61236 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

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. 

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 PM10¥2.5 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 PM2.5, 

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; email address: weinstock.lewis@epa.gov. 

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; email address: hanley.tim@epa.gov. 

SUPPLEMENTARY INFORMATION: 

I. General Information 

A. Does this action apply to me? 

Categories and entities potentially 

regulated by this action include: 

Category NAICS code 1 Examples of regulated entities 

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. 

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 


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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. 

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. 

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 PM10¥2.5

C. Requirements for Candidate Equivalent 

Methods PM2.5 and PM10¥2.5

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 

PM10¥2.5 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 PM10¥2.5, 

PM2.5, PM10, 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 PM2.5

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 PM10¥2.5

Stations 

3. Requirements for Operation of PM2.5

Stations 

4. Requirements for Operation of PM10

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 PM10¥2.5 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 PM2.5

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 

(μm) in diameter, PM2.5), EPA is revising 

the level of the 24-hour PM2.5 standard 

to 35 micrograms per cubic meter (μg/ 

m3), 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 PM2.5 standard at 15 

μg/m3, 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 PM2.5

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 PM2.5 secondary standard by 

making it identical to the revised 24- 

hour PM2.5 primary standard, retaining 

the annual PM2.5 and 24-hour PM10

secondary standards, and revoking the 

annual PM10 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 

PM2.5. 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 PM10¥2.5, 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 PM10¥2.5 (see 

appendix O to 40 CFR part 50). This 

FRM is based on paired filter-based 

samplers for PM2.5 and PM10 and it will 

serve as the standard of reference for 

measurements of PM10¥2.5

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 PM10¥2.5 FRM is 

also important in the development of 

alternative PM10¥2.5 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 

PM10¥2.5. These data should be useful in 

improving the understanding of 

PM10¥2.5 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 μm in diameter 

(PM10). However, EPA is retaining the 

24-hour PM10 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 PM10

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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61239 

2NOy refers to a broad class of nitrogencontaining reactive compounds in ambient air, 

explained in more detail in sections V.E.1 and V.E.7 

of this preamble. 

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 PM2.5, 

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 PM2.5. The new 

criteria for PM2.5 FEMs and ARMs will 

facilitate the commercialization and 

EPA approval of continuous PM2.5 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 PM10¥2.5, 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 PM10¥2.5 will facilitate 

approval of filter-based methods for 

direct sampling of PM10¥2.5

concentrations that can be chemically 

speciated using post-sampling 

laboratory analysis. The FEM criteria are 

also expected to encourage 

commercialization of highly timeresolved continuous methods. The EPA 

is hopeful that the PM2.5 and PM10¥2.5

FEM criteria together will result in the 

approval and commercialization of 

methods that provide equivalent 

measurements of PM2.5, PM10, and 

PM10¥2.5 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. PM10¥2.5

measurements may be made on a 1-in3 day schedule rather than the proposed 

every day schedule, NOy 2

measurements may be waived by the 

EPA Administrator based on certain 

criteria, and as explained later in this 

section, PM10¥2.5 chemical speciation 

will be required in addition to PM10¥2.5

mass concentration measurements. 

The EPA estimated that the proposed 

rule would have required States to 

operate about 225 PM10¥2.5 monitors 

based on the population and estimated 

PM10¥2.5 concentrations of metropolitan 

statistical areas (MSAs) with 

populations of 100,000 or more. In 

addition, PM10¥2.5 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 PM10¥2.5, the 

final monitoring rule does not include 

the proposed requirement for the broad 

network of PM10¥2.5 monitoring stations 

in MSAs over 100,000 population. 

However, the final monitoring rule does 

require PM10¥2.5 monitors at the 

required NCore multipollutant 

monitoring stations. The data gathered 

from these stations should be useful in 

improving understanding of PM10¥2.5

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 PM10¥2.5 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 

PM10¥2.5 monitors, or any part of the 

proposed five-part suitability test for 

PM10¥2.5 monitoring sites, which as 

proposed would have controlled 

whether PM10¥2.5 data from a 

monitoring site could be compared to 

the proposed PM10¥2.5 NAAQS. These 

proposed requirements were tied to the 

establishment of a PM10¥2.5 NAAQS 

with a qualified PM10¥2.5 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 PM10¥2.5

NAAQS, our goal nevertheless will be to 

locate PM10¥2.5 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 PM10¥2.5 speciation to be conducted 

at NCore multipollutant monitoring 

stations. The EPA had proposed a 

requirement for PM10¥2.5 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 

PM10¥2.5 NAAQS. This would have 

concentrated the PM10¥2.5 speciation 

monitoring in areas that have high 

populations and high exposures to 

PM10¥2.5. Since EPA is requiring 

PM10¥2.5 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 PM2.5 at NCore stations. 

The collocation of both PM10¥2.5 and 

PM2.5 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 PM10, 

PM10¥2.5, and PM2.5 at a variety of urban 

and rural locations. The EPA will work 

with States to ensure that PM10¥2.5

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 


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and related source emissions that prove 

to be of concern to public health. 

Because the 24-hour PM10 NAAQS is 

being retained in all parts of the 

country, this final rule retains the 

existing minimum monitoring network 

design requirements for PM10. These 

longstanding requirements are based on 

the population of a MSA and its 

historical PM10 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 PM10 air 

quality affect the required number of 

PM10 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 

PM10 monitors have been recording 

concentrations well below the PM10

NAAQS and are candidates for 

discontinuation at a State’s initiative. 

States may choose to retain PM10

monitors that are recording 

concentrations below the PM10 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 PM2.5 and ozone (O3) 

monitoring networks. In response to 

comments, the final requirements 

require more O3 and PM2.5 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 O3

and PM2.5, as did the pre-existing 

monitoring rule, EPA does not intend to 

encourage net reductions in the number 

of O3 and PM2.5 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 O3 and PM2.5. 

For PM2.5, 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 (SO2), and nitrogen 

dioxide (NO2) 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 O3, 

PM2.5, and PM10 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 caseby-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 PM10¥2.5

monitoring is to better understand 

PM10¥2.5 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 PM10¥2.5 monitors 

than proposed, the quality system for 

PM10¥2.5 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 PM2.5 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 PM10, 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 PM10 standards, new 

nonattainment designations for PM10

will not be required under the 

provisions of the Clean Air Act. The 

same is true for CO, NO2, SO2, 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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61241 

3Throughout 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. 

4As explained in section IV.B of this preamble, 

the term ‘‘PM10c’’ refers to a PM10 Federal reference 

method (FRM) that is designated as a PM10c FRM 

under the final NAAQS rule appearing elsewhere in 

today’s Federal Register. In essence, it would be a 

PM2.5 FRM with the inertial fractionator used to 

separate out particles larger than 2.5 microns 

removed so that all PM10 is collected. Unlike other 

PM10 instruments, a PM10c instrument must control 

flow to a specified flow rate of 16.67 liters/minute 

at local conditions of temperature and pressure. A 

PM10¥2.5 FRM consists of a PM2.5 FRM and a PM10c

FRM of the same model. See also 71 FR 2720. 

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 PM10¥2.5 monitors, 

increased O3 monitor distance from 

roadways (for newly established O3

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. 

The following provisions in 40 CFR 

part 53 and part 58 are effective on 

December 18, 2006: 

• The criteria and process for EPA 

Administrator approval of FRMs, FEMs, 

and ARMs or where applicable Regional 

Administrator approval of ARMs. 

Manufacturers of continuous PM2.5 and 

PM10¥2.5 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 

PM2.5 continuous monitor as ARMs 

beginning today, either independently 

or in cooperation with instrument 

manufactures. 

• 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. 

• 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. 

• The criteria for EPA Regional 

Administrator approval for removal of 

monitors that are in excess of minimum 

required, if a State seeks such removal. 

• The criteria for use of data from 

SPMs in determinations of attainment/ 

nonattainment. 

• The elimination of the requirement 

for reporting of certain PM2.5 monitor 

operating parameters. 

• The revised requirement for 

separation between roadways and O3

monitors, for new O3 monitors whose 

placement has not already been 

approved as of December 18, 2006. 

• The new specification for probe 

heights for PM10¥2.5 monitors. 

The new requirement to archive all 

PM10c and PM10¥2.5 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 PM10c or PM10¥2.5 filters this 

early, so most will be affected later.4

The requirement to submit mass data 

on blank PM2.5 filters begins on January 

1, 2007. 

The required date to begin daily PM2.5

sampling at certain PM2.5 monitoring 

sites is January 1, 2007. The EPA 

believes this will affect about 50 PM2.5

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 PM2.5, PM10, or O3

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 O3 and PM2.5 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 PM10¥2.5 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 NAAQSrelated 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 NAAQSrelated 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 


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61242 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

5Technical 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. 

6Additional 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. 

7Additional information on CASTNET is 

available at: http://www.epa.gov/castnet/. 

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 PM10¥2.5

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 PM10¥2.5 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 PM10¥2.5

concentrations in rural and less 

urbanized locations, in addition to the 

PM10¥2.5 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 PM10¥2.5 for collection 

of filters used in chemical speciation 

and for continuous methods that 

measure both PM2.5 and PM10¥2.5. The 

EPA has determined that continuous 

monitoring of PM2.5 has many 

advantages over the filter-based FRM. 

This final rule makes it more practical 

for manufacturers and users of 

continuous PM2.5 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. 

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 

PM2.5 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 PM2.5 attainment 

programs. 

The EPA will also continue to operate 

the Clean Air Status and Trends 

Network (CASTNET), which monitors 

for O3, PM, and chemical components of 

PM in rural areas across the nation.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. 

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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61243 

8Section 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. 

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 preexisting 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 PM2.5-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 PM2.5 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 PM10¥2.5 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. 

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 (PM10¥2.5) 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 PM10¥2.5, EPA believes an 

FRM for PM10¥2.5 is still highly 

desirable to aid in a variety of needed 


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61244 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

9Henderson, 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. 

research studies.9 This new FRM is 

defined as the standard of reference for 

measurement of PM10¥2.5

concentrations in ambient air. It will be 

an acceptable and readily available 

PM10¥2.5 measurement method for new 

NCore multipollutant monitoring sites 

to be located at approximately 75 urban 

and rural locations. Availability of an 

approved FRM for PM10¥2.5 will also 

help provide consistency among 

PM10¥2.5 measurements used in future 

health studies of the adverse health 

effects associated with exposure to 

thoracic coarse particles. Lastly, the 

PM10¥2.5 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 

PM10¥2.5. 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 PM10¥2.5, as 

appropriate. 

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 PM10¥2.5 monitoring networks. 

Alternative methods are needed that 

provide a more direct measurement of 

ambient PM10¥2.5 concentrations. 

Methods are also needed that collect 

samples of PM10¥2.5 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 offsite 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 

PM10¥2.5 by focusing on the explicit test 

and qualification requirements 

necessary for designation of such types 

of methods as FEMs for PM10¥2.5. In 

fact, EPA anticipates that alternative 

FEMs will eventually provide most of 

the PM10¥2.5 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 PM2.5. Accordingly, 

as proposed, EPA is also establishing 

new requirements in part 53 for 

designation of continuous FEMs for 

PM2.5. See 71 FR 2721. The PM2.5 and 

PM10¥2.5 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 

PM10¥2.5 or PM2.5 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, noncontinuous methods for PM2.5. 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 PM10¥2.5. 

B. Requirements for Candidate 

Reference Methods for PM10¥2.5

No comments were received related 

specifically to the PM10¥2.5 FRM 

designation requirements. These 

provisions are adopted as proposed. 

Because of the nearly complete 

similarity between the specifications for 

the new PM10¥2.5 reference method and 

for the existing PM2.5 reference method, 

the designation requirements for 

PM10¥2.5 reference methods are 

essentially the same as those for PM2.5

reference methods. As set forth in the 

new appendix O to 40 CFR part 50, the 

PM10¥2.5 reference method specifies a 

pair of samplers consisting of a 

conventional PM2.5 sampler and a 

special PM10 sampler. The PM2.5

sampler must meet all requirements for 

a PM2.5 reference method in 40 CFR part 

50, appendix L, as well as additional 

requirements in part 53. However, the 

PM10 sampler required by the method is 

not a conventional PM10 sampler as 

described in 40 CFR part 50, appendix 

J; rather, it is a sampler specified to be 

identical to the PM2.5 sampler of the 

pair, except that the PM2.5 particle size 

separator is removed. This special PM10

sampler is identified as a ‘‘PM10c’’

sampler to differentiate it from 

conventional PM10 samplers that meet 

the less exacting requirements of 40 CFR 

part 50, appendix J. In view of the 

similarity of the PM10¥2.5 FRM 

requirements to those of the PM2.5 FRM, 

the new requirements will allow a 

PM10¥2.5 sampler pair consisting of 

samplers that have already been shown 

to meet the PM2.5 FRM requirements 

(except for the PM2.5 particle size 

separator in the case of the PM10c

sampler) to be designated as a PM10¥2.5

reference method without further 

testing. 

C. Requirements for Candidate 

Equivalent Methods for PM2.5 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 PM2.5, 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 PM10¥2.5 candidate FEMs as well. 

Class I methods are limited to minor 

deviations from the FRM; Class II covers 


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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 postweighing of sample filters, require less 

frequent on-site service, may be less 

costly to operate, and offer near realtime, 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 PM10¥2.5 and PM2.5 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 

PM10¥2.5 than available with the FRM. 

These methods are also most likely to 

fulfill the substantial need for collecting 

PM10¥2.5 samples that are physically 

separated from other particle sizes, or 

nearly so, for chemical species analysis. 

New requirements for Class II FEMs for 

PM10¥2.5 are being established in this 

final rule, and some of the previously 

established requirements for Class II 

FEMs for PM2.5 are being changed 

somewhat to make them more 

consistent with the corresponding new 

requirements for PM10¥2.5 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 PM2.5

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 PM2.5 and PM10¥2.5 are similar, so 

concurrent testing for PM2.5 and 

PM10¥2.5 methods of both classes can be 

carried out, substantially reducing the 

testing burden for candidate FEMs that 

measure both PM2.5 and PM10¥2.5 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 PM10¥2.5 and PM2.5 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 PM2.5 and PM10¥2.5, 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 


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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 PM2.5

and PM10¥2.5, 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 PM2.5

(or similar comparisons of PM10¥2.5

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 ±2.0 μg/m3 for PM2.5 methods 

and ±7.0 μg/m3 for PM10¥2.5 methods 

have been added. For Class II FEMs for 

PM10¥2.5, the fixed intercept limit has 

been reduced from ±7.0 to ±3.5 μg/m3. 

(The intercept requirements proposed 

for candidate Class II PM2.5 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 PM10 and PM2.5

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 PM10¥2.5

provisions and some new definitions, 


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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 PM2.5 and PM10¥2.5, 

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 PM2.5

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 

PM2.5 methods that have been approved 

by EPA for use specifically within a 

State, local, or Tribal air monitoring 

network for purposes of comparison to 

the NAAQS and to meet other 

monitoring objectives, but which may 

not have been approved as 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 PM10¥2.5. 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 


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10See S. Rep. No. 91–1196. 91st Cong. 2d Sess. 

10 (1970) (NAAQS is to be set to protect sensitive, 

at-risk population groups). 

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 hardcopy 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. 

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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61249 

establishing a network of PM10¥2.5

stations as an addendum to the annual 

monitoring network plan (see 71 FR 

2740, 2779) since the only required 

PM10¥2.5 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 PM10¥2.5 suitability tests for 

NAAQS comparisons likewise is not 

being adopted since EPA is not 

finalizing the proposed PM10¥2.5

NAAQS. 

The proposed prescriptive wording 

with reference to public hearings in the 

context of reviews of changes to 

violating PM2.5 monitors and/or 

community monitoring zones (71 FR 

2780) has been modified to specify that 

draft plans containing such proposed 

changes to PM2.5 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 PM2.5

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 PM2.5

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 PM2.5.

The EPA proposed that manual 

PM10¥2.5 samplers at SLAMS stations 

must operate on a daily schedule, 

without a requirement for any 

collocated continuously operated FEM 

PM10¥2.5 samplers. See 71 FR 2780. 

Numerous commenters noted that a 1- 

in-3 day sampling frequency was 

acceptable for PM2.5 sites and said that 

the same sampling frequency for 

PM10¥2.5 would produce sufficient data 

for comparison to the proposed 24-hour 

PM10¥2.5 NAAQS averaged over 3 years. 

Commenters also noted the lack of 

currently available continuous FEM 

PM10¥2.5 instruments and the 

burdensome resource requirements 

associated with daily sampling 

requirements using the proposed filterbased FRM. 

The proposed requirement for daily 

PM10¥2.5 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 PM10¥2.5

NAAQS. Since EPA is not finalizing a 

PM10¥2.5 NAAQS but instead is 

requiring a more limited set of PM10¥2.5

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 PM10¥2.5 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 PM10¥2.5

sampling frequency requirement in this 

final rule to 1-in-3 days. 

The EPA proposed reducing the 

sample frequency requirement for PM10

manual methods. Reducing the sample 

frequency for PM10 was possible since 

EPA had proposed to have daily 

sampling of PM10¥2.5 to support 

protection from thoracic coarse 

particles. As published elsewhere in 

today’s Federal Register, EPA is 

retaining the 24-hour PM10 standard and 

not finalizing a PM10¥2.5 standard. The 

EPA is also only finalizing a limited 

network of PM10¥2.5 monitors at multipollutant NCore stations for scientific 

purposes. Therefore, since the existing 

requirement for PM10 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 PM10 NAAQS 

and in seasons exempted by the 

Regional Administrator. 

4. Monitoring Network Completion for 

PM10¥2.5 and NCore Sites 

The proposed requirement for 

specified numbers of PM10¥2.5 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 PM10¥2.5,

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 (O3), 

PM2.5, lead (Pb), and PAMS pollutants 

and to eliminate altogether the 

minimum number of required monitors 

for carbon monoxide (CO), sulfur 

dioxide (SO2) and nitrogen dioxide 

(NO2) 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, 

PM2.5, and O3 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, SO2, and NO2 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 


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61250 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

11 ‘‘Draft National Ambient Air Monitoring 

Strategy,’’ December 2005. 

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 PM2.5 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, PM10, SO2, 

or NO2 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 O3, PM2.5, PM10, 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 casespecific 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. 

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 O3, PM2.5, and PM10

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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 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 PM2.5 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 

PM2.5 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 PM2.5 field 

blank mass in addition to PM2.5 filterbased 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 


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61252 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

instrument and meeting appendix A and 

E requirements) would not be used by 

EPA in attainment/nonattainment 

findings for PM2.5 or O3 if the monitor 

stopped operating by the end of those 2 

years. See 71 FR 2745. For CO, SO2, 

NO2, Pb, and the 24-hour PM10 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 O3 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 

PM2.5 and O3 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, SO2, NO2, Pb, and PM10 NAAQS. 

Unlike the PM2.5 and O3 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 


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12EPA is recodifying this provision in section 

58.30 of the final monitoring rule, but is not 

reconsidering or otherwise reevaluating it. 

contributing to the violation. The EPA 

has worked in this way with States in 

the past. In the case of PM10, 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 PM10 standards, 

new nonattainment designations for 

PM10 will not be required under the 

provisions of the Clean Air Act. 

