF> 
mass sites, chemically-speciated PM<INF>2.5</INF> sites, and 
O<INF>3</INF> precursor measurements sites (PAMS). These criteria 
will be used by EPA in evaluating the adequacy of the air pollutant 
monitoring networks.
    1.1 Monitoring Objectives. The ambient air monitoring networks 
must be designed to meet three basic monitoring objectives. These 
basic objectives are listed below. The appearance of any one 
objective in the order of this list is not based upon a prioritized 
scheme. Each objective is important and must be considered 
individually.
    (a) Provide air pollution data to the general public in a timely 
manner. Data can be presented to the public in a number of 
attractive ways including through air quality maps, newspapers, 
Internet sites, and as part of weather forecasts and public 
advisories.
    (b) Support compliance with ambient air quality standards and 
emissions strategy development. Data from FRM, FEM, and ARM monitors 
for NAAQS pollutants will be used for comparing an area's air 
pollution levels against the NAAQS. Data from monitors of various 
types can be used in the development of attainment and maintenance 
plans. SLAMS, and especially NCore station data, will be used to 
evaluate the regional air quality models used in developing emission 
strategies, and to track trends in air pollution abatement control 
measures' impact on improving air quality. In monitoring locations 
near major air pollution sources, source-oriented monitoring data 
can provide insight into how well industrial sources are controlling 
their pollutant emissions.
    (c) Support for air pollution research studies. Air pollution 
data from the NCore network can be used to supplement data collected 
by researchers working on health effects assessments and atmospheric 
processes, or for monitoring methods development work.
    1.1.1 In order to support the air quality management work 
indicated in the three basic air monitoring objectives, a network 
must be designed with a variety of types of monitoring sites. 
Monitoring sites must be capable of informing managers about many 
things including the peak air pollution levels, typical levels in 
populated areas, air pollution transported into and outside of a 
city or region, and air pollution levels near specific sources. To 
summarize some of these sites, here is a listing of six general site 
types:
    (a) Sites located to determine the highest concentrations 
expected to occur in the area covered by the network.
    (b) Sites located to measure typical concentrations in areas of 
high population density.
    (c) Sites located to determine the impact of significant sources 
or source categories on air quality.
    (d) Sites located to determine general background concentration 
levels.
    (e) Sites located to determine the extent of regional pollutant 
transport among populated areas; and in support of secondary 
standards.
    (f) Sites located to measure air pollution impacts on 
visibility, vegetation damage, or other welfare-based impacts.
    1.1.2 This appendix contains criteria for the basic air 
monitoring requirements. The total number of monitoring sites that 
will serve the variety of data needs will be substantially higher 
than these minimum requirements provide. The optimum size of a 
particular network involves trade-offs among data needs and 
available resources. This regulation intends to provide for national 
air monitoring needs, and to lend support for the flexibility 
necessary to meet data collection needs of area air quality 
managers. The EPA, State, and local agencies will periodically 
collaborate on network design issues through the network assessment 
process outlined in Sec.  58.10.
    1.1.3 This appendix focuses on the relationship between 
monitoring objectives, site types, and the geographic location of 
monitoring sites. Included are a rationale and set of general 
criteria for identifying candidate site locations in terms of 
physical characteristics which most closely match a specific 
monitoring objective. The criteria for more specifically locating 
the monitoring site, including spacing from roadways and vertical 
and horizontal probe and path placement, are described in appendix E 
to this part.
    1.2 Spatial Scales. (a) To clarify the nature of the link 
between general monitoring objectives, site types, and the physical 
location of a particular monitor, the concept of spatial scale of 
representativeness is defined. The goal in locating monitors is to 
correctly match the spatial scale represented by the sample of 
monitored air with the spatial scale most appropriate for the 
monitoring site type, air pollutant to be measured, and the 
monitoring objective.
    (b) Thus, spatial scale of representativeness is described in 
terms of the physical dimensions of the air parcel nearest to a 
monitoring site throughout which actual pollutant concentrations are 
reasonably similar. The scales of representativeness of most 
interest for the monitoring site types described above are as 
follows:
    (1) Microscale--Defines the concentrations in air volumes 
associated with area dimensions ranging from several meters up to 
about 100 meters.
    (2) Middle scale--Defines the concentration typical of areas up 
to several city blocks in size with dimensions ranging from about 
100 meters to 0.5 kilometer.
    (3) Neighborhood scale--Defines concentrations within some 
extended area of the city that has relatively uniform land use with 
dimensions in the 0.5 to 4.0 kilometers range. The neighborhood and 
urban scales listed below have the potential to overlap in 
applications that concern secondarily formed or homogeneously 
distributed air pollutants.
    (4) Urban scale--Defines concentrations within an area of city-
like dimensions, on the order of 4 to 50 kilometers. Within a city, 
the geographic placement of sources may result in there being no 
single site that can be said to represent air quality on an urban 
scale.
    (5) Regional scale--Defines usually a rural area of reasonably 
homogeneous geography without large sources, and extends from tens 
to hundreds of kilometers.

[[Page 61317]]

    (6) National and global scales--These measurement scales 
represent concentrations characterizing the nation and the globe as 
a whole.
    (c) Proper siting of a monitor requires specification of the 
monitoring objective, the types of sites necessary to meet the 
objective, and then the desired spatial scale of representativeness. 
For example, consider the case where the objective is to determine 
NAAQS compliance by understanding the maximum ozone concentrations 
for an area. Such areas would most likely be located downwind of a 
metropolitan area, quite likely in a suburban residential area where 
children and other susceptible individuals are likely to be 
outdoors. Sites located in these areas are most likely to represent 
an urban scale of measurement. In this example, physical location 
was determined by considering ozone precursor emission patterns, 
public activity, and meteorological characteristics affecting ozone 
formation and dispersion. Thus, spatial scale of representativeness 
was not used in the selection process but was a result of site 
location.
    (d) In some cases, the physical location of a site is determined 
from joint consideration of both the basic monitoring objective and 
the type of monitoring site desired, or required by this appendix. 
For example, to determine PM<INF>2.5</INF> concentrations which are 
typical over a geographic area having relatively high 
PM<INF>2.5</INF> concentrations, a neighborhood scale site is more 
appropriate. Such a site would likely be located in a residential or 
commercial area having a high overall PM<INF>2.5</INF> emission 
density but not in the immediate vicinity of any single dominant 
source. Note that in this example, the desired scale of 
representativeness was an important factor in determining the 
physical location of the monitoring site.
    (e) In either case, classification of the monitor by its type 
and spatial scale of representativeness is necessary and will aid in 
interpretation of the monitoring data for a particular monitoring 
objective (e.g., public reporting, NAAQS compliance, or research 
support).
    (f) Table D-1 of this appendix illustrates the relationship 
between the various site types that can be used to support the three 
basic monitoring objectives, and the scales of representativeness 
that are generally most appropriate for that type of site.

 Table D-1 of Appendix D to Part 58. Relationship Between Site Types and
                      Scales of Representativeness
------------------------------------------------------------------------
                 Site type                    Appropriate siting scales
------------------------------------------------------------------------
1. Highest concentration..................  Micro, middle, neighborhood
                                             (sometimes urban or
                                             regional for secondarily
                                             formed pollutants).
2. Population oriented....................  Neighborhood, urban.
3. Source impact..........................  Micro, middle, neighborhood.
4. General/background & regional transport  Urban, regional.
5. Welfare-related impacts................  Urban, regional.
------------------------------------------------------------------------

2. General Monitoring Requirements

    (a) The National ambient air monitoring system includes several 
types of monitoring stations, each targeting a key data collection 
need and each varying in technical sophistication.
    (b) Research grade sites are platforms for scientific studies, 
either involved with health or welfare impacts, measurement methods 
development, or other atmospheric studies. These sites may be 
collaborative efforts between regulatory agencies and researchers 
with specific scientific objectives for each. Data from these sites 
might be collected with both traditional and experimental 
techniques, and data collection might involve specific laboratory 
analyses not common in routine measurement programs. The research 
grade sites are not required by regulation; however, they are 
included here due to their important role in supporting the air 
quality management program.
    (c) The NCore multipollutant sites are sites that measure 
multiple pollutants in order to provide support to integrated air 
quality management data needs. NCore sites include both neighborhood 
and urban scale measurements in general, in a selection of 
metropolitan areas and a limited number of more rural locations. 
Continuous monitoring methods are to be used at the NCore sites when 
available for a pollutant to be measured, as it is important to have 
data collected over common time periods for integrated analyses. 
NCore multipollutant sites are intended to be long-term sites useful 
for a variety of applications including air quality trends analyses, 
model evaluation, and tracking metropolitan area statistics. As 
such, the NCore sites should be placed away from direct emission 
sources that could substantially impact the ability to detect area-
wide concentrations. The Administrator must approve the NCore sites.
    (d) Monitoring sites designated as SLAMS sites, but not as NCore 
sites, are intended to address specific air quality management 
interests, and as such, are frequently single-pollutant measurement 
sites. The EPA Regional Administrator must approve the SLAMS sites.
    (e) This appendix uses the statistical-based definitions for 
metropolitan areas provided by the Office of Management and Budget 
and the Census Bureau. These areas are referred to as metropolitan 
statistical areas (MSA), micropolitan statistical areas, core-based 
statistical areas (CBSA), and combined statistical areas (CSA). A 
CBSA associated with at least one urbanized area of 50,000 
population or greater is termed a Metropolitan Statistical Area 
(MSA). A CBSA associated with at least one urbanized cluster of at 
least 10,000 population or greater is termed a Micropolitan 
Statistical Area. CSA consist of two or more adjacent CBSA. In this 
appendix, the term MSA is used to refer to a Metropolitan 
Statistical Area. By definition, both MSA and CSA have a high degree 
of integration; however, many such areas cross State or other 
political boundaries. MSA and CSA may also cross more than one air 
shed. The EPA recognizes that State or local agencies must consider 
MSA/CSA boundaries and their own political boundaries and 
geographical characteristics in designing their air monitoring 
networks. The EPA recognizes that there may be situations where the 
EPA Regional Administrator and the affected State or local agencies 
may need to augment or to divide the overall MSA/CSA monitoring 
responsibilities and requirements among these various agencies to 
achieve an effective network design. Full monitoring requirements 
apply separately to each affected State or local agency in the 
absence of an agreement between the affected agencies and the EPA 
Regional Administrator.

