Particulate Matter Air Quality Standards: Background and Current Developments

Congressional research reportJan 10, 2005

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Order Code RL31531

CRS Report for Congress

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Particulate Matter Air Quality Standards:

Background and Current Developments

Updated January 10, 2005

Robert Esworthy

Specialist in Environmental Policy

Resources, Science, and Industry Division

Congressional Research Service ˜ The Library of Congress

Particulate Matter Air Quality Standards:

Background and Current Developments

Summary

The Environmental Protection Agency (EPA) is nearing completion of its

review of contentious air quality standards for particulate matter (PM), with final

action expected in late 2005. The current standards are among the most far-reaching

regulations on EPA’s agenda. Promulgated in 1997, but only now being

implemented, the standards could potentially prevent the loss of thousands of lives

annually at an annual cost estimated by the agency to be $8.6 billion.

The Clean Air Act (CAA, Sections 108 and 109) requires that air quality criteria

used in determining National Ambient Air Quality Standards (NAAQS) reflect the

latest scientific information. The act includes provisions for the periodic review and

revision, as appropriate, of existing criteria and standards. It is this periodic review

process that is nearing completion. In October 2004, EPA released Air Quality

Criteria for Particulate Matter, reflecting the agency’s synthesis of relevant PM

research conducted since the agency’s last review, completed in 1996. This report,

referred to as a “criteria document,” will provide the scientific basis for assessments

and policy decisions regarding the adequacy of the current PM NAAQS. Further

decisions, including recommendations regarding the standards, are expected early in

2005, following the release of what is referred to as a “staff paper.”

Meanwhile, EPA is continuing implementation of the 1997 particulate matter

standards, which had been delayed several years by litigation and other factors. On

January 5, 2005, EPA published the final designations of geographical areas for the

fine particulate matter or “PM2.5” (particles less than 2.5 micrometers in diameter)

NAAQS. EPA designated 225 counties in 20 states, and the District of Columbia,

as “nonattainment areas”; those areas with (or contributing to) air quality levels

exceeding the annual and 24-hour PM2.5 standards.

Congress and a wide variety of stakeholders have closely followed the evolution

and development of PM NAAQS. In 1997, when the current standards were

promulgated, Congress held 28 days of hearings on the EPA rule. Subsequently,

more than 100 plaintiffs sued to overturn the standards. This litigation went to the

Supreme Court before being resolved, largely in EPA’s favor, in February 2001.

Since FY1998, in an effort to expedite research and strengthen the science

underlying EPA’s review of the standards, Congress has appropriated funding

specifically for PM research annually ($62 million for FY2005). The research,

including re-analysis of key studies underlying the 1997 standards, has largely

confirmed EPA’s earlier conclusions, although new questions have been raised

regarding the methodology used in some of the studies. The National Academy of

Sciences (NAS) has issued four reports on the state of PM research at EPA, and EPA

released a report reviewing its five-year progress of PM research.

Because of the potential impacts particulate matter standards could have on both

public health and the economy, EPA’s reassessment of the PM standards will likely

be of continued interest to Congress. This report will be updated as events warrant.

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Recent Developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Review of Particulate Matter Scientific Data . . . . . . . . . . . . . . . . . . . . 2

Implementation of Current (1997) PM NAAQS . . . . . . . . . . . . . . . . . . 2

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Process for Setting National Ambient Air Quality Standards . . . . . . . . . . . . 4

History of Particulate Matter Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1997 Ozone NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Legal Challenges to the 1997 PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Court of Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Supreme Court . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

On Remand to the Court of Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Health Effects of Particulate Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Science Behind the 1997 PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . 12

Particulate Matter Scientific Knowledge Since 1997 . . . . . . . . . . . . . . . . . 14

Increased Particulate Matter Research Funding . . . . . . . . . . . . . . . . . . 14

National Academy of Science (NAS) Particulate Matter

Research Priorities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

HEI-Sponsored National Morbidity Mortality and

Air Pollution Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Re-analyses of Selected Time-Series Studies . . . . . . . . . . . . . . . . . . . 20

Status of EPA’s Review of the 1997 PM NAAQS . . . . . . . . . . . . . . . . . . . 20

Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

2004 Particulate Matter Criteria Document . . . . . . . . . . . . . . . . . . . . . 21

EPA Particulate Matter Staff Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Opposing Views, Potential Challenges and Litigation . . . . . . . . . . . . 24

Implementation of the 1997 PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . 26

PM2.5 Monitoring Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

PM2.5 Attainment/Nonattainment Geographical Designation . . . . . . . . 27

Other Activities Impacting PM NAAQS Implementation . . . . . . . . . . . . . . 28

Current CAA Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Proposed Regulations and Legislation . . . . . . . . . . . . . . . . . . . . . . . . . 29

California Particulate Matter Standards . . . . . . . . . . . . . . . . . . . . . . . . 29

International Particulate Matter Standards . . . . . . . . . . . . . . . . . . . . . . 30

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

List of Tables

Table 1. Changes to Particulate Matter National Ambient

Air Quality Standards (NAAQS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Table 2. Research Priorities for Particulate Matter Identified by

the National Academy of Sciences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 3. California’s State Particulate Matter Standards and

the 1997 National Primary Particulate Matter Standards . . . . . . . . . . . . . . . 30

Table 4. PM10 and PM2.5 Air Quality Standard Comparison of

United States and Selected Countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Particulate Matter Air Quality Standards:

Background and Current Developments

Introduction

Under the Clean Air Act (CAA), EPA is responsible for protecting public health

and the environment from emissions that pollute ambient, or outdoor, air. Under

Sections 108-109 of the CAA, Congress mandated that EPA set national ambient air

quality standards (NAAQS) for pollutants whose emissions “may reasonably be

anticipated to endanger public health or welfare” and “the presence of which in the

ambient air results from numerous or diverse mobile or stationary sources” (42

U.S.C. 7408(a)(1)).

EPA has identified and promulgated NAAQS for six principal pollutants

classified by the agency as “criteria pollutants”: particulate matter (PM), ozone (O3,

a key measure of smog), nitrogen dioxide (NO2, or, inclusively, nitrogen oxides,1

NOx), sulfur oxides (SOx, or, specifically, SO2), carbon monoxide (CO), and lead

(Pb). Every five years, according to the statute (but less frequently in practice), EPA

is required to review the latest scientific studies and either reaffirm or modify the

NAAQS. The most recent changes, a strengthening of the particulate matter and

ozone standards, were promulgated jointly in 1997.

Since they were modified in 1997, the particulate matter standards (also referred

to as the PM NAAQS) issued by EPA,2 and the subsequent review to evaluate

whether to revise these standards again, have been the source of significant

controversy. The particulate matter standards have prompted a national debate

regarding how much scientific information is necessary before a regulation can be put

in place, and the appropriate levels of health protection. Congress has been especially

interested in EPA’s promulgation of these CAA standards and has held numerous

hearings on particulate matter.

As required by the CAA, EPA has been reviewing the current particulate matter

standards. The agency recently finalized its review of the scientific research

completed since 1996 and is expected to complete its determination of whether to

increase or decrease the stringency of the standard, or reaffirm the current standards,

by late 2005 or early 2006.

The NAAQS is for NO2; nitrogen gases that are ozone precursors are referred to as NOx.

The original PM NAAQS were for “Total Suspended Particulates” (TSP). In 1987, the

standards focused on particles smaller than 10 microns (PM10). In 1997 EPA added

standards for “fine” particles smaller than 2.5 microns (PM2.5), for the first time. EPA also

revised the existing NAAQS for PM10 (61 Federal Register 38652-38896, December 13,

1996). See discussion later in this report.

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This report is intended to assist the reader in understanding the history of the

particulate matter standards.3 Following a brief summary of recent developments

regarding the implementation and re-evaluation of the 1997 standards, the report

provides a broad overview of the standard-setting process, followed by a description

of revisions to earlier standards, legal challenges to the 1997 standard, and particulate

matter health effects research. EPA’s ongoing progress in reviewing the 1997

standard is then summarized. Other activities that potentially impact the

implementation and review of the particulate matter standards, such as other air

quality regulations and proposed legislation, are also discussed in this report.

Recent Developments

Review of Particulate Matter Scientific Data. In October 2004, EPA

released Air Quality Criteria for Particulate Matter. Referred to as a “criteria

document,” the report has undergone extensive peer review and comment, and

presents the results of the EPA’s review of numerous studies and related research

compiled since the agency completed its previous review in 1996. The information

in the report will serve as the scientific basis for further assessment by EPA technical

staff in developing options to be considered regarding policy decisions affecting the

adequacy of the current PM NAAQS promulgated in 1997. The ultimate

determination by the EPA Administrator of whether to change the existing PM

NAAQS is not expected until late 2005 or early 2006.

Implementation of Current (1997) PM NAAQS. EPA recently completed

the process for designating geographical areas as attainment or nonattainment with

respect to the current particulate matter air quality standard. The EPA Administrator

signed a final rule on December 17, 2004, designating of all or part of 225 counties4

in 20 states, as well as the District of Columbia, for nonattainment of the NAAQS for

fine particulalte matter or “PM2.5” (particles less than 2.5 micrometers (µm) in

diameter). The final rule was published in the Federal Register on January 5, 2005

(70 Fed. Reg. 944-1019), and goes into effect April 5, 2005 (90 days from the date

of publication).

Nonattainment designation begins a process in which states (and tribes) must

develop and adopt emission control programs sufficient to bring air quality into

compliance by an EPA-defined deadline. States are required to submit

“implementation” plans for how they will meet the PM2.5 NAAQS by early 2008, and

must be in compliance by 2010 unless they are granted a five-year extension. For a

more detailed discussion of the implementation of the 1997 PM NAAQS, and the

associated designation process, see CRS Report RL32431, Particulate Matter

(PM2.5): National Ambient Air Quality Standards (NAAQS) Implementation.

Given the historical nature of the report, portions of the discussion are unchanged from an

August 6, 2002, report under the same title, prepared by Anne L. Hardenberg, formerly of

the Congressional Research Service, Resources, Science, and Industry Division.