With respect to the second situation, 

applicable to the CO, SO2, NO2, Pb, and 

24-hour PM10 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 longterm 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 PM2.5 monitors that lack FRM, 

FEM, or ARM status that nevertheless 

would be suitable for an initial study of 

PM2.5 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 PM2.5

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. 

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 counterproductive. 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 PM2.5

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 

PM2.5 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 PM2.5

sites must be population-oriented to be 

comparable to the PM2.5 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 

PM10¥2.5 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 

PM2.5 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 PM2.5 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 


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61254 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

PM10¥2.5. The EPA proposed a new fivepart suitability test for the comparison 

of PM10¥2.5 data to the proposed 

qualified PM10¥2.5 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 PM10¥2.5

qualified indicator and on the proposed 

PM10¥2.5 NAAQS five-part sitesuitability test. These issues are now 

moot since EPA is not adopting a 

NAAQS using a PM10¥2.5 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 SO2, NO2, O3, CO, 

PM2.5, PM10 and PM10¥2.5 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 PM10¥2.5,

PM2.5, PM10 and Total Suspended 

Particulates 

The EPA proposed to revise some of 

the PM2.5 and PM10 QA requirements in 

an attempt to provide consistency in 

implementation and assessment. Since 

PM10¥2.5 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 

PM10¥2.5, PM2.5, and PM10 methods. See 

71 FR 2728. This requirement would 

have increased the audit frequency for 

PM10 monitoring and decreased the 

audit frequency for PM2.5 monitoring. 

Most commenters endorsed the 

proposed approach but a few 

commenters voiced concerns regarding 

the increased frequency for high-volume 

samplers for PM10 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 PM10 and TSP 

only. 

The EPA proposed to revise the 

sampling frequency for the 

implementation of the PM2.5

Performance Evaluation Program (PEP). 

See 71 FR 2726. This proposed 

approach, based on historical PM2.5

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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61255 

13 ‘‘Proposal to Change PM2.5 and PM10

Collocation Sampling Frequency Requriements,’’

Mike Papp and Louise Camalier; November 2005. 

http://www.epa.gov/ttn/amtic/pmgainf.html. 

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 

PM2.5 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 (μ/m3) to 3 

μ/m3 for PM2.5 and PM10c (low-volume 

samplers) and from 20 μ/m3 to 15 μ/m3

for PM10 (high-volume samplers). 

Statistical evaluation of 3 years of PM2.5

and PM10 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. 

Based upon the decision that there is 

no need to implement a PM10¥2.5

monitoring program broad enough to 

systematically determine attainment/ 

nonattainment with a PM10¥2.5 NAAQS, 

EPA has modified the proposed 

PM10¥2.5 collocation precision 

requirement and the Performance 

Evaluation Program (PEP) requirements 

in this final rule. See 71 FR 2726. The 

proposed quality system for PM10¥2.5

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 PM10¥2.5 indicator at this time, 

so EPA is now requiring a network of 

PM10¥2.5 monitors only at NCore 

stations. The goal of these monitors will 

be to improve our understanding of 

PM10¥2.5, support health studies for 

future reviews of the NAAQS, and 

promote improvements in the 

monitoring technology. States may 

choose to operate additional PM10¥2.5

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 PM10¥2.5. 

Also, since it is now anticipated that a 

primary quality assurance organization 

would have very few PM10¥2.5 sites, the 

proposal, if adopted without change, 

would have required almost every 

NCore site to have a collocated second 

PM10¥2.5 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 PM10¥2.5 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 PM10¥2.5 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 PM10¥2.5 site in each 

primary quality assurance organization 

each year. The proposed rule would 

have required five or eight PEP audits 

for PM10¥2.5 in each organization. See 

71 FR 2787, 2788. Since the PEP is 

already being run, at present, for the 

PM2.5 network and it is expected that 

the PM10¥2.5 FRMs will utilize the same 

FRMs as the PM2.5 samplers, the PEP 

audit for the PM10¥2.5 site can count 

towards the required number of PEP 

audits for PM2.5 sites. It will be 

necessary to place a PM10c 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 PM10¥2.5 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 PM10¥2.5 samplers for 

purposes of tracking precision will also 

be minor in most cases. Many of the 

primary quality assurance organizations 

that will implement the PM10¥2.5

monitor at NCore sites are required to 

implement PM2.5 and PM10 networks. 

Some or most of the initial PM10¥2.5

deployments will be with manual FRM 

instruments, similar to the instruments 

used in the PM2.5 networks and to some 

of the instruments used in the PM10

networks. The EPA will allow 

collocated PM10¥2.5 monitors to be 

included in the primary quality 

assurance organization’s count for 

required PM2.5 and PM10 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 

PM10¥2.5 sites that are not already both 

PM2.5 and PM10 sites. The only 

restriction to this aggregated collocation 

count will be for monitoring 

organizations that are operating highvolume PM10 samplers. Since the PM10c

monitor in a PM10¥2.5 FRM will be a 

low-volume sampler, PM10 high-volume 

and PM10 low-volume samplers cannot 

be aggregated together in the collocation 


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61256 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

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 PM10¥2.5 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 PM10 and PM2.5

networks. 

For any FEMs that might be used at 

PM10¥2.5 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 PM2.5. 

The EPA proposed to revise the text 

of 40 CFR part 58, appendix A to cover 

PM10¥2.5 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 PM2.5 PEP programs, or 

from some other independent 

organization. An independent 

organization could be another unit of 

the same agency that is sufficiently 

separated in terms of organizational 

reporting and which can provide for 

independent filter weighing and 

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 PM2.5, PM10¥2.5, and/or 

other NAAQS pollutants, would be 

required to agree that EPA hold back 

part of the grant funds they would 

otherwise receive directly. 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 PM2.5, 

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, SO2, Pb, and 

NO2, 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, SO2, Pb, and NO2 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 


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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 

PM2.5) 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 SO2, NO2, CO, and O3, 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 SO2, NO2, CO, and O3

because there is sufficient QC 

information collected at the site level to 

perform adequate assessments. 

The precision and bias statistics for 

PM measurements (PM10, PM10¥2.5 and 

PM2.5) 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 SO2, NO2, CO, and O3. 

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 SO2 and 

NO2 manual audit checks. A review of 

all SLAMS/NAMS/PAMS sites by 

monitor type revealed that no 

monitoring organizations are using 

manual SO2 or NO2 methods, nor are 

any monitoring organizations expected 

to use these older technologies. 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 onepoint QC check concentration ranges for 

the gaseous pollutants SO2, NO2, O3, 

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 PM10

collocation requirement. See 71 FR 

2726. Fifteen percent of all PM2.5 sites 

are required to maintain collocated 

samplers. For PM10, 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 PM10 collocation 

requirement to match the PM2.5

requirement. This proposed change 

would make the collocation requirement 

consistent for PM2.5 and PM10. 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 PM2.5 flow rate audits. 


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61258 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

14The 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. 

15Technical 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. 

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. 

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 SO2, 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 highsensitivity measurements of CO, SO2, 

and total reactive nitrogen (NOy) 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 PM2.5. 

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 O3, with most expected to use the O3

ultraviolet photometry FEM and the 

nitric oxide (NO) and NO2

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 NOy, 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

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 PM2.5

The EPA proposed amendments that 

expanded the allowed use of alternative 

PM2.5 measurement methods through 

ARMs. See 71 FR 2729. The EPA also 

proposed to extend the existing 

provisions for approval of a 

nondesignated PM2.5 method as a 

substitute for a FRM or FEM at a 

specific individual site to a network of 

sites. This approval would be extended 

on a network basis to allow for 

flexibility in operating a hybrid network 

of PM2.5 FRM and continuous monitors. 

The size of the network, in which the 

ARM could be approved, would be 

based on the location of test sites 

operated during the testing of the 

candidate ARM. The proposed 

amendments 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 PM2.5 NAAQS. 

Many comments were received on 

EPA’s proposal regarding ARMs for 

PM2.5. 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 

PM2.5 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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 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 PM2.5 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 PM2.5 ARMs, 

has been strengthened to address 

concerns about additive bias in cleaner 

environments. The EPA performed an 

extensive investigation into developing 

equivalency criteria for PM2.5

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 PM2.5

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 nonlinear 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 PM2.5

continuous monitor data quality is 

sufficiently comparable to FRMs for 

integration into the agency’s PM2.5

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 PM2.5 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 tightlycontrolled 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 ongoing 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 PM2.5 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 

PM2.5 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 PM2.5

continuous monitors across various 

monitoring agency networks. 

The QA requirements for approval of 

continuous PM2.5 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 PM2.5 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 PM2.5 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 longterm 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 


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61260 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

16To 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 nonrequired sites, the goal is a total of about 75 sites, 

about 20 of which will be rural. 

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 PM2.5 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, PM2.5 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

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 PM2.5, PM10, O3, 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 O2; CO, SO2, and total reactive 

nitrogen (NOy) (using high-sensitivity 

methods, where appropriate); PM2.5

(with both a FRM and a continuous 

monitor); PM2.5 chemical speciation; 

PM10¥2.5 (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, SO2, and NOy 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 PM2.5 and 

PM10¥2.5, 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 NOy measurement, since this 

measurement in some but not all cases 

is little different from the existing NO2

measurement by chemiluminescence, 

which uses the same measurement 

principle as NOy. 

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 NOX method 

provides comparable data to the NOy

method, monitoring agencies should be 

allowed to operate NOX instead of the 

more challenging measurement of NOy. 

However, EPA notes much of the reason 

for NOy and NOX reading being so close 

may be a positive bias with current 

typical NOX (NO + NO2) instruments 

which may over report NO2. Since 

further development of the NOX method 

is underway, monitoring agencies which 

seek waivers for the NOy method are 

encouraged to utilize high sensitivity 

versions of the chemiluminescence 

method so that they are capable of 

switching from high sensitivity NOX to 

high sensitivity NOy 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 NOy method in 

areas where measured NOX is expected 

to provide virtually the same data as 

NOy. This is largely expected to be in 

urban environments until such time as 

the NO2 method (and hence the NOX) is 

sufficiently improved that having 

separate measurements of NOy and NOX

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 


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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 

PM2.5 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 highsensitivity monitors for CO, SO2, and 

NOy that are part of the NCore 

requirement. 

Although EPA is retaining the 24-hour 

PM10 NAAQS for requisite protection 

against short-term exposure to thoracic 

coarse particles and is not promulgating 

a PM10¥2.5 NAAQS, the NCore stations 

are also being required to deploy a 

PM10¥2.5 FRM or FEM to build a dataset 

for scientific research purposes, 

including supporting health studies and 

future reviews of the PM NAAQS. 

Separate PM10 monitoring will not be 

required at NCore stations. For many 

PM10¥2.5 methods, including the FRM, 

PM10 data will be readily available as 

part of the calculated PM10¥2.5

measurement. Even if a PM10¥2.5

method that does not report PM10 is 

approved as an FEM and is deployed to 

one or more NCore sites, PM10 will still 

be available by virtue of the 

independent measurements of PM2.5

and PM10¥2.5 (which could 

appropriately be summed). Therefore, 

EPA is not making measurements of 

PM10 a requirement of the NCore 

network. Also, since the NCore network 

of PM10¥2.5 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 PM10¥2.5 speciation to be conducted 

at NCore multipollutant monitoring 

stations. The EPA had proposed a 

requirement for PM10¥2.5 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 

PM10¥2.5 NAAQS. This would have 

concentrated the PM10¥2.5 speciation 

monitoring in areas that have high 

populations and high exposures to 

PM10¥2.5. Since EPA is requiring 

PM10¥2.5 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 PM2.5 at NCore stations. 

The collocation of both PM10¥2.5 and 

PM2.5 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 PM10 and 

PM10¥2.5, and PM2.5 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 

PM10¥2.5 Stations 

For PM10¥2.5, EPA proposed a new 

minimum network requirement based 

on metropolitan statistical area (MSA) 

population and estimated PM10¥2.5

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 PM10¥2.5 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 PM10¥2.5 design values by 

analyzing concentrations from existing 

collocated or nearly collocated PM10

and PM2.5 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 PM10¥2.5

NAAQS. Monitoring agencies were 

given the option of proposing other 

procedures for calculating estimated 

PM10¥2.5 design values as a substitute 

for EPA-calculated values. 

The EPA’s proposal would have 

required as many as five PM10¥2.5

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 PM10¥2.5

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 PM10¥2.5 network 

would be approximately 250 monitors 

based on these proposed requirements 

and the most recent estimates of 

PM10¥2.5 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 


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17As explained earlier, an approved regional 

method (ARM) is a PM2.5 method that has been 

approved specifically within a State, local, or Tribal 

air monitoring network for purposes of comparison 

to the National Ambient Air Quality Standards and 

to meet other monitoring objectives. See section 

V.D.2 of this preamble. 

estimated size of the required PM10¥2.5

network to approximately 225 monitors 

(not counting PM10¥2.5 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 

PM10¥2.5 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 PM10¥2.5 NAAQS. 

The EPA received extensive 

comments on all aspects of the PM10¥2.5

network design proposal including the 

minimum monitoring requirements, 

five-part suitability test for PM10¥2.5

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 PM10¥2.5 NAAQS 

but instead will be retaining the current 

24-hour PM10 standard. Therefore, the 

elements of the PM10¥2.5 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 PM10¥2.5 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 PM2.5

Stations 

The PM2.5 network includes over 

1,200 FRM samplers at approximately 

900 sites that are operated to determine 

compliance with the NAAQS; track 

trends, development, and accountability 

of emission control programs; and 

provide data for health and ecosystem 

assessments that contribute to periodic 

reviews of the NAAQS. More than 500 

continuous PM2.5 monitors are operated 

to support public reporting and 

forecasting of the AQI. 

The EPA proposed to modify the 

network minimum requirements for 

PM2.5 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 PM2.5 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. 

The EPA proposed to require that all 

sites counted by a State towards meeting 

the minimum requirement for the 

number of PM2.5 sites have an FRM, 

FEM, or ARM monitor. The EPA also 

proposed that at least one-half of all the 

required PM2.5 sites be required to 

operate PM2.5 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 PM2.5 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 PM2.5 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 PM2.5

problem and possibly in more need of 

other types of data to address it. 

We proposed to retain the current 

siting criteria for PM2.5, 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 PM2.5 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 

PM2.5. To meet these requirements, 

IMPROVE samplers could be used even 

though they would not be eligible for 

comparison to the PM2.5 NAAQS; these 

samplers are currently used in visibility 

monitoring programs in Class I areas 

and national parks. Sites in other States 

which are located at places that make 

them appropriate as background and 

transport sites could also fulfill these 

minimum siting requirements. 

The preamble to the proposal also 

pointed out that in most MSAs, the 

PM2.5 monitor recording the maximum 

annual PM2.5 concentrations is the same 

as the monitor showing the maximum 

24-hour PM2.5 concentrations, 

suggesting that generally it will be these 

common high-reading monitors that will 

determine attainment/nonattainment for 

both the annual and 24-hour PM2.5

NAAQS. 71 FR 2742. The preamble 

further noted that where this is the case, 

supplemental monitors, such as 

continuous PM2.5 monitors and PM2.5

speciation monitors, should already be 

well located to help in understanding 

the causes of the high PM2.5

concentrations. In a relatively small 

number of cases, certain microscale 

PM2.5 monitors that have not been 

eligible for comparison to the annual 

PM2.5 NAAQS and that have been 

complying with the pre-existing 24-hour 

PM2.5 NAAQS of 65 μg/m3, 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 PM2.5 standard. In 

these cases, EPA noted that States may 

choose to move accompanying 

speciation and continuous monitors to 


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the new site of particular interest to get 

a better characterization of PM2.5 at that 

location. 

The EPA received a number of 

comments regarding the PM2.5 network 

design. Several commenters expressed 

concern regarding the provision to allow 

fewer required sites when monitored 

PM2.5 concentrations are significantly 

above the PM2.5 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 PM2.5 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 PM2.5 monitoring 

network to provide for one-half the 

required sites, rounded-up, to operate 

PM2.5 continuous monitors. 

Commenters expressed concern that 

requiring PM2.5 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 PM2.5

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 PM2.5 monitoring sites, 

questioning EPA’s proposal to keep the 

siting requirements for PM2.5 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 PM2.5 monitoring sites 

when monitored PM2.5 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 PM2.5 NAAQS (less than or equal to 

85 percent of the annual and 24-hour 

PM2.5 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 PM2.5 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 PM2.5

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 PM2.5 monitoring 

requirements. In a CSA, each MSA must 

meet the MSA requirements separately. 

In considering the comments on 

requiring one-half the required PM2.5

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 

PM2.5 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 

PM2.5 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 PM2.5

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 PM2.5 NAAQS, 

EPA agrees that the proposed change in 

the level of the primary 24-hour PM2.5

NAAQS from 65 μg/m3 to 35 μg/m3

raised the issue of whether any 

commensurate changes would be 

needed in these requirements. The EPA 

has considered the original 

requirements for PM2.5 network design 

promulgated in 1997 and their rationale, 

how the PM2.5 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 PM2.5

NAAQS in combination with the annual 

PM2.5 NAAQS, and whether these or any 

changes should be required by a general 

rule or developed on a case-by-case 

basis. 


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61264 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

18The possible additional monitoring discussed 

in the text above could be compared solely to the 

24-hour PM2.5 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 populationoriented middle-scale areas, may not be compared 

to the annual PM2.5 NAAQS. 

In specifying monitor siting criteria 

for the original PM2.5 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 PM2.5 concentrations across 

each annual NAAQS nonattainment 

area. Accordingly, the PM2.5 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 PM2.5 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 PM2.5

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 populationoriented to be compared to either 

NAAQS. Part 58 App. D section 

2.8.1.2.3. 

In practice, the majority of PM2.5

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 communityoriented. The existing PM2.5 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 PM2.5

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 PM2.5 networks 

that were deployed were, and the 

networks that are now operating 

currently are, consistent with the 

intended level of protection of the 

annual PM2.5 NAAQS. Consistency or 

inconsistency with regard to the 24-hour 

PM2.5 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 PM2.5 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 PM2.5

NAAQS. 71 FR 2742. The EPA 

continues to believe this, noting that the 

monitors used in the epidemiology 

studies underlying the 24-hour PM2.5

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 PM2.5 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 

PM2.5 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 PM2.5 NAAQS. States may 

also propose, and EPA would be 

inclined to approve, the placement of 

PM2.5 monitors in populated areas too 

small to be subject to the requirements 

regarding minimum numbers of 

monitors, if there is reason to believe 

PM2.5 concentrations are of concern. Of 

particular interest may be smaller cities 

and towns which presently lack any 

PM2.5 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 PM2.5. 

States also remain free to place SPM at 

any location, without need for EPA 

review or approval.18

The proposed rule text for 40 CFR 58, 

appendix D inadvertently failed to 

include rule text on PM2.5 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 PM2.5 concentrations 

and their causes at that location. 

Finally, this final rule clarifies that 

IMPROVE monitors operated by an 


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19As 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.’’

organization other than the State may be 

counted as satisfying the State’s 

obligation to operate background and 

transport monitoring sites for PM2.5. 