3. Design Criteria for NCore Sites

    (a) Each State (i.e. the fifty States, District of Columbia, 
Puerto Rico, and the Virgin Islands) is required to operate at least 
one NCore site. States may delegate this requirement to a local 
agency. States with many MSAs 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 are required to identify one to two additional NCore 
sites in order to account for their unique situations. These 
additional sites shall be located to avoid proximity to large 
emission sources. Any State or local agency can propose additional 
candidate NCore sites or modifications to these requirements for 
approval by the Administrator. The NCore locations should be 
leveraged with other multipollutant air monitoring sites including 
PAMS sites, National Air Toxics Trends Stations (NATTS) sites, 
CASTNET sites, and STN sites. Site leveraging includes using the 
same monitoring platform and equipment to meet the objectives of the 
variety of programs where possible and advantageous.
    (b) The NCore sites must measure, at a minimum, PM<INF>2.5</INF> 
particle mass using continuous and integrated/filter-based samplers, 
speciated PM<INF>2.5</INF>, PM<INF>10-2.5</INF> particle mass, 
speciated PM<INF>10-2.5</INF>, O<INF>3</INF>, SO<INF>2</INF>, CO, 
NO/NO<INF>y</INF>, wind speed, wind direction, relative humidity, 
and ambient temperature.
    (1) Although the measurement of NO<INF>y</INF> is required in 
support of a number of monitoring objectives, available commercial 
instruments may indicate little difference in their measurement of 
NO<INF>y</INF> compared to the conventional measurement of 
NO<INF>X</INF>, particularly in areas with relatively fresh sources 
of nitrogen emissions. Therefore, in areas with negligible expected 
difference between NO<INF>y</INF> and NO<INF>X</INF> measured 
concentrations, the Administrator may allow

[[Page 61318]]

for waivers that permit NO<INF>X</INF> monitoring to be substituted 
for the required NO<INF>y</INF> monitoring at applicable NCore 
sites.
    (2) EPA recognizes that, in some cases, the physical location of 
the NCore site may not be suitable for representative meteorological 
measurements due to the site's physical surroundings. It is also 
possible that nearby meteorological measurements may be able to 
fulfill this data need. In these cases, the requirement for 
meteorological monitoring can be waived by the Administrator.
    (c) In addition to the continuous measurements listed above, 10 
of the NCore locations must also measure lead (Pb) either at the 
same sites or elsewhere within the MSA/CSA boundary. These ten Pb 
sites are included within the NCore networks because they are 
intended to be long-term in operation, and not impacted directly 
from a single Pb source. These locations for Pb monitoring must be 
located in the most populated MSA/CSA in each of the 10 EPA Regions. 
Alternatively, it is also acceptable to use the Pb concentration 
data provided at urban air toxics sites. In approving any 
substitutions, the Administrator must consider whether these 
alternative sites are suitable for collecting long-term lead trends 
data for the broader area.
    (d) Siting criteria are provided for urban and rural locations. 
Sites with significant historical records that do not meet siting 
criteria may be approved as NCore by the Administrator. Sites with 
the suite of NCore measurements that are explicitly designed for 
other monitoring objectives are exempt from these siting criteria 
(e.g., a near-roadway site).
    (1) Urban NCore stations are to be generally located at urban or 
neighborhood scale to provide representative concentrations of 
exposure expected throughout the metropolitan area; however, a 
middle-scale site may be acceptable in cases where the site can 
represent many such locations throughout a metropolitan area.
    (2) Rural NCore stations are to be located to the maximum extent 
practicable at a regional or larger scale away from any large local 
emission source, so that they represent ambient concentrations over 
an extensive area.

4. Pollutant-Specific Design Criteria for SLAMS Sites

    4.1 Ozone (O<INF>3</INF>) Design Criteria. (a) State, and where 
appropriate, local agencies must operate O<INF>3</INF> sites for 
various locations depending upon area size (in terms of population 
and geographic characteristics) and typical peak concentrations 
(expressed in percentages below, or near the O<INF>3</INF> NAAQS). 
Specific SLAMS O<INF>3</INF> site minimum requirements are included 
in Table D-2 of this appendix. The NCore sites are expected to 
complement the O<INF>3</INF> data collection that takes place at 
single-pollutant SLAMS sites, and both types of sites can be used to 
meet the network minimum requirements. The total number of 
O<INF>3</INF> sites needed to support the basic monitoring 
objectives of public data reporting, air quality mapping, 
compliance, and understanding O<INF>3</INF>-related atmospheric 
processes will include more sites than these minimum numbers 
required in Table D-2 of this appendix. The EPA Regional 
Administrator and the responsible State or local air monitoring 
agency must work together to design and/or maintain the most 
appropriate O<INF>3</INF> network to service the variety of data 
needs in an area.

    Table D-2 of Appendix D to Part 58.-- SLAMS Minimum O3 Monitoring
                              Requirements
------------------------------------------------------------------------
                                  Most recent 3-year  Most recent 3-year
                                     design value        design value
       MSA population1, 2           concentrations      concentrations
                                    >=85% of any O3     <85% of any O3
                                        NAAQS 3            NAAQS3, 4
------------------------------------------------------------------------
>10 million.....................                  4                   2
4-10 million....................                  3                   1
350,000-<4 million..............                  2                   1
50,000-<350,000 5...............                  1                   0
------------------------------------------------------------------------
\1\ Minimum monitoring requirements apply to the Metropolitan
  statistical area (MSA).
\2\ Population based on latest available census figures.
\3\ The ozone (O3) National Ambient Air Quality Standards (NAAQS) levels
  and forms are defined in 40 CFR part 50.
\4\ These minimum monitoring requirements apply in the absence of a
  design value.
\5\ Metropolitan statistical areas (MSA) must contain an urbanized area
  of 50,000 or more population.

    (b) Within an O<INF>3</INF> network, at least one O<INF>3</INF> 
site for each MSA, or CSA if multiple MSAs are involved, must be 
designed to record the maximum concentration for that particular 
metropolitan area. More than one maximum concentration site may be 
necessary in some areas. Table D-2 of this appendix does not account 
for the full breadth of additional factors that would be considered 
in designing a complete O<INF>3</INF> monitoring program for an 
area. Some of these additional factors include geographic size, 
population density, complexity of terrain and meteorology, adjacent 
O<INF>3</INF> monitoring programs, air pollution transport from 
neighboring areas, and measured air quality in comparison to all 
forms of the O<INF>3</INF> NAAQS (i.e., 8-hour and 1-hour forms). 
Networks must be designed to account for all of these area 
characteristics. Network designs must be re-examined in periodic 
network assessments. Deviations from the above O<INF>3</INF> 
requirements are allowed if approved by the EPA Regional 
Administrator.
    (c) The appropriate spatial scales for O<INF>3</INF> sites are 
neighborhood, urban, and regional. Since O<INF>3</INF> requires 
appreciable formation time, the mixing of reactants and products 
occurs over large volumes of air, and this reduces the importance of 
monitoring small scale spatial variability.
    (1) Neighborhood scale--Measurements in this category represent 
conditions throughout some reasonably homogeneous urban sub-region, 
with dimensions of a few kilometers. Homogeneity refers to pollutant 
concentrations. Neighborhood scale data will provide valuable 
information for developing, testing, and revising concepts and 
models that describe urban/regional concentration patterns. These 
data will be useful to the understanding and definition of processes 
that take periods of hours to occur and hence involve considerable 
mixing and transport. Under stagnation conditions, a site located in 
the neighborhood scale may also experience peak concentration levels 
within a metropolitan area.
    (2) Urban scale--Measurement in this scale will be used to 
estimate concentrations over large portions of an urban area with 
dimensions of several kilometers to 50 or more kilometers. Such 
measurements will be used for determining trends, and designing 
area-wide control strategies. The urban scale sites would also be 
used to measure high concentrations downwind of the area having the 
highest precursor emissions.
    (3) Regional scale--This scale of measurement will be used to 
typify concentrations over large portions of a metropolitan area and 
even larger areas with dimensions of as much as hundreds of 
kilometers. Such measurements will be useful for assessing the 
O<INF>3</INF> that is transported to and from a metropolitan area, 
as well as background concentrations. In some situations, 
particularly when considering very large metropolitan areas with 
complex source mixtures, regional scale sites can be the maximum 
concentration location.
    (d) EPA's technical guidance documents on O<INF>3</INF> 
monitoring network design should be used to evaluate the adequacy of 
each existing O<INF>3</INF> monitor, to relocate an existing site, 
or to locate any new O<INF>3</INF> sites.
    (e) For locating a neighborhood scale site to measure typical 
city concentrations, a reasonably homogeneous geographical area near 
the center of the region should be selected which is also removed 
from the influence of major NO<INF>X</INF> sources. For an urban 
scale site to measure the high concentration areas, the emission 
inventories should be

[[Page 61319]]

used to define the extent of the area of important nonmethane 
hydrocarbons and NO<INF>X</INF> emissions. The meteorological 
conditions that occur during periods of maximum photochemical 
activity should be determined. These periods can be identified by 
examining the meteorological conditions that occur on the highest 
O<INF>3</INF> air quality days. Trajectory analyses, an evaluation 
of wind and emission patterns on high O<INF>3</INF> days, can also 
be useful in evaluating an O<INF>3</INF> monitoring network. In 
areas without any previous O<INF>3</INF> air quality measurements, 
meteorological and O<INF>3</INF> precursor emissions information 
would be useful.
    (f) Once the meteorological and air quality data are reviewed, 
the prospective maximum concentration monitor site should be 
selected in a direction from the city that is most likely to observe 
the highest O<INF>3</INF> concentrations, more specifically, 
downwind during periods of photochemical activity. In many cases, 
these maximum concentration O<INF>3</INF> sites will be located 10 
to 30 miles or more downwind from the urban area where maximum 
O<INF>3</INF> precursor emissions originate. The downwind direction 
and appropriate distance should be determined from historical 
meteorological data collected on days which show the potential for 
producing high O<INF>3</INF> levels. Monitoring agencies are to 
consult with their EPA Regional Office when considering siting a 
maximum O<INF>3</INF> concentration site.
    (g) In locating a neighborhood scale site which is to measure 
high concentrations, the same procedures used for the urban scale 
are followed except that the site should be located closer to the 
areas bordering on the center city or slightly further downwind in 
an area of high density population.
    (h) For regional scale background monitoring sites, similar 
meteorological analysis as for the maximum concentration sites may 
also inform the decisions for locating regional scale sites. 
Regional scale sites may be located to provide data on O<INF>3</INF> 
transport between cities, as background sites, or for other data 
collection purposes. Consideration of both area characteristics, 
such as meteorology, and the data collection objectives, such as 
transport, must be jointly considered for a regional scale site to 
be useful.
    (i) Since O<INF>3</INF> levels decrease significantly in the 
colder parts of the year in many areas, O<INF>3</INF> is required to 
be monitored at SLAMS monitoring sites only during the ``ozone 
season'' as designated in the AQS files on a State-by-State basis 
and described below in Table D-3 of this appendix. Deviations from 
the O<INF>3</INF> monitoring season must be approved by the EPA 
Regional Administrator, documented within the annual monitoring 
network plan, and updated in AQS. Information on how to analyze 
O<INF>3</INF> data to support a change to the O<INF>3</INF> season 
in support of the 8-hour standard for a specific State can be found 
in reference 8 to this appendix.