Includes 7 cities: Baltimore, MD; St. Louis, MO; Alexandria, VA; Fairfax, VA; Falls

Church, VA; Manassas, VA; and Manassas Park, VA.

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Overview

Similar to the review that led to the establishment of the existing PM NAAQS

in 1997, EPA’s current review of the national particulate matter standards is expected

to be controversial. Both the health effects of particulate matter and the economic

effects associated with particulate matter control are potentially significant.

On the one hand, large concentrations of particulate matter have been known to

cause deaths, most infamously in London’s “Killer Fog,” which killed as many as

4,000 people in December 1952. Smaller concentrations of particulate matter have

also been linked to health effects, particularly for sensitive populations, such as

children, asthmatics, and the elderly. Stricter controls on particulate matter should

mean fewer health effects.

In issuing its 1997 NAAQS for particulate matter which included a standard for

fine particles (PM2.5) for the first time, EPA projected that attaining the new standard

for PM2.5 would annually reduce deaths in Los Angeles County by approximately 280

and reduce cases of respiratory symptoms by roughly 20,000.5 For Philadelphia

County, an area with relatively cleaner air, attaining the 1997 PM2.5 standard was

estimated to reduce deaths by 40 and cases of respiratory symptoms by 1,000 each

year.6 Overall, EPA estimated that partial attainment of the 1997 PM2.5 standard

would annually result in the avoidance of 3,300 to 15,600 incidences of premature

mortality nationwide.7

The 1997 PM NAAQS and the supporting scientific data generated significant

scrutiny and controversy, and were the subject of multiple lawsuits. Various

stakeholders disagreed on whether the standards were too strong or too weak.

Although the standards were upheld in litigation, EPA, Congress, the Clean Air

Scientific Advisory Committee mandated by the 1977 CAA Amendments, and other

scientific groups recognized the need to enhance the scientific basis for the PM

NAAQS. The resulting coordinated research effort has advanced the understanding

of the potential health effects associated with particulate matter, but critical

information gaps continue.

Achieving the PM NAAQS will entail costs. In particular, some of the areas

expected to be out of compliance with the 1997 PM2.5 standards have not previously

been designated nonattainment for any other NAAQS. Many large industries, such

as utilities, refineries, and the trucking industry, are concerned that they likely will

be affected by the necessary controls on particulate matter emissions to achieve

compliance. Stricter controls on particulate matter will likely mean more costs for

61 Federal Register 65651, December 13, 1996.

EPA, Regulatory Impact Analysis for the Particulate Matter and Ozone National Ambient

Air Quality Standards and Proposed Regional Haze Rule, July 1997, p. ES-18. Available

at [http://www.epa.gov/ttn/oarpg/naaqsfin/ria.html].

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affected industries. EPA estimated the costs to partially attain the 1997 PM2.5 standard

by 2010 at $8.6 billion annually,8 while industry estimates were several times higher.

Another concern of areas facing nonattainment designation, particularly of local

businesses and governments, is that it will have potential negative impacts on an

area’s economic development. Nonattainment designation requires new major

sources of pollution to offset their pollution by equivalent, or greater, emission

reductions from existing sources, and requires highway and transit planners to

demonstrate that new projects “conform” to the area’s state implementation plans.

Although EPA has not analyzed the potential economic impact of designating areas

as nonattainment for particulate matter, a recent EPA analysis found that ozone

nonattainment designations had no net negative impact on those areas.9

Due to the significance of these issues, Congress is likely to remain interested

in the outcome of EPA’s ongoing implementation and review of the existing PM

NAAQS.

Process for Setting National Ambient Air Quality Standards10

The first step in regulating criteria pollutants is the issuance of what is known

as a “criteria document.” This document must “accurately reflect the latest scientific

knowledge useful in indicating the kind and extent of all identifiable effects on public

health or welfare which may be expected from the presence of such pollutant in the

ambient air” (42 U.S.C. 7408(a)(2)). Included in this document is information on

“variable factors” that change public health effects, other types of pollutants that may

interact with the criteria pollutants to adversely affect public health, and “known or

anticipated adverse effects on welfare” (42 U.S.C. 7408(a)(2)(A-C)).

Subsequent to the preparation of the criteria document, EPA has inserted an

administrative step into the process known as the “staff paper.” The staff paper,

compiled by EPA technical staff, provides the Administrator with a report that

describes the policy implications of the criteria document and provides

recommendations based on these implications. Emphasis is placed on “identifying

those conclusions and uncertainties in the available scientific literature that the staff

believes should be considered in selecting particulate pollutant indicators, forms,

averaging times, and levels for the primary (health) and secondary (welfare)

standards” (EPA, Particulate Matter Staff Paper (1996), p. I-1).

Both the staff paper and the criteria document are reviewed by the Clean Air

Scientific Advisory Committee (CASAC). This committee, mandated under Section

109(d)(2)of the CAA, consists of seven outside experts who recommend revisions

to the documents and comment on the desirability of new standards, as appropriate.

EPA, Regulatory Impact Analysis, July 1997, Table 13-1.

U.S. EPA, Office of Air and Radiation, The Historical Record: Nonattainment Status and

Economic Growth, February 26, 2002.

For more information on the standard-setting process, see CRS Report 97-722 ENR, Air

Quality Standards: The Decisionmaking Process.

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The CASAC creates a panel to review each NAAQS. Each panel consists of the

members of the CASAC plus consultant members to assure full coverage of the

expertise needed to assess fully the issues involved. The panel recommends

improvements and eventually, after further meetings that are open to the public and

reviews, signs off only when they are convinced that each of the two documents

accurately reflects the status of the science. The CASAC “closure letter” represents

panel members’ agreement that the criteria document and the staff paper provide an

adequate scientific basis for regulatory decision making.

With the release of the criteria document and the staff paper, EPA is to issue

proposed standards to control the criteria pollutant. These standards are known as

primary and secondary national ambient air quality standards (NAAQS). Primary

NAAQS are set at a level “requisite to protect the public health” with an “adequate

margin of safety” (42 U.S.C. 7409(b)(1)). Secondary NAAQS are set at a level

“requisite to protect the public welfare” (42 U.S.C. 7409(b)(2)).11 Secondary

standards are implemented in the same manner as primary NAAQS, with the key

difference that there is no federally enforceable specified deadline for attainment.

After EPA promulgates a nationwide standard for a criteria pollutant, the agency

is to designate geographical areas as in “attainment” or “nonattainment” with the

standards through a federal-states/tribes cooperative process. Areas are to be

identified as “nonattainment” when they violate or contribute to the violation of

National Ambient Air Quality Standards (NAAQS), or “attainment/unclassified”

when they meet the standard or the data are insufficient for making a determination

of compliance with the NAAQS. Nonattainment designation begins a process in

which states (and tribes) must develop and adopt emission control programs

sufficient to bring air quality into compliance by an EPA-defined deadline (statutory

for the primary standards).

Following designation of an area as nonattainment, the state where the area is

located must develop a State Implementation Plan (SIP) that demonstrates how

attainment with the NAAQS will be achieved, and submit it to the EPA within three

years of designation (Section 110 of the CAA). These plans must include, among

other items, emissions limitations, monitoring provisions, and enforcement programs

designed to achieve compliance with the standard, generally within a 10-year period.

Thus, under the statute, EPA sets only the nationwide standard for criteria pollutants;

the states are responsible for placing limits on emissions that contribute to criteria

pollution and for regulating entities emitting criteria pollutants. (If states fail to

develop an adequate implementation plan, EPA can impose one).

Reviews and updates of the criteria document are to take place at least every five

years and standards may be modified on the basis of new information identified and

evaluated during the update of the criteria document.

The use of public welfare in the CAA “includes, but is not limited to, effects on soils,

water, crops, vegetation, manmade materials, animals, wildlife, weather, visibility, and

climate, damage to and deterioration of property, and hazards to transportation, as well as

effects on economic values and on personal comfort and well-being, whether caused by

transformation, conversion, or combination with other air pollutants” (42 U.S.C. 7602(h)).

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History of Particulate Matter Standards

EPA set the first particulate matter standards in 1971. The first standards were

based on total suspended particulate matter (TSP). Monitors for TSP detected

particles up to 45 micrometers (:m) in diameter. There were two forms to the

primary standards: 24-hour (daily) average and annual geometric mean. The primary

standards were set at a 24-hour average not to exceed 260 micrograms of particulate

matter per cubic meter of air (:g/m3) more than once per year, and an annual

geometric mean of 75 :g/m3. The secondary standards were set only in the 24-hour

form at 150 :g/m3, not to be exceeded more than once per year.

EPA began revising the criteria document for the PM NAAQS in 1979. Three

draft criteria documents were prepared, comments were received, and several public

meetings were held. In 1984, EPA issued its final criteria document and proposed

changes to the 1971 standards. These changes were finalized in 1987. Because

research indicated that health effects were associated with smaller particles, the

indicator for particulate matter was changed from TSP to particles with a diameter

of 10 :m or less in 1987. These particles are generally denoted PM10. The form of the

annual standard was changed from annual geometric mean to annual arithmetic

mean.12 Primary NAAQS for PM10 were set at a 24-hour average of 150 :g/m3, with

no more than one expected exceedance averaged over three years, and an annual

arithmetic mean of 50 :g/m3 averaged over three years. Secondary NAAQS were set

at levels identical to primary NAAQS.

EPA’s announcement of the next round of revisions to the particulate matter

criteria document came in 1994. After drafts of both the criteria document and staff

paper were provided for public comment, EPA issued proposed changes to the 1987

standards in November 1996. During the comment period for the proposed changes,

EPA held four public hearings at locations across the nation, in addition to two

satellite broadcasts. EPA also developed a toll-free national hotline and an e-mail

address to facilitate participation by interested persons. EPA notes that it received

more than 14,000 calls and 4,000 e-mails in response to the proposed changes, with

a total of over 50,000 comments.

Final NAAQS from this second round of revisions were issued July 18, 1997,

as per a court order.13 In these new standards EPA added the indicator PM2.5, because

of new data showing significant public health effects from fine particles. This

indicator regulates particles with a diameter less than 2.5 :m, also known as “fine

particles.” EPA retained the PM10 indicator to regulate “coarse” particles.