4. Requirements for Operation of PM10

Stations 

PM10 monitors currently are deployed 

throughout the country at about 1,200 

sites, with most metropolitan areas 

already operating more PM10 monitors 

than are required by current monitoring 

requirements. 

In the January 17, 2006, proposal 

notice, EPA proposed changes to the 

PM10 requirements in coordination with 

new minimum requirements for a 

PM10¥2.5 monitoring network in support 

of the proposed 24-hour PM10¥2.5

NAAQS which would have eventually 

replaced the PM10 NAAQS entirely. See 

71 FR 2742. As already explained, EPA 

is not finalizing the proposed NAAQS 

for PM10¥2.5 and instead is retaining the 

24-hour PM10 NAAQS for all parts of the 

U.S. This change has necessitated a 

different approach for PM10 minimum 

monitoring requirements from the one 

proposed. 

Rather than revoking PM10 monitoring 

requirements, as proposed, EPA believes 

that a robust nationwide monitoring 

network is required to provide 

compliance data for the 24-hour PM10

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 PM10 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 PM10 monitors that is similar 

to the required numbers of ozone and 

PM2.5 monitors, EPA believes these 

criteria are appropriate. With regard to 

the comparison to the required numbers 

of ozone and PM2.5 monitors, EPA has 

considered two directionally opposite 

factors. PM10 is less spatially uniform 

than O3 or PM2.5, suggesting the need for 

relatively more intensive monitoring in 

areas with PM10 problems, but PM10

concentrations in most areas are below 

the PM10 NAAQS (unlike for O3 and 

PM2.5) suggesting that fewer monitors 

should be required overall for PM10. 

This final rule therefore retains the 

current PM10 minimum network 

requirements, except that these will no 

longer be called ‘‘NAMS’’ requirements. 

The current PM10 minimum 

monitoring requirements in section 

3.7.7 of part 58 appendix D are based on 

MSA population and three different 

ranges of ambient PM10 concentrations 

as compared to the PM10 NAAQS. For 

MSAs in the lowest category of ambient 

PM10 concentrations, those for which 

ambient PM10 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 PM10

concentrations, those for which ambient 

PM10 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 PM10 ambient data for 2003–

2005 and current census population 

statistics, a minimum of between 200 

and 500 PM10 FRM/FEM monitors will 

be required across all affected MSAs. 

Over 800 PM10 monitors are in fact 

currently deployed in these MSAs. 

About 400 other PM10 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 PM10, 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 PM10 monitors have 

been recording concentrations well 

below the 24-hour PM10 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 PM10 monitors deployed, EPA 

believes, consistent with the basis for 

retaining the 24-hour PM10 standard, 

priority should be given to maintaining 

monitors sited in urban and industrial 19

areas. States may of course choose to 

retain PM10 monitors that are recording 

concentrations below the PM10 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 PM10

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 PM10 networks below the 

minimum requirements for monitoring 

within MSAs given in 40 CFR part 58 

appendix D. 

In addition, if States and Tribes are 

considering deploying new PM10

monitors, EPA recommends, again 

consistent with the basis for retaining 

the 24-hour PM10 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 PM10 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 (PM10) 

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 PM2.5 and 

PM10, in some sentences referring 

explicitly to PM2.5, PM10, or both, and in 

some sentences referring only in general 

to particulate matter. In this final rule, 

section 4.6 (Particulate Matter (PM10) 


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Design Criteria) addresses this subject 

matter for PM10, while section 4.7 (Fine 

Particulate Matter (PM2.5) Design 

Criteria) does so for PM2.5. 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 PM10, in terms of 

clarifying and preserving the effective 

substance of the 1997 rule for PM10. 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 

PM2.5 specifically but not PM10, (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 

PM10, (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 PM10

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 PM10

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 PM10

monitoring, because of the short 

transport distances for PM10, especially 

when emitted near ground level. In 

contrast, because PM2.5 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, 

SO2, NO2, 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, SO2, 

and NO2 monitoring networks, and 

reduce the requirements for Pb. See 71 

FR 27423. The proposal allowed for 

reductions in ambient air monitoring for 

CO, SO2, NO2, and Pb, particularly 

where measured levels are well below 

the applicable NAAQS and air quality 

problems are not expected, except in 

cases with ongoing regulatory 

requirements for monitoring such as SIP 

or permit provisions. 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, SO2, and NOy 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 (O3) monitors currently are 

deployed throughout the country at 

about 1,200 sites, with most 

metropolitan areas already operating 

more O3 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 O3 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 O3 in an area. 

For O3, 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 O3, 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 O3 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 PM2.5 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 O3. Similar to 

the comments received on PM2.5, 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 O3

across a metropolitan area. 

In response to concerns about 

allowing one less O3 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 O3 NAAQS (less than or equal to 85 

percent of the O3 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 O3

monitoring sites. 

To address the comments concerning 

the most appropriate Census Bureaudefined area for which to apply the O3

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 


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O3 will be characterized in high 

concentration areas, EPA is adopting 

MSA as the appropriate unit of a 

metropolitan area to apply the 

minimum O3 monitoring requirements. 

All other monitoring requirements for 

O3 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 O3, 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 O3

standard. Conventional NO2/NOX

monitors would only be required at 

Type 2 sites. High sensitivity NOy

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 O3 monitoring 

initiatives. However, some commenters 

were concerned with the proposed 

requirement for NOy monitoring at one 

Type 1 or one Type 3 site. Several 

commenters stated that the PAMS NOy

requirement is not likely to be 

beneficial. They argued that NOy data in 

urban areas are likely to be 

indistinguishable from NOX data, the 

commercial NOy instrumentation is not 

yet fully developed, NOy monitors are 

difficult to site properly, and that few 

States have the modeling capability to 

employ NOy data. 

The EPA disagrees with the 

commenters’ statements that PAMS NOy

measurements will not be beneficial. As 

compared to NOX measurements, NOy

measurements provide a more complete 

measurement of the available reactive 

nitrogen species involved in the 

photochemical reactions that lead to O3

formation. One of the primary uses of 

NOy data is for O3 modeling. However, 

O3 modeling is not the only use for NOy

data. Long-term measurements of NOy

provide the best indicator of the 

effectiveness of NOX controls at 

reducing the reactive nitrogen 

compounds involved in O3 formation. In 

addition, a relatively simple analysis of 

the O3-to-NOy ratio, or VOC-to-NOy ratio 

can be performed to identify if an area 

is ‘‘NOX limited’’ or ‘‘VOC limited’’

which would indicate if additional NOX

controls would be more beneficial than 

additional VOC controls. 

Ideally, the NOX method should 

measure NO and NO2, whereas NOy

measurements include NO, NO2, and 

other important reactive nitrogen 

species (referred to here as NOz) which 

includes nitrous acids [nitric acid 

(HNO3), 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 NOX monitors also measure 

(and misreport as NO2) some NOz 

species. The NOy method was 

developed as an extension of the NOX

method to accurately measure all 

reactive nitrogen compounds. 

Nonetheless, EPA will allow for waivers 

of the NOy method (via an alternative 

plan provided for under paragraph 5.3 

of appendix D to part 53) in areas where 

measured NOX is expected to provide 

virtually the same data as NOy. This is 

largely expected to be in areas with 

fresh oxides of nitrogen emissions until 

such time as the NO2 method (and 

hence the NOX method) is sufficiently 

improved that having separate 

measurements of NOy and NOX provides 

more useful information than the 

existing technology. The EPA has 

evaluated a number of commercially 

available NOy 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 NOy monitor 

(installing a 10 meter tower and meeting 

proper fetch characteristics) may be 

difficult in some urban settings, EPA 

believes that NOy monitors can be 

adequately sited at most PAMS areas. 

Nonetheless, if siting a NOy 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 NOX instead of 

monitoring for NOy. 

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 PM10¥2.5 and O3 monitoring 

sites. See 71 FR 2748. 

1. Vertical Placement of PM10¥2.5

Samplers 

Specific probe siting criteria were 

required to support the proposed 

PM10¥2.5 network. The EPA proposed 

vertical probe placement requirements 

that limited microscale PM10¥2.5 sites to 

an allowable height range of 2 to 7 

meters and neighborhood and large 

scale PM10¥2.5 sites to a range of 2 to 15 

meters. These ranges were identical to 

the existing requirements for PM10. The 

range for middle-scale PM10¥2.5 sites 

was limited to 2 to 7 meters which 

represented a change from PM10 where 

2 to 15 meters was the allowed vertical 

placement range for middle-scale sites. 

Several commenters supported the 

proposed PM10¥2.5 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 


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importance of keeping identical inlet 

requirements for PM10¥2.5 and PM2.5 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 PM10¥2.5

sites. This requirement is consistent 

with current requirements for 

microscale PM monitors but would 

require modifications for existing PM2.5

and PM10 monitors located between 8 

and 15 meters above ground that were 

intended for middle-scale PM10¥2.5

measurement. The EPA does not expect 

this requirement to have a major impact 

on monitoring networks since this final 

rule requires PM10¥2.5 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 vehiclerelated nitric oxide emissions. See 71 

FR 2748. 

Many commenters believed that the 

scavenging effects of oxides of nitrogen 

on O3 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 O3 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 PM2.5

filters and require a minimum storage 

requirement of 1 year. The EPA 

proposed that retention requirements be 

expanded to require archival of PM2.5, 

PM10¥2.5, and PM10c (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 


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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 PM10¥2.5 FEM and 

FRM determinations, Class II equivalent 

methods for PM10¥2.5 and Class III 

equivalent methods for PM2.5 and 

PM10¥2.5; 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 

PM1010¥2.5, 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-forprofit 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 


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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, 


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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 PM2.5 are currently 

measured by the Federal reference 

method in 40 CFR part 50, appendix L 

(Reference Method for the 

Determination of Fine Particulate as 

PM2.5 in the Atmosphere) or by FRM or 

FEM that meet the requirements in 40 

CFR part 53. Ambient air concentrations 

of PM10¥2.5 will be measured by the 

final FRM in 40 CFR part 50, appendix 

O (Reference Method for the 

Determination of Coarse Particulate 

Matter as PM10¥2.5 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 PM10¥2.5 is 

similar to the existing methods for PM2.5

and PM10. 

Procedures are included in this final 

rule that allow for approval of an FEM 

for PM10¥2.5 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. 

■ 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] 

■ 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] 

■ 2. Sections 53.1 through 53.5 are 

revised to read as follows: 

§ 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 

§ 53.4, or a person or entity who 

assumes the rights and obligations of an 

applicant under § 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), 


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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 § 53.4, or a method 

tested at the initiative of the 

Administrator in accordance with 

§ 53.7. 

Class I equivalent method means an 

equivalent method for PM2.5 or PM10¥2.5

which is based on a sampler that is very 

similar to the sampler specified for 

reference methods in appendix L or 

appendix O (as applicable) of part 50 of 

this chapter, with only minor deviations 

or modifications, as determined by EPA. 

Class II equivalent method means an 

equivalent method for PM2.5 or PM10¥2.5

that utilizes a PM2.5 sampler or PM10¥2.5

sampler in which integrated PM2.5

samples or PM10¥2.5 samples are 

obtained from the atmosphere by 

filtration and subjected to a subsequent 

filter conditioning process followed by 

a gravimetric mass determination, but 

which is not a Class I equivalent method 

because of substantial deviations from 

the design specifications of the sampler 

specified for reference methods in 

appendix L or appendix O (as 

applicable) of part 50 of this chapter, as 

determined by EPA. 

Class III equivalent method means an 

equivalent method for PM2.5 or PM10¥2.5

that is an analyzer capable of providing 

PM2.5 or PM10¥2.5 ambient air 

measurements representative of onehour or less integrated PM2.5 or PM10¥2.5

concentrations as well as 24-hour 

measurements determined as, or 

equivalent to, the mean of 24 one-hour 

consecutive measurements. 

CO means carbon 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 § 53.11 or § 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 § 53.11 or § 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 PM10 or PM2.5

which utilizes a sampler that requires 

manual preparation, loading, and 

weighing of filter samples is considered 

a manual method even though the 

sampler may be capable of 

automatically collecting a series of 

sequential samples. 

NO means nitrogen oxide. 

NO2 means nitrogen dioxide. 

NOX means oxides of nitrogen and is 

defined as the sum of the concentrations 

of NO2 and NO. 

O3 means ozone. 

Operated simultaneously means that 

two or more collocated samplers or 

analyzers are operated concurrently 

with no significant difference in the 

start time, stop time, and duration of the 

sampling or measurement period. 

Pb means lead. 

PM means PM10, PM10C, PM2.5, 

PM10¥2.5, 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 PM2.5, designed to collect 

PM2.5 from an ambient air sample, but 

lacking the ability to automatically 

analyze or measure the collected sample 

to determine the mass concentrations of 

PM2.5 in the sampled air. 

PM10 sampler means a device, 

associated with a manual method for 

measuring PM10, designed to collect 

PM10 from an ambient air sample, but 

lacking the ability to automatically 

analyze or measure the collected sample 

to determine the mass concentrations of 

PM10 in the sampled air. 

PM10C sampler means a PM10 sampler 

that meets the special requirements for 

a PM10C sampler that is part of a 

PM10¥2.5 reference method sampler, as 

specified in appendix O to part 50 of 

this chapter, or a PM10 sampler that is 

part of a PM10¥2.5 sampler that has been 

designated as an equivalent method for 

PM10¥2.5. 


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PM10¥2.5 sampler means a sampler, or 

a collocated pair of samplers, associated 

with a manual method for measuring 

PM10¥2.5 and designed to collect either 

PM10¥2.5 directly or PM10C and PM2.5

separately and simultaneously from 

concurrent ambient air samples, but 

lacking the ability to automatically 

analyze or measure the collected 

sample(s) to determine the mass 

concentrations of PM10¥2.5 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 PM10 sampler, 

PM2.5 sampler, or PM10¥2.5 sampler 

subjected to testing as part of a 

candidate method in accordance with 

subparts C, D, E, or F of this part. 

Ultimate purchaser means the first 

person or entity who purchases a 

Federal reference method or a Federal 

equivalent method for purposes other 

than resale. 

§ 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 

SO2 and lead, appendices A and G of 

part 50 of this chapter specify unique 

manual FRM for measuring these 

pollutants. Except as provided in 

§ 53.16, other manual methods for SO2

and lead will not be considered for FRM 

determinations under this part. 

(2) PM10. A FRM for measuring PM10

must be a manual method that meets all 

requirements specified in appendix J of 

part 50 of this chapter and must include 

a PM10 sampler that has been shown in 

accordance with this part to meet all 

requirements specified in this subpart A 

and subpart D of this part. 

(3) PM2.5. A FRM for measuring PM2.5

must be a manual method that meets all 

requirements specified in appendix L of 

part 50 of this chapter and must include 

a PM2.5 sampler that has been shown in 

accordance with this part to meet the 

applicable requirements specified in 

this subpart A and subpart E of this part. 

Further, FRM samplers must be 

manufactured in an ISO 9001-registered 

facility, as defined in § 53.1 and as set 

forth in § 53.51. 

(4) PM10¥2.5. A FRM for measuring 

PM10¥2.5 must be a manual method that 

meets all requirements specified in 

appendix O of part 50 of this chapter 

and must include PM10C and PM2.5

samplers that have been shown in 

accordance with this part to meet the 

applicable requirements specified in 

this subpart A and subpart E of this part. 

Further, PM10¥2.5 FRM samplers must 

be manufactured in an ISO 9001- 

registered facility, as defined in § 53.1 

and as set forth in § 53.51. 

(b) Automated methods. An 

automated FRM for measuring CO, O3, 

or NO2 must utilize the measurement 

principle and calibration procedure 

specified in the appropriate appendix to 

part 50 of this chapter and must have 

been shown in accordance with this part 

to meet the requirements specified in 

this subpart A and subpart B of this 

part. 

§ 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 PM10, PM2.5, or PM10¥2.5

must have been shown in accordance 

with this part to satisfy the following 

additional requirements, as applicable: 

(1) PM10. A PM10 sampler associated 

with a manual method for PM10 must 

satisfy the requirements of subpart D of 

this part. 

(2) PM2.5 Class I. A PM2.5 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 PM2.5 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 PM2.5

methods in subparts C and F of this 

part, a Class II PM2.5 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 PM2.5 in subpart 

C of this part. 

(4) PM10¥2.5 Class I. A PM10¥2.5 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 

PM10¥2.5 methods in subpart C of this 

part). 

(5) PM10¥2.5 Class II. (i) A PM10¥2.5

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 

PM10¥2.5 methods in subpart C of this 

part and in paragraph (b)(3)(iii) of this 

section, a Class II PM10¥2.5 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 PM10¥2.5 in subpart C of this 

part. 

(6) ISO 9001. All designated FEMs for 

PM2.5 or PM10¥2.5 must be manufactured 

in an ISO 9001-registered facility, as 

defined in § 53.1 and as set forth in 

§ 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 PM10 must 

be shown in accordance with this part 

to satisfy the applicable requirements of 

subpart D of this part. 

(3) A Class III automated FEM for 

PM2.5 or PM10¥2.5 must be shown in 

accordance with this part to satisfy the 

requirements in paragraphs (b)(3)(i) 

through (iii) of this section, as 

applicable. 

(i) All pertinent requirements of 40 

CFR part 50, appendix L, including 

sampling height, range of operational 

conditions, ambient temperature and 

pressure sensors, outdoor enclosure, 

electrical power supply, control devices 

and operator interfaces, data output 

port, operation/instruction manual, data 

output and reporting requirements, and 

any other requirements that would be 

reasonably applicable to the method, 

unless adequate (as determined by the 

Administrator) rationale can be 


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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 § 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 §§ 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 windtunnel tests similar to those described in 

§ 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 PM2.5 or 

PM10¥2.5 must be manufactured in an 

ISO 9001-registered facility, as defined 

in § 53.1 and as set forth in § 53.51. 

§ 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 § 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 PM2.5 or 

PM10¥2.5 must meet all applicable 

requirements in reference 1 of appendix 

A of this subpart, using appropriate 

graphical, nomenclature, and 

mathematical conventions such as those 

specified in references 3 and 4 of 

appendix A of this subpart. 

(3) A copy of a comprehensive 

operation or instruction manual 

providing a complete and detailed 

description of the operational, 

maintenance, and calibration 

procedures prescribed for field use of 

the candidate method and all 

instruments utilized as part of that 

method (under § 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 § 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 


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from these references include the 

following: 

(i) The applicant shall maintain and 

include records of all relevant 

measuring equipment, including the 

make, type, and serial number or other 

identification, and most recent 

calibration with identification of the 

measurement standard or standards 

used and their National Institute of 

Standards and Technology (NIST) 

traceability. These records shall 

demonstrate the measurement capability 

of each item of measuring equipment 

used for the application and include a 

description and justification (if needed) 

of the measurement setup or 

configuration in which it was used for 

the tests. The calibration results shall be 

recorded and identified in sufficient 

detail so that the traceability of all 

measurements can be determined and 

any measurement could be reproduced 

under conditions close to the original 

conditions, if necessary, to resolve any 

anomalies. 