  Table D-3 to Appendix D of Part 58. Ozone Monitoring Season by State
------------------------------------------------------------------------
              State                   Begin month          End month
------------------------------------------------------------------------
Alabama.........................  March.............  October
Alaska..........................  April.............  October
Arizona.........................  January...........  December
Arkansas........................  March.............  November
California......................  January...........  December
Colorado........................  March.............  September
Connecticut.....................  April.............  September
Delaware........................  April.............  October
District of Columbia............  April.............  October
Florida.........................  March.............  October
Georgia.........................  March.............   October
Hawaii..........................  January...........  December
Idaho...........................  May...............  September
Illinois........................  April.............  October
Indiana.........................  April.............  September
Iowa............................  April.............  October
Kansas..........................  April.............  October
Kentucky........................  March.............  October
Louisiana AQCR 019,022..........  March.............  October
Louisiana AQCR 106..............  January...........  December
Maine...........................  April.............  September
Maryland........................  April.............  October
Massachusetts...................  April.............  September
Michigan........................  April.............  September
Minnesota.......................  April.............  October
Mississippi.....................  March.............  October
Missouri........................  April.............  October
Montana.........................  June..............  September
Nebraska........................  April.............  October
Nevada..........................  January...........  December
New Hampshire...................  April.............  September
New Jersey......................  April.............  October
New Mexico......................  January...........  December
New York........................  April.............  October
North Carolina..................  April.............  October
North Dakota....................  May...............  September
Ohio............................  April.............  October
Oklahoma........................  March.............  November
Oregon..........................  May...............  September
Pennsylvania....................  April.............  October
Puerto Rico.....................  January...........  December
Rhode Island....................  April.............  September
South Carolina..................  April.............  October
South Dakota....................  June..............  September
Tennessee.......................  March.............  October
Texas AQCR 106,153, 213, 214,     January...........  December
 216.
Texas AQCR 022, 210, 211, 212,    March.............  October
 215, 217, 218.
Utah............................  May...............  September
Vermont.........................  April.............  September
Virginia........................  April.............  October
Washington......................  May...............  September
West Virginia...................  April.............  October
Wisconsin.......................  April 15..........  October 15
Wyoming.........................  April.............  October
American Samoa..................  January...........  December
Guam............................  January...........  December
Virgin Islands..................  January...........  December
------------------------------------------------------------------------

    4.2 Carbon Monoxide (CO) Design Criteria. (a) There are no 
minimum requirements for the number of CO monitoring sites. 
Continued operation of existing SLAMS CO sites using FRM or FEM is 
required until discontinuation is approved by the EPA Regional 
Administrator. Where SLAMS CO monitoring is ongoing, at least one 
site must be a maximum concentration site for that area under 
investigation.
    (b) Microscale and middle scale measurements are useful site 
classifications for SLAMS sites since most people have the potential 
for exposure on these scales. Carbon monoxide maxima occur primarily 
in areas near major roadways and intersections with high traffic 
density and often poor atmospheric ventilation.
    (1) Microscale--This scale applies when air quality measurements 
are to be used to represent distributions within street canyons, 
over sidewalks, and near major roadways. In the case with carbon 
monoxide, microscale measurements in one location can often be 
considered as representative of other similar locations in a city.
    (2) Middle scale--Middle scale measurements are intended to 
represent areas with dimensions from 100 meters to 0.5 kilometer. In 
certain cases, middle scale measurements may apply to areas that 
have a total length of several kilometers, such as ``line'' emission 
source areas. This type of emission sources areas would include air 
quality along a commercially developed street or shopping plaza, 
freeway corridors, parking lots and feeder streets.
    (c) After the spatial scale and type of site has been determined 
to meet the monitoring objective for each location, the technical 
guidance in reference 2 of this appendix should be used to evaluate 
the adequacy of each existing CO site and must be used to relocate 
an existing site or to locate any new sites.
    4.3 Nitrogen Dioxide (NO<INF>2</INF>) Design Criteria. (a) There 
are no minimum requirements for the number of NO<INF>2</INF> 
monitoring sites. Continued operation of existing SLAMS 
NO<INF>2</INF> sites using FRM or FEM is required until 
discontinuation is approved by the EPA Regional Administrator. Where 
SLAMS NO<INF>2</INF> monitoring is ongoing, at least one 
NO<INF>2</INF> site in the area must be located to measure the 
maximum concentration of NO<INF>2</INF>.
    (b) NO/NO<INF>y</INF> measurements are included within the NCore 
multipollutant site requirements and the PAMS program. These NO/
NO<INF>y</INF> measurements will produce conservative estimates for 
NO<INF>2</INF> that can be used to ensure tracking continued 
compliance with the NO<INF>2</INF> NAAQS. NO/NO<INF>y</INF> monitors 
are used at these sites because it is important to collect data on 
total reactive nitrogen species for understanding O<INF>3</INF> 
photochemistry.
    4.4 Sulfur Dioxide (SO<INF>2</INF>) Design Criteria. (a) There 
are no minimum requirements for the number of SO<INF>2</INF> 
monitoring sites. Continued operation of existing SLAMS 
SO<INF>2</INF> sites using FRM or FEM is required until 
discontinuation is approved by the EPA Regional Administrator. Where 
SLAMS SO<INF>2</INF> monitoring is ongoing, at least one of the 
SLAMS SO<INF>2</INF> sites must be a maximum concentration site for 
that specific area.
    (b) The appropriate spatial scales for SO<INF>2</INF> SLAMS 
monitoring are the microscale, middle, and possibly neighborhood 
scales. The multi-pollutant NCore sites can provide

[[Page 61320]]

for metropolitan area trends analyses and general control strategy 
progress tracking. Other SLAMS sites are expected to provide data 
that are useful in specific compliance actions, for maintenance plan 
agreements, or for measuring near specific stationary sources of 
SO<INF>2</INF>.
    (1) Micro and middle scale--Some data uses associated with 
microscale and middle scale measurements for SO<INF>2</INF> include 
assessing the effects of control strategies to reduce concentrations 
(especially for the 3-hour and 24-hour averaging times) and 
monitoring air pollution episodes.
    (2) Neighborhood scale--This scale applies where there is a need 
to collect air quality data as part of an ongoing SO<INF>2</INF> 
stationary source impact investigation. Typical locations might 
include suburban areas adjacent to SO<INF>2</INF> stationary sources 
for example, or for determining background concentrations as part of 
these studies of population responses to exposure to SO<INF>2</INF>.
    (c) Technical guidance in reference 1 of this appendix should be 
used to evaluate the adequacy of each existing SO<INF>2</INF> site, 
to relocate an existing site, or to locate new sites.
    4.5 Lead (Pb) Design Criteria. (a) State, and where appropriate, 
local agencies are required to conduct Pb monitoring for all areas 
where Pb levels have been shown or are expected to be of concern 
over the most recent 2 years. As a minimum, there must be two SLAMS 
sites in any area where Pb concentrations currently exceed or have 
exceeded the Pb NAAQS in the most recent 2 years, and at least one 
of these two required sites must be a maximum concentration site. 
Where the Pb air quality violations are widespread or the emissions 
density, topography, or population locations are complex and varied, 
the EPA Regional Administrator may require more than two Pb ambient 
air monitoring sites.
    (b) The most important spatial scales to effectively 
characterize the emissions from point sources are the micro, middle, 
and neighborhood scales.
    (1) Microscale--This scale would typify areas in close proximity 
to lead point sources. Emissions from point sources such as primary 
and secondary lead smelters, and primary copper smelters may under 
fumigation conditions likewise result in high ground level 
concentrations at the microscale. In the latter case, the microscale 
would represent an area impacted by the plume with dimensions 
extending up to approximately 100 meters. Data collected at 
microscale sites provide information for evaluating and developing 
``hot-spot'' control measures.
    (2) Middle scale--This scale generally represents Pb air quality 
levels in areas up to several city blocks in size with dimensions on 
the order of approximately 100 meters to 500 meters. The middle 
scale may for example, include schools and playgrounds in center 
city areas which are close to major Pb point sources. Pb monitors in 
such areas are desirable because of the higher sensitivity of 
children to exposures of elevated Pb concentrations (reference 3 of 
this appendix). Emissions from point sources frequently impact on 
areas at which single sites may be located to measure concentrations 
representing middle spatial scales.
    (3) Neighborhood scale--The neighborhood scale would 
characterize air quality conditions throughout some relatively 
uniform land use areas with dimensions in the 0.5 to 4.0 kilometer 
range. Sites of this scale would provide monitoring data in areas 
representing conditions where children live and play. Monitoring in 
such areas is important since this segment of the population is more 
susceptible to the effects of Pb. Where a neighborhood site is 
located away from immediate Pb sources, the site may be very useful 
in representing typical air quality values for a larger residential 
area, and therefore suitable for population exposure and trends 
analyses.
    (c) Technical guidance is found in references 4 and 5 of this 
appendix. These documents provide additional guidance on locating 
sites to meet specific urban area monitoring objectives and should 
be used in locating new sites or evaluating the adequacy of existing 
sites.
    4.6 Particulate Matter (PM<INF>10</INF>) Design Criteria. (a) 
State, and where applicable local, agencies must operate the minimum 
number of required PM<INF>10</INF> SLAMS sites listed in Table D-4 
of this appendix.

    Table D-4 of Appendix D to Part 58. PM10 Minimum Monitoring Requirements (Number of Stations per MSA) \1\
----------------------------------------------------------------------------------------------------------------
                                                      High concentration        Medium         Low concentration
                 Population category                          \2\          concentration \3\         \4,5\
----------------------------------------------------------------------------------------------------------------
>1,000,000..........................................               6-10                 4-8                 2-4
500,000-1,000,000...................................                4-8                 2-4                 1-2
250,000-500,000.....................................                3-4                 1-2                 0-1
100,000-250,000.....................................                1-2                 0-1                  0
----------------------------------------------------------------------------------------------------------------
\1\ Selection of urban areas and actual numbers of stations per area within the ranges shown in this table will
  be jointly determined by EPA and the State Agency.
\2\ High concentration areas are those for which ambient PM10 data show ambient concentrations exceeding the
  PM10 NAAQS by 20 percent or more.
\3\ Medium concentration areas are those for which ambient PM10 data show ambient concentrations exceeding 80
  percent of the PM10 NAAQS.
\4\ Low concentration areas are those for which ambient PM10 data show ambient concentrations less than 80
  percent of the PM10 NAAQS.
\5\ These minimum monitoring requirements apply in the absence of a design value.