According to EPA, the annual geometric mean was replaced because it was greatly

influenced by days of relatively clean air and de-emphasized the effects of short-term peak

concentrations. EPA indicated that the annual arithmetic mean did a better job of addressing

these problems. See 52 Federal Register 24640. July 1, 1987.

EPA was under a court order entered in American Lung Association v. Browner, CIV-93643-TUC-ACM (D. Ariz., October 6, 1994) to publish the final PM standards by July 19,

1997.

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The form of the 24-hour standards was also changed in 1997. The previous

form was known as the “one-expected-exceedance” form; monitoring stations could

exceed the 24-hour PM NAAQS only once, averaged over three years. With the 1997

final rule, EPA changed to a concentration-based percentile form. This percentile

form indicates the percent of the time that a monitoring station can exceed the

standard. For instance, a 99th percentile 24-hour standard indicates that a monitoring

station can exceed the standard 1% of the time, or 3.65 days a year, if monitoring

occurs every day. The form of the annual standard remained the same in the 1997

revisions.

Finally, EPA revised the levels of the PM NAAQS. The new PM2.5 indicator

was set at 65 :g/m3, based on a three-year average of the 98th percentile of 24-hour

PM2.5 concentrations, and at 15 :g/m3 for the annual arithmetic mean averaged over

three years. The levels of PM10 remained the same; however, the form of the PM10

24-hour standard was changed to be based on a three-year average of the 99th

percentile of 24-hour PM10 concentrations. By changing the form to a concentrationbased percentile, EPA allowed more exceedances than were previously permitted

under the 1987 standard. Thus, although the level of the PM10 standards was not

changed, the change in form had the effect of weakening the PM10 standard by

allowing more exceedances. Nonetheless, the new PM2.5 standards would require

additional controls. Secondary standards were set equal to these new primary

NAAQS. The changes to the PM NAAQS are summarized in Table 1.

Table 1. Changes to Particulate Matter

National Ambient Air Quality Standards (NAAQS)

1971

1987

1997

Total Suspended

Particulate Matter

PM10

PM10 and PM2.5

24-hour average (not

to be exceeded more

than once per year)

24-hour average (1expected-exceedance,

3-year average)

24-hour average

(concentration-based

percentile)

Annual geometric

mean

Annual arithmetic

mean

Annual arithmetic

mean

24-hour

Primary

NAAQS

260 :g/m3

150 :g/m3

PM10: 150 :g/m3 (99th

percentile)

PM2.5: 65 :g/m3 (98th

percentile)

Annual

Primary

NAAQS

75 :g/m3

50 :g/m3

PM10: 50 :g/m3

PM2.5: 15 :g/m3

Level of

Secondary

NAAQS

150 :g/m3 24-hour

standard

Same as primary

Indicator

Form

Source: Prepared by the Congressional Research Service.

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As proposed, the new PM NAAQS generated significant controversy.14 Once

finalized, the standards were subject to lawsuits from a number of parties, some

seeking a stronger standard, others seeking a weaker standard.

1997 Ozone NAAQS. The final PM NAAQS were signed by the EPA

Administrator at the same time as new NAAQS for ground-level ozone, on July 16,

1997. The two NAAQS were jointly published on July 18, 1997 (62 Federal Register

38652-38896). Generally referred to as the 8-hour ozone standard, the new standard

for ground-level ozone requires a more stringent concentration limit (0.08 parts per

million vs. the previous 0.12), but it averages the ozone concentrations measured

over 8 hours rather than the previous 1 hour. (See CRS Report RL32345,

Implementation of EPA’s 8-Hour Ozone Standard.)

Ozone is not a pollutant that is directly emitted; rather it forms in the

atmosphere in the presence of sunlight, primarily as the result of reactions including

volatile organic compounds (VOCs). Nitrogen oxides (NOx) are considered PM2.5,

as well as ozone precursors. Thus, the emitters of NOx, such as various industrial

processes, motor vehicles, and other fuel combustion sources, will be subject to

controls for purposes of meeting two different NAAQS. In addition, many of the

areas designated nonattainment with respect to the 8-hour ozone standards are

expected to overlap with those designated nonattainment for the PM NAAQS. In its

PM2.5 guidance for geographical area designation, EPA recommended states consider

using the same boundaries for nonattainment for both PM2.5 and 8-hour ozone.

Implementation of the 8-hour ozone standard, which currently precedes the PM

NAAQS implementation, as well as challenges or other delays, will likely impact the

implementation, and potentially the review of the PM NAAQS. Following their joint

promulgation in 1997, both the ozone and the PM NAAQS were the subject of many

of the same challenges and litigation, including a Supreme Court decision in 2001

(see discussion later in this report).

On April 15, 2004, EPA designated areas in 32 states and the District of

Columbia (474 counties in all) as “nonattainment areas” for the new ozone air quality

standard (69 Federal Register 23857-23951). The EPA designations, and the new

implementation rule (69 Federal Register 23951-24000) that accompanied the

designations, have been challenged for being too lenient by several states and various

public interest groups, and too restrictive by industry groups. Since June of 2004,

several petitions for reconsideration15 have been submitted to EPA, and 17 challenges

have been filed in the U.S. Court of Appeals for the District of Columbia Circuit (as

of December 2004). Based on an unopposed motion filed by EPA November 24,

2004, the cases have been aligned by the issues into two consolidations (South Coast

Air Quality Management District v. EPA, No. 04-1200 (D.C. Cir. filed 6/25/04), and

Alcoa Inc. v. EPA, No. 04-1189 (D.C. Cir. filed 6/18/04)). The outcome of these

For more information on Congressional hearings related to the proposed standards and

issues related to implementation of the standard, see CRS Report 97-8 ENR, Air Quality:

Background Analysis of EPA’s 1997 Ozone and Particulate Matter Standards, pp. 27-31.

For information regarding the petitions for reconsideration see EPA’s Office of Air and

Radiation website at [http://www.epa.gov/ttn/naaqs/ozone/o3imp8hr/whatsnew.html].

CRS-9

challenges, and their potential impact on the PM NAAQS implementation and

review, may not be known for some time.

Legal Challenges to the 1997 PM NAAQS

Court of Appeals. On July 18, 1997, the day of promulgation for the final

PM NAAQS (and new 8-hour ozone standard), the American Trucking Associations

(ATA), together with five other groups, filed a suit against the EPA. Several other

groups also challenged EPA’s PM NAAQS in court, including states, industries,

small businesses, environmental groups, and private persons. In all, more than 100

petitioners challenged EPA’s PM NAAQS, including three states and over 60

utilities; six states filed briefs in support of EPA. These plaintiffs filed a total of 38

cases against EPA; the cases were consolidated by the U.S. Court of Appeals for the

District of Columbia Circuit.16

The plaintiffs advanced ten arguments against EPA’s 1997 revisions to the

particulate matter standards. Various plaintiffs claimed that EPA:

Unconstitutionally interpreted §§ 108 and 109 of the CAA;

Arbitrarily and capriciously chose PM10 as the coarse particle

indicator;

! Must consider costs in setting NAAQS;

! Must consider the financial impact of complying with the NAAQS

on the Abandoned Mine Reclamation Fund;

! Must treat PM2.5 as a “new” pollutant and develop a separate criteria

document;

! Must identify a biological mechanism through which particulate

matter causes health effects;

! Must set secondary PM NAAQS such that all visibility impairment

is eliminated;

! Failed to comply with relevant requirements of the National

Environmental Policy Act;

! Violated the Unfunded Mandates Reform Act in revising PM

NAAQS by not preparing an official Regulatory Impact Statement;

and

! Violated the Regulatory Flexibility Act, as amended by the Small

Business Regulatory Enforcement Fairness Act, in revising PM

NAAQS by not performing a regulatory flexibility analysis to

determine the impact of the NAAQS on small entities.

The Court of Appeals rejected the last eight claims of the petitioners. On the

first claim, the Court noted that EPA’s construction of the NAAQS section of the

CAA allowed the agency to set NAAQS at “any point between zero and a hair below

American Trucking Associations v. EPA, 175 F.3d 1027 (D.C. Cir. 1999). The challenges

to the PM standards were also consolidated with challenges made to EPA’s ozone standards

released the same day.

CRS-10

the concentrations yielding London’s Killer Fog.”17 The court ruled that the statutory

language was an unconstitutional delegation of legislative power. However, rather

than hold these sections of the CAA unconstitutional, the Court of Appeals decided

to “give the agency an opportunity to extract a determinate standard on its own.”18

In its decision, the Court of Appeals presented some options for the “intelligible

principle” EPA might use to develop a constitutional interpretation of the act.

As to the second claim, the Court of Appeals agreed that EPA’s use of PM10 as

the coarse particle indicator was arbitrary and capricious. PM10 includes all particles

smaller than 10 :m. Because EPA had also chosen PM2.5 as an indicator of fine

particulate matter, the choice of PM10 constituted a “double regulation” of PM2.5 and

an “underregulation” of PM10-2.5, that is, particles between 2.5 and 10 :m in

diameter.19 The Court of Appeals vacated the PM10 standard and directed EPA to

select a different indicator.

The challenge to the science behind the PM NAAQS — the claim that EPA had

to identify a biological mechanism — was unsuccessful before this court. The

petitioners had argued that EPA had to prove that particulate matter caused health

effects before issuing standards, and that there was no scientific basis to regulate

coarse particulate matter. Although the Court of Appeals found that EPA’s retention

of PM10 as an indicator was arbitrary and capricious, the court found “ample support

for EPA’s decision to regulate coarse particulate pollution above the 1987 levels.”20

The Court of Appeals’ decision was 2-1, with the dissenter arguing that Sections

108 and 109 did not effect an unconstitutional delegation of legislative power and

therefore did not violate the nondelegation doctrine.21 For invoking the nondelegation

doctrine, the decision was variously seen as “[giving] a warning to overzealous

regulators,”22 “[lobbing] a constitutional time bomb that potentially could have

governmentwide impact,”23 and as “[defying] 60 years of Supreme Court rulings.”24

EPA’s then-Administrator, Carol Browner, called the ruling “extreme, illogical, and

175 F.3d at 1037.

175 F.3d at 1038.

175 F.3d at 1054.

175 F.3d at 1057 (Tatel, dissenting).

Lieberman, Ben. “Clearing the Air on Regulatory Excess.” The Washington Times 19 May

1999: A16.