(ii) Test data shall be collected 

according to the standards of good 

practice and by qualified personnel. 

Test anomalies or irregularities shall be 

documented and explained or justified. 

The impact and significance of the 

deviation on test results and 

conclusions shall be determined. Data 

collected shall correspond directly to 

the specified test requirement and be 

labeled and identified clearly so that 

results can be verified and evaluated 

against the test requirement. 

Calculations or data manipulations must 

be explained in detail so that they can 

be verified. 

(6) A statement that the method, 

analyzer, or sampler tested in 

accordance with this part is 

representative of the candidate method 

described in the application. 

(c) For candidate automated methods 

and candidate manual methods for 

PM10, PM2.5, and PM10¥2.5 the 

application shall also contain the 

following: 

(1) A detailed description of the 

quality system that will be utilized, if 

the candidate method is designated as a 

reference or equivalent method, to 

ensure that all analyzers or samplers 

offered for sale under that designation 

will have essentially the same 

performance characteristics as the 

analyzer(s) or samplers tested in 

accordance with this part. In addition, 

the quality system requirements for 

candidate methods for PM2.5 and 

PM10¥2.5 must be described in sufficient 

detail, based on the elements described 

in section 4 of reference 1 (Quality 

System Requirements) of appendix A of 

this subpart. Further clarification is 

provided in the following sections of 

reference 2 of appendix A of this 

subpart: part A (Management Systems), 

sections 2.2 (Quality System and 

Description), 2.3 (Personnel 

Qualification and Training), 2.4 

(Procurement of Items and Services), 2.5 

(Documents and Records), and 2.7 

(Planning); part B (Collection and 

Evaluation of Environmental Data), 

sections 3.1 (Planning and Scoping), 3.2 

(Design of Data Collection Operations), 

and 3.5 (Assessment and Verification of 

Data Usability); and part C (Operation of 

Environmental Technology), sections 

4.1 (Planning), 4.2 (Design of Systems), 

and 4.4 (Operation of Systems). 

(2) A description of the durability 

characteristics of such analyzers or 

samplers (see § 53.9(c)). For methods for 

PM2.5 and PM10¥2.5 the warranty 

program must ensure that the required 

specifications (see Table A–1 to this 

subpart) will be met throughout the 

warranty period and that the applicant 

accepts responsibility and liability for 

ensuring this conformance or for 

resolving any nonconformities, 

including all necessary components of 

the system, regardless of the original 

manufacturer. The warranty program 

must be described in sufficient detail to 

meet appropriate provisions of the 

ANSI/ASQC and ISO 9001 standards 

(references 1 and 2 in appendix A of 

this subpart) for controlling 

conformance and resolving 

nonconformance, particularly sections 

4.12, 4.13, and 4.14 of reference 1 in 

appendix A of this subpart. 

(i) Section 4.12 in reference 1 of 

appendix A of this subpart requires the 

manufacturer to establish and maintain 

a system of procedures for identifying 

and maintaining the identification of 

inspection and test status throughout all 

phases of manufacturing to ensure that 

only instruments that have passed the 

required inspections and tests are 

released for sale. 

(ii) Section 4.13 in reference 1 of 

appendix A of this subpart requires 

documented procedures for control of 

nonconforming product, including 

review and acceptable alternatives for 

disposition; section 4.14 in reference 1 

of appendix A of this subpart requires 

documented procedures for 

implementing corrective (4.14.2) and 

preventive (4.14.3) action to eliminate 

the causes of actual or potential 

nonconformities. In particular, section 

4.14.3 requires that potential causes of 

nonconformities be eliminated by using 

information such as service reports and 

customer complaints to eliminate 

potential causes of nonconformities. 

(d) For candidate reference or 

equivalent methods for PM2.5 and Class 

II or Class III equivalent methods for 

PM10¥2.5, the applicant, if requested by 

EPA, shall provide to EPA for test 

purposes one sampler or analyzer that is 

representative of the sampler or 

analyzer associated with the candidate 

method. The sampler or analyzer shall 

be shipped FOB destination to Director, 

National Exposure Research Laboratory, 

Reference and Equivalent Method 

Program (MD-D205–03), U.S. 

Environmental Protection Agency, 4930 

Old Page Road, Durham, North Carolina 

27703, scheduled to arrive concurrent 

with or within 30 days of the arrival of 

the other application materials. This 

analyzer or sampler may be subjected to 

various tests that EPA determines to be 

necessary or appropriate under § 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. 

§ 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 § 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 


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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: 

§ 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. 

§ 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 § 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 

§ 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, PM10 sampler, PM2.5

sampler, or PM10¥2.5 sampler offered for 

sale as part of a FRM or FEM shall 

function within the limits of the 

performance specifications referred to in 

§ 53.20(a), § 53.30(a), § 53.50, or § 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 

§ 53.4(b)(3). 

(d) Any analyzer, PM10 sampler, PM2.5

sampler, or PM10¥2.5 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, 

PM10 samplers, PM2.5 samplers, or 

PM10¥2.5 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 § 53.11 or § 53.16 or if 

adjustment of the analyzer or sampler is 

necessary under § 53.11(b). 

(g) If an applicant modifies an 

analyzer, PM10 sampler, PM2.5 sampler, 

or PM10¥2.5 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 § 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 § 53.8(b) of a 

new FRM or FEM determination for the 

modified analyzer or sampler. 

(h) An applicant who has offered 

PM2.5 or PM10¥2.5 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 

§ 53.11. 

(i) An applicant who has offered PM2.5

or PM10¥2.5 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 

§ 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. 

Pollutant Ref. or equivalent Manual or automated 

Applicable 

part 50 appendix 

Applicable subparts of part 53 

A B C D E F 

SO2 .............. Reference ................................ Manual ..................................... A ...................

Equivalent ................................ Manual ..................................... ...................... ✓ ✓ 


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TABLE A–1 TO SUBPART A OF PART 53.—SUMMARY OF APPLICABLE REQUIREMENTS FOR REFERENCE AND EQUIVALENT

METHODS FOR AIR MONITORING OF CRITERIA POLLUTANTS.—Continued 

Pollutant Ref. or equivalent Manual or automated 

Applicable 

part 50 appendix 

Applicable subparts of part 53 

A B C D E F 

Automated ............................... ...................... ✓ ✓ ✓ 

CO ................ Reference ................................ Automated ............................... C .................. ✓ ✓ 

Equivalent ................................ Manual ..................................... ...................... ✓ ✓ 

Automated ............................... ...................... ✓ ✓ ✓ 

O3 ................. Reference ................................ Automated ............................... D .................. ✓ ✓ 

Equivalent ................................ Manual ..................................... ...................... ✓ ✓ 

Automated ............................... ...................... ✓ ✓ ✓ 

NO2 .............. Reference ................................ Automated ............................... F ................... ✓ ✓ 

Equivalent ................................ Manual ..................................... ...................... ✓ ✓ 

Automated ............................... ...................... ✓ ✓ ✓ 

Pb ................. Reference ................................ Manual ..................................... G ..................

Equivalent ................................ Manual ..................................... ...................... ✓ ✓ 

PM10 ............. Reference ................................ Manual ..................................... J ................... ✓ ✓ 

Equivalent ................................ Manual ..................................... ...................... ✓ ✓ ✓ 

Automated ............................... ...................... ✓ ✓ ✓ 

PM2.5 ............ Reference ................................ Manual ..................................... L ................... ✓ ✓ 

Equivalent Class I ................... Manual ..................................... L ................... ✓ ✓ ✓ 

Equivalent Class II .................. Manual ..................................... L1 .................. ✓ ✓2 ✓ ✓1,2

Equivalent Class III ................. Automated ............................... L1 .................. ✓ ✓ ✓1 ✓1

PM10–2.5 ........ Reference ................................ Manual ..................................... O2 ................. ✓ ✓ 

Equivalent Class I ................... Manual ..................................... O2 ................. ✓ ✓ 

Equivalent Class II .................. Manual ..................................... O2 ................. ✓ ✓2 ✓1 ✓1, 2

Equivalent Class III ................. Automated ............................... L1,O1, 2 .......... ✓ ✓ ✓1 ✓1

1Some requirements may apply, based on the nature of each particular candidate method, as determined by the Administrator. 

2Alternative Class III requirements may be substituted. 


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■ 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 PM2.5 in Ambient Air Using 

Designated Reference or Class I Equivalent 

Methods. U.S. EPA, National Exposure 

Research Laboratory, Research Triangle Park, 

NC, November 1998 or later edition. 

Currently available at http://www.epa.gov/ 

ttn/amtic/pmqainf.html. 

■ 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 SO2, 

CO, O3, and NO2. 

53.33 Test procedure for methods for Pb. 

53.34 Test procedures for methods for PM10

and Class I methods for PM2.5.

53.35 Test procedures for Class II and Class 

III methods for PM2.5 and PM10¥2.5.

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 PM10, PM2.5, and 

PM10¥2.5 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 PM10¥2.5 and PM2.5

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 SO2, CO, O3, 

NO2

Figure C–2 to Subpart C of Part 53—

Illustration of the Slope and Intercept 

Limits for Class II and Class III PM2.5

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 PM10¥2.5

Candidate Equivalent Methods 

Figure C–4 to Subpart C of Part 53—

Illustration of the Minimum Limits for 

Correlation Coefficient for PM2.5 and 

PM10¥2.5 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 

§ 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 

§ 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 


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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 PM2.5 and 

PM10¥2.5, all submitted information 

must meet the requirements of the 

ANSI/ASQC E4 Standard, sections 6 

(reference 1 of appendix A of this 

subpart). 

§ 53.31 [Reserved] 

§ 53.32 Test procedures for methods for 

SO2, CO, O3, and NO2. 

(a) Comparability. Comparability is 

shown for SO2, CO, O3, and NO2

methods when the differences between: 

(1) Measurements made by a 

candidate manual method or by a test 

analyzer representative of a candidate 

automated method, and; 

(2) Measurements made 

simultaneously by a reference method 

are less than or equal to the values for 

maximum discrepancy specified in table 

C–1 of this subpart. 

(b) Test measurements. All test 

measurements are to be made at the 

same test site. If necessary, the 

concentration of pollutant in the 

sampled ambient air may be augmented 

with artificially generated pollutant to 

facilitate measurements in the specified 

ranges, as described under paragraph 

(f)(4) of this section. 

(c) Requirements for measurements or 

samples. All test measurements made or 

test samples collected by means of a 

sample manifold as specified in 

paragraph (f)(4) of this section shall be 

at a room temperature between 20° and 

30° C, and at a line voltage between 105 

and 125 volts. All methods shall be 

calibrated as specified in § 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 § 53.4(b)(3), is permitted 

only every 3 days. Automatic 

adjustments which the test analyzer 

performs by itself are permitted at any 

time. The submitted records shall show 

clearly when manual adjustments were 

made and describe the operations 

performed. 

(2) All test measurements shall be 

made with the same test analyzer; use 

of multiple test analyzers is not 

permitted. The test analyzer shall be 

operated continuously during the entire 

series of test measurements. 

(3) If a test analyzer should 

malfunction during any of these tests, 

the entire set of measurements shall be 

repeated, and a detailed explanation of 

the malfunction, remedial action taken, 

and whether recalibration was necessary 

(along with all pertinent records and 

charts) shall be submitted. 

(4) Ambient air shall be sampled from 

a common intake and distribution 

manifold designed to deliver 

homogenous air samples to both 

methods. Precautions shall be taken in 

the design and construction of this 

manifold to minimize the removal of 

particulate matter and trace gases, and 

to insure that identical samples reach 

the two methods. If necessary, the 

concentration of pollutant in the 

sampled ambient air may be augmented 

with artificially generated pollutant. 

However, at all times the air sample 

measured by the candidate and 

reference methods under test shall 

consist of not less than 80 percent 

ambient air by volume. Schematic 

drawings, physical illustrations, 

descriptions, and complete details of the 

manifold system and the augmentation 

system (if used) shall be submitted. 

(g) Tests. (1) Conduct the first set of 

simultaneous measurements with the 

candidate and reference methods: 

(i) Table C–1 of this subpart specifies 

the type (1-or 24-hour) and number of 

measurements to be made in each of the 

three test concentration ranges. 

(ii) The pollutant concentration must 

fall within the specified range as 

measured by the reference method. 

(iii) The measurements shall be made 

in the sequence specified in table C–2 

of this subpart, except for the 1-hour 

SO2 measurements, which are all in the 

high range. 

(2) For each pair of measurements, 

determine the difference (discrepancy) 

between the candidate method 

measurement and reference method 

measurement. A discrepancy which 

exceeds the discrepancy specified in 

table C–1 of this subpart constitutes a 

failure. Figure C–1 of this subpart 

contains a suggested format for 

reporting the test results. 

(3) The results of the first set of 

measurements shall be interpreted as 

follows: 

(i) Zero failures: The candidate 

method passes the test for 

comparability. 


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(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 secondset measurements shall be interpreted as 

follows: 

(A) One or two failures: The candidate 

method passes the test for 

comparability. 

(B) Three or more failures: The 

candidate method fails the test for 

comparability. 

(iv) For SO2, the 1-hour and 24-hour 

measurements shall be interpreted 

separately, and the candidate method 

must pass the tests for both 1- and 24- 

hour measurements to pass the test for 

comparability. 

(4) A 1-hour measurement consists of 

the integral of the instantaneous 

concentration over a 60-minute 

continuous period divided by the time 

period. Integration of the instantaneous 

concentration may be performed by any 

appropriate means such as chemical, 

electronic, mechanical, visual judgment, 

or by calculating the mean of not less 

than 12 equally-spaced instantaneous 

readings. Appropriate allowances or 

corrections shall be made in cases 

where significant errors could occur due 

to characteristic lag time or rise/fall time 

differences between the candidate and 

reference methods. Details of the means 

of integration and any corrections shall 

be submitted. 

(5) A 24-hour measurement consists 

of the integral of the instantaneous 

concentration over a 24-hour 

continuous period divided by the time 

period. This integration may be 

performed by any appropriate means 

such as chemical, electronic, 

mechanical, or by calculating the mean 

of twenty-four (24) sequential 1-hour 

measurements. 

(6) For O3 and CO, no more than six 

1-hour measurements shall be made per 

day. For SO2, no more than four 1-hour 

measurements or one 24-hour 

measurement shall be made per day. 

One-hour measurements may be made 

concurrently with 24-hour 

measurements if appropriate. 

(7) For applicable methods, control or 

calibration checks may be performed 

once per day without adjusting the test 

analyzer or method. These checks may 

be used as a basis for a linear 

interpolation-type correction to be 

applied to the measurements to correct 

for drift. If such a correction is used, it 

shall be applied to all measurements 

made with the method, and the 

correction procedure shall become a 

part of the method. 

§ 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 § 53.4(a). The audit 

samples are 3⁄4 × 8-inch glass fiber strips 

containing known amounts of Pb at the 

following nominal levels: 100 

micrograms per strip (μg/strip); 300 μg/ 

strip; 750 μg/strip. The true amount of 

Pb, in total μg/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 (μg/m3) for 

each analysis of each filter. Calculate 

the indicated total Pb amount for the 

audit samples in μg/strip for each 

analysis of each strip. Label these test 

results as R1A, R1B, R1C, R2A, R2B, * * *, 

Q1A, Q1B, Q1C, * * *, 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 μg/m3

for each analysis of each filter. Label 

these test results as C1A, C1B, C2C, * * *, 

where C denotes results from the 

candidate method. For candidate 

methods which provide a direct 

measurement of Pb concentrations 

without a separable procedure, 

C1A=C1B=C1C, C2A=C2B=C2C, 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: 

Equation 1

Ri ave = RRR iA iB iC + +

3

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: 

Equation 2

Q QQQ iA iB iC

i ave = + +

3

Where, i is audit sample number. 

(ii) Calculate the percent difference 

(Dq) between the indicated Pb 

concentration for each audit sample and 

the true Pb concentration (Tq) using 

equation 3 of this section: 

Equation 3

D Q T

T

i qi

qi

qi = − × ave 100%

(2) If any difference value (Dqi) 

exceeds ±5 percent, the accuracy of the 


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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 μg/m3. 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 μg/m3 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: 

Equation 4

P

R R

R

i i

i

Ri = − × max min

 ave

100%

or 

Equation 5

P C C

C

i i

i

Ci = − × max min

 ave

100%

where, i indicates the filter number. 

(2) If any reference method precision 

value (PRi) 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 (PCi) exceeds 15 percent, the 

candidate method fails the precision 

test. 

(4) The candidate method passes this 

test if all precision values (i.e., all PRi’s 

and all PCi’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: 

Equation 6

D

C R

R in

ij ik

ik

= − ×100%

where, i is the filter number, and n numbers 

from 1 to 9 for the nine possible 

difference combinations for the three 

determinations for each method (j = A, 

B, C, candidate; k = A, B, C, reference). 

(2) If none of the percent differences 

(D) exceeds ±20 percent, the candidate 

method passes the test for 

comparability. 

(3) If one or more of the percent 

differences (D) exceed ±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. 

§ 53.34 Test procedure for methods for 

PM10 and Class I methods for PM2.5. 

(a) Comparability. Comparability is 

shown for PM10 methods and for Class 

I methods for PM2.5 when the 

relationship between: 

(1) Measurements made by a 

candidate method, and 

(2) Measurements made by a 

corresponding reference method on 

simultaneously collected samples (or 

the same sample, if applicable) at each 

of one or more test sites (as required) is 

such that the linear regression 

parameters (slope, intercept, and 

correlation coefficient) describing the 

relationship meet the requirements 

specified in table C–4 of this subpart. 

(b) Methods for PM10. Test 

measurements must be made, or derived 

from particulate samples collected, at 

not less than two test sites, each of 

which must be located in a geographical 

area characterized by ambient 

particulate matter that is significantly 

different in nature and composition 

from that at the other test site(s). 

Augmentation of pollutant 

concentrations is not permitted, hence 

appropriate test sites must be selected to 

provide the minimum number of test 

PM10 concentrations in the ranges 

specified in table C–4 of this subpart. 

The tests at the two sites may be 

conducted in different calendar seasons, 

if appropriate, to provide PM10

concentrations in the specified ranges. 

(c) PM10 methods employing the same 

sampling procedure as the reference 

method but a different analytical 

method. Candidate methods for PM10

which employ a sampler and sample 

collection procedure that are identical 

to the sampler and sample collection 

procedure specified in the reference 

method, but use a different analytical 

procedure, may be tested by analyzing 

common samples. The common samples 

shall be collected according to the 

sample collection procedure specified 

by the reference method and shall be 

analyzed in accordance with the 

analytical procedures of both the 

candidate method and the reference 

method. 

(d) Methods for PM2.5. Augmentation 

of pollutant concentrations is not 

permitted, hence appropriate test sites 

must be selected to provide the 

minimum number of test measurement 

sets to meet the requirements for PM2.5

concentrations in the ranges specified in 

table C–4 of this subpart. Only one test 

site is required, and the site need only 

meet the PM2.5 ambient concentration 

levels required by table C–4 of this 

subpart and the requirements of 

§ 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 PM10 or PM2.5

measurements as necessary (see table C–

4 of this subpart), each set consisting of 

three reference method and three 

candidate method measurements, all 

obtained simultaneously. 