    (b) Although microscale monitoring may be appropriate in some 
circumstances, the most important spatial scales to effectively 
characterize the emissions of PM<INF>10</INF> from both mobile and 
stationary sources are the middle scales and neighborhood scales.
    (1) Microscale--This scale would typify areas such as downtown 
street canyons, traffic corridors, and fence line stationary source 
monitoring locations where the general public could be exposed to 
maximum PM<INF>10</INF> concentrations. Microscale particulate 
matter sites should be located near inhabited buildings or locations 
where the general public can be expected to be exposed to the 
concentration measured. Emissions from stationary sources such as 
primary and secondary smelters, power plants, and other large 
industrial processes may, under certain plume conditions, likewise 
result in high ground level concentrations at the microscale. In the 
latter case, the microscale would represent an area impacted by the 
plume with dimensions extending up to approximately 100 meters. Data 
collected at microscale sites provide information for evaluating and 
developing hot spot control measures.
    (2) Middle scale--Much of the short-term public exposure to 
coarse fraction particles (PM<INF>10</INF>) is on this scale and on 
the neighborhood scale. People moving through downtown areas or 
living near major roadways or stationary sources, may encounter 
particulate pollution that would be adequately characterized by 
measurements of this spatial scale. Middle scale PM<INF>10</INF> 
measurements can be appropriate for the evaluation of possible 
short-term exposure public health effects. In many situations, 
monitoring sites that are representative of micro-scale or middle-
scale impacts are not unique and are representative of many similar 
situations. This can occur along traffic corridors or other 
locations in a residential district. In this case, one location is 
representative of a neighborhood of small scale sites and is 
appropriate for evaluation of long-term or chronic effects. This 
scale also includes the characteristic concentrations for other 
areas with dimensions of a few hundred meters such as the parking 
lot and feeder streets associated with shopping centers, stadia, and 
office buildings. In the case of PM<INF>10</INF>, unpaved or 
seldomly swept parking lots associated with these sources could be 
an important source

[[Page 61321]]

in addition to the vehicular emissions themselves.
    (3) Neighborhood scale--Measurements in this category represent 
conditions throughout some reasonably homogeneous urban sub-region 
with dimensions of a few kilometers and of generally more regular 
shape than the middle scale. Homogeneity refers to the particulate 
matter concentrations, as well as the land use and land surface 
characteristics. In some cases, a location carefully chosen to 
provide neighborhood scale data would represent not only the 
immediate neighborhood but also neighborhoods of the same type in 
other parts of the city. Neighborhood scale PM<INF>10</INF> sites 
provide information about trends and compliance with standards 
because they often represent conditions in areas where people 
commonly live and work for extended periods. Neighborhood scale data 
could provide valuable information for developing, testing, and 
revising models that describe the larger-scale concentration 
patterns, especially those models relying on spatially smoothed 
emission fields for inputs. The neighborhood scale measurements 
could also be used for neighborhood comparisons within or between 
cities.
    4.7 Fine Particulate Matter (PM<INF>2.5</INF>) Design Criteria.
    4.7.1 General Requirements. (a) State, and where applicable 
local, agencies must operate the minimum number of required 
PM<INF>2.5</INF> SLAMS sites listed in Table D-5 of this appendix. 
The NCore sites are expected to complement the PM<INF>2.5</INF> data 
collection that takes place at non-NCore SLAMS sites, and both types 
of sites can be used to meet the minimum PM<INF>2.5</INF> network 
requirements. Deviations from these PM<INF>2.5</INF> monitoring 
requirements must be approved by the EPA Regional Administrator.

      Table D-5 of Appendix D to Part 58. PM2.5 Minimum Monitoring
                              Requirements
------------------------------------------------------------------------
                                  Most recent 3-year  Most recent 3-year
                                  design value >=85%   design value <85%
      MSA population \1,2\        of any PM2.5 NAAQS  of any PM2.5 NAAQS
                                          \3\              \3\, \4\
------------------------------------------------------------------------
>1,000,000......................                  3                   2
500,000-1,000,000...............                  2                   1
50,000-<500,000 \5\.............                  1                  0
------------------------------------------------------------------------
\1\ Minimum monitoring requirements apply to the Metropolitan
  statistical area (MSA).
\2\ Population based on latest available census figures.
\3\ The PM2.5 National Ambient Air Quality Standards (NAAQS) levels and
  forms are defined in 40 CFR part 50.
\4\ These minimum monitoring requirements apply in the absence of a
  design value.
\5\ Metropolitan statistical areas (MSA) must contain an urbanized area
  of 50,000 or more population.

    (b) Specific Design Criteria for PM<INF>2.5</INF>. The required 
monitoring stations or sites must be sited to represent community-
wide air quality. These sites can include sites collocated at PAMS. 
These monitoring stations will typically be at neighborhood or 
urban-scale; however, in certain instances where population-oriented 
micro-or middle-scale PM<INF>2.5</INF> monitoring are determined by 
the Regional Administrator to represent many such locations 
throughout a metropolitan area, these smaller scales can be 
considered to represent community-wide air quality.
    (1) At least one monitoring station is to be sited in a 
population-oriented area of expected maximum concentration.
    (2) For areas with more than one required SLAMS, a monitoring 
station is to be sited in an area of poor air quality.
    (3) Additional technical guidance for siting PM<INF>2.5</INF> 
monitors is provided in references 6 and 7 of this appendix.
    (c) The most important spatial scale to effectively characterize 
the emissions of particulate matter from both mobile and stationary 
sources is the neighborhood scale for PM<INF>2.5</INF>. For purposes 
of establishing monitoring sites to represent large homogenous areas 
other than the above scales of representativeness and to 
characterize regional transport, urban or regional scale sites would 
also be needed. Most PM<INF>2.5</INF> monitoring in urban areas 
should be representative of a neighborhood scale.
    (1) Microscale--This scale would typify areas such as downtown 
street canyons and traffic corridors where the general public would 
be exposed to maximum concentrations from mobile sources. In some 
circumstances, the microscale is appropriate for particulate sites; 
community-oriented SLAMS sites measured at the microscale level 
should, however, be limited to urban sites that are representative 
of long-term human exposure and of many such microenvironments in 
the area. In general, microscale particulate matter sites should be 
located near inhabited buildings or locations where the general 
public can be expected to be exposed to the concentration measured. 
Emissions from stationary sources such as primary and secondary 
smelters, power plants, and other large industrial processes may, 
under certain plume conditions, likewise result in high ground level 
concentrations at the microscale. In the latter case, the microscale 
would represent an area impacted by the plume with dimensions 
extending up to approximately 100 meters. Data collected at 
microscale sites provide information for evaluating and developing 
hot spot control measures. Unless these sites are indicative of 
population-oriented monitoring, they may be more appropriately 
classified as SPM.
    (2) Middle scale--People moving through downtown areas, or 
living near major roadways, encounter particle concentrations that 
would be adequately characterized by this spatial scale. Thus, 
measurements of this type would be appropriate for the evaluation of 
possible short-term exposure public health effects of particulate 
matter pollution. In many situations, monitoring sites that are 
representative of microscale or middle-scale impacts are not unique 
and are representative of many similar situations. This can occur 
along traffic corridors or other locations in a residential 
district. In this case, one location is representative of a number 
of small scale sites and is appropriate for evaluation of long-term 
or chronic effects. This scale also includes the characteristic 
concentrations for other areas with dimensions of a few hundred 
meters such as the parking lot and feeder streets associated with 
shopping centers, stadia, and office buildings.
    (3) Neighborhood scale--Measurements in this category would 
represent conditions throughout some reasonably homogeneous urban 
sub-region with dimensions of a few kilometers and of generally more 
regular shape than the middle scale. Homogeneity refers to the 
particulate matter concentrations, as well as the land use and land 
surface characteristics. Much of the PM<INF>2.5</INF> exposures are 
expected to be associated with this scale of measurement. In some 
cases, a location carefully chosen to provide neighborhood scale 
data would represent the immediate neighborhood as well as 
neighborhoods of the same type in other parts of the city. 
PM<INF>2.5</INF> sites of this kind provide good information about 
trends and compliance with standards because they often represent 
conditions in areas where people commonly live and work for periods 
comparable to those specified in the NAAQS. In general, most 
PM<INF>2.5</INF> monitoring in urban areas should have this scale.
    (4) Urban scale--This class of measurement would be used to 
characterize the particulate matter concentration over an entire 
metropolitan or rural area ranging in size from 4 to 50 kilometers. 
Such measurements would be useful for assessing trends in area-wide 
air quality, and hence, the effectiveness of large scale air 
pollution control strategies. Community-oriented PM<INF>2.5</INF> 
sites may have this scale.
    (5) Regional scale--These measurements would characterize 
conditions over areas with dimensions of as much as hundreds of 
kilometers. As noted earlier, using representative conditions for an 
area implies some degree of homogeneity in that area. For this 
reason, regional scale measurements would be most applicable to 
sparsely populated areas. Data characteristics of this scale would 
provide information about larger scale processes of particulate 
matter

[[Page 61322]]