May, Randolph J. “D.C. Circuit Decision Draws Needed Spotlight to Nondelegation

Doctrine.” Legal Times 21 Jun. 1999: 20.

Lieberman, Joseph I. and Henry Waxman. “A New Arena for Attacks on Clean Air: The

Courts.” The Hartford Courant 10 Sept. 1999: A23.

CRS-11

bizarre.”25 In contrast, the U.S. Chamber of Commerce stated “this ruling strikes

right at the heart of EPA’s abuse of regulatory authority.”26

Supreme Court. EPA sought to have the Court of Appeals rehear the case,

but was denied. EPA then appealed the ruling to the Supreme Court. EPA sought the

Court’s opinion on whether the CAA impermissibly delegates legislative power to

the agency.27 ATA and other groups also appealed the decision and asked the

Supreme Court to review the question of whether EPA must take the cost of the

standards into account when setting NAAQS. The Supreme Court consolidated the

cases and issued its decision on February 27, 2001.28

On the two principal issues (whether EPA was unconstitutionally exercising

legislative power, and whether costs should be considered in setting NAAQS), the

Supreme Court ruled in EPA’s favor. Justice Scalia wrote the unanimous opinion of

the Court, and some Justices added separate concurring opinions. The Court affirmed

the judgment of the Court of Appeals regarding cost consideration in setting

NAAQS: “the text of 109(b) ... unambiguously bars cost considerations from the

NAAQS-setting process.”29 The Court overturned the judgment of the Court of

Appeals regarding the nondelegation doctrine, stating “Section 109(b)(1) ... fits

comfortably within the scope of discretion permitted by our precedent.”30 The Court

stated that the provision contains an “intelligible principle” to guide the

Administrator in setting standards, and that is all that is constitutionally required.

On Remand to the Court of Appeals. In the original case, the petitioners

had raised other challenges to the standards that the Court of Appeals stated “cannot

be resolved until such time as EPA may develop a constitutional construction of the

act.”31 Because the Supreme Court subsequently ruled that Sections 108 and 109

were constitutional in respect to delegation, the Court remanded the case to the Court

of Appeals for consideration of petitioners’ arguments raised under CAA

§307(d)(9).32 The question facing the Court of Appeals was whether EPA reasonably

exercised its discretion under the CAA in establishing PM2.5 NAAQS (the PM10

standard was vacated in the earlier decision).33 The plaintiffs in this case advanced

nine arguments against EPA’s rulemaking. Various plaintiffs claimed that EPA:

Kennedy, James. “Court Decision on Ozone, PM Rules Called ‘Extreme, Illogical’ by

Browner.” Daily Environment Report 21 May 1999: AA-1.

Kennedy, James. “EPA Eyes Appeal of PM-Ozone Ruling, Says Ruling Supportive of

Science, Process.” Daily Environment Report 17 May 1999.

EPA also sought the Supreme Court’s opinion on two ozone questions unrelated to the PM

discussion in this report.

Whitman v. American Trucking Associations, 531 U.S. 457 (2001).

531 U.S. at 471.

531 U.S. at 476.

ATA v. EPA, 175 F.3d at 1034.

American Trucking Associations v. EPA, 283 F.3d 355 (D.C. Cir 2002).

283 F.3d at 363-364.

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Did not identify or apply any legal standard in setting NAAQS;

Did not show the 1987 PM standards to be inadequate to protect

public health;

! Attributed adverse health effects to PM that are accounted for by

other factors, such as the presence of other pollutants, temperature,

and humidity;

! Conceded that NAAQS rely on questionable assumptions, such as

the existence of a “continuum of health risks”;

! Failed to justify the 24-hour standard;

! Did not present enough evidence in the rulemaking record to support

the level of the annual standard;

! Must obtain and publish underlying data from studies it uses in

rulemaking;

! Should have set a stricter daily standard; and

! Set secondary standards that were inadequate to improve visibility.

The Court of Appeals rejected all these claims with the exception of the fifth claim

(failure to justify the 24-hour standard), which it declined to consider because the

claim was not raised in the original case.34 The effect of these cases has been to

demonstrate that EPA does have authority to promulgate NAAQS, that cost cannot

be considered in setting the NAAQS, that EPA’s revision of the PM NAAQS was not

arbitrary and capricious, and that stricter regulation of particulate matter was

supported by the record, although selection of PM10 as the coarse particle indicator

was arbitrary and capricious.

Health Effects of Particulate Matter

Science Behind the 1997 PM NAAQS. EPA began its review of the

relevant scientific literature in 1994 to determine what studies to include in the

criteria document. The studies selected were peer-reviewed, mainly by non-EPA

researchers. In researching particulate matter health effects, EPA reviewed more than

2,000 studies. In the criteria document, EPA noted, “recent studies [provide]

evidence that serious health effects (mortality, exacerbation of chronic disease,

increased hospital admissions, etc.) are associated with exposures to ambient levels

of particulate matter found in contemporary U.S. urban air sheds even at

concentrations below current U.S. PM standards.”35

The reviewed studies, taken as a whole, revealed significant health effects from

particulate matter. Health effects EPA found to be associated with particulate matter

include:

283 F.3d at 358, 371.

EPA, Air Quality Criteria for Particulate Matter, April 1996, EPA/600/P-95-001aF. p.

13-1, at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_pr_cd.html].

CRS-13

Premature mortality from short-term exposure (based on 38 analyses

and re-analyses of studies published between 1988 and 1996),36 and

long-term exposure (based on studies from the 1987 revision and 2

new studies);37

! Aggravation of respiratory and cardiovascular disease from shortterm exposure (based on 12 studies);38

! Changes in lung function and increased respiratory symptoms (based

on 26 short-term and 7 long-term studies);39

! Changes to lung tissues and structure (based on studies from the

1987 revision);40 and

! Altered respiratory defense mechanisms (based on studies from the

1987 revision).41

Of the epidemiological studies EPA reviewed, more than 80 of them addressed

particulate matter’s association with morbidity and mortality based on short-term

exposures. Of these 80, 60 studies found statistically significant associations between

increases in various indicators of particulate matter and increases in morbidity or

mortality.42 Many of these studies were based on PM10 or TSP, because of the lack

of data on PM2.5 concentrations.

Two studies aroused particular interest on the part of scientists, industry,

Congress, and the public. In one, researchers tracked more than 550,000 participants

from 1982-1989 in 154 U.S. cities.43 This study is known as the American Cancer

Society (ACS) Study.44 In the other, researchers tracked just over 8,100 adults for 1416 years in six U.S. cities beginning in the 1970s.45 This study is known as the Six

Cities Study.46 Because EPA relied particularly (although not solely) on these studies

in supporting its view that long-term exposure to fine particulate matter is associated

61 Federal Register 65642, December 13, 1996.

61 Federal Register 65643, December 13, 1996,

EPA, Criteria Document, April 1996, Tables 13-3, 4, 5.

61 Federal Register 65643, December 13, 1996.

61 Federal Register 65644, December 13, 1996.

61 Federal Register 65646, December 13, 1996.

Health Effects Institute, “Statement: Synopsis of the Particle Epidemiology Reanalysis

Project.” Reanalysis of the Harvard Six Cities Study and the American Cancer Society Study

of Particulate Air Pollution and Mortality, July 2000 (includes Nov. 1, 2001 errata sheet),

p. i. Available at [http://www.healtheffects.org/Pubs/Rean-ExecSumm.pdf], viewed

November 21, 2004.

Pope, C. Arden, III, et al. “Particulate Air Pollution as a Predictor of Mortality in a

Prospective Study of U.S. Adults.” American Journal of Respiratory and Critical Care

Medicine 151 (1995): 669-674.

HEI July 2000, “Statement.” p. i.

Dockery, Douglas W. et al. “An Association Between Air Pollution and Mortality in Six

U.S. Cities.” New England Journal of Medicine 329 (1993): 1753-1759.

CRS-14

with mortality, many people wished to see the underlying data. The researchers who

did the studies were concerned that releasing the data would violate the privacy of the

studies’ subjects. To solve this dilemma, the researchers agreed to release their data

to the Health Effects Institute for re-analysis. The Health Effects Institute (HEI) was

begun in 1980 and is funded jointly by industry and EPA to supply “high-quality,

impartial, and relevant science on the health effects of pollutants from motor vehicles

and from other sources in the environment.”47

HEI created a nine-member Expert Panel to provide oversight for the project

and to select researchers to complete the re-analysis. This re-analysis team consisted

of 30 epidemiologists and biostatisticians. After the re-analysis team completed its

work, the research was peer-reviewed by a separate independent team of eight

experts. HEI completed its re-analysis of the two studies in 2000.

The re-analysis was divided into two sections. First, the researchers attempted

to replicate the results of the original studies. Then, researchers used different models

and variables to determine the sensitivity of the results — that is, whether results

would change when subjected to different approaches. In the first part of the project,

researchers were able to replicate the results of the two studies using the original data

and the same methods. In the second part, a number of sensitivity analyses were

conducted. On the whole, these analyses did not materially change the results of the

studies, although they did indicate the need for further research on particulate matter.

HEI’s conclusion was:

Overall, the Reanalysis assured the quality of the original data, replicated the

original results, and tested those results against alternative risk models and

analytic approaches without substantively altering the original finding of an

association between indicators of particulate matter air pollution and mortality.48

Particulate Matter Scientific Knowledge Since 1997

Increased Particulate Matter Research Funding. Congressional

recognition of the need for more research on health effects of particulate matter, and

the need to expedite research, led to an increased amount of funding directed toward

such study. The FY1998 appropriations for EPA (P.L. 105-65) included language

directing the National Academy of Sciences (NAS) to develop a research plan for

particulate matter that EPA was to follow. Additional money for such research was

appropriated above and beyond EPA’s general budget. This action by Congress,

based on consultation with EPA, NAS, and numerous scientific and research

stakeholder groups, was one result of the controversy regarding the 1997 PM

NAAQS. In particular, the Conference Report (H.Rept. 105-297) supporting the

FY1998 appropriations noted that any research conducted with this funding would

be available to the public, thus avoiding the controversy stemming from the ACS and

Six Cities studies.