(4) Candidate PM10 method 

measurements shall be nominal 24-hour 

(±1 hour) integrated measurements or 

shall be averaged to obtain the mean 

concentration for a nominal 24-hour 

period. PM2.5 measurements may be 

either nominal 24-or 48-hour integrated 

measurements. All collocated 

measurements in a measurement set 

must cover the same nominal 24-or 48- 

hour time period. 

(5) For samplers, retrieve the samples 

promptly after sample collection and 

analyze each sample according to the 

reference method or candidate method, 

as appropriate, and determine the PM10

or PM2.5 concentration in μg/m3. If the 

conditions of paragraph (c) of this 

section apply, collect sample sets only 


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with the three reference method 

samplers. Guidance for quality 

assurance procedures for PM2.5 methods 

is found in ‘‘Quality Assurance 

Document 2.12’’ (reference (2) in 

appendix A to this subpart). 

(f) Sequential samplers. For 

sequential samplers, the sampler shall 

be configured for the maximum number 

of sequential samples and shall be set 

for automatic collection of all samples 

sequentially such that the test samples 

are collected equally, to the extent 

possible, among all available sequential 

channels or utilizing the full available 

sequential capability. 

(g) Calculation of reference method 

averages and precisions. (1) For each of 

the measurement sets, calculate the 

average PM10 or PM2.5 concentration 

obtained with the reference method 

samplers, using equation 7 of this 

section: 

Equation 7

Rj = =

∑Ri j

i

,

1

3

3

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 PM10 or PM2.5 measurements as 

the standard deviation, PRj, using 

equation 8 of this section: 

Equation 8

P

R R

Rj

ij ij

i i =

− 



 



 = =

∑ , , ∑ 2

1

3 2

1

3 1

3

2

(3) For each measurement set, also 

calculate the precision of the reference 

method PM10 or PM2.5 measurements as 

the relative standard deviation, RPRj, in 

percent, using equation 9 of this section: 

Equation 9

RPRj

P

R

Rj

j

×100%

(h) Acceptability of measurement sets. 

Each measurement set is acceptable and 

valid only if the three reference method 

measurements and the three candidate 

method measurements are obtained and 

are valid, R ̄ j falls within the acceptable 

concentration range specified in table 

C–4 of this subpart, and either PRj or 

RPRj is within the corresponding limit 

for reference method precision specified 

in table C–4 of this subpart. For each 

site, table C–4 of this subpart specifies 

the minimum number of measurement 

sets required having R ̄ j above and below 

specified concentrations for 24- or 48- 

hour samples. Additional measurement 

sets shall be obtained, as necessary, to 

provide the minimum number of 

acceptable measurement sets for each 

category and the minimum total number 

of acceptable measurement sets for each 

test site. If more than the minimum 

number of measurement sets are 

collected that meet the acceptability 

criteria, all such measurement sets shall 

be used to demonstrate comparability. 

(i) Candidate method average 

concentration measurement. For each of 

the acceptable measurement sets, 

calculate the average PM10 or PM2.5

concentration measurements obtained 

with the candidate method samplers, 

using equation 10 of this section: 

Equation 10

C

Ci j

i

j = =

∑ ,

1

3

3

Where: 

C = The concentration measurements from 

the candidate methods; 

i = The measurement number in the set; and 

j = The measurement set number. 

(j) Test for comparability. (1) For each 

site, plot all of the average PM10 or PM2.5

measurements obtained with the 

candidate method (C ̄ j) against the 

corresponding average PM10 or PM2.5

measurements obtained with the 

reference method (R ̄ j. For each site, 

calculate and record the linear 

regression slope and intercept, and the 

correlation coefficient. 

(2) To pass the test for comparability, 

the slope, intercept, and correlation 

coefficient calculated under paragraph 

(j)(1) of this section must be within the 

limits specified in table C–4 of this 

subpart for all test sites. 

§ 53.35 Test procedure for Class II and 

Class III methods for PM2.5 and PM10¥2.5.

(a) Overview. Class II and Class III 

candidate equivalent methods shall be 

tested for comparability of PM2.5 or 

PM10¥2.5 measurements to 

corresponding collocated PM2.5 or 

PM10¥2.5 reference method 

measurements at each of multiple field 

sites, as required. Comparability is 

shown for the candidate method when 

simultaneous collocated measurements 

made by candidate and reference 

methods meet the comparability 

requirements specified in this section 

§ 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 

§ 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 PM2.5, 

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 PM10¥2.5 representative of locations 

in proximity to urban sources of 

PM10¥2.5 such as high-density traffic on 

paved roads, industrial sources, and 

construction activities. For Class III 

methods, one test site shall be selected 

in each of the four following general 

locations (A, B, C, and D), and at least 

one of the test sites shall have 

characteristic wintertime temperatures 

of 0° 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 PM2.5, 

nitrates, and semi-volatile organic 

pollutants. 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61283 

(B) Test site B shall be in a western 

city characterized by a high ratio of 

PM10¥2.5 to PM2.5, 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 PM2.5 and 

PM10¥2.5 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 PM2.5 and PM10¥2.5

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 § 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 

§ 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 PM2.5 or 

PM10¥2.5 24-hour (nominal) concurrent 

concentration measurements shall be 

obtained during each test campaign at 

each test site. To be considered 

acceptable for the test, each 

measurement set shall consist of at least 

two valid reference method 

measurements and at least two valid 

candidate method measurements, and 

the PM2.5 or PM10¥2.5 measured 

concentration, as determined by the 

average of the reference method 

measurements, must fall within the 

acceptable concentration range specified 

in table C–4 of this subpart. Each 

measurement set shall include all valid 

measurements obtained. For each 

measurement set containing fewer than 

three reference method measurements 

or fewer than three candidate method 

measurements, an explanation and 

appropriate justification shall be 

provided to account for the missing 

measurement or measurements. 

(3) More than 23 valid measurement 

sets may be obtained during a particular 

test campaign to provide a more 

advantageous range of concentrations, 

more representative conditions, 

additional higher or lower 

measurements, or to otherwise improve 

the comparison of the methods. All 

valid data sets obtained during each test 

campaign shall be submitted and shall 

be included in the analysis of the data. 

(4) The integrated-sample reference 

method measurements shall be of at 

least 22 hours and not more than 25 

hours duration. Each reference method 

sample shall be retrieved promptly after 

sample collection and analyzed 

according to the reference method to 

determine the PM2.5 or PM10¥2.5

measured concentration in μg/m3. 

Guidance and quality assurance 

procedures applicable to PM2.5 or 

PM10¥2.5 reference methods are found in 

‘‘Quality Assurance Document 2.12’’

(reference (2) in appendix A to this 

subpart). 

(5) Candidate method measurements 

shall be timed or processed and 

averaged as appropriate to determine an 

equivalent mean concentration 

representative of the same time period 

as that of the concurrent integratedsample 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 § 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 Ri,j is the measurement of 

reference method sampler i on test day 

j. In the event that one of the reference 

method measurements is missing or 

invalid due to a specific, positivelyidentified 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 × R1,j/(R1,j

+ R2,j) and 2 × R1,j/(R1,j + R3,j). If both 

quantities fall outside of the interval, 

(0.93, 1.07), then R1,j is an outlier. 

(ii) Calculate the quantities 2 × R2,j/ 

(R2,j + R1,j) and 2 × R2,j/(R2,j + R3,j). If 

both quantities fall outside of the 

interval, (0.93, 1.07), then R2,j is an 

outlier. 

(iii) Calculate the quantities 2 × R3,j/ 

(R3,j + R1,j) and 2 × R3,j/(R3,j + R2,j). If 

both quantities fall outside of the 


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61284 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

interval, (0.93, 1.07), then R3,j is an 

outlier. 

(iv) If this test indicates that one of 

the reference method measurements in 

the measurement set is an outlier, the 

outlier measurement shall be eliminated 

from the measurement set, and the other 

two measurements considered valid. If 

the test indicates that more than one 

reference method measurement in the 

measurement set is an outlier, the entire 

measurement set (both reference and 

candidate method measurements) shall 

be excluded from further data analysis 

for the tests of this section. 

(2) For each of the measurement sets 

for each test site, calculate the mean 

concentration for the reference method 

measurements, using equation 11 of this 

section: 

Equation 11

R

n j ij R i

n

= =

∑

1

1

,

Where: 

R ̄ j = The mean concentration measured by 

the reference method for the 

measurement set; 

Ri,j = The measurement of reference method 

sampler i on test day j; and 

n = The number of valid reference method 

measurements in the measurement set 

(normally 3). 

(3) Any measurement set for which R ̄ j

does not fall in the acceptable 

concentration range specified in table 

C–4 of this subpart is not valid, and the 

entire measurement set (both reference 

and candidate method measurements) 

must be eliminated from further data 

analysis. 

(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.) 

Equation 12

C

m j ij C i

n

= =

∑

1

1

,

Where: 

C ̄ j = The mean concentration measured by 

the candidate method for the 

measurement set; 

Ci,j = 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, 

RPj, using equation 13 of this section: 

Equation 13

RP

R

R

n

R

n j

j

ij ij

i

n

i

n

=

− 



 





− × = =

∑ ∑ 1

1

1

100

2

1

2

1

, ,

%

(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: 

Equation 14

RP

J

RPj

j

J

= ( ) =

∑

1 2

1

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, CPj, using equation 15 of 

this section: 

Equation 15

CP

C

C

m

C

m j

j

ij ij

i

m

i

m

=

− 



 





− × = =

∑ ∑ 1

1

1

100

2

1

2

1

, ,

%

(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: 

Equation 16

CP

J

CPj

j

J

= ( ) =

∑

1 2

1

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: 

Equation 17

R

J j j R

j

J

= =

∑

1

1

(2) For each test site, calculate the 

mean concentration measured by the 

candidate method, C ̄ , using equation 18 

of this section: 

Equation 18

C

J

Cj

j

J

= =

∑

1

1

(3) For each test site, calculate the 

linear regression slope and intercept of 

the mean candidate method 

measurements (C ̄ j) against the mean 

reference method measurements (R ̄ j), 

using equations 19 and 20 of this 

section, respectively: 

Equation 19

Slope

R RC C

R R

j j

j

J

j

j

J =

( ) − ( ) −

( ) −

=

=

∑

∑

1

2

1

Equation 20

Intercept = C − × slope R

(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, r2), 

using equation 21 of this section: 

Equation 21

r

R RC C

RR CC

j j

j

J

j

j

J

j

j

J =

( ) − ( ) −

( ) − ( ) −

=

= =

∑

∑ ∑

1

2

1

2

1


ER17OC06.025</MATH> ER17OC06.026</MATH> ER17OC06.027</MATH> ER17OC06.028</MATH> ER17OC06.029</MATH> ER17OC06.030</MATH> ER17OC06.031</MATH> ER17OC06.032</MATH> ER17OC06.033</MATH> ER17OC06.034</MATH> ER17OC06.035</MATH>pwalker on PROD1PC61 with RULES3
Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61285 

(2) For each test site, calculate the 

concentration coefficient of variation, 

CCV, using equation 22 of this section: 

Equation 22

CCV

R

R R

J

j

j

J

=

( ) −

−

=

∑ 1

1

2

1

(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

Pollutant Concentration range, parts per million 

Simultaneous measurements required Maximum 

discrepancy 

specification, 

parts per 

million 

1-hr 24-hr 

First 

set 

Second 

set 

First 

set 

Second 

set 

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

Measurement 

Concentration range 

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. 

TABLE C–2 TO SUBPART C OF PART

53.—SEQUENCE OF TEST MEASUREMENTS—Continued 

Measurement 

Concentration range 

First set Second set 

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, μg/m3 ..... 0.5–4.0 

Minimum number of 24-hr 

measurements ...................... 5 

Maximum analytical precision, 

percent .................................. 15 

Maximum analytical accuracy, 

percent .................................. ± 5 

Maximum difference, percent of 

reference method .................. ± 20 

TABLE C–4 TO SUBPART C OF PART 53.—TEST SPECIFICATIONS FOR PM10, PM2.5 AND PMR10¥2.5 CANDIDATE

EQUIVALENT METHODS

Specification PM10

PM2.5 PM10¥2.5

Class I Class II Class III Class II Class III 

Acceptable concentration range 

(Rj), μg/m3.

15–300 ............. 3–200 ............... 3–200 ............... 3–200 ............... 3–200 ............... 3–200 

Minimum number of test sites .... 2 ....................... 1 ....................... 2 ....................... 4 ....................... 2 ....................... 4 

Minimum number of candidate 

method samplers or analyzers 

per site.

3 ....................... 3 ....................... 31 ..................... 31 ..................... 31 ..................... 31


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TABLE C–4 TO SUBPART C OF PART 53.—TEST SPECIFICATIONS FOR PM10, PM2.5 AND PMR10¥2.5 CANDIDATE

EQUIVALENT METHODS—Continued 

Specification PM10

PM2.5 PM10¥2.5

Class I Class II Class III Class II Class III 

Number of reference method 

samplers per site.

3 ....................... 3 ....................... 31 ..................... 31 ..................... 31 ..................... 31

Minimum number of acceptable 

sample sets per site for PM10

methods: 

Rj < 60 μg/m3 ...................... 3 

Rj > 60 μg/m3 ...................... 3 

Total ............................. 10 

Minimum number of acceptable 

sample sets per site for PM2.5

and PM10–2.5 candidate equivalent methods: 

Rj < 30 μg/m3 for 24-hr or 

Rj < 20 μg/m3 for 48-hr 

samples.

........................... 3 

Rj > 30 μg/m3 for 24-hr or 

Rj > 20 μg/m3 for 48-hr 

samples.

........................... 3 

Each season ........................ ........................... 10 ..................... 23 ..................... 23 ..................... 23 ..................... 23 

Total, each site .................... ........................... 10 ..................... 23 ..................... 23 (46 for twoseason sites).23 ..................... 23 (46 for twoseason sites) 

Precision of replicate reference 

method measurements, PRj or 

RPRj′, respectively; RP for 

Class II or III PM2.5 or 

PM10–2.5′, maximum.

5 μg/m3 or 7% .. 2 μg/m3 or 5% 10%2 ................ 10%2 ................ 10%2 ................ 10%2

Precision of PM2.5 or PM10–2.5

candidate method, CP, each 

site.

........................... .......................... 10%2 ................ 15%2 ................ 15%2 ................ 15%2

Slope of regression relationship 1±0.10 ............... 1±0.05 .............. 1±0.10 .............. 1±0.10 .............. 1±0.10 .............. 1±0.12 

Intercept of regression relationship, μg/m3.0±5 .................... 0±1 ................... Between: 

13.55–(15.05 

× slope), but 

not less than 

¥1.5; and 

16.56–(15.05 

× slope), but 

not more than 

+ 1.5.

Between: 

15.05–(17.32 

× slope), but 

not less than 

¥2.0; and 

15.05–(13.20 

× slope), but 

not more than 

+ 2.0.

Between: 

62.05–(70.5 × 

slope), but 

not less than 

¥3.5; and 

78.95–(70.5 × 

slope), but 

not more than 

+ 3.5.

Between: 

70.50–(82.93 

× slope), but 

not less than 

¥7.0; and 

70.50–(61.16 

× slope), but 

not more than 

+ 7.0 

Correlation of reference method 

and candidate method measurements.

≥0.97 ................. ≥0.97.

1Some 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 

area.

Los Angeles basin or 

California Central 

Valley.

Western city such as 

Denver, Salt Lake 

City, or Albuquerque.

Midwestern city ......... Northeastern or midAtlantic city. 

Test site characteristics.Relatively high PM2.5, 

nitrates, and semivolatile organic pollutants.

Cold weather, higher 

elevation, winds, 

and dust.

Substantial temperature variation, high 

nitrates, wintertime 

conditions.

High sulfate and high 

relative humidity. 

Class III Field test 

campaigns (Total: 

5).

Winter and summer .. Winter only ................ Winter only ................ Summer only. 

Class II Field test 

campaigns (Total: 

2).

Site A or B, any season Site C or D, any season. 


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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—Continued 

Candidate method Test site A B C D 

PM10¥2.5 ..................... Test site location 

area.

Los Angeles basin or 

California Central 

Valley.

Western city such as 

Las Vegas or 

Phoenix.

Midwestern city ......... Large city east of the 

Mississippi River. 

Test site characteristics.Relatively high PM2.5, 

nitrates, and semivolatile organic pollutants.

High PM10¥2.5 to 

PM2.5 ratio, windblown dust.

Substantial temperature variation, high 

nitrates, wintertime 

conditions.

High sulfate and high 

relative humidity. 

Class III Field test 

campaigns (Total: 

5).

Winter and summer .. Winter only ................ Winter only ................ Summer only. 

Class II Field test 

campaigns (Total: 

2).

Site A or B, any season 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 SO2, CO, O3, 

NO2

Candidate Method llllllllllll

Reference Method llllllllllll

Applicant llllllllllllllll

b First Set b Second Set b Type 

b 1 Hour b 24 Hour 

Concentration 

range Date Time 

Concentration, ppm 

Difference Table C–1 

spec. Pass or fail 

Candidate Reference 

Low 1 

llll ppm 2 

to llll ppm 3 

4 

5 

6 

Medium 1 

llll ppm 2 

to llll ppm 3 

4 

5 

6 

High 1 

llll ppm 2 

to llll ppm 3 

4 

5 

6 

7 

8 

Total Failures: 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61289 

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 PM2.5 in Ambient Air Using 

Designated Reference or Class I Equivalent 

Methods. U.S. EPA, National Exposure 

Research Laboratory, Research Triangle Park, 

NC, November 1998 or later edition. 

Currently available at http://www.epa.gov/ 

ttn/amtic/pmqainf.html. 

Subpart E—Procedures for Testing 

Physical (Design) and Performance 

Characteristics of Reference Methods 

and Class I and Class II Equivalent 

Methods for PM2.5 or PM10¥2.5

■ 7. The heading for subpart E is revised 

as set out above. 

■ 8. Section 53.50 is revised to read as 

follows: 

§ 53.50 General provisions. 

(a) A candidate method for PM2.5 or 

PM10¥2.5 described in an application for 

a FRM or FEM determination submitted 

under § 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 § 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 PM2.5 or PM10¥2.5

sampler associated with a candidate 

reference method or Class I or Class II 

equivalent method meets all design and 

performance specifications set forth in 

appendix L or O, respectively, of part 50 

of this chapter as well as additional 

requirements specified in this subpart E. 

Some or all of these tests may also be 

applicable to a candidate Class III 

equivalent method or analyzer, as may 

be determined under § 53.3(b)(3). 

(b) PM2.5 methods—(1) Reference 

method. A sampler associated with a 

candidate reference method for PM2.5

shall be subject to the provisions, 

specifications, and test procedures 

prescribed in §§ 53.51 through 53.58. 

(2) Class I method. A sampler 

associated with a candidate Class I 

equivalent method for PM2.5 shall be 

subject to the provisions, specifications, 

and test procedures prescribed in all 

sections of this subpart. 