emissions, losses and transport. PM<INF>2.5</INF> transport 
contributes to elevated particulate concentrations and may affect 
multiple urban and State entities with large populations such as in 
the eastern United States. Development of effective pollution 
control strategies requires an understanding at regional 
geographical scales of the emission sources and atmospheric 
processes that are responsible for elevated PM<INF>2.5</INF> levels 
and may also be associated with elevated O<INF>3</INF> and regional 
haze.
    4.7.2 Requirement for Continuous PM<INF>2.5</INF> Monitoring. 
State, or where appropriate, local agencies must operate continuous 
fine particulate analyzers equal to at least one-half (round up) the 
minimum required sites listed in Table D-5 of this appendix. At 
least one required FRM/FEM monitor in each MSA must be collocated. 
State and local air monitoring agencies must use methodologies and 
quality assurance/quality control(QA/QC) procedures approved by the 
EPA Regional Administrator for these sites.
    4.7.3 Requirement for PM<INF>2.5</INF> Background and Transport 
Sites. Each State shall install and operate at least one 
PM<INF>2.5</INF> site to monitor for regional background and at 
least one PM<INF>2.5</INF> site to monitor regional transport. These 
monitoring sites may be at community-oriented sites and this 
requirement may be satisfied by a corresponding monitor in an area 
having similar air quality in another State. State and local air 
monitoring agencies must use methodologies and QA/QC procedures 
approved by the EPA Regional Administrator for these sites. Methods 
used at these sites may include non-federal reference method 
samplers such as IMPROVE or continuous PM<INF>2.5</INF> monitors.
    4.7.4 PM<INF>2.5</INF> Chemical Speciation Site Requirements. 
Each State shall continue to conduct chemical speciation monitoring 
and analyses at sites designated to be part of the PM<INF>2.5</INF> 
Speciation Trends Network (STN). The selection and modification of 
these STN sites must be approved by the Administrator. The 
PM<INF>2.5</INF> chemical speciation urban trends sites shall 
include analysis for elements, selected anions and cations, and 
carbon. Samples must be collected using the monitoring methods and 
the sampling schedules approved by the Administrator. Chemical 
speciation is encouraged at additional sites where the chemically 
resolved data would be useful in developing State implementation 
plans and supporting atmospheric or health effects related studies.
    4.7.5 Special Network Considerations Required When Using 
PM<INF>2.5</INF> Spatial Averaging Approaches. (a) The 
PM<INF>2.5</INF> NAAQS, specified in 40 CFR part 50, provides State 
and local air monitoring agencies with an option for spatially 
averaging PM<INF>2.5</INF> air quality data. More specifically, two 
or more community-oriented (i.e., sites in populated areas) 
PM<INF>2.5</INF> monitors may be averaged for comparison with the 
annual PM<INF>2.5</INF> NAAQS. This averaging approach is directly 
related to epidemiological studies used as the basis for the 
PM<INF>2.5</INF> annual NAAQS. Spatial averaging does not apply to 
comparisons with the daily PM<INF>2.5</INF> NAAQS.
    (b) State and local agencies must carefully consider their 
approach for PM<INF>2.5</INF> network design when they intend to 
spatially average the data for compliance purposes. These State and 
local air monitoring agencies must define the area over which they 
intend to average PM<INF>2.5</INF> air quality concentrations. This 
area is defined as a Community Monitoring Zone (CMZ), which 
characterizes an area of relatively similar annual average air 
quality. State and local agencies can define a CMZ in a number of 
ways, including as part or all of a metropolitan area. These CMZ 
must be defined within a State or local agencies network 
description, as required in Sec.  58.10 of this part and approved by 
the EPA Regional Administrator. When more than one CMZ is described 
within an agency's network design plan, CMZs must not overlap in 
their geographical coverage. The criteria that must be used for 
evaluating the acceptability of spatial averaging are defined in 
appendix N to 40 CFR part 50.
    4.8 Coarse Particulate Matter (PM<INF>10-2.5</INF>) Design 
Criteria.
    4.8.1 General Monitoring Requirements. (a) The only required 
monitors for PM<INF>10-2.5</INF> are those required at NCore 
Stations.
    (b) Although microscale monitoring may be appropriate in some 
circumstances, middle and neighborhood scale measurements are the 
most important station classifications for PM<INF>10-2.5</INF> to 
assess the variation in coarse particle concentrations that would be 
expected across populated areas that are in proximity to large 
emissions sources.
    (1) Microscale--This scale would typify relatively small areas 
immediately adjacent to: Industrial sources; locations experiencing 
ongoing construction, redevelopment, and soil disturbance; and 
heavily traveled roadways. Data collected at microscale stations 
would characterize exposure over areas of limited spatial extent and 
population exposure, and may provide information useful for 
evaluating and developing source-oriented control measures.
    (2) Middle scale--People living or working near major roadways 
or industrial districts encounter particle concentrations that would 
be adequately characterized by this spatial scale. Thus, 
measurements of this type would be appropriate for the evaluation of 
public health effects of coarse particle exposure. Monitors located 
in populated areas that are nearly adjacent to large industrial 
point sources of coarse particles provide suitable locations for 
assessing maximum population exposure levels and identifying areas 
of potentially poor air quality. Similarly, monitors located in 
populated areas that border dense networks of heavily-traveled 
traffic are appropriate for assessing the impacts of resuspended 
road dust. This scale also includes the characteristic 
concentrations for other areas with dimensions of a few hundred 
meters such as school grounds and parks that are nearly adjacent to 
major roadways and industrial point sources, locations exhibiting 
mixed residential and commercial development, and downtown areas 
featuring office buildings, shopping centers, and stadiums.
    (3) Neighborhood scale--Measurements in this category would 
represent conditions throughout some reasonably homogeneous urban 
sub-region with dimensions of a few kilometers and of generally more 
regular shape than the middle scale. Homogeneity refers to the 
particulate matter concentrations, as well as the land use and land 
surface characteristics. This category includes suburban 
neighborhoods dominated by residences that are somewhat distant from 
major roadways and industrial districts but still impacted by urban 
sources, and areas of diverse land use where residences are 
interspersed with commercial and industrial neighborhoods. In some 
cases, a location carefully chosen to provide neighborhood scale 
data would represent the immediate neighborhood as well as 
neighborhoods of the same type in other parts of the city. The 
comparison of data from middle scale and neighborhood scale sites 
would provide valuable information for determining the variation of 
PM<INF>10-2.5</INF> levels across urban areas and assessing the 
spatial extent of elevated concentrations caused by major industrial 
point sources and heavily traveled roadways. Neighborhood scale 
sites would provide concentration data that are relevant to 
informing a large segment of the population of their exposure levels 
on a given day.
    4.8.2 PM<INF>10-2.5</INF> Chemical Speciation Site Requirements. 
PM<INF>10-2.5</INF> chemical speciation monitoring and analyses is 
required at NCore sites. The selection and modification of these 
sites must be approved by the Administrator. Samples must be 
collected using the monitoring methods and the sampling schedules 
approved by the Administrator.

5. Network Design for Photochemical Assessment Monitoring Stations 
(PAMS)

    The PAMS program provides more comprehensive data on 
O<INF>3</INF> air pollution in areas classified as serious, severe, 
or extreme nonattainment for O<INF>3</INF> than would otherwise be 
achieved through the NCore and SLAMS sites. More specifically, the 
PAMS program includes measurements for O<INF>3</INF>, oxides of 
nitrogen, VOC, and meteorology.
    5.1 PAMS Monitoring Objectives. PAMS design criteria are site 
specific. Concurrent measurements of O<INF>3</INF>, oxides of 
nitrogen, speciated VOC, CO, and meteorology are obtained at PAMS 
sites. Design criteria for the PAMS network are based on locations 
relative to O<INF>3</INF> precursor source areas and predominant 
wind directions associated with high O<INF>3</INF> events. Specific 
monitoring objectives are associated with each location. The overall 
design should enable characterization of precursor emission sources 
within the area, transport of O<INF>3</INF> and its precursors, and 
the photochemical processes related to O<INF>3</INF> nonattainment. 
Specific objectives that must be addressed include assessing ambient 
trends in O<INF>3</INF>, oxides of nitrogen, VOC species, and 
determining spatial and diurnal variability of O<INF>3</INF>, oxides 
of nitrogen, and VOC species. Specific monitoring objectives 
associated with each of these sites may result in four distinct site 
types. Detailed guidance for the locating of these sites may be 
found in reference 9 of this appendix.
    (a) Type 1 sites are established to characterize upwind 
background and transported O<INF>3</INF> and its precursor 
concentrations entering the area and will identify those areas which 
are subjected to transport.

[[Page 61323]]

    (b) Type 2 sites are established to monitor the magnitude and 
type of precursor emissions in the area where maximum precursor 
emissions are expected to impact and are suited for the monitoring 
of urban air toxic pollutants.
    (c) Type 3 sites are intended to monitor maximum O<INF>3</INF> 
concentrations occurring downwind from the area of maximum precursor 
emissions.
    (d) Type 4 sites are established to characterize the downwind 
transported O<INF>3</INF> and its precursor concentrations exiting 
the area and will identify those areas which are potentially 
contributing to overwhelming transport in other areas.
    5.2 Monitoring Period. PAMS precursor monitoring must be 
conducted annually throughout the months of June, July and August 
(as a minimum) when peak O<INF>3</INF> values are expected in each 
area. Alternate precursor monitoring periods may be submitted for 
approval to the Administrator as a part of the annual monitoring 
network plan required by Sec.  58.10.
    5.3 Minimum Monitoring Network Requirements. A Type 2 site is 
required for each area. Overall, only two sites are required for 
each area, providing all chemical measurements are made. For 
example, if a design includes two Type 2 sites, then a third site 
will be necessary to capture the NO<INF>y</INF> measurement. The 
minimum required number and type of monitoring sites and sampling 
requirements are listed in Table D-6 of this appendix. Any 
alternative plans may be put in place in lieu of these requirements, 
if approved by the Administrator.

  Table D-6 of Appendix D to Part 58. Minimum Required PAMS Monitoring
                        Locations and Frequencies
------------------------------------------------------------------------
                                                     Sampling frequency
                                                   (all daily except for
        Measurement             Where required           upper air
                                                      meteorology) \1\
------------------------------------------------------------------------
Speciated VOC2............  Two sites per area,    During the PAMS
                             one of which must be   monitoring period:
                             a Type 2 site.         (1) Hourly auto GC,
                                                    or (2) Eight 3-hour
                                                    canisters, or (3) 1
                                                    morning and 1
                                                    afternoon canister
                                                    with a 3-hour or
                                                    less averaging time
                                                    plus Continuous
                                                    Total Non-methane
                                                    Hydrocarbon
                                                    measurement.
Carbonyl sampling.........  Type 2 site in areas   3-hour samples every
                             classified as          day during the PAMS
                             serious or above for   monitoring period.
                             the 8-hour ozone
                             standard.
NOX.......................  All Type 2 sites.....  Hourly during the
                                                    ozone monitoring
                                                    season.\3\
NOy.......................  One site per area at   Hourly during the
                             the Type 3 or Type 1   ozone monitoring
                             site.                  season.
CO (ppb level)............  One site per area at   Hourly during the
                             a Type 2 site.         ozone monitoring
                                                    season.
Ozone.....................  All sites............  Hourly during the
                                                    ozone monitoring
                                                    season.
Surface met...............  All sites............  Hourly during the
                                                    ozone monitoring
                                                    season.
Upper air meteorology.....  One representative     Sampling frequency
                             location within PAMS   must be approved as
                             area.                  part of the annual
                                                    monitoring network
                                                    plan required in 40
                                                    CFR 58.10.
------------------------------------------------------------------------
\1\ Daily or with an approved alternative plan.
\2\ Speciated VOC is defined in the ``Technical Assistance Document for
  Sampling and Analysis of Ozone Precursors'', EPA/600-R-98/161,
  September 1998.
\3\ Approved ozone monitoring season as stipulated in Table D-3 of this
  appendix.

    5.4 Transition Period. A transition period is allowed for 
phasing in the operation of newly required PAMS programs (due 
generally to reclassification of an area into serious, severe, or 
extreme nonattainment for ozone). Following the date of 
redesignation or reclassification of any existing O<INF>3</INF> 
nonattainment area to serious, severe, or extreme, or the 
designation of a new area and classification to serious, severe, or 
extreme O<INF>3</INF> nonattainment, a State is allowed 1 year to 
develop plans for its PAMS implementation strategy. Subsequently, a 
minimum of one Type 2 site must be operating by the first month of 
the following approved PAMS season. Operation of the remaining 
site(s) must, at a minimum, be phased in at the rate of one site per 
year during subsequent years as outlined in the approved PAMS 
network description provided by the State.