Health Effects Institute. “What is the Health Effects Institute?” Available at

[http://www.healtheffects.org/about.htm], viewed November 19, 2004.

HEI,”Statement,” July 2000, pp. i-ii.

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The FY1998 appropriation more than doubled the funding provided to EPA for

particulate matter research.49 Congress increased funding in subsequent years, nearly

tripling the funding in FY2001 compared to FY1997. Congress provided $65.5

million for particulate matter research in FY2002, $64.4 million in FY2003, and

$58.6 million in FY2004. The funding has supported numerous EPA intramural and

extramural particulate matter research projects, and the establishment of five

academically based particulate matter research centers around the country. The

conference report (H.Rept. 108-892) for the FY2005 Consolidated Appropriations

Act (P.L 108-447) includes $61.0 million for particulate matter research for FY2005.

National Academy of Science (NAS) Particulate Matter Research

Priorities. NAS established the Committee on Research Priorities for Airborne

Particulate Matter to fulfill the Congressional request. The committee has released

four reports50 pursuant to the legislation. The first report identified 10 priorities for

particulate matter research. A description of how the committee is monitoring

particulate matter research and revisions to the priorities were included in the second

report. The priorities, as revised, are listed in Table 2 presented on the next page.

The third report provided a review of EPA’s progress in particulate matter research

from 1998 to mid-2000. The committee’s fourth report, published March 24, 2004,

is a final review of progress and includes recommendations for future directions in

particulate matter research.

In the third report, the committee indicated that EPA had made some progress

in targeting research for the priorities in the period 1998 to mid-2000, but found that

other areas of particulate matter research were not proceeding as well. In the report,

the committee designated research under six of the priorities (2, 3, 4, 6, 7, and 8) as

either not proceeding as planned, not targeted toward the committee’s priorities, or

not yet adequate. The committee’s report noted that research for priorities 1, 5, 9, and

10 was proceeding satisfactorily. An April 2002 HEI paper came to a similar

conclusion. HEI indicated that current research is providing important information

under research priorities 5, 9, and 10. According to HEI, particulate matter research

has begun to determine what aspects of particles cause health effects, suggest what

biological mechanisms may be responsible for particulate matter’s reported health

impacts, and identify which groups are most susceptible.51

National Academy of Sciences, National Research Council, Committee on Research

Priorities for Airborne Particulate Matter, Research Priorities for Airborne Particulate

Matter: III. Early Research Progress. (Washington, D.C.: National Academy Press, 2000),

p. 2 (hereafter Research Priorities III).

The four reports are available from the National Academy of Sciences, National Research

Council, Committee on Research Priorities for Airborne Particulate Matter, Washington,

D.C., National Academy Press: Research Priorities for Airborne Particulate Matter: I.

Immediate Priorities and a Long-Range Research Portfolio (Report 1, 1998); Research

Priorities for Airborne Particulate Matter: II. Evaluating Research Progress and Updating

the Portfolio (Report 2, 1999); Research Priorities for Airborne Particulate Matter: III.

Early Research Progress (Report 3, 2000); Research Priorities for Airborne Particulate

Matter: IV. Continuing Research Progress (Report 4, 2004). See [http://www.nap.edu].

Health Effects Institute, “Understanding the Health Effects of Components of the

(continued...)

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Table 2. Research Priorities for Particulate Matter Identified by

the National Academy of Sciences

Priority

Example Research Question

Outdoor Measures Versus

Actual Human Exposure

How is the concentration of PM measured

outdoors related to personal PM exposure?

Exposures of Susceptible

Subpopulations

What components of PM most affect the health

of particularly vulnerable people?

Characterization of

Emissions Sources

What are the characteristics of PM emitted by

primary sources?

Air-Quality Model

Development and Testing

How are source emissions and ambient PM

concentrations related?

Assessment of Hazardous

PM Components

What aspects of PM negatively affect health?

Dosimetry

In vulnerable populations, where does PM

deposit in the respiratory tract and where does it

ultimately end up?

Combined Effects of PM

and Other Pollutants

How can the effects of PM and the effects of

other pollutants be separated?

Susceptible Subpopulations

Who is particularly vulnerable to PM?

Mechanisms of Injury

How does PM cause harm?

Analysis and Measurement

How do models and measurement errors affect

risk estimates?

Source: Table prepared by Congressional Research Service, based on pages 39-93 of NAS report.

National Academy of Sciences, National Research Council, Committee on Research Priorities for

Airborne Particulate Matter, Research Priorities for Airborne Particulate Matter: II. Evaluating

Research Progress and Updating the Portfolio (Washington, D.C.: National Academy Press, 1999).

In its fourth and final report released in March 2004, the NAS Committee on

Research Priorities for Airborne Particulate Matter described the overall progress on

several of the priority topics as “encouraging” and demonstrating that targeted

research can resolve some key uncertainties. However, the committee determined

that much remained to be done from the original research agenda.

The committee emphasized the characterization of emission sources (topic 3),

air quality model development and testing (topic 4), and assessment of particulate

matter hazardous components (topic 5). The need to advance the assessment of

particulate matter hazardous components was identified as a central component for

advancing several of the topic research areas, including developing targeted exposure

studies under topic 2, refining emission inventories and models under topics 3 and

(...continued)

Particulate Matter Mix: Progress and Next Steps,” HEI Perspectives: Insights from HEI’s

Research Programs, April 2002. Available at [http://www.healtheffects.org/Pubs/

Perspectives-2.pdf].

CRS-17

4, advancing research on biological mechanisms under topic 9, and identifying

susceptible subpopulations under topic 8. The committee identified the need for

further methodological research as evidenced by recent findings on the sensitivity of

time-series results to modeling approaches52 (see discussion in the next section of this

report). The final NAS report contained extensive discussion of progress (or lack of

progress) and recommendations for continuing under each topic area.

Research results under these topics reflect an expansion of the scope of health

concerns and the emergence of new challenges since the committee’s initial report

in 1998. The report highlighted seven challenges for the coming years that are

central to continuing the particulate matter research agenda:

completing the particulate matter emission inventory and improving

air quality models necessary for NAAQS implementation;

! developing a systematic program for accessing toxicity of particulate

matter mixture components;

! enhancing air quality monitoring for research to serve multiple

purposes;

! investigating the health effects of long-term exposure to air

pollutants;

! improving toxicological approaches;

! expanding beyond a particulate matter research program to a multipollutant program;

! integrating research and collaboration across disciplines.

The conclusions in the committee’s fourth report parallel EPA’s own

assessment of the particulate matter research program as presented in the agency’s

report released in September 2004. Particulate Matter Research Program: Five

Years of Progress53 highlights the research funded under the program, provides an

update of what has been learned and summarizes future research challenges and

recommendations. In the report, EPA contends that the research to date reconfirms

links between exposure and serious health problems, has provided new evidence

regarding cardiovascular effects, and where and how exposure occurs indoors and

outdoors, and has resulted in the development of more sophisticated air measuring

and modeling tools. However, despite these achievements, the agency emphasized

that many uncertainties remain, and research must be expanded and redirected to

addresses these gaps.

HEI-Sponsored National Morbidity Mortality and Air Pollution

Studies. In 1994, the Health Effects Institute (HEI) initiated a research program to

investigate the complex set of issues associated with human health effects of

exposure to particulate matter. HEI has funded more than 40 studies and re-analyses

Subsequent to the release of the committee’s third report, problems were identified with

the application of a model and statistical package widely used in time-series analysis. The

recognition of these problems required re-analysis of several research studies that were the

basis for characterizing short-term risks associated with air pollutants.

U.S. Environmental Protection Agency, Office of Research and Development, EPA

600/R-04/058, July 2004, at [http://www.epa.gov/pmresearch].

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during the last 10 years, as well as several “special” reports on particulate matter

research. As presented earlier in this report, HEI was responsible for the re-analyses

of the ACS and Six Cities studies. Also, as part of their collaboration on particulate

matter, EPA and HEI maintain a website where researchers can post current

particulate matter research projects.54 These projects are submitted to HEI and are

reviewed by HEI staff before being posted on the website. The site includes more

than 500 particulate matter projects.

A major area of focus for the HEI-sponsored particulate matter research has

been uncertainties regarding the associated impacts of particulate matter on daily

mortality, including the effects of other pollutants. In 1996 HEI provided funding

initiating the National Morbidity, Mortality and Air Pollution Study (NMMAPS)

conducted by researchers at Johns Hopkins University,55 which to date has resulted

in a series of three primary reports and several re-analyses. These analyses concluded

that “PM10 concentrations were positively associated with mortality and morbidity

outcomes on average across locations.”

The initial report released in May 2000, NMMAPS I, was a compilation of

methodological approaches for three topical priorities: measurement error in air

pollution exposure, mortality displacement, and methods for combining evidence in

multiple locations.56 Results of the study, which included analyses of the 20 and 90

largest U.S. cities and hospital admissions of the elderly in 14 cities, were the basis

of the second report — NMMAPS II.57 This report was of particular interest because

of its results, as well as the subsequent discovery by the authors of errors in a

statistical software program used to analyze the data that lead to bias in the results

(more discussion follows).

A third HEI-sponsored NMMAPS report (NMMAPS III),58 published in May

2004, is a study of time-series data (1987-1994) of PM10 effects on mortality for the

20 largest U.S. cities. The study examined the question of whether there is a

threshold below which there does not appear to be an association between particulate

The address is [http://www.pmra.org].

Departments of Epidemiology and Biostatistics, Johns Hopkins School of Public Health,

Baltimore MD, and Department of Environmental Health, Harvard School of Public Health.

For copies of relevant publications and information regarding ongoing research visit [http://

www.biostat.jhsph.edu/biostat/research/update.main.htm].