(3) Class II method. A sampler 

associated with a candidate Class II 

equivalent method for PM2.5 shall be 

subject to the provisions, specifications, 

and test procedures prescribed in all 

applicable sections of this subpart, as 

specified in subpart F of this part or as 

specified in § 53.3(a)(3). 

(c) PM10¥2.5 methods—(1) Reference 

method. A sampler associated with a 

reference method for PM10¥2.5, as 

specified in appendix O to part 50 of 

this chapter, shall be subject to the 

requirements in this paragraph (c)(1). 

(i) The PM2.5 sampler of the PM10¥2.5

sampler pair shall be verified to be 

either currently designated under this 

part 53 as a FRM for PM2.5, or shown to 

meet all requirements for designation as 

a FRM for PM2.5, in accordance with this 

part 53. 

(ii) The PM10C sampler of the 

PM10¥2.5 sampler pair shall be verified 

to be of like manufacturer, design, 

configuration, and fabrication to the 

PM2.5 sampler of the PM10¥2.5 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 PM10¥2.5

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 PM10¥2.5 shall 

meet the requirements in this paragraph 

(c)(2). 

(i) The PM2.5 sampler of the PM10¥2.5

sampler pair shall be verified to be 

either currently designated under this 

part 53 as a FRM or Class I FEM for 

PM2.5, or shown to meet all 

requirements for designation as a FRM 

or Class I FEM for PM2.5, in accordance 

with this part 53. 

(ii) The PM10c sampler of the PM10¥2.5

sampler pair shall be verified to be of 

similar design to the PM10¥2.5 sampler 

and to meet all requirements for 

designation as a FRM or Class I FRM for 

PM2.5, in accordance with this part 53, 

except for replacement of the particle 

size separator specified in section 7.3.4 


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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 PM10¥2.5

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 PM10¥2.5 shall be 

subject to the applicable requirements of 

this subpart E, as described in 

§ 53.3(a)(5). 

(d) The provisions of § 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 

§§ 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 

§ 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 PM2.5 or PM10¥2.5 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 § 53.58 for both FRM and Class I 

FEM samplers for PM2.5. 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 § 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. 

■ 9. Section 53.51 is revised to read as 

follows: 

§ 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 PM2.5

or PM10¥2.5 are properly manufactured 

to meet all applicable design and 

performance specifications and have 

been properly tested according to all 

applicable test requirements for such 

designation. Documentation is required 

to show that instruments and 

components of a PM2.5 or PM10¥2.5

sampler are manufactured in an ISO 

9001-registered facility under a quality 

system that meets ISO–9001 

requirements for manufacturing quality 

control and testing. 

(2) In addition, specific tests are 

required by paragraph (d) of this section 

to verify that critical features of 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 § 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 § 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 PM2.5 or PM10¥2.5 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 PM2.5 or PM10¥2.5

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 


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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 PM2.5

(WINS) impactor jet diameter. For 

samplers utilizing the WINS impactor 

particle size separator specified in 

paragraphs 7.3.4.1, 7.3.4.2, and 7.3.4.3 

of appendix L to part 50 of this chapter, 

the diameter of the jet of each impactor 

manufactured for a PM2.5 or PM10¥2.5

sampler under the impactor design 

specifications set forth in 40 CFR part 

50, appendix L, shall be verified against 

the tolerance specified on the drawing, 

using standard, NIST-traceable ZZ go/no 

go plug gages. This test shall be a final 

check of the jet diameter following all 

fabrication operations, and a record 

shall be kept of this final check. The 

manufacturer shall submit evidence that 

this procedure is incorporated into the 

manufacturing procedure, that the test is 

or will be routinely implemented, and 

that an appropriate procedure is in 

place for the disposition of units that 

fail this tolerance test. 

(2) VSCC separator. For samplers 

utilizing the BGI VSCCTM Very Sharp 

Cut Cyclone particle size separator 

specified in paragraph 7.3.4.4 of 

appendix L to part 50 of this chapter, 

the VSCC manufacturer shall identify 

the critical dimensions and 

manufacturing tolerances for the device, 

develop appropriate test procedures to 

verify that the critical dimensions and 

tolerances are maintained during the 

manufacturing process, and carry out 

those procedures on each VSCC 

manufactured to verify conformance of 

the manufactured products. The 

manufacturer shall also maintain 

records of these tests and their results 

and submit evidence that this procedure 

is incorporated into the manufacturing 

procedure, that the test is or will be 

routinely implemented, and that an 

appropriate procedure is in place for the 

disposition of units that fail this 

tolerance test. 

(3) Verification of surface finish. The 

anodization process used to treat 

surfaces specified to be anodized shall 

be verified by testing treated specimen 

surfaces for weight and corrosion 

resistance to ensure that the coating 

obtained conforms to the coating 

specification. The specimen surfaces 

shall be finished in accordance with 

military standard specification 8625F, 

Type II, Class I (reference 4 in appendix 

A of this subpart) in the same way the 

sampler surfaces are finished, and 

tested, prior to sealing, as specified in 

section 4.5.2 of reference 4 in appendix 

A of this subpart. 

(e) Final assembly and inspection 

requirements. Each sampler shall be 

tested after manufacture and before 

delivery to the final user. Each 

manufacturer shall document its postmanufacturing 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 ISOcertified 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 ISOcertified 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. 

■ 10. Section 53.52 is amended by 

revising paragraph (e)(1) to read as 

follows: 

§ 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 § 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. 

* * * * * 

■ 11. Section 53.53 is amended by 

revising paragraph (e)(1) to read as 

follows: 

§ 53.53 Test for flow rate accuracy, 

regulation, measurement accuracy, and cutoff. 

* * * * * 

(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 

§ 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. 

* * * * * 

■ 12. Section 53.54 is amended by 

revising paragraph (d)(1) to read as 

follows: 

§ 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 

§ 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. 

* * * * * 

■ 13. Section 53.33 is amended by: 

■ a. Revising paragraphs (a)(1) 

introductory text and (a)(2). 

■ b. Revising paragraph (e)(1). 

■ c. Revising paragraph (g)(5)(i) to read 

as follows. 

§ 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 


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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 °C and +40 °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 

PM2.5 or PM10–2.5 method (as applicable) 

to pass this test procedure. 

* * * * * 

(e) * * * (1) Setup of the sampler 

shall be performed as required in this 

paragraph (e) and otherwise as 

described in the sampler’s operation or 

instruction manual referred to in 

§ 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: 

Equation 16

TT T diff ind ave ref ave = − , ,

Where: 

Tind,ave = The mean ambient air temperature 

indicated by the test sampler, °C; and 

Tref,ave = The mean ambient air temperature 

measured by the reference temperature 

instrument, °C. 

* * * * * 

■ 14. Section 53.56 is amended by 

revising paragraphs (a)(2) and (e)(1) to 

read as follows: 

§ 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 

PM2.5 or PM10¥2.5 method (as 

applicable) to pass this test procedure. 

* * * * * 

(e) * * * (1) Setup of the sampler 

shall be performed as required in this 

paragraph (e) and otherwise as 

described in the sampler’s operation or 

instruction manual referred to in 

§ 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. 

* * * * * 

■ 15. Section 53.57 is amended by 

revising paragraphs (a), (b), and (e)(1) to 

read as follows: 

§ 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 nonsampling 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 °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 

§ 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 magazinetype sequential samplers) as directed by 

the sampler’s operation or instruction 

manual. 

* * * * * 

■ 16. Section 53.58 is revised to read as 

follows: 

§ 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 


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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 PM2.5 (or PM10¥2.5, as 

applicable) concentrations that are 

reasonably uniform over the test area 

and that meet the minimum level 

requirement of paragraph (g)(2) of this 

section is acceptable for this test. 

(d) Required facilities and equipment. 

(1) An appropriate test site and suitable 

electrical power to accommodate three 

test samplers are required. 

(2) Teflon sample filters, as specified 

in section 6 of 40 CFR part 50, appendix 

L, conditioned and preweighed as 

required by section 8 of 40 CFR part 50, 

appendix L, as needed for the test 

samples. 

(e) Test setup. (1) Three identical test 

samplers shall be installed at the test 

site in their normal configuration for 

collecting PM samples in accordance 

with the instructions in the associated 

manual referred to in § 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 § 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 Ci,j, where i is the 

sampler number (i = 1,2,3) and j is the 

test period (j = 1,2, * * * 10). 

(2)(i) For each test period, calculate 

and record the average of the three 

measured PM concentrations as Cave,j

where j is the test period using equation 

26 of this section: 

Equation 26

C C ave j j

i

, , = × =

∑ 1

3 1

1

3

(ii) If Cave,j < 3 μg/m3 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: 

 Equation 27

P

C C

j

i j

i

i j

i =

− 



 



 = =

∑ ∑ , ,

2

1

3

1

3 2

1

3

2

(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: 

Equation 28

RP

P

C j

j

ave j

= × 100%

,

(h) Test results. (1) The candidate 

method passes the precision test if 

either Pj or RPj 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 μg. 

■ 17. Section 53.59 is amended by 

revising paragraphs (a) and (b)(5) to read 

as follows: 

§ 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 


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61294 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

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. 

* * * * * 

■ 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

Subpart E procedure Performance test Performance specification Test conditions Part 50, appendix L reference 

§ 53.52 Sample leak check 

test.

Sampler leak check facility External leakage: 80 mL/ 

min, max.

Internal leakage: 80 mL/ 

min, max.

Controlled leak flow rate of 

80 mL/min.

Sec. 7.4.6. 

§ 53.53 Base flow rate test Sample flow rate ...............

1. Mean .............................

2. Regulation .....................

3. Meas accuracy ..............

4. CV accuracy .................

5. Cut-off ...........................

1. 16.67 ? 5% L/min .........

2. 2%, max ........................

3. 2%, max ........................

4. 0.3%, max .....................

5. Flow rate cut-off if flow 

rate deviates more than 

10% from design flow 

rate for >60 ± ?30 seconds.

(a) 6-hour normal operational test plus flow 

rate cut-off test.

(b) Normal conditions ........

(c) Additional 55 mm Hg 

pressure drop to simulate loaded filter.

(d) Variable flow restriction 

used for cut-off test.

Sec. 7.4.1, 

Sec. 7.4.2 

Sec. 7.4.3 

Sec. 7.4.4 

Sec. 7.4.5. 

§ 53.54 Power interruption 

test.

Sample flow rate: ..............

1. Mean .............................

2. Regulation .....................

3. Meas. accuracy .............

4. CV accuracy .................

5. Occurrence time of 

power interruptions.

6. Elapsed sample time ....

7. Sample volume .............

1. 16.67 ?± 5% L/Min .......

2. 2%, max ........................

3. 2%, max ........................

4. 0.3% max ......................

5. ? ± 2 min if >60 seconds 

6. ? ± 20 seconds ..............

7. ± ?2%, max ...................

(a) 6-hour normal operational test.

(b) Nominal conditions ......

(c) Additional 55 mm Hg 

pressure drop to simulate loaded filter.

(d) 6 power interruptions of 

various durations.

Sec. 7.4.1, 

Sec. 7.4.2 

Sec. 7.4.3 

Sec. 7.4.5 

Sec. 7.4.12 

Sec. 7.4.13 

Sec. 7.4.15.4 

Sec. 7.4.15.5. 

§ 53.55 Temperature and 

line voltage test.

Sample flow rate ...............

1. Mean .............................

2. Regulation .....................

3. Meas. accuracy .............

4. CV accuracy .................

5. Temperature meas. accuracy.

6. Proper operation ...........

1. 16.6 ±? 5% L/min .........

2. 2%, max ........................

3. 2%, max ........................

4. 0.3% max ......................

5. 2 °C ...............................

(a) 6-hour normal operational test.

(b) Normal conditions ........

(c) Additional 55 mm Hg 

pressure drop to simulate loaded filter.

(d) Ambient temperature at 

¥20 and +40 °C.

(e) Line voltage: 105 Vac 

to 125 Vac.

Sec. 7.4.1, 

Sec. 7.4.2 

Sec. 7.4.3 

Sec. 7.4.5 

Sec. 7.4.8 

Sec. 7.4.15.1. 

§ 53.56 Barometric pressure effect test.Sample flow rate ...............

1. Mean .............................

2. Regulation .....................

3. Meas. accuracy .............

4. CV accuracy .................

5. Pressure meas. accuracy.

6. Proper operation ...........

1. 16.67 ?± ? 5% L/min ....

2. 2%, max ........................

3. 2%, max ........................

3. 2%, max ........................

4. 0.3%, max .....................

5. 10 mm Hg .....................

(a) 6-hour normal operational test.

(b) Normal conditions ........

(c) Additional 55 mm Hg 

pressure drop to simulate loaded filter.

(d) Barometric pressure at 

600 and 800 mm Hg.

Sec. 7.4.1, 

Sec. 7.4.2 

Sec. 7.4.3 

Sec. 7.4.5 

Sec. 7.4.9. 

§ 53.57 Filter temperature control test.1. Filter temp meas. accuracy.

2. Ambient temp. meas. 

accuracy.

3. Filter temp. control accuracy, sampling and 

non-sampling.

1. 2 °C ...............................

2. 2 °C ...............................

3. Not more than 5 °C 

above ambient temp. for 

more than 30 min..

(a) 4-hour simulated solar 

radiation, sampling.

(b) 4-hour simulated solar 

radiation, non-sampling.

(c) Solar flux of 1000 ?50 

W/m2.

Sec. 7.4.8 

Sec. 7.4.10 

Sec. 7.4.11. 

§ 53.58 Field precision test 1. Measurement precision 

2. Storage deposition test 

for sequential samplers.

1. Pj < 2 μg/m3 or RPj < 

5%.

2. 50 μg max. average 

weight gain/blank filter.

(a) 3 collocated samplers 

at 1 site for at least 10 

days;.

(b) PM2.5 conc. > 3 μg/m3

(c) 24- or 48-hour samples 

(d) 5- or 10-day storage 

period for inactive stored 

filters.

Sec. 5.1 

Sec. 7.3.5 

Sec. 8 

Sec. 9 

Sec. 10. 


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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—Continued 

Subpart E procedure Performance test Performance specification Test conditions Part 50, appendix L reference 

The Following Requirement Is Applicable to Class I Candidate Equivalent Methods Only 

§ 53.59 Aerosol transport 

test.

Aerosol transport ............... 97%, min. for all channels Determine aerosol transport through any new or 

modified components 

with respect to the reference method sampler 

before the filter for each 

channel.

■ 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 PM2.5 in Ambient Air Using 

Designated Reference or Class I Equivalent 

Methods. U.S. EPA, National Exposure 

Research Laboratory, Research Triangle Park, 

NC, November 1998 or later edition. 

Currently available at http://www.epa.gov/ 

ttn/amtic/pmqainf.html. 

* * * * * 

(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] 

■ 20. Section 53.60 is amended by: 

■ a. Revising paragraph (b); 

■ b. Revising paragraph (c); 

■ c. Revising paragraph (d) introductory 

text; and 

■ d. Revising paragraph (f)(4) to read as 

follows: 

§ 53.60 General provisions. 

* * * * * 

(b) A candidate method described in 

an application for a FRM or FEM 

determination submitted under § 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 § 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 

§ 53.3(a)(3), a Class II PM2.5 sampler 

must meet the additional requirements 

as specified in paragraph (d) of this 

section. 

(d) Except as provided in paragraphs 

(d)(1), (2), and (3) of this section, all 

Class II samplers are subject to the 

additional tests and performance 

requirements specified in § 53.62 (full 

wind tunnel test), § 53.65 (loading test), 

and § 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 

§ 53.62 (full wind tunnel evaluation), 

§ 53.63 (wind tunnel inlet aspiration 

test), or § 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. 

* * * * * 

■ 21. The section heading of § 53.61 is 

revised to read as follows: 

§ 53.61 Test conditions. 

* * * * * 

■ 22. Section 53.66 is amended by 

revising paragraph (e)(2)(iii) to read as 

follows: 

§ 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. 

* * * * * 

■ 23. Table F–1 to subpart F is revised 

to read as follows: 


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TABLE F–1 TO SUBPART F OF PART 53.—PERFORMANCE SPECIFICATIONS FOR PM2.5 CLASS II EQUIVALENT SAMPLERS

Performance test Specifications Acceptance criteria 

§ 53.62 Full Tunnel Evaluation ........................... Solid VOAG produced aerosol at 2 km/hr and 

24 km/hr.

Dp50 2.5 μm ± 0.2 μm Numerical Analysis Results: 95% ≤ ? Rc ≤ ? 105% 

§ 53.63 Wind Tunnel Inlet Aspriation Test ......... Liquid VOAG produced aerosol at 2 km/hr 

and 24 km/hr.

Relative Aspiration: 95% ≤ ? A ≤ ? 105% 

§ 53.64 Static Fractionator Test ......................... Evaluation of the fractionator under static conditions.Dp50 = 2.5 μm ? 0.2 μm Numerical Analysis 

Results: 95% ? ≤ Rc ? ≤ 105% 

§ 53.65 Loading Test .......................................... Loading of the clean candidate under laboratory conditions.Acceptance criteria as specified in the postloading evaluation test (§ 53.62, § 53.63, or 

§ 53.64) 

§ 53.66 Volatility Test ......................................... Polydisperse liquid aerosol produced by air 

nebulization of A.C.S. reagent grade glycerol, 99.5% minimum purity.

Regression Parameters Slope = 1 ± 0.1, Intercept = 0 ± ? 0.15mg r ≥ 0.97. 

■ 24. In Figure E–1 to subpart F, the 

figure number ‘‘E–1’’ is revised to read 

‘‘F–1.’’

PART 58—[AMENDED] 

■ 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. 

■ 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 

§ 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 PM2.5 method that 

has been approved specifically within a 

State or local air monitoring network for 

purposes of comparison to the NAAQS 

and to meet other monitoring objectives. 

AQCR means air quality control 

region. 

CO means carbon monoxide. 

Combined statistical area (CSA) is 

defined by the U.S. Office of 

Management and Budget as a 

geographical area consisting of two or 

more adjacent Core Based Statistical 

Areas (CBSA) with employment 

interchange of at least 15 percent. 

Combination is automatic if the 

employment interchange is 25 percent 

and determined by local opinion if more 

than 15 but less than 25 percent (http:// 

www.census.gov/population/estimates/ 

metro-city/List6.txt). 

Community monitoring zone (CMZ) 

means an optional averaging area with 

established, well defined boundaries, 

such as county or census block, within 

an MPA that has relatively uniform 

concentrations of annual PM2.5 as 

defined by appendix N of part 50 of this 

chapter. Two or more communityoriented 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 PM2.5

NAAQS. 

Core-based statistical area (CBSA) is 

defined by the U.S. Office of 

Management and Budget, as a statistical 

geographic entity consisting of the 

county or counties associated with at 

least one urbanized area/urban cluster 

of at least 10,000 population, plus 

adjacent counties having a high degree 

of social and economic integration. 

Metropolitan 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 highconcentration 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 § 53.11 or 

§ 53.16 of this chapter. 