6. References

    1. Ball, R.J. and G.E. Anderson. Optimum Site Exposure Criteria 
for SO<INF>2</INF> Monitoring. The Center for the Environment and 
Man, Inc., Hartford, CT. Prepared for U.S. Environmental Protection 
Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-
77-013. April 1977.
    2. Ludwig, F.F., J.H.S. Kealoha, and E. Shelar. Selecting Sites 
for Carbon Monoxide Monitoring. Stanford Research Institute, Menlo 
Park, CA. Prepared for U.S. Environmental Protection Agency, 
Research Triangle Park, NC. EPA Publication No. EPA-450/3-75-077, 
September 1975.
    3. Air Quality Criteria for Lead. Office of Research and 
Development, U.S. Environmental Protection Agency, Washington D.C. 
EPA Publication No. 600/8-89-049F. August 1990. (NTIS document 
numbers PB87-142378 and PB91-138420.)
    4. Optimum Site Exposure Criteria for Lead Monitoring. PEDCo 
Environmental, Inc. Cincinnati, OH. Prepared for U.S. Environmental 
Protection Agency, Research Triangle Park, NC. EPA Contract No. 68-
02-3013. May 1981.
    5. Guidance for Conducting Ambient Air Monitoring for Lead 
Around Point Sources. Office of Air Quality Planning and Standards, 
U.S. Environmental Protection Agency, Research Triangle Park, NC. 
EPA-454/R-92-009. May 1997.
    6. Koch, R.C. and H.E. Rector. Optimum Network Design and Site 
Exposure Criteria for Particulate Matter. GEOMET Technologies, Inc., 
Rockville, MD. Prepared for U.S. Environmental Protection Agency, 
Research Triangle Park, NC. EPA Contract No. 68-02-3584. EPA 450/4-
87-009. May 1987.
    7. Watson et al. Guidance for Network Design and Optimum Site 
Exposure for PM<INF>2.5</INF> and PM<INF>10</INF>. Prepared for U.S. 
Environmental Protection Agency, Research Triangle Park, NC. EPA-
454/R-99-022, December 1997.
    8. Guideline for Selecting and Modifying the Ozone Monitoring 
Season Based on an 8-Hour Ozone Standard. Prepared for U.S. 
Environmental Protection Agency, RTP, NC. EPA-454/R-98-001, June 
1998.
    9. Photochemical Assessment Monitoring Stations Implementation 
Manual. Office of Air Quality Planning and Standards, U.S. 
Environmental Protection Agency, Research Triangle Park, NC. EPA-
454/B-93-051. March 1994.

37. Appendix E to part 58 is revised to read as follows:

Appendix E to Part 58--Probe and Monitoring Path Siting Criteria for 
Ambient Air Quality Monitoring

1. Introduction.
2. Horizontal and Vertical Placement.
3. Spacing from Minor Sources.
4. Spacing From Obstructions.
5. Spacing From Trees.
6. Spacing From Roadways.
7. Cumulative Interferences on a Monitoring Path.
8. Maximum Monitoring Path Length.
9. Probe Material and Pollutant Sample Residence Time.
10. Waiver Provisions.
11. Summary.
12. References.

1. Introduction

    (a) This appendix contains specific location criteria applicable 
to SLAMS, NCore, and PAMS ambient air quality monitoring probes, 
inlets, and optical paths after the general location has been 
selected based on the monitoring objectives and spatial scale of 
representation discussed in appendix D to this part. Adherence to 
these

[[Page 61324]]

siting criteria is necessary to ensure the uniform collection of 
compatible and comparable air quality data.
    (b) The probe and monitoring path siting criteria discussed in 
this appendix must be followed to the maximum extent possible. It is 
recognized that there may be situations where some deviation from 
the siting criteria may be necessary. In any such case, the reasons 
must be thoroughly documented in a written request for a waiver that 
describes how and why the proposed siting deviates from the 
criteria. This documentation should help to avoid later questions 
about the validity of the resulting monitoring data. Conditions 
under which the EPA would consider an application for waiver from 
these siting criteria are discussed in section 10 of this appendix.
    (c) The pollutant-specific probe and monitoring path siting 
criteria generally apply to all spatial scales except where noted 
otherwise. Specific siting criteria that are phrased with a ``must'' 
are defined as requirements and exceptions must be approved through 
the waiver provisions. However, siting criteria that are phrased 
with a ``should'' are defined as goals to meet for consistency but 
are not requirements.

2. Horizontal and Vertical Placement

    The probe or at least 80 percent of the monitoring path must be 
located between 2 and 15 meters above ground level for all ozone, 
sulfur dioxide and nitrogen dioxide monitoring sites, and for 
neighborhood scale Pb, PM<INF>10</INF>, PM<INF>10-2.5</INF>, 
PM<INF>2.5</INF>, and carbon monoxide sites. Middle scale 
PM<INF>10-2.5</INF> sites are required to have sampler inlets 
between 2 and 7 meters above ground level. Microscale Pb, 
PM<INF>10</INF>, PM<INF>10-2.5</INF> and PM<INF>2.5</INF> sites are 
required to have sampler inlets between 2 and 7 meters above ground 
level. The inlet probes for microscale carbon monoxide monitors that 
are being used to measure concentrations near roadways must be 
3<plus-minus>\1/2\ meters above ground level. The probe or at least 
90 percent of the monitoring path must be at least 1 meter 
vertically or horizontally away from any supporting structure, 
walls, parapets, penthouses, etc., and away from dusty or dirty 
areas. If the probe or a significant portion of the monitoring path 
is located near the side of a building, then it should be located on 
the windward side of the building relative to the prevailing wind 
direction during the season of highest concentration potential for 
the pollutant being measured.

3. Spacing From Minor Sources

    (a) It is important to understand the monitoring objective for a 
particular location in order to interpret this particular 
requirement. Local minor sources of a primary pollutant, such as 
SO<INF>2</INF>, lead, or particles, can cause high concentrations of 
that particular pollutant at a monitoring site. If the objective for 
that monitoring site is to investigate these local primary pollutant 
emissions, then the site is likely to be properly located nearby. 
This type of monitoring site would in all likelihood be a microscale 
type of monitoring site. If a monitoring site is to be used to 
determine air quality over a much larger area, such as a 
neighborhood or city, a monitoring agency should avoid placing a 
monitor probe, path, or inlet near local, minor sources. The plume 
from the local minor sources should not be allowed to 
inappropriately impact the air quality data collected at a site. 
Particulate matter sites should not be located in an unpaved area 
unless there is vegetative ground cover year round, so that the 
impact of wind blown dusts will be kept to a minimum.
    (b) Similarly, local sources of nitric oxide (NO) and ozone-
reactive hydrocarbons can have a scavenging effect causing 
unrepresentatively low concentrations of O<INF>3</INF> in the 
vicinity of probes and monitoring paths for O<INF>3</INF>. To 
minimize these potential interferences, the probe or at least 90 
percent of the monitoring path must be away from furnace or 
incineration flues or other minor sources of SO<INF>2</INF> or NO. 
The separation distance should take into account the heights of the 
flues, type of waste or fuel burned, and the sulfur content of the 
fuel.

4. Spacing From Obstructions

    (a) Buildings and other obstacles may possibly scavenge 
SO<INF>2</INF>, O<INF>3</INF>, or NO<INF>2</INF>, and can act to 
restrict airflow for any pollutant. To avoid this interference, the 
probe, inlet, or at least 90 percent of the monitoring path must 
have unrestricted airflow and be located away from obstacles. The 
distance from the obstacle to the probe, inlet, or monitoring path 
must be at least twice the height that the obstacle protrudes above 
the probe, inlet, or monitoring path. An exception to this 
requirement can be made for measurements taken in street canyons or 
at source-oriented sites where buildings and other structures are 
unavoidable.
    (b) Generally, a probe or monitoring path located near or along 
a vertical wall is undesirable because air moving along the wall may 
be subject to possible removal mechanisms. A probe, inlet, or 
monitoring path must have unrestricted airflow in an arc of at least 
180 degrees. This arc must include the predominant wind direction 
for the season of greatest pollutant concentration potential. For 
particle sampling, a minimum of 2 meters of separation from walls, 
parapets, and structures is required for rooftop site placement.
    (c) Special consideration must be given to the use of open path 
analyzers due to their inherent potential sensitivity to certain 
types of interferences, or optical obstructions. A monitoring path 
must be clear of all trees, brush, buildings, plumes, dust, or other 
optical obstructions, including potential obstructions that may move 
due to wind, human activity, growth of vegetation, etc. Temporary 
optical obstructions, such as rain, particles, fog, or snow, should 
be considered when siting an open path analyzer. Any of these 
temporary obstructions that are of sufficient density to obscure the 
light beam will affect the ability of the open path analyzer to 
continuously measure pollutant concentrations. Transient, but 
significant obscuration of especially longer measurement paths could 
occur as a result of certain meteorological conditions (e.g., heavy 
fog, rain, snow) and/or aerosol levels that are of a sufficient 
density to prevent the open path analyzer's light transmission. If 
certain compensating measures are not otherwise implemented at the 
onset of monitoring (e.g., shorter path lengths, higher light source 
intensity), data recovery during periods of greatest primary 
pollutant potential could be compromised. For instance, if heavy fog 
or high particulate levels are coincident with periods of projected 
NAAQS-threatening pollutant potential, the representativeness of the 
resulting data record in reflecting maximum pollutant concentrations 
may be substantially impaired despite the fact that the site may 
otherwise exhibit an acceptable, even exceedingly high overall valid 
data capture rate.

5. Spacing From Trees

    (a) Trees can provide surfaces for SO<INF>2</INF>, 
O<INF>3</INF>, or NO<INF>2</INF> adsorption or reactions, and 
surfaces for particle deposition. Trees can also act as obstructions 
in cases where they are located between the air pollutant sources or 
source areas and the monitoring site, and where the trees are of a 
sufficient height and leaf canopy density to interfere with the 
normal airflow around the probe, inlet, or monitoring path. To 
reduce this possible interference/obstruction, the probe, inlet, or 
at least 90 percent of the monitoring path must be at least 10 
meters or further from the drip line of trees.
    (b) The scavenging effect of trees is greater for O<INF>3</INF> 
than for other criteria pollutants. Monitoring agencies must take 
steps to consider the impact of trees on ozone monitoring sites and 
take steps to avoid this problem.
    (c) For microscale sites of any air pollutant, no trees or 
shrubs should be located between the probe and the source under 
investigation, such as a roadway or a stationary source.

6. Spacing From Roadways

    6.1 Spacing for Ozone and Oxide of Nitrogen Probes and 
Monitoring Paths. In siting an O<INF>3</INF> analyzer, it is 
important to minimize destructive interferences from sources of NO, 
since NO readily reacts with O<INF>3</INF>. In siting NO<INF>2</INF> 
analyzers for neighborhood and urban scale monitoring, it is 
important to minimize interferences from automotive sources. Table 
E-1 of this appendix provides the required minimum separation 
distances between a roadway and a probe or, where applicable, at 
least 90 percent of a monitoring path for various ranges of daily 
roadway traffic. A sampling site having a point analyzer probe 
located closer to a roadway than allowed by the Table E-1 
requirements should be classified as middle scale rather than 
neighborhood or urban scale, since the measurements from such a site 
would more closely represent the middle scale. If an open path 
analyzer is used at a site, the monitoring path(s) must not cross 
over a roadway with an average daily traffic count of 10,000 
vehicles per day or more. For those situations where a monitoring 
path crosses a roadway with fewer than 10,000 vehicles per day, one 
must consider the entire segment of the monitoring path in the area 
of potential atmospheric interference from automobile emissions. 
Therefore, this calculation must include the length of the 
monitoring path over the roadway plus any segments of the

[[Page 61325]]

monitoring path that lie in the area between the roadway and the 
minimum separation distance, as determined from Table E-1 of this 
appendix. The sum of these distances must not be greater than 10 
percent of the total monitoring path length.