Jonathan M. Samet, et al. The National Morbidity, Mortality and Air Pollution Study Part

I: Methods and Methodologic Issues (NMMAPS I), Final Version, Cambridge, MA, Health

Effects Institute, no. 94, part I, October 2000. Available at [http://www.healtheffects.org/

Pubs/Samet.pdf].

Jonathan M. Samet, et al. The National Morbidity, Mortality and Air Pollution Study Part

II: Morbidity and Mortality from Air Pollution in the United States (NMMAPS II),

Cambridge, MA: Health Effects Institute, no. 94, part II, 2000. Available at [http://www.

healtheffects.org/Pubs/Samet2.pdf].

Michael J. Daniels, et al. The National Morbidity, Mortality and Air Pollution Study Part

III: PM10 Concentrations-Response Curves and Thresholds for the 20 Largest U.S. Cities,

Cambridge, MA: Health Effects Institute, no. 94, part III, 2004. Available at [http://www.

healtheffects.org/Pubs/Daniels94-3.pdf].

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matter levels and mortality. A critique of the approach and results of the study by a

Special Panel of the HEI Review Committee concluded that the development and

application of complex statistical methods to describe concentration-response

relationships has advanced the understanding of air pollutant health effects, and the

results of the study have important implications for setting air quality standards.59

However, because of several limitations presented in their review, the panel was

apprehensive about the study’s conclusions, and cautions drawing conclusions from

the apparent absence of a threshold in the concentration-response relationship.

The original NMMAPS II report released in 2000 had found a 0.41% increase

in daily mortality for every additional 10 :g/m3 of PM10 for the 90 largest U.S. cities

over an eight-year period. However, in May 2002, the researchers announced they

had discovered errors in a statistical software program used to analyze the data and

determined that the errors overstated this percentage. In a re-analyses, completed in

2002, researchers found a 0.27% increase.60 Despite the error, the researchers stated

that the conclusions of their report remain unchanged, namely:

Overall, this study provides strong evidence of association between PM10 levels

and exacerbation of chronic heart and lung disease sufficiently severe to warrant

hospitalization. The association cannot be explained by confounding [the

presence of other pollutants] that is addressed in both stages of the analysis,

although there is always the possibility of some residual confounding.

Confounding by weather was considered above and can be set aside.61

The error was associated with the application of a general additive model

(GAM) in the S-Plus statistical software. GAMs, effective for conducting nonlinear

regression analysis of one or more variables (e.g., air pollution, weather, time), had

been widely used in contemporary time-series research of health effects on air

pollution and other similar applications since about 1990. The researchers found that

their application of GAM in conjunction with the default conversion criteria in the

software could result in upward or downward bias of estimated relative risk,

potentially skewing the final results.62 The researchers conducted a re-analysis of the

NMMAPS substituting alternative approaches in place of the model that created the

error. In the re-analysis the researchers concluded that:

While the quantitative estimates changed with the tighter convergence criteria in

the gam function or switching to GLM (approaches used in the re-analysis), the

major scientific findings of the NMMAPS did not. Strong evidence remains of

NMMAPS III, May 2004, p. 23-29.

Francesca Dominici, et al., A Special Report to the Health Effects Institute on the Revised

Analyses of the NMMAPS II Data, 2003, Health Effects Institute, Cambridge , MA. See also

Joel Schwartz, et al, A Special Report to the Health Effects Institute on the Revised Analyses

of the NMMAPS II Data: Morbidity and Mortality Among Elderly Residents of Cities with

Daily Measurements, 2003, Health Effects Institute, Cambridge, MA.

NMMAPS II, 2000, p. 44.

Fancesca Dominici, et al., On the Use of Generalized Additive Models in Time Series

Studies of Air Pollution and Health: Commentary, American Journal of Epidemiology 2002,

156, pp. 193-203. Available at [http://aje.oupjournals.org].

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an association between acute exposure to particulate air pollution (PM10) and

daily mortality one day later (lag 1). This association was strongest for

respiratory and cardiovascular causes of death, as anticipated based on concepts

of susceptibility.63

The re-analyses of the NMMAPS were part of a larger effort for re-analyses of

more than 40 selected time-series studies at the request of the EPA and the CASAC.

HEI compiled its review of these re-analyses in a special report entitled Revised

Analyses of Time-Series Studies of Air Pollution and Health, released in May 2003.64

Re-analyses of Selected Time-Series Studies. The discovery of the

problems65 associated with certain applications of GAMs occurred as EPA was

proceeding with its review of the inventory of scientific information for reassessment

of the PM NAAQS. This model had been the basis for numerous particulate matter

times-series studies conducted since 1990, many of which were the basis of EPA’s

review, and their results were potentially affected. The reported errors associated

with the GAM had no effect on the results of the Harvard Six Cities Study and the

American Cancer Society study, both of which were re-analyzed in depth and

confirmed in 2000.

During the summer of 2002, EPA and the CASAC conducted an extensive

evaluation of the studies included in the review. Roughly 40 studies were identified

for re-analysis, including the NMMAPS. EPA requested that the researchers of the

potentially affected studies conduct re-analyses to ensure the validity of their results,

providing necessary guidance. The agency relied on the HEI to review the reanalyses and compile its evaluation of changes in the original results. HEI was not

specifically tasked with evaluating the original designs and methods of the studies.

The HEI reported that overall, although the effects varied substantially across

studies, the re-analyses resulted in estimates of effect lower than the original

analyses. However, there continues to be an association of particulate matter with

mortality/morbidity, particularly with respect to cardiovascular and respiratory

diseases. The HEI review also commented that the revisions “renewed the interest

in important questions and uncertainties that should inform future time-series

analysis of air pollution and health.”66

Status of EPA’s Review of the 1997 PM NAAQS

EPA’s review of the 1997 PM NAAQS, which began not long after the current

standards were promulgated,67 is ongoing. As discussed previously in this report, the

Francesca Dominici et al. 2003, p. 19.

Health Effects Institute website, at [http://www.healtheffects.org/Pubs/TimeSeries.pdf].

In addition to the concerns raised by the NMMAPS researchers, Health Canada found that

the use of GAMs under certain conditions caused underestimates of standard errors.

HEI, Special Report, May 2003, p. v.

For details of EPA’s original plans for reviewing the PM NAAQS, see 62 Federal

(continued...)

CRS-21

CAA requires the criteria document for each criteria pollutant to be reviewed and, if

appropriate, the NAAQS revised, every five years. As the implementation of the

1997 PM NAAQS has been delayed, so too has the review.

Schedule. The American Lung Association and several public interest groups

filed an action in March 2003, in response to EPA’s failure to meet the 2002 statutory

deadline for review of the PM and ozone NAAQS. Through a consent decree68

approved by the District Court of the District of Columbia on July 31, 2003, EPA and

the parties to the lawsuit reached an agreement that included the establishment of

deadlines for issuance of the particulate matter criteria document by July 30, 2004,

a preliminary decision regarding revisions to the PM NAAQS by March 31, 2005,

and final revised PM NAAQS (if deemed appropriate) by December 20, 2005.

On July 12, 2004, EPA filed an opposed motion for a further extension of the

particulate matter criteria document until October 29, 2004, which was granted by

the court. At the time of the motion, EPA expressed concern with its ability to meet

the remaining deadlines, and the court, in its July 23, 2004 order, further directed the

parties to consult to address the remaining consent decree deadlines. EPA shared a

proposal for extending the remaining particulate matter deadlines with the plaintiffs

on August 13, 2004, and it was later submitted to the court as part of a negotiation

with the parties of the consent agreement.69 Specifically, EPA proposed the following

modifications to the PM NAAQS schedule:

Extension from March 31, 2005, to December 31, 2005, to sign

notice of proposed rulemaking setting forth its proposed decision

concerning EPA’s review of the PM NAAQS;

! Extension from December 20, 2005, to September 30, 2006, for

EPA to sign a notice of final rulemaking setting forth EPA’s final

decision concerning review of the PM NAAQS.

As of December 2004, the plaintiffs, who have offered to continue consultations with

EPA, were considering the agency’s proposal.

2004 Particulate Matter Criteria Document. Following the federal court

approval extending the deadline, EPA announced the availability of the updated

criteria document, Air Quality Criteria for Particulate Matter, in the October 29,

2004, Federal Register (69 FR 63111). The 2004 criteria document is not intended

to be a complete and detailed literature review, but rather a thorough evaluation of

information relevant to PM NAAQS criteria development from pertinent literature

that has become available between 1996 through April 2002. A few studies

(...continued)

Consent agreement, July 2003, C.A. No. 03-778 (ESH), American Lung Association, et

al v. the U.S. Environmental Protection et al. (EPA), U.S. District Court for the District of

Columbia.

Joint Status Report, September 2004,C.A. No. 03-778 (ESH), American Lung Association,

et al v. the U.S. Environmental Protection et al. (EPA), U.S. District Court for the District

of Columbia.

CRS-22

published through 2003 were determined to be critical to the assessment and included

in the review. Although a primary focus of the review was on the latest available

dosimetric and health effects data, other scientific data were also included to provide

information on the nature, sources, size distribution, measurement, and

concentrations of PM in the environment and contributions of ambient particulate

matter to total human exposure.

The criteria document is the result of extensive public comment and rigorous

review by experts from academia, various U.S. federal and state government units,

non-governmental health and environmental organizations, and private industry. The

document also reflects the review and deliberations of interim drafts, and the final

approval and recommendations of the congressionally mandated CASAC. Drafts

were revised in response to comments, and as necessary, to include relevant studies

completed between drafts.

EPA issued its first draft of the criteria document in October 1999. A second

draft was issued in March 2001, and included relevant studies through December

2000. Each of these two drafts was reviewed by CASAC and sent back with

comments to the agency. EPA published a third draft of the criteria document in

April 2002. CASAC reviewed this criteria document at its meeting in mid-July 2002.

Although CASAC had originally indicated that closure on the criteria document was

likely, assuming EPA made the modifications requested by CASAC in the second

review,70 CASAC did not close on the criteria document at the July 2002 meeting.

EPA modified the criteria document to reflect changes to the outcomes of studies that

were affected by the software problem found in the NMMAPS study.