Federal reference method (FRM) 

means a method of sampling and 


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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 § 53.11 or § 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 (pathaveraged 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 PM2.5. 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 (PM2.5, speciated 

PM2.5, PM10–2.5), O3, SO2, CO, nitrogen 

oxides (NO/NO2/NOy), 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. NOX means 

oxides of nitrogen and is defined as the 

sum of the concentrations of NO2 and 

NO. 

NOy means the sum of all total 

reactive nitrogen oxides, including NO, 

NO2, and other nitrogen oxides referred 

to as NOZ.

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 pathintegrated 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 PM10, PM110C, PM2.5, 

PM10¥2.5, 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. 

PM10¥2.5 means particulate matter 

with an aerodynamic diameter less than 

or equal to a nominal 10 micrometers 

and greater than a nominal 2.5 

micrometers as measured by a reference 

method based on appendix O to part 50 

of this chapter and designated in 

accordance with part 53 of this chapter 

or by an equivalent method designated 

in accordance with part 53 of this 

chapter. 

Point analyzer means an automated 

analytical method that measures 

pollutant concentration in an ambient 

air sample extracted from the 

atmosphere at a specific inlet probe 

point and that has been designated as a 

reference or equivalent method in 

accordance with part 53 of this chapter. 

Population-oriented monitoring (or 

sites) means residential areas, 

commercial areas, recreational areas, 

industrial areas where workers from 

more than one company are located, and 

other areas where a substantial number 

of people may spend a significant 

fraction of their day. 

Primary quality assurance 

organization means a monitoring 

organization or other organization that 

is responsible for a set of stations that 

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. 


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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 § 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. 

SO2 means sulfur dioxide. 

Special purpose monitor (SPM) 

station means a monitor included in an 

agency’s monitoring network that the 

agency has designated as a special 

purpose monitor station in its 

monitoring network plan and in the Air 

Quality System, and which the agency 

does not count when showing 

compliance with the minimum 

requirements of this subpart for the 

number and siting of monitors of 

various types. 

State agency means the air pollution 

control agency primarily responsible for 

development and implementation of a 

plan under the Act. 

State speciation site means a 

supplemental PM2.5 speciation station 

that is not part of the speciation trends 

network. 

Station means a single monitor, or a 

group of monitors with a shared 

objective, located at a particular site. 

STN station means a PM2.5 speciation 

station designated to be part of the 

speciation trends network. This network 

provides chemical species data of fine 

particulate. 

Traceable means that a local standard 

has been compared and certified, either 

directly or via not more than one 

intermediate standard, to a National 

Institute of Standards and Technology 

(NIST)-certified primary standard such 

as a NIST-traceable Reference Material 

(NTRM) or a NIST-certified Gas 

Manufacturer’s Internal Standard 

(GMIS). 

TSP (total suspended particulates) 

means particulate matter as measured 

by the method described in appendix B 

of part 50 of this chapter. 

Urbanized area means an area with a 

minimum residential population of at 

least 50,000 people and which generally 

includes core census block groups or 

blocks that have a population density of 

at least 1,000 people per square mile 

and surrounding census blocks that 

have an overall density of at least 500 

people per square mile. The Census 

Bureau notes that under certain 

conditions, less densely settled territory 

may be part of each Urbanized Area. 

VOC means volatile organic 

compounds. 

§ 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. 

§ 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. 

■ 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 

§ 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. 


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(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 PM2.5 NAAQS as described in 

§ 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 PM2.5 monitoring network 

that impact the location of a violating 

PM2.5 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 PM2.5

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 

PM2.5, 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 § 58.14. 

§ 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. 

§ 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. Areaspecific PAMS operating schedules 

must be included as part of the PAMS 

network description and must be 

approved by the Regional 

Administrator. 

(d) For manual PM2.5 samplers: 

(1) Manual PM2.5 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 PM2.5 monitor. 

For SLAMS PM2.5 sites with both 

manual and continuous PM2.5 monitors 

operating, the monitoring agency may 

request approval for a reduction to 1-in6 day PM2.5 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 PM2.5 data 

quality assessments, the location of 

current PM2.5 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 PM2.5 NAAQS must 

have an FRM or FEM operate on a daily 

schedule. 

(2) Manual PM2.5 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 PM2.5 speciation samplers 

at STN stations must operate on a 1-in3 day sampling frequency. 

(e) For PM10 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 


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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 

PM10 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 PM10

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. 

(f) For manual PM10–2.5 samplers: 

(1) Manual PM10–2.5 samplers at NCore 

stations must operate on at least a 1-in3 day schedule at sites without a 

collocated continuously operating 

federal equivalent PM10–2.5 method that 

has been designated in accordance with 

part 53 of this chapter. 

(2) Manual PM10–2.5 speciation 

samplers at NCore stations must operate 

on at least a 1-in-3 day sampling 

frequency. 

§ 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. 

§ 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 § 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 


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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 PM2.5, O3, CO, PM10, SO2, Pb, 

or NO2 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, PM10, 

SO2, or NO2 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 PM2.5 SLAMS monitor which 

EPA has determined cannot be 

compared to the relevant NAAQS 

because of the siting of the monitor, in 

accordance with § 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. 

§ 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. 

§ 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 SO2; CO; O3; NO2; 

NO; NOY; NOX; Pb; PM10 mass 

concentration; PM2.5 mass 

concentration; for filter-based PM2.5

FRM/FEM the field blank mass, 

sampler-generated average daily 

temperature, and sampler-generated 

average daily pressure; chemically 

speciated PM2.5 mass concentration 

data; PM10–2.5 mass concentration; 

chemically speciated PM10–2.5 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, 


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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, NH3, and HNO3

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 PM2.5, 

PM10, and PM10¥2.5 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 healthrelated air pollution studies. 

■ 28. Subpart C is revised to read as 

follows: 

Subpart C—Special Purpose Monitors 

§ 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 § 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 § 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 § 58.11, § 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 § 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 § 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 PM2.5 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, SO2, NO2, Pb, or 24-hour PM10

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. 

■ 29. Subpart D is revised to read as 

follows: 

Subpart D—Comparability of Ambient 

Data to NAAQS 

§ 58.30 Special considerations for data 

comparisons to the NAAQS. 

(a) Comparability of PM2.5 data. (1) 

There are two forms of the PM2.5

NAAQS described in part 50 of this 

chapter. The PM2.5 monitoring site 

characteristics (see appendix D to this 

part, section 4.7.1) impact how the 

resulting PM2.5 data can be compared to 

the annual PM2.5 NAAQS form. PM2.5

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 PM2.5

NAAQS. For example, if the PM2.5

monitoring site is adjacent to a unique 

dominating local PM2.5 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 PM2.5 NAAQS. 

(2) There are cases where certain 

population-oriented microscale or 

middle scale PM2.5 monitoring sites are 

determined by the Regional 

Administrator to collectively identify a 

larger region of localized high ambient 

PM2.5 concentrations. In those cases, 

data from these population-oriented 

sites would be eligible for comparison to 

the annual PM2.5 NAAQS. 

(b) [Reserved] 

Subpart E—[Removed and Reserved] 

■ 30. Subpart E of part 58 is removed 

and reserved. 

Subpart F—[Amended] 

■ 31. Section 58.50 is revised to read as 

follows: 

§ 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. 


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Subpart G—[Amended] 

■ 32. Sections 58.60 and 58.61 are 

revised to read as follows: 

§ 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 § 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. 

§ 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. 

■ 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 SO2, NO2, O3, CO, PM2.5, PM10

and PM10¥2.5 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 (SO2) and 

nitrogen dioxide (NO2) 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 permitgranting 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 permitgranting 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 


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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 functionthat 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 PM2.5 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 

PM10–2.5 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 (SO2), nitrogen oxide (NO), 

and nitrogen dioxide (NO2) 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 (O3) 

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 O3

transfer standard. Consult references 7 and 8 

of this appendix for guidance on primary and 

transfer standards for O3. 

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. 


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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 

SO2, NO2, O3, 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 SO2, NO2, O3 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 SO2, NO2, and O3, 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 

SO2, NO2, O3, or CO. Each calendar quarter 

(during which analyzers are operated), 

evaluate at least 25 percent of the SLAMS 

analyzers that monitor for SO2, NO2, O3, 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: 

Audit level 

Concentration range, ppm 

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 


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Audit level 

Concentration range, ppm 

O3 SO2 NO2 CO 

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) NO2 audit gas for 

chemiluminescence-type NO2 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–NOX

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 NO2

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 SO2, 

NO2, and O3 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 PM10, PM10¥2.5 and 

PM2.5. 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 PM10, PM10¥2.5 and PM2.5

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 

PM2.5. 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 


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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 ±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 ± 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 PM2.5, 

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 PM2.5 measurement if the latter 

measurement is unavailable. Any PM2.5

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 

PM10¥2.5. For the PM10¥2.5 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 

PM10¥2.5 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 PM10¥2.5 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 PM10¥2.5 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 PM2.5 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 μg/m3. 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 PM2.5 are described in 

section 4.3.2 of this appendix. 

3.2.8 PM10¥2.5 Performance Evaluation 

Program. For the PM10¥2.5 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 

PM10¥2.5 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 PM10¥2.5 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 

PM10. For each network of manual PM10

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 PM10 shall 

be considered separately from one another. 

However, PM10 samplers used in the PM10–2.5

network, may be counted along with the 

PM10 samplers in the PM10 network as long 

as the PM10 samplers in both networks are 

the same method designation. PM10 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 PM10, 

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 


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61308 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

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 PM2.5, PM10 (low-volume 

instruments), and PM10¥2.5. High-volume 

PM10 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 PM2.5, PM10, PM10¥2.5 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: 

Range Pb concentration, μg/strip Equivalent ambient Pb concentration, μg/m3 1

1 ......... 100–300 0.5–1.5 

2 ......... 400–1,000 3.0–5.0 

1Equivalent ambient Pb concentration in μ/m3 is based on sampling at 1.7 m3/min for 24 hours on a 20.3 cm × 25.4 cm (8 inch × 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 μg 

Pb/strip) and the corresponding measured 

concentrations (in μg 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 

PM2.5. Follow the same procedure as 

described in section 3.2.5 of this appendix. 

PM2.5 samplers used in the PM10–2.5 network, 

may be counted along with the PM2.5

samplers in the PM2.5 network as long as the 

PM2.5 samplers in both networks are the same 

method designation. 

3.3.6 Collocated Sampling Procedures for 

PM10–2.5. All designated FRMs within the 

PM10–2.5 monitoring network must have 15 

percent of the monitors collocated (values of 

0.5 and greater round up) at the PM10–2.5

sites. All FRM method designations can be 

aggregated. 

3.3.6.1 The EPA shall ensure that each 

designated FEM within the PM10–2.5

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 PM10–2.5 site; 

primary quality assurance organizations 

already monitoring for PM10 and PM2.5 using 

FRMs or FEMs; and an appropriate 

distribution among rural and urban NCore 

sites. Monitoring organizations implementing 

PM10 samplers and PM2.5 FRM samplers of 

the same method designation as the PM10–2.5

FRM can include the PM10–2.5 monitors in 

their respective PM10 and PM2.5 count. 

Follow the same procedures as described in 

sections 3.2.6.2 and 3.2.6.3 of this appendix. 

3.3.7 PM2.5 Performance Evaluation 

Program (PEP) Procedures. Follow the same 

procedure as described in section 3.2.7 of 

this appendix. 

3.3.8 PM10–2.5 Performance Evaluation 

Program (PEP) Procedures. One performance 

evaluation audit, as described in section 3.2.7 

of this appendix must be performed at one 

PM10–2.5 site in each primary quality 

assurance organization each year. Monitoring 

organizations implementing PM2.5 FRM 

samplers of the same method designation in 

both the PM2.5 and the PM10–2.5 networks can 

include the PM10–2.5 performance evaluation 

audit in their respective PM2.5 performance 

evaluation count as long as the performance 

evaluation is conducted at the PM10–2.5 site. 

The calculations for evaluating bias between 

the primary monitor(s) and the performance 

evaluation monitors for PM10–2.5 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 SO2, NO2, O3 and CO and by primary 

quality assurance organization for PM10, 

PM2.5, PM10–2.5 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 μg/m3. 

(2) Pb: 0.15 μg/m3. 

(3) PM10 (Hi-Vol): 15 μg/m3. 

(4) PM10 (Lo-Vol): 3 μg/m3. 

(5) PM10–2.5 and PM2.5: 3 μg/m3. 

4.1 Statistics for the Assessment of QC 

Checks for SO2, NO2, O3 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 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61309 

each single point check, calculate the percent 

difference, di, as follows: 

Equation 1

d meas audit

audit i = − ×100

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 SO2, NO2, O3, 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: 

Equation 2

CV

nd d

n n

n

X

i

i

n

i

i

n

n

=

⋅ − 



 





( ) − ⋅ = = −

−

∑ ∑ 2

1 1

2

01 1

2 1

1

. ,

where, X2

0.1,n–1 is the 10th percentile of a chisquared distribution with n–1 degrees of 

freedom. 

4.1.3 Bias Estimate. The bias estimate is 

calculated using the one-point QC checks for 

SO2, NO2, O3, or CO described in section 

3.2.1 of this appendix and the performance 

evaluation program for PM10–2.5 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: 

Equation 3

AB AB t AS

n

=+ ⋅ 0 95 1 . ,n−

where, n is the number of single point checks 

being aggregated; t0.95,n–1 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: 

Equation 4

AB

n

di

i

n

= ⋅ =

∑1

1

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: 

Equation 5

AS

nd d

n n

i

i

n

i

i

n

=

⋅ − 



 





( ) −

= =

∑ ∑ 1

2

1

2

1

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 onepoint QC Checks. The annual performance 

evaluations for SO2, NO2, O3, 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: 

Equation 6

Upper obability Limit m S Pr . =+ ⋅ 1 96

Equation 7

Lower Probability Limit = m -1.96 S

where, m is the mean (equation 8 of this 

appendix): 

Equation 8

m

k

di

i

k

= ⋅ =

∑ 1

1

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: 

Equation 9

S

kd d

k k

i

i

k

i

i

k

=

⋅ − 



 





( ) −

= =

∑ ∑ 2

1 1

2

1

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. Ninetyfive 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 PM10. 

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: 

Equation 10

d X Y

X Y i

i i

i i

= −

( ) + ⋅ / 2

100

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: 

Equation 11

CV

nd d

n n

n

X

i

i

n

i

i

n

n

=

⋅ − 



 





( ) − ⋅ = = −

−

∑ ∑ 2

1 1

2

01 1 2 1

1

. ,

2

where, n is the number of valid data pairs 

being aggregated, and X 2

0.1.n–1 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; t0.95,n–1 is the 

95th quantile of a t-distribution with n1 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. 


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61310 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

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 PM2.5

and PM10–2.5.

4.3.1 Precision Estimate. Precision for 

collocated instruments for PM2.5 and PM10–2.5

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 PM10–2.5. The PM2.5

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: 

Equation 12

D

n

d

j

i

i

n j

= ⋅ =

∑ 1

1

where, nj is the number of pairs and d1, d2, 

dnj 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: 

Equation 13

Upper D t s

n df

j

 90% Confidence Interval =+ ⋅ 0 95 . ,

Equation 14

Lower Confidence Interval D t s

n df

j

90% =− ⋅ 0 95 . ,

Where, t0.95,df is the 95th quantile of a tdistribution with degrees of freedom 

df = nj ¥1 and s is an estimate of the 

variability of the average bias calculated 

using equation 15 of this appendix: 

Equation 15

s

d D

n

i

i

n

j

j

=

( ) −

−

=

∑ 2

1

1

4.4 Statistics for the Assessment of Pb. 

4.4.1 Precision Estimate. Follow the same 

procedures as described for PM10 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: 

Equation 16

rel error

measured concentration audit concentra . = − tion

audit concentration

rel error

rel mass error

( )

= +





 



 1

1 . ( ) . − rel volumeerror .

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: 

Equation 17

rel error

relative mass error relative volumeerror . ≤+

1− relative volumeerror


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

t0.95,n–1 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; t0.95,n–1 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: 

Equation 18

bias

mass bias vol bias

vol bias = +− ⋅ .100 . 100

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 § 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. 


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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 via the ‘‘primary quality assurance organization’’.Source owner/operator. 

Monitoring Duration ................................. Indefinitely .............................................................................. Usually up to 12 months. 

Annual Performance Evaluation (PE) ..... Standards and equipment different from those used for 

spanning, calibration, and verifications. Prefer different 

personnel.

Personnel, standards and equipment 

different from those used for spanning, calibration, and verifications. 

PE audit rate: 

—Automated .................................... 100% per year ....................................................................... 100% per quarter. 

—Manual .......................................... Varies depending on pollutant. See Table A–2 of this appendix.100% per quarter. 

Precision Assessment: 

—Automated .................................... One-point QC check biweekly but data quality dependent ... One point QC check biweekly. 

—Manual .......................................... Varies depending on pollutant. See Table A–2 of this appendix.One site: 1 every 6 days or every third 

day for daily monitoring (TSP and 

Pb). 

Reporting 

—Automated .................................... By site—EPA performs calculations annually ....................... By site—source owner/operator performs calculations each sampling 

quarter. 

—Manual .......................................... By reporting organization—EPA performs calculations annually.By site—source owner/operator performs calculations each sampling 

quarter. 

TABLE A–2 OF APPENDIX A TO PART 58. MINIMUM DATA ASSESSMENT REQUIREMENTS FOR SLAMS SITES

Method Assessment method Coverage Minimum frequency Parameters reported 

Automated Methods 

1-Point QC for SO2, NO2, 

O3, CO.

Response check at concentration 0.01–0.1 ppm 

SO2, NO2, O3, and 1–10 

ppm CO.

Each analyzer ................... Once per 2 weeks ............. Audit concentration 1 and 

measured concentration 2. 

Annual performance evaluation for SO2, NO2, O3, 

CO.

See section 3.2.2 of this 

appendix.

Each analyzer ................... Once per year ................... Audit concentration 1 and 

measured concentration 2 for each level. 

Flow rate verification PM10, 

PM2.5, PM10–2.5.

Check of sampler flow rate Each sampler .................... Once every month ............ Audit flow rate and measured flow rate indicated 

by the sampler. 

Semi-annual flow rate audit 

PM10, PM2.5, PM10–2.5.

Check of sampler flow rate 

using independent 

standard.

Each sampler .................... Once every 6 .................... Audit flow rate and measured flow rate indicated 

by the sampler. 

Collocated sampling PM2.5, 

PM10–2.5.

Collocated samplers ......... 15% ................................... Every 12 days ................... Primary sampler concentration and duplicate 

sampler concentration. 

Performance evaluation 

program PM2.5, PM10–2.5.

Collocated samplers ......... 1. 5 valid audits for primary QA orgs, with ≤ 5 

sites.

2. 8 valid audits for primary QA orgs, with > 5 

sites.

3. All samplers in 6 years

Over all 4 quarters ............ Primary sampler concentration and performance evaluation sampler 

concentration. 

Manual Methods 

Collocated sampling PM10, 

TSP, PM10–2.5, PM2.5.

Collocated samplers ......... 15% ................................... Every 12 days PSD—

every 6 days.

Primary sampler concentration and duplicate 

sampler concentration. 