 Table E-1 to Appendix E of Part 58. Minimum Separation Distance Between
 Roadways and Probes or Monitoring Paths for Monitoring Neighborhood and
    Urban Scale Ozone (O3) and Oxides of Nitrogen (NO, NO2, NOX, NOy)
------------------------------------------------------------------------
                                              Minimum         Minimum
 Roadway average daily traffic, vehicles   distance \1\    distance 1, 2
                 per day                     (meters)        (meters)
------------------------------------------------------------------------
<=1,000.................................              10              10
10,000..................................              10              20
15,000..................................              20              30
20,000..................................              30              40
40,000..................................              50              60
70,000..................................             100             100
>=110,000...............................             250            250
------------------------------------------------------------------------
\1\ Distance from the edge of the nearest traffic lane. The distance for
  intermediate traffic counts should be interpolated from the table
  values based on the actual traffic count.
\2\ Applicable for ozone monitors whose placement has not already been
  approved as of December 18, 2006.

    6.2 Spacing for Carbon Monoxide Probes and Monitoring Paths. (a) 
Street canyon and traffic corridor sites (microscale) are intended 
to provide a measurement of the influence of the immediate source on 
the pollution exposure of the population. In order to provide some 
reasonable consistency and comparability in the air quality data 
from microscale sites, a minimum distance of 2 meters and a maximum 
distance of 10 meters from the edge of the nearest traffic lane must 
be maintained for these CO monitoring inlet probes. This should give 
consistency to the data, yet still allow flexibility of finding 
suitable locations.
    (b) Street canyon/corridor (microscale) inlet probes must be 
located at least 10 meters from an intersection and preferably at a 
midblock location. Midblock locations are preferable to intersection 
locations because intersections represent a much smaller portion of 
downtown space than do the streets between them. Pedestrian exposure 
is probably also greater in street canyon/corridors than at 
intersections.
    (c) In determining the minimum separation between a neighborhood 
scale monitoring site and a specific roadway, the presumption is 
made that measurements should not be substantially influenced by any 
one roadway. Computations were made to determine the separation 
distance, and Table E-2 of this appendix provides the required 
minimum separation distance between roadways and a probe or 90 
percent of a monitoring path. Probes or monitoring paths that are 
located closer to roads than this criterion allows should not be 
classified as a neighborhood scale, since the measurements from such 
a site would closely represent the middle scale. Therefore, sites 
not meeting this criterion should be classified as middle scale.

 Table E-2 to Appendix E of Part 58. Minimum Separation Distance Between
   Roadways and Probes or Monitoring Paths for Monitoring Neighborhood
                          Scale Carbon Monoxide
------------------------------------------------------------------------
                                                              Minimum
     Roadway average daily traffic, vehicles per day       distance \1\
                                                             (meters)
------------------------------------------------------------------------
<=10,000................................................              10
15,000..................................................              25
20,000..................................................              45
30,000..................................................              80
40,000..................................................             115
50,000..................................................             135
>=60,000................................................            150
------------------------------------------------------------------------
\1\ Distance from the edge of the nearest traffic lane. The distance for
  intermediate traffic counts should be interpolated from the table
  values based on the actual traffic count.

    6.3 Spacing for Particulate Matter (PM<INF>2.5</INF>, 
PM<INF>10</INF>, Pb) Inlets. (a) Since emissions associated with the 
operation of motor vehicles contribute to urban area particulate 
matter ambient levels, spacing from roadway criteria are necessary 
for ensuring national consistency in PM sampler siting.
    (b) The intent is to locate localized hot-spot sites in areas of 
highest concentrations whether it be from mobile or multiple 
stationary sources. If the area is primarily affected by mobile 
sources and the maximum concentration area(s) is judged to be a 
traffic corridor or street canyon location, then the monitors should 
be located near roadways with the highest traffic volume and at 
separation distances most likely to produce the highest 
concentrations. For the microscale traffic corridor site, the 
location must be between 5 and 15 meters from the major roadway. For 
the microscale street canyon site the location must be between 2 and 
10 meters from the roadway. For the middle scale site, a range of 
acceptable distances from the roadway is shown in figure E-1 of this 
appendix. This figure also includes separation distances between a 
roadway and neighborhood or larger scale sites by default. Any site, 
2 to 15 meters high, and further back than the middle scale 
requirements will generally be neighborhood, urban or regional 
scale. For example, according to Figure E-1 of this appendix, if a 
PM sampler is primarily influenced by roadway emissions and that 
sampler is set back 10 meters from a 30,000 ADT (average daily 
traffic) road, the site should be classified as microscale, if the 
sampler height is between 2 and 7 meters. If the sampler height is 
between 7 and 15 meters, the site should be classified as middle 
scale. If the sample is 20 meters from the same road, it will be 
classified as middle scale; if 40 meters, neighborhood scale; and if 
110 meters, an urban scale.

[[Page 61326]]

[GRAPHIC] [TIFF OMITTED] TR17OC06.061

7. Cumulative Interferences on a Monitoring Path

    (This paragraph applies only to open path analyzers.) The 
cumulative length or portion of a monitoring path that is affected 
by minor sources, trees, or roadways must not exceed 10 percent of 
the total monitoring path length.

8. Maximum Monitoring Path Length

    (This paragraph applies only to open path analyzers.) The 
monitoring path length must not exceed 1 kilometer for analyzers in 
neighborhood, urban, or regional scale. For middle scale monitoring 
sites, the monitoring path length must not exceed 300 meters. In 
areas subject to frequent periods of dust, fog, rain, or snow, 
consideration should be given to a shortened monitoring path length 
to minimize loss of monitoring data due to these temporary optical 
obstructions. For certain ambient air monitoring scenarios using 
open path analyzers, shorter path lengths may be needed in order to 
ensure that the monitoring site meets the objectives and spatial 
scales defined in appendix D to this part. The Regional 
Administrator may require shorter path lengths, as needed on an 
individual basis, to ensure that the SLAMS sites meet the appendix D 
requirements. Likewise, the Administrator may specify the maximum 
path length used at NCore monitoring sites.

9. Probe Material and Pollutant Sample Residence Time

    (a) For the reactive gases, SO<INF>2</INF>, NO<INF>2</INF>, and 
O<INF>3</INF>, special probe material must be used for point 
analyzers. Studies <SUP>20-24</SUP> have been conducted to determine 
the suitability of materials such as polypropylene, polyethylene, 
polyvinyl chloride, Tygon[supreg], aluminum, brass, stainless steel, 
copper, Pyrex[supreg] glass and Teflon[supreg] for use as intake 
sampling lines. Of the above materials, only Pyrex[supreg] glass and 
Teflon[supreg] have been found to be acceptable for use as intake 
sampling lines for all the reactive gaseous pollutants. Furthermore, 
the EPA<SUP>25</SUP> has specified borosilicate glass or FEP 
Teflon[supreg] as the only acceptable probe materials for delivering 
test atmospheres in the determination of reference or equivalent 
methods. Therefore, borosilicate glass, FEP Teflon[supreg] or their 
equivalent must be the only material in the sampling train (from 
inlet probe to the back of the analyzer) that can be in contact with 
the ambient air sample for existing and new SLAMs.
    (b) For volatile organic compound (VOC) monitoring at PAMS, FEP 
Teflon[supreg] is unacceptable as the probe material because of VOC 
adsorption and desorption reactions on the FEP Teflon[supreg]. 
Borosilicate glass, stainless steel, or its equivalent are the 
acceptable probe materials for VOC and carbonyl sampling. Care must 
be taken to ensure that the sample residence time is kept to 20 
seconds or less.
    (c) No matter how nonreactive the sampling probe material is 
initially, after a period of use reactive particulate matter is 
deposited on the probe walls. Therefore, the time it takes the gas 
to transfer from the probe inlet to the sampling device is also 
critical. Ozone in the presence of nitrogen oxide (NO) will show 
significant losses even in the most inert probe material when the 
residence time exceeds 20 seconds.<SUP>26</SUP> Other studies 
<SUP>27-28</SUP> indicate that a 10-second or less residence time is 
easily achievable. Therefore, sampling probes for reactive gas 
monitors at NCore must have a sample residence time less than 20 
seconds.

10. Waiver Provisions

    Most sampling probes or monitors can be located so that they 
meet the requirements of this appendix. New sites with rare 
exceptions, can be located within the limits of this appendix. 
However, some existing sites may not meet these requirements and 
still produce useful data for some purposes. The EPA will consider a 
written request from the State agency to waive one or more siting 
criteria for some monitoring sites providing that the State can 
adequately demonstrate the need (purpose) for monitoring or 
establishing a monitoring site at that location.
    10.1 For establishing a new site, a waiver may be granted only 
if both of the following criteria are met:
    10.1.1 The site can be demonstrated to be as representative of 
the monitoring area as it would be if the siting criteria were being 
met.
    10.1.2 The monitor or probe cannot reasonably be located so as 
to meet the siting criteria because of physical constraints (e.g., 
inability to locate the required type of site the necessary distance 
from roadways or obstructions).
    10.2 However, for an existing site, a waiver may be granted if 
either of the criteria in sections 10.1.1 and 10.1.2 of this 
appendix are met.
    10.3 Cost benefits, historical trends, and other factors may be 
used to add support to the criteria in sections 10.1.1 and 10.1.2 of 
this appendix, however, they in themselves, will not be acceptable 
reasons for granting a waiver. Written requests for waivers must be 
submitted to the Regional Administrator.

11. Summary

    Table E-4 of this appendix presents a summary of the general 
requirements for probe and monitoring path siting criteria with 
respect to distances and heights. It is apparent from Table E-4 that 
different elevation distances above the ground are shown for the 
various pollutants. The discussion in this appendix for each of the 
pollutants describes reasons for elevating the monitor, probe, or 
monitoring path. The differences in the specified range of heights

[[Page 61327]]

are based on the vertical concentration gradients. For CO, the 
gradients in the vertical direction are very large for the 
microscale, so a small range of heights are used. The upper limit of 
15 meters is specified for consistency between pollutants and to 
allow the use of a single manifold or monitoring path for monitoring 
more than one pollutant.