Following the fourth external review in June 2003, the CASAC reached closure

on Chapters 1 through 6 during its August 21-25, 2003, meeting, requiring only

minor changes. The chapters on toxicology (Chapter 7), human health (Chapter 8),

and integrative synthesis (Chapter 9) required extensive revision and restructuring.

Additional CASAC and public reviews of the three revised chapters in December

2003 and June 2004 resulted in closure on Chapters 7 and 8. Chapter 9 continued to

be reviewed and revised until CASAC completed its overall review71 after a

September 20, 2004 teleconference.

The two-volume report contains extensive discussions of the findings and their

relevance to establishing PM NAAQS in the context of the defined research

priorities. The bullets below provide brief highlights of some of the conclusions

excerpted from Chapter 9 of the 2004 criteria document, but without the associated

details and caveats. Readers interested in the specific referenced findings should

CASAC review, September 2001, Review of the Air Quality Criteria Document for

Particulate Matter: Second External Review Draft EPA (600/P-99/002bB): A CASAC

Review, letter to the Administrator, September 27, 2001, EPA-SAB-CASAC-LTR-01-001,

p. 2. Available at [http://www.epa.gov/sab/casacl01001.pdf].

CASAC final review, October 2004, EPA’s Fourth External Review Draft of Air Quality

Criteria for Particulate Matter: A Peer Review by the Clean Air Scientific Advisory

Committee Particulate Matter Review Panel, U.S. EPA, EPA-SAB-CASAC-05-01.

Available at [http://www.epa.gov/sab/pdf/casac05001.pdf].

CRS-23

refer to the corresponding sections of Chapter 9 (identified in parentheses) as well as

relevant chapters in the document. The criteria document conclusions include the

following:

The 1996 recommendation that fine and coarse particles be

considered as separate subclasses of particulate matter pollution is

reinforced (Chap. 9, sec. 9.2.1);

! Epidemiological evidence continues to support likely causal

associations between PM2.5 and PM10 and morbidity and mortality

from cardiovascular and respiratory diseases, but suggest no clear

thresholds in particulate matter-mortality relationships (Chap. 9, sec.

9.2.2);

! New epidemiological re-analyses and extensions of previous studies

show substantial evidence for increased lung cancer; toxicological

evidence supports plausible association between particles

(particularly fine particles) with physiological endpoints indicative

of increased risk of heart disease, and supports plausible biological

pathways for respiratory effects (Chap. 9, sec. 9.2.3);

! Recent studies support considering older adults and children as

susceptible groups, given the overlap between age categories and

pre-existence of cardiopulmonary diseases; evidence from

toxicological studies suggests there are populations who are

genetically predisposed to particulate matter-related effects (Chap.

9, sec. 9.2.4);

! Local visibility standards intended to reflect “adverse thresholds”

associated with minimum visual range, and the criteria used to set

these standards, may be relevant for consideration in assessing

national secondary standards (Chap. 9, sec. 9.3.1);

! Considerable uncertainty remains with respect to the impact of the

deposition of particulate matter on vegetation ecosystems; this issue

requires additional research (Chap. 9, sec. 9.3.2);

! No significant advances have been made since the 1996 particulate

matter review in reducing the uncertainties regarding the relationship

of particulate matter to climate change processes (Chap. 9, sec.

9.3.3);

! Insufficient data with respect to pollutant concentration, particle

size, and chemical composition continue to prohibit quantifying

pollutant exposure levels that result in observable soiling and

damage to man-made materials (Chap. 9, sec. 9.3.4).

EPA Particulate Matter Staff Paper. A draft staff paper issued in 2001 by

EPA’s Office of Air Quality Planning and Standards for this new round of review did

not contain any policy recommendations. However, a subsequent draft staff paper

released in August 200372 indicated that “the latest scientific, health and technical

Office of Air Quality Planning and Standards (OAQPS), U.S. Environmental Protection

Agency, Review of the National Ambient Air Quality Standards for Particulate Matter:

Policy Assessment of Scientific and Technical Information, EPA OAQPS Staff Paper —

(continued...)

CRS-24

information does not support relaxing” EPA’s current PM NAAQS, and

recommends that the agency consider revising standards to provide additional health

protection. This is a draft paper and does not reflect the technical staff’s official final

recommendations.

The staff paper will not be finalized until, as in the past, EPA technical staff

interpret the most relevant information in the current criteria document and,

combined with other relevant information, recommend options to be considered

regarding policy decisions affecting the adequacy of the current 1997 PM NAAQS.

The paper will not be used as the basis for any policy decisions until it is reviewed

by the CASAC, others in the scientific community, industry, public interest groups,

and the general public. As discussed earlier in this report, following its review of the

staff paper, the CASAC panel will recommend improvements and eventually, after

further meetings that are open to the public and reviews, sign off only when the panel

are convinced that the paper accurately reflects the status of the science.

The staff assessment, in conjunction with the CASAC closure letter, will be

used by the EPA Administrator to determine whether or not changes to the PM

NAAQS are necessary. The CAA specifies that the Administrator shall use his/her

“judgment ..., based on [the] criteria [document] and allowing an adequate margin

of safety” to determine the NAAQS “requisite to protect the public health” (CAA,

§109(b)(1)). Based on the recent EPA deadline proposal submitted for consideration

by the court described earlier in this report, proposed modifications to the standards

are not expected until December 2005, followed by a final rule in December 2006.

As EPA proceeds with the review of the particulate matter criteria and standards, the

agency is continuing implementation of the PM NAAQS promulgated in 1997.

Opposing Views, Potential Challenges and Litigation. As discussed

earlier, the decisions by the Administrator of the EPA in July 1997 to revise ambient

air quality standards (NAAQS) for ozone and particulate matter refocused attention

on the criteria and the process by which these decisions are made. The new standards

were the subject of numerous oversight hearings as well as litigation, which

culminated in a Supreme Court ruling February 27, 2001.

Stakeholders continue to challenge the adequacy of the scientific data supporting

the PM NAAQS. According to the EPA Docket,73 numerous comments have been

submitted throughout the current criteria document review process. Despite the

agency’s attempts to be responsive to the concerns raised, varying interpretations of

the data and their conclusions, and disagreements regarding which studies to include

or not include, are likely to continue.

(...continued)

First Draft (EPA-452/D-03-001), August 2003. Obtained from EPA website at [http://www.

epa.gov/ttn/naaqs/standards/pm/s_pm_cr_sp.html] on November 16, 2004.

EPA Docket #OAR-2001-0017, available on EPA’s E-Docket website at [http://docket.

epa.gov/edkpub/index.jsp], viewed November 22, 2004.

CRS-25

EPA’s NAAQS rulemaking is subject to several statutory procedural

requirements, compliance with which is subject to judicial review.74 Given the

history of the previous review and development of PM NAAQS, it is likely that

litigation or other challenges will occur and potentially further delay the process.

Also, the agency’s criteria document and subsequent staff paper could be

challenged under the Data Quality Act (DQA; also referred to as the Information

Quality Act), enacted in December 2000.75 Intended to ensure quality, objectivity,

utility, and integrity of information, the DQA required the Office of Management and

Budget (OMB) to issue policy and procedural guidance to federal agencies. The act

required each covered agency to issue its own information quality guidelines within

one year of the issuance of the OMB guidelines. Following review and comment on

earlier proposals, OMB published its guidelines on February 22, 2002 (67 Federal

by OMB.77

Those who have submitted public comment in response to a federal agency

action and who are dissatisfied with how their correction requests were handled

through the Administrative Procedures Act process could appeal that agency’s

decision through the DQA administrative appeal process. For additional background

regarding the DQA, see CRS Report RL32532, The Information Quality Act: OMB’s

Guidance and Initial Implementation.

EPA will likely encounter more extensive challenges following its

determinations regarding revisions to the 1997 PM NAAQS. The first suits

challenging the ozone and 1997 PM NAAQS were filed in the D.C. Circuit Court of

Appeals on July 18, 1997, the day the final rules appeared in the Federal Register.

During 1997 a total of 38 suits were filed for judicial review of various aspects of the

ozone and PM NAAQS. These suits were consolidated in the American Trucking

Associations v. U.S. E.P.A., argued December 17, 1998, and decided May 14, 1999

(175 F.3d 1027 (D.C. Cir. 1999)). Many of the stakeholders who were party to those

lawsuits are expected to continue to challenge the justification of the current

standards as well as modifications as a result of the current review.

The 1997 standards have been attacked both as overly stringent and as

inadequately protective of health; as ignoring costs and as giving costs too much

deference; as going beyond what is scientifically conclusive; and as failing to be

The basic framework is spelled out in the CAA, §307(d) (42 U.S.C. §7607(d)) and details

the requirements for public notice and participation in the process.

Enacted in December 2000 as Section 515 of the Treasury and General Government

Appropriations Act for Fiscal Year 2001 (P.L. 106-554) (44 U.S.C. 3504(d)(1) and 3516).

For a copy of the OMB guidelines, see [http://www.whitehouse.gov/omb/fedreg/

reproducible2.pdf].

Agencies’ guidelines are published on OMB’s website, although it cautioned the public

that the list is not complete and will be updated as more guidelines are posted online. See

[http://www.whitehouse.gov/omb/inforeg/agency_info_quality_links.html].

CRS-26

sufficiently precautionary.78 EPA’s general interpretation of the criteria supporting

NAAQS has been the subject of various challenges. Some have argued, and continue

to argue, that the science does not enable the agency to establish a clear threshold,

and if there is no “threshold,” then there cannot be a “margin of safety” as required

by the CAA. As a result, the whole NAAQS process of necessity becomes a risk

management decision — that is, one in which the EPA Administrator balances risks

with costs to decide where to set the standard. Others argue that the lack of a

threshold justifies the tightest possible standards.

Another, continuing debate comes from the view that only in adding a margin

of safety does the Administrator layer a policy judgment onto an objective —

scientifically determined NAAQS. Some argue that this judgmental aspect means

that the margin of safety phrase implicitly endorses the consideration of costs in

setting NAAQS; as discussed later, the lead industry sued EPA over lead standards

on the basis that the margin of safety required EPA to take costs into account in

setting NAAQS, but the court ruled that the statute and its legislative history are

against that interpretation (Lead Industries Association v. Environmental Protection

Agency, 647 F.2d 1130 (D.C. Cir. 1980)).

These issues were the subject of numerous oversight hearings as well as

litigation, which culminated in the Supreme Court ruling of February 27, 2001

(discussed earlier in this report). The court upheld those NAAQS setting procedures

at question, in particular definitively rejecting the consideration of costs in setting

NAAQS.

Implementation of the 1997 PM NAAQS

PM2.5 Monitoring Network. Revising the PM NAAQS in 1997, which added

standards for PM2.5, necessitated establishing a monitoring network to measure the

fine particles. At the time the new NAAQS were being finalized, EPA also developed

methods for monitoring fine particles. Using funding specifically authorized for this

purpose in EPA appropriations FY1998-FY2000,79 the agency worked closely with

states and tribes to initiate the deployment of a portion of the network of 1,200

monitors in January of 1999.

PM2.5 attainment or nonattainment designations are to be made primarily on the

basis of three-year federally referenced PM2.5 monitoring data.80 The majority of the

monitors were not in place until January of 2000; therefore, the necessary three years

of data became available at the end of 2002. In response to the need for additional

time to establish effective PM2.5 monitoring, and other delays, Congress mandated

See CRS Report 97-8, Air Quality: EPA’s New Ozone and Particulate Matter Standards.

Appropriations for monitoring averaged roughly $50 million per year, P.L. 105-65, P.L.

105-226, P.L. 106-74.

A federally referenced monitor is one that has been accepted for use by EPA for

comparison of the NAAQS by meeting the design specifications, and certain precision and

bias (performance) specifications (40 Code of Federal Regulations Part 58).

CRS-27

that EPA designate nonattainment areas for the PM2.5 standard by the end of 2005

(Title VI of the 1998 Transportation Equity Act for the 21st Century, P.L.105-178).

Operation of the network of monitors was phased in from 1999 through 2000,

making three-year monitoring data available at different points depending on area

location. Rather than a staggered designation schedule that would likely result in

hampering cross-coordination of implementation plans, the EPA proposed a single

date for state/tribal recommendations and final EPA designations. In the agency

guidance, states/tribes were expected to rely on data collected during 2000-2002 for

their area designation recommendations. EPA considered the 2001-2003 data to

make the final designations.

PM2.5 Attainment/Nonattainment Geographical Designation. 81 An area

designated as nonattainment is defined as any area that does not meet, or that

contributes to ambient air quality in a nearby area that does not meet, an air quality

standard. Nonattainment designation begins a process in which states (and tribes)

must develop and adopt emission control programs sufficient to bring air quality into

compliance by an EPA defined deadline.

The CAA (Section 107(d)(1)(A); 42 U.S.C. 7407) establishes a cooperative

federal-state/tribe82 process for designating nonattainment areas and setting their

boundaries. However, it provides the EPA Administrator discretion in determining

the final boundaries. Based on provisions of the CAA and non-binding EPA

guidance, 18 states and the District of Columbia recommended 145 counties as

potential nonattainment areas for PM2.5 NAAQS at the end of February 2004.83

By the end of June 2004, EPA completed its review of the state/tribe

submissions and, using its authorized discretion, recommended modifications

resulting in nonattainment designations for 244 counties in 21 states and the District

of Columbia. As required by statute, the EPA notified each of the affected states

regarding its specific modifications to allow sufficient opportunity to provide new

information and demonstrate why a proposed modification was inappropriate. Some

states responding to the EPA’s proposal continued to support their original

recommendations.

For a more detailed discussion of the implementing the 1997 PM NAAQS and the

associated designation process and associated issues, see CRS Report RL32431, Particulate

Matter (PM2.5): National Ambient Air Quality Standards (NAAQS) Implementation.

Tribes are not required, but were encouraged, to submit PM area designation

recommendations. The area designation requirements under the CAA (Section 107) are

specific with respect to states, but not tribes. EPA plans to follow the same designation

process for tribes per sections 110(o) and 301(d) of the CAA and pursuant to the 1988

Tribal Authority Rule, which specifies that tribes shall be treated as states in selected cases

(40 Code of Federal Regulations Part 49). Tribes have participated in the PM2.5 designation

recommendation process, recommending designations of attainment/unclassified (see [http://

www.epa.gov/pmdesignations]).

For PM2.5 geographical designation recommendations from individual states and tribes, see

EPA’s “PM2.5 Designations” website at [http://www.epa.gov/pmdesignations].

CRS-28

EPA’s final nonattainment designations for all or part of 225 counties in 20

states, and the District of Columbia, published in the January 5, 2005, Federal

are primarily the result of removing 19 counties from the list of nonattainment areas,

and redefining other counties by designating only specified geographical locations

(“partial”) within the county as nonattainment.

The final PM2.5 designation rule allows states to submit no later than February

22, 2005, certified, quality-assured 2004 monitoring data that suggests a change in

designation is appropriate for consideration (70 Federal Register 948). A

nonattainment designation could be withdrawn if the EPA agrees that the additional

data warrants such a change.

Other Activities Impacting PM NAAQS Implementation

Current CAA Regulation. EPA has concluded that in many cases, PM2.5

attainment will be reached as the result of implementing strategies developed under

the 1999 visibility protection regulations (“Regional Haze Rule”)84; voluntary diesel

engine retrofit programs; new federal standards on cars, light trucks, and heavy duty

diesel engines that are scheduled to be implemented between 2004 and 2010; and the

1998 regional strategy to reduce nitrogen oxides from eastern states referred to as the

“NOx SIP Call.”85 Although it was primarily designed to meet the ozone NAAQS,

EPA predicts the NOx SIP call will also provide some benefits in terms of reduced

levels of nitrate fine particles.

According to a December 2004, EPA report, The Particle Pollution Report:

Current Understanding of Air Quality and Emissions through 2003, monitored

concentrations of PM2.5 have decreased 10 percent, and PM10 have decreased 7 percent

since 1999, primarily in areas with the highest concentrations.86 EPA attributes a

large portion of these decreases to the Acid Rain Program.

On April 15, 2004, EPA designated areas in 32 states and the District of

Columbia (474 counties) as “nonattainment areas” for a new ozone air quality

standard.87 Many of the areas designated nonattainment for the new ozone standards

are likely to be the same as those designated for PM NAAQS, and the approaches to

control ozone included in state implementation plans will likely control particulate

64 Federal Register 35714, July 1, 1999. EPA recently published a proposal revising the

regional haze rule, intended to provide guidelines for state and tribal air quality agencies to

use in determining how to set air pollution limits (69 Federal Register 25184, May 5, 2004).

See CRS Report RL32483, Visibility, Regional Haze, and the Clean Air Act: Status of

Implementation.

64 Federal Register 35714, October 27, 1998. For background see CRS Report RS20553,

Air Quality and Electricity: Initiatives to Increase Pollution Controls.

U.S. Environmental Protection Agency, EPA 454-R-04-002, December 2004. Revised

report posted on EPA’s website [http://www.epa.gov/airtrends/pm.html],December 23,

2004.

See CRS Report RL32345, Implementation of EPA’s 8-Hour Ozone Standard.

CRS-29

matter, including PM2.5 indirectly. The agency’s non-binding guidance for PM2.5 area

designations recommended that states/tribes consider using the same boundaries for

nonattainment for both the PM2.5 and 8-hour ozone standards, to facilitate consistency

in future implementation plans.

Proposed Regulations and Legislation. Proposed legislation and EPA

regulations for controlling coal-fired electric power plants’ emissions, such as “Clear

Skies”/multi-pollutant legislation and the proposed “Clean Air Interstate Rule”

(CAIR, also referred to as the Interstate Air Quality Rule”(IAQ)) to be implemented

between 2004 and 2015,88 could also contribute national and regional measures for

attaining PM2.5 standards. The EPA predicts that, of an estimated 120 eastern

counties out of compliance with PM2.5 NAAQS in 2002, the Clean Air Interstate

Rule will bring 28 more counties into compliance in addition to the 58 counties

predicted to come into compliance under existing programs.89 The extent of

pollution reduction that is projected as a result of these proposals has been the subject

of considerable debate among stakeholders, and some Members of Congress.

California Particulate Matter Standards. States are permitted to adopt

more stringent ambient air quality standards than EPA’s NAAQS. Since 1982,

California has had more stringent particulate matter standards than the national

standards. California’s standards for PM10 are 30 :g/m3 annual geometric average and

50 :g/m3 24-hour average, as compared to EPA’s 1997 PM10 standards of 50 :g/m3

annual arithmetic mean and 150 :g/m3 24-hour average.

In 1999, the California legislature passed a bill requiring examination of the

standards for their adequacy in protecting health, particularly that of children. A

December 2000 report by the California Air Resources Board (CARB) found that the

PM standards were not adequate to protect human health. The 1999 California law

mandated revision of these standards by December 31, 2002. California’s process for

revision is somewhat similar to EPA’s NAAQS revision process in that a staff paper

is produced and an Air Quality Advisory Committee reviews the report.

In May 2002, CARB staff published a paper suggesting revising the standards

for PM10 and establishing new standards for PM2.5. The staff paper maintained the

level and form of the 24-hour PM10 standard but tightened the annual standard to 20

:g/m3 annual arithmetic average, not to be exceeded. The new standards for PM2.5

were recommended to be 12 :g/m3 annual arithmetic average, not to be exceeded,

and 25 :g/m3 24-hour average standard, not to be exceeded. The staff had not

originally recommended a 24-hour standard for PM2.5, but did so after the Air Quality

Advisory Committee concluded that adequate information existed to set a standard.

In June 2002, CARB held a public hearing on the staff paper recommendations.

Because of the software problem revealed in the NMMAPS study discussed above,

CARB decided not to include the PM2.5 24-hour standard on the agenda for the

For a further discussion, see CRS Report RL31779, Air Quality: Multi-Pollutant

Legislation in the 108th Congress, and CRS Report RL32273, Air Quality: EPA’s Proposed