Flow rate verification PM10

(low Vol), PM10–2.5, PM2.5.

Check of sampler flow rate Each sampler .................... Once every month ............ Audit flow rate and measured flow rate indicated 

by the sampler. 


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Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 61313 

TABLE A–2 OF APPENDIX A TO PART 58. MINIMUM DATA ASSESSMENT REQUIREMENTS FOR SLAMS SITES—Continued 

Method Assessment method Coverage Minimum frequency Parameters reported 

Flow rate verification PM10

(High-Vol), TSP.

Check of sampler flow rate Each sampler .................... Once every quarter ........... Audit flow rate and measured flow rate indicated 

by the sampler. 

Semi-annual flow rate audit 

PM10, TSP, PM10–2.5, 

PM2.5.

Check of sampler flow rate 

using independent 

standard.

Each sampler, all locations Once every 6 months ....... Audit flow rate and measured flow rate indicated 

by the sampler. 

Manual Methods Lead ....... 1. Check of sample flow 

rate as for TSP.

2. Check of analytical system with Pb audit strips.

1. Each sampler ................

2. Analytical .......................

1. Include with TSP ...........

2. Each quarter .................

1. Same as for TSP. 

2. Actual concentration. 

Performance evaluation 

program PM2.5, PM10–2.5.

Collocated samplers ......... 1. 5 valid audits for primary QA orgs, with ≤ 5 

sites.

2. 8 valid audits for primary QA orgs, with ≥ 5 

sites.

3. All samplers in 6 years

Over all 4 quarters ............ Primary sampler concentration and performance evaluation sampler 

concentration. 

1Effective 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

Primary sampler method 

designation 

Total no. of monitors Total no. collocated No. of collocated FRM 

No. of collocated monitors of 

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 § 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 § 53.11 or § 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 PM2.5 Methods as Approved 

Regional Methods (ARMs) Operated Within a 

Network of Sites. A method for PM2.5 that has 

not been designated as an FRM or FEM as 

defined in § 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 

PM2.5 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 PM10 samplers shall be 

required for the test, as determination of the 

PM2.5/PM10 ratio at the test site shall not be 

required. 

2.4.1.4 The test specification for PM2.5

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 PM2.5

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. 


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61314 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

2.4.1.6 For purposes of determining bias, 

FRM data with concentrations less than 3 

micrograms per cubic meter (μg/m3) 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 PM2.5 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 realtime, to the data output from the PM2.5

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 


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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 § 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 § 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 SO2, 

CO, NO2, O3, PM2.5, or PM10¥2.5 must be 

reference or equivalent methods as defined in 

§ 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 SO2, CO, NO2, O3, PM2.5, 

or PM10¥2.5 monitoring methodologies are 

proposed for monitors not intended for 

NAAQS comparison, such techniques must 

be detailed in the network description 

required by § 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 O3 monitoring at 

PAMS must be automated reference or 

equivalent methods as defined in § 50.1 of 

this chapter. 

4.2 Methods used for NO, NO2 and NOX

monitoring at PAMS should be automated 

reference or equivalent methods as defined 

for NO2 in § 50.1 of this chapter. If alternative 

NO, NO2 or NOX monitoring methodologies 

are proposed, such techniques must be 

detailed in the network description required 

by § 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 § 58.10 and subsequently 

approved by the Administrator. 

5.0 Particulate Matter Episode Monitoring 

5.1 For short-term measurements of PM10

during air pollution episodes (see § 51.152 of 

this chapter) the measurement method must 

be: 

5.1.1 Either the ‘‘Staggered PM10’’ method 

or the ‘‘PM10 Sampling Over Short Sampling 

Times’’ method, both of which are based on 

the reference method for PM10 and are 

described in reference 1: or 

5.1.2 Any other method for measuring 

PM10: 

5.1.2.1 Which has a measurement range 

or ranges appropriate to accurately measure 

air pollution episode concentration of PM10, 

5.1.2.2 Which has a sample period 

appropriate for short-term PM10

measurements, and 

5.1.2.3 For which a quantitative 

relationship to a reference or equivalent 

method for PM10 has been established at the 

use site. Procedures for establishing a 

quantitative site-specific relationship are 

contained in reference 1. 

5.2 PM10 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 


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those described in section 3 of appendix A 

to this part for the PM10 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 PM2.5 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, PM10

mass sites, PM2.5 mass sites, chemicallyspeciated PM2.5 sites, and O3 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 § 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. 


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(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 PM2.5 concentrations which are 

typical over a geographic area having 

relatively high PM2.5 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 PM2.5 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. 

TABLE D–1 OF APPENDIX D TO PART

58. RELATIONSHIP BETWEEN SITE

TYPES AND SCALES OF REPRESENTATIVENESS—Continued 

Site type Appropriate siting 

scales 

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 areawide 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 singlepollutant 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, PM2.5 particle mass using 

continuous and integrated/filter-based 

samplers, speciated PM2.5, PM10–2.5 particle 

mass, speciated PM10–2.5, O3, SO2, CO, NO/ 

NOy, wind speed, wind direction, relative 

humidity, and ambient temperature. 

(1) Although the measurement of NOy is 

required in support of a number of 

monitoring objectives, available commercial 

instruments may indicate little difference in 

their measurement of NOy compared to the 

conventional measurement of NOX, 

particularly in areas with relatively fresh 

sources of nitrogen emissions. Therefore, in 

areas with negligible expected difference 

between NOy and NOX measured 

concentrations, the Administrator may allow 


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for waivers that permit NOX monitoring to be 

substituted for the required NOy 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 (O3) Design Criteria. (a) State, 

and where appropriate, local agencies must 

operate O3 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 O3

NAAQS). Specific SLAMS O3 site minimum 

requirements are included in Table D–2 of 

this appendix. The NCore sites are expected 

to complement the O3 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 O3 sites needed to support 

the basic monitoring objectives of public data 

reporting, air quality mapping, compliance, 

and understanding O3-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 O3 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

MSA population1, 2

Most recent 3- 

year design value 

concentrations 

≥85% of any O3

NAAQS3

Most recent 3- 

year design value 

concentrations 

<85% of any O3

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). 

2Population based on latest available census figures. 

3The ozone (O3) National Ambient Air Quality Standards (NAAQS) levels and forms are defined in 40 CFR part 50. 4These 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 O3 network, at least one O3

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 O3 monitoring program for an 

area. Some of these additional factors include 

geographic size, population density, 

complexity of terrain and meteorology, 

adjacent O3 monitoring programs, air 

pollution transport from neighboring areas, 

and measured air quality in comparison to all 

forms of the O3 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 O3 requirements are allowed 

if approved by the EPA Regional 

Administrator. 

(c) The appropriate spatial scales for O3

sites are neighborhood, urban, and regional. 

Since O3 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 subregion, 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 O3 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 

O3 monitoring network design should be 

used to evaluate the adequacy of each 

existing O3 monitor, to relocate an existing 

site, or to locate any new O3 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 NOX sources. For an urban 

scale site to measure the high concentration 

areas, the emission inventories should be 


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used to define the extent of the area of 

important nonmethane hydrocarbons and 

NOX 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 O3 air quality days. 

Trajectory analyses, an evaluation of wind 

and emission patterns on high O3 days, can 

also be useful in evaluating an O3 monitoring 

network. In areas without any previous O3 air 

quality measurements, meteorological and O3

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 O3 concentrations, 

more specifically, downwind during periods 

of photochemical activity. In many cases, 

these maximum concentration O3 sites will 

be located 10 to 30 miles or more downwind 

from the urban area where maximum O3

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 O3 levels. Monitoring agencies are to 

consult with their EPA Regional Office when 

considering siting a maximum O3

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 O3

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 O3 levels decrease significantly in 

the colder parts of the year in many areas, O3

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 O3 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 O3 data to 

support a change to the O3 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, 216.

January .... December 

Texas AQCR 022, 

210, 211, 212, 

215, 217, 218.

March ....... October 

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 (NO2) Design 

Criteria. (a) There are no minimum 

requirements for the number of NO2

monitoring sites. Continued operation of 

existing SLAMS NO2 sites using FRM or FEM 

is required until discontinuation is approved 

by the EPA Regional Administrator. Where 

SLAMS NO2 monitoring is ongoing, at least 

one NO2 site in the area must be located to 

measure the maximum concentration of NO2. 

(b) NO/NOy measurements are included 

within the NCore multipollutant site 

requirements and the PAMS program. These 

NO/NOy measurements will produce 

conservative estimates for NO2 that can be 

used to ensure tracking continued 

compliance with the NO2 NAAQS. NO/NOy

monitors are used at these sites because it is 

important to collect data on total reactive 

nitrogen species for understanding O3

photochemistry. 

4.4 Sulfur Dioxide (SO2) Design Criteria. 

(a) There are no minimum requirements for 

the number of SO2 monitoring sites. 

Continued operation of existing SLAMS SO2

sites using FRM or FEM is required until 

discontinuation is approved by the EPA 

Regional Administrator. Where SLAMS SO2

monitoring is ongoing, at least one of the 

SLAMS SO2 sites must be a maximum 

concentration site for that specific area. 

(b) The appropriate spatial scales for SO2

SLAMS monitoring are the microscale, 

middle, and possibly neighborhood scales. 

The multi-pollutant NCore sites can provide 


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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 SO2. 

(1) Micro and middle scale—Some data 

uses associated with microscale and middle 

scale measurements for SO2 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 SO2 stationary 

source impact investigation. Typical 

locations might include suburban areas 

adjacent to SO2 stationary sources for 

example, or for determining background 

concentrations as part of these studies of 

population responses to exposure to SO2. 

(c) Technical guidance in reference 1 of 

this appendix should be used to evaluate the 

adequacy of each existing SO2 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 (PM10) Design 

Criteria. (a) State, and where applicable local, 

agencies must operate the minimum number 

of required PM10 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

Population category High concentration 2

Medium concentration 3Low concentration 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 

1Selection 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. 5These 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 PM10 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 

PM10 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 

(PM10) 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 PM10

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 PM10, unpaved or 

seldomly swept parking lots associated with 

these sources could be an important source 


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in addition to the vehicular emissions 

themselves. 

(3) Neighborhood scale—Measurements in 

this category represent conditions throughout 

some reasonably homogeneous urban subregion 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 PM10 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 largerscale 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 (PM2.5) Design 

Criteria. 

4.7.1 General Requirements. (a) State, and 

where applicable local, agencies must 

operate the minimum number of required 

PM2.5 SLAMS sites listed in Table D–5 of this 

appendix. The NCore sites are expected to 

complement the PM2.5 data collection that 

takes place at non-NCore SLAMS sites, and 

both types of sites can be used to meet the 

minimum PM2.5 network requirements. 

Deviations from these PM2.5 monitoring 

requirements must be approved by the EPA 

Regional Administrator. 

TABLE D–5 OF APPENDIX D TO PART 58. PM2.5 MINIMUM MONITORING REQUIREMENTS

MSA population 1,2

Most recent 3- 

year design value 

≥85% of any 

PM2.5 NAAQS3

Most recent 3- 

year design value 

<85% of any 

PM2.5 NAAQS3, 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). 

2Population based on latest available census figures. 

3The PM2.5 National Ambient Air Quality Standards (NAAQS) levels and forms are defined in 40 CFR part 50. 4These 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 PM2.5. 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 middlescale PM2.5 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 

PM2.5 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 PM2.5. 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 PM2.5 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 

PM2.5 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. PM2.5 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 PM2.5 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 PM2.5

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 


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emissions, losses and transport. PM2.5

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 PM2.5 levels and may 

also be associated with elevated O3 and 

regional haze. 

4.7.2 Requirement for Continuous PM2.5

Monitoring. State, or where appropriate, local 

agencies must operate continuous fine 

particulate analyzers equal to at least onehalf (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 PM2.5 Background 

and Transport Sites. Each State shall install 

and operate at least one PM2.5 site to monitor 

for regional background and at least one 

PM2.5 site to monitor regional transport. 

These monitoring sites may be at communityoriented 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 PM2.5 monitors. 

4.7.4 PM2.5 Chemical Speciation Site 

Requirements. Each State shall continue to 

conduct chemical speciation monitoring and 

analyses at sites designated to be part of the 

PM2.5 Speciation Trends Network (STN). The 

selection and modification of these STN sites 

must be approved by the Administrator. The 

PM2.5 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 PM2.5 Spatial 

Averaging Approaches. (a) The PM2.5

NAAQS, specified in 40 CFR part 50, 

provides State and local air monitoring 

agencies with an option for spatially 

averaging PM2.5 air quality data. More 

specifically, two or more communityoriented (i.e., sites in populated areas) PM2.5

monitors may be averaged for comparison 

with the annual PM2.5 NAAQS. This 

averaging approach is directly related to 

epidemiological studies used as the basis for 

the PM2.5 annual NAAQS. Spatial averaging 

does not apply to comparisons with the daily 

PM2.5 NAAQS. 

(b) State and local agencies must carefully 

consider their approach for PM2.5 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 PM2.5 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 § 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 (PM10¥2.5) 

Design Criteria. 

4.8.1 General Monitoring Requirements. 

(a) The only required monitors for PM10¥2.5

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 

PM10¥2.5 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 sourceoriented 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 PM10–2.5 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 PM10–2.5 Chemical Speciation Site 

Requirements. PM10–2.5 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 O3 air pollution in 

areas classified as serious, severe, or extreme 

nonattainment for O3 than would otherwise 

be achieved through the NCore and SLAMS 

sites. More specifically, the PAMS program 

includes measurements for O3, oxides of 

nitrogen, VOC, and meteorology. 

5.1 PAMS Monitoring Objectives. PAMS 

design criteria are site specific. Concurrent 

measurements of O3, 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 O3 precursor source areas and 

predominant wind directions associated with 

high O3 events. Specific monitoring 

objectives are associated with each location. 

The overall design should enable 

characterization of precursor emission 

sources within the area, transport of O3 and 

its precursors, and the photochemical 

processes related to O3 nonattainment. 

Specific objectives that must be addressed 

include assessing ambient trends in O3, 

oxides of nitrogen, VOC species, and 

determining spatial and diurnal variability of 

O3, 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 O3 and its precursor 

concentrations entering the area and will 

identify those areas which are subjected to 

transport. 


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(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 O3 concentrations occurring 

downwind from the area of maximum 

precursor emissions. 

(d) Type 4 sites are established to 

characterize the downwind transported O3

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 O3 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 § 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 NOy

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

Measurement Where required Sampling frequency (all daily except for upper air meteorology) 1

Speciated VOC2 Two sites per area, one of which must be a Type 2 site ........ During the PAMS monitoring period: (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 classified as serious or above for the 8- 

hour ozone standard.

3-hour samples every day during the PAMS monitoring period. 

NOX ................... All Type 2 sites ......................................................................... Hourly during the ozone monitoring season.3

NOy ................... One site per area at the Type 3 or Type 1 site ....................... Hourly during the ozone monitoring season. 

CO (ppb level) ... One site per area at a Type 2 site ........................................... Hourly during the 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 location within PAMS area ....................... Sampling frequency must be approved as part of the annual 

monitoring network plan required in 40 CFR 58.10. 

1 Daily or with an approved alternative plan. 

2Speciated VOC is defined in the ‘‘Technical Assistance Document for Sampling and Analysis of Ozone Precursors’’, EPA/600–R–98/161, 

September 1998. 3Approved 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 O3

nonattainment area to serious, severe, or 

extreme, or the designation of a new area and 

classification to serious, severe, or extreme 

O3 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 SO2 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 PM2.5

and PM10. 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 


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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, PM10, PM10–2.5, PM2.5, and carbon 

monoxide sites. Middle scale PM10–2.5 sites 

are required to have sampler inlets between 

2 and 7 meters above ground level. 

Microscale Pb, PM10, PM10–2.5 and PM2.5 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±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 SO2, 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 O3

in the vicinity of probes and monitoring 

paths for O3. 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 SO2 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 SO2, O3, or NO2, 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 SO2, O3, 

or NO2 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 O3 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 O3 analyzer, it is important to 

minimize destructive interferences from 

sources of NO, since NO readily reacts with 

O3. In siting NO2 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 


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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) 

Roadway average daily traffic, 

vehicles per day 

Minimum distance 1 (meters) Minimum distance 1, 2 (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. 2Applicable 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

Roadway average daily traffic, vehicles per day 

Minimum 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 (PM2.5, 

PM10, 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. 


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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, SO2, NO2, and 

O3, special probe material must be used for 

point analyzers. Studies 20¥24 have been 

conducted to determine the suitability of 

materials such as polypropylene, 

polyethylene, polyvinyl chloride, Tygon, 

aluminum, brass, stainless steel, copper, 

Pyrex glass and Teflon for use as intake 

sampling lines. Of the above materials, only 

Pyrex glass and Teflon have been found to 

be acceptable for use as intake sampling lines 

for all the reactive gaseous pollutants. 

Furthermore, the EPA25 has specified 

borosilicate glass or FEP Teflon as the only 

acceptable probe materials for delivering test 

atmospheres in the determination of 

reference or equivalent methods. Therefore, 

borosilicate glass, FEP Teflon 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 is 

unacceptable as the probe material because of 

VOC adsorption and desorption reactions on 

the FEP Teflon. 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.26 Other 

studies 27¥28 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 


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

Pollutant Scale (maximum monitoring path 

length, meters) 

Height from 

ground to 

probe, inlet 

or 80% of 

monitoring 

path 1

Horizontal 

and vertical 

distance 

from supporting 

structures 2

to probe, 

inlet or 90% 

of monitoring path 1

(meters) 

Distance 

from trees 

to probe, 

inlet or 90% 

of monitoring path 1

(meters) 

Distance from roadways to probe, 

inlet or monitoring path 1

(meters) 

SO2 3,4,5,6 ............................. Middle (300 m) Neighborhood 

Urban, and Regional (1 km).

2–15 .......... > 1 ............. > 10 ........... N/A 

CO 4,5,7 ................................ Micro, middle (300 m), Neighborhood (1 km).3±1⁄2: 2–15 > 1 ............. > 10 ........... 2–10; see Table E–2 of this appendix for middle and neighborhood scales. 

NO2, O3 3,4,5 ........................ Middle (300 m) Neighborhood, 

Urban, and Regional (1 km).

2–15 .......... > 1 ............. > 10 ........... See Table E–1 of this appendix 

for all scales. 

Ozone precursors (for 

PAMS) 3,4,5.

Neighborhood and Urban (1 km) 2–15 .......... > 1 ............. > 10 ........... See Table E–4 of this appendix 

for all scales. 

PM,Pb 3,4,5,6,8 ...................... Micro: Middle, Neighborhood, 

Urban and Regional.

2–7 (micro); 

2–7 (middle 

PM10–2.5); 

2–15 (all 

other 

scales).

> 2 (all 

scales, 

horizontal 

distance 

only).

> 10 (all 

scales).

2–10 (micro); see Figure E–1 of 

this appendix for all 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. 2When probe is located on a rooftop, this separation distance is in reference to walls, parapets, or penthouses located on roof.

3Should 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. 

6The 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. 7For 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 SO2 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 


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61328 Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / Rules and Regulations 

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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