                                Table E-4 of Appendix E to Part 58. Summary of Probe and Monitoring Path Siting Criteria
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          Horizontal and
                                                                                         vertical distance
                                              Scale (maximum      Height from ground      from supporting     Distance from trees      Distance from
                Pollutant                    monitoring path      to probe, inlet or     structures \2\ to    to probe, inlet or     roadways to probe,
                                             length, meters)       80% of monitoring    probe, inlet or 90%    90% of monitoring    inlet or monitoring
                                                                       path \1\         of monitoring path    path \1\  (meters)     path \1\  (meters)
                                                                                           \1\  (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO2 3,4,5,6.............................  Middle (300 m)         2-15................  > 1.................  > 10................  N/A
                                           Neighborhood Urban,
                                           and Regional (1 km).
CO 4,5,7................................  Micro, middle (300     3<plus-minus>\1/2\:   > 1.................  > 10................  2-10; see Table E-2
                                           m), Neighborhood (1    2-15.                                                             of this appendix for
                                           km).                                                                                     middle and
                                                                                                                                    neighborhood scales.
NO2, O3 3,4,5...........................  Middle (300 m)         2-15................  > 1.................  > 10................  See Table E-1 of this
                                           Neighborhood, Urban,                                                                     appendix for all
                                           and Regional (1 km).                                                                     scales.
Ozone precursors (for PAMS) 3,4,5.......  Neighborhood and       2-15................  > 1.................  > 10................  See Table E-4 of this
                                           Urban (1 km).                                                                            appendix for all
                                                                                                                                    scales.
PM,Pb 3,4,5,6,8.........................  Micro: Middle,         2-7 (micro); 2-7      > 2 (all scales,      > 10 (all scales)...  2-10 (micro); see
                                           Neighborhood, Urban    (middle PM10	2.5);    horizontal distance                         Figure E-1 of this
                                           and Regional.          2-15 (all other       only).                                      appendix for all
                                                                  scales).                                                          other scales.
--------------------------------------------------------------------------------------------------------------------------------------------------------
N/A--Not applicable.
\1\ Monitoring path for open path analyzers is applicable only to middle or neighborhood scale CO monitoring and all applicable scales for monitoring
  SO2,O3, O3 precursors, and NO2.
\2\ When probe is located on a rooftop, this separation distance is in reference to walls, parapets, or penthouses located on roof.
\3\ Should be >20 meters from the dripline of tree(s) and must be 10 meters from the dripline when the tree(s) act as an obstruction.
\4\ Distance from sampler, probe, or 90% of monitoring path to obstacle, such as a building, must be at least twice the height the obstacle protrudes
  above the sampler, probe, or monitoring path. Sites not meeting this criterion may be classified as middle scale (see text).
\5\ Must have unrestricted airflow 270 degrees around the probe or sampler; 180 degrees if the probe is on the side of a building.
\6\ The probe, sampler, or monitoring path should be away from minor sources, such as furnace or incineration flues. The separation distance is
  dependent on the height of the minor source's emission point (such as a flue), the type of fuel or waste burned, and the quality of the fuel (sulfur,
  ash, or lead content). This criterion is designed to avoid undue influences from minor sources.
\7\ For microscale CO monitoring sites, the probe must be >10 meters from a street intersection and preferably at a midblock location.
\8\ Collocated monitors must be within 4 meters of each other and at least 2 meters apart for flow rates greater than 200 liters/min or at least 1 meter
  apart for samplers having flow rates less than 200 liters/min to preclude airflow interference.

12. References

    1. Bryan, R.J., R.J. Gordon, and H. Menck. Comparison of High 
Volume Air Filter Samples at Varying Distances from Los Angeles 
Freeway. University of Southern California, School of Medicine, Los 
Angeles, CA. (Presented at 66th Annual Meeting of Air Pollution 
Control Association. Chicago, IL. June 24-28, 1973. APCA 73-158.)
    2. Teer, E.H. Atmospheric Lead Concentration Above an Urban 
Street. Master of Science Thesis, Washington University, St. Louis, 
MO. January 1971.
    3. Bradway, R.M., F.A. Record, and W.E. Belanger. Monitoring and 
Modeling of Resuspended Roadway Dust Near Urban Arterials. GCA 
Technology Division, Bedford, MA. (Presented at 1978 Annual Meeting 
of Transportation Research Board, Washington, DC. January 1978.)
    4. Pace, T.G., W.P. Freas, and E.M. Afify. Quantification of 
Relationship Between Monitor Height and Measured Particulate Levels 
in Seven U.S. Urban Areas. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (Presented at 70th Annual Meeting of Air 
Pollution Control Association, Toronto, Canada. June 20-24, 1977. 
APCA 77-13.4.)
    5. Harrison, P.R. Considerations for Siting Air Quality Monitors 
in Urban Areas. City of Chicago, Department of Environmental 
Control, Chicago, IL. (Presented at 66th Annual Meeting of Air 
Pollution Control Association, Chicago, IL. June 24-28, 1973. APCA 
73-161.)
    6. Study of Suspended Particulate Measurements at Varying 
Heights Above Ground. Texas State Department of Health, Air Control 
Section, Austin, TX. 1970. p.7.
    7. Rodes, C.E. and G.F. Evans. Summary of LACS Integrated 
Pollutant Data. In: Los Angeles Catalyst Study Symposium. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. EPA 
Publication No. EPA-600/4-77-034. June 1977.
    8. Lynn, D.A. et al. National Assessment of the Urban 
Particulate Problem: Volume 1, National Assessment. GCA Technology 
Division, Bedford, MA. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. EPA Publication No. EPA-450/3-75-024. 
June 1976.
    9. Pace, T.G. Impact of Vehicle-Related Particulates on TSP 
Concentrations and Rationale for Siting Hi-Vols in the Vicinity of 
Roadways. OAQPS, U.S. Environmental Protection Agency, Research 
Triangle Park, NC. April 1978.
    10. Ludwig, F.L., J.H. Kealoha, and E. Shelar. Selecting Sites 
for Monitoring Total Suspended Particulates. Stanford Research 
Institute, Menlo Park, CA. Prepared for U.S. Environmental 
Protection Agency, Research Triangle Park, NC. EPA Publication No. 
EPA-450/3-77-018. June 1977, revised December 1977.
    11. Ball, R.J. and G.E. Anderson. Optimum Site Exposure Criteria 
for SO<INF>2</INF> Monitoring. The Center for the Environment and 
Man, Inc., Hartford, CT. Prepared for U.S. Environmental Protection 
Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-
77-013. April 1977.
    12. Ludwig, F.L. and J.H.S. Kealoha. Selecting Sites for Carbon 
Monoxide Monitoring. Stanford Research Institute, Menlo Park, CA. 
Prepared for U.S. Environmental Protection Agency, Research Triangle 
Park, NC. EPA Publication No. EPA-450/3-75-077. September 1975.
    13. Ludwig, F.L. and E. Shelar. Site Selection for the 
Monitoring of

[[Page 61328]]

Photochemical Air Pollutants. Stanford Research Institute, Menlo 
Park, CA. Prepared for U.S. Environmental Protection Agency, 
Research Triangle Park, NC. EPA Publication No. EPA-450/3-78-013. 
April 1978.
    14. Lead Analysis for Kansas City and Cincinnati, PEDCo 
Environmental, Inc., Cincinnati, OH. Prepared for U.S. Environmental 
Protection Agency, Research Triangle Park, NC. EPA Contract No. 66-
02-2515, June 1977.
    15. Barltrap, D. and C.D. Strelow. Westway Nursery Testing 
Project. Report to the Greater London Council. August 1976.
    16. Daines, R. H., H. Moto, and D. M. Chilko. Atmospheric Lead: 
Its Relationship to Traffic Volume and Proximity to Highways. 
Environ. Sci. and Technol., 4:318, 1970.
    17. Johnson, D. E., et al. Epidemiologic Study of the Effects of 
Automobile Traffic on Blood Lead Levels, Southwest Research 
Institute, Houston, TX. Prepared for U.S. Environmental Protection 
Agency, Research Triangle Park, NC. EPA-600/1-78-055, August 1978.
    18. Air Quality Criteria for Lead. Office of Research and 
Development, U.S. Environmental Protection Agency, Washington, DC 
EPA-600/8-83-028 aF-dF, 1986, and supplements EPA-600/8-89/049F, 
August 1990. (NTIS document numbers PB87-142378 and PB91-138420.)
    19. Lyman, D. R. The Atmospheric Diffusion of Carbon Monoxide 
and Lead from an Expressway, Ph.D. Dissertation, University of 
Cincinnati, Cincinnati, OH. 1972.
    20. Wechter, S.G. Preparation of Stable Pollutant Gas Standards 
Using Treated Aluminum Cylinders. ASTM STP. 598:40-54, 1976.
    21. Wohlers, H.C., H. Newstein and D. Daunis. Carbon Monoxide 
and Sulfur Dioxide Adsorption On and Description From Glass, Plastic 
and Metal Tubings. J. Air Poll. Con. Assoc. 17:753, 1976.
    22. Elfers, L.A. Field Operating Guide for Automated Air 
Monitoring Equipment. U.S. NTIS. p. 202, 249, 1971.
    23. Hughes, E.E. Development of Standard Reference Material for 
Air Quality Measurement. ISA Transactions, 14:281-291, 1975.
    24. Altshuller, A.D. and A.G. Wartburg. The Interaction of Ozone 
with Plastic and Metallic Materials in a Dynamic Flow System. 
Intern. Jour. Air and Water Poll., 4:70-78, 1961.
    25. Code of Federal Regulations. Title 40 part 53.22, July 1976.
    26. Butcher, S.S. and R.E. Ruff. Effect of Inlet Residence Time 
on Analysis of Atmospheric Nitrogen Oxides and Ozone, Anal. Chem., 
43:1890, 1971.
    27. Slowik, A.A. and E.B. Sansone. Diffusion Losses of Sulfur 
Dioxide in Sampling Manifolds. J. Air. Poll. Con. Assoc., 24:245, 
1974.
    28. Yamada, V.M. and R.J. Charlson. Proper Sizing of the 
Sampling Inlet Line for a Continuous Air Monitoring Station. 
Environ. Sci. and Technol., 3:483, 1969.
    29. Koch, R.C. and H.E. Rector. Optimum Network Design and Site 
Exposure Criteria for Particulate Matter, GEOMET Technologies, Inc., 
Rockville, MD. Prepared for U.S. Environmental Protection Agency, 
Research Triangle Park, NC. EPA Contract No. 68-02-3584. EPA 450/4-
87-009. May 1987.
    30. Burton, R.M. and J.C. Suggs. Philadelphia Roadway Study. 
Environmental Monitoring Systems Laboratory, U.S. Environmental 
Protection Agency, Research Triangle Park, N.C. EPA-600/4-84-070 
September 1984.
    31. Technical Assistance Document For Sampling and Analysis of 
Ozone Precursors. Atmospheric Research and Exposure Assessment 
Laboratory, U.S. Environmental Protection Agency, Research Triangle 
Park, NC 27711. EPA 600/8-91-215. October 1991.
    32. Quality Assurance Handbook for Air Pollution Measurement 
Systems: Volume IV. Meteorological Measurements. Atmospheric 
Research and Exposure Assessment Laboratory, U.S. Environmental 
Protection Agency, Research Triangle Park, NC 27711. EPA 600/4-90-
0003. August 1989.
    33. On-Site Meteorological Program Guidance for Regulatory 
Modeling Applications. Office of Air Quality Planning and Standards, 
U.S. Environmental Protection Agency, Research Triangle Park, NC 
27711. EPA 450/4-87-013. June 1987F.

Appendix F--[Removed and Reserved]

38. Appendix F to part 58 is removed and reserved.

[FR Doc. 06-8478 Filed 10-16-06; 8:45 am]
BILLING CODE 6560-50-P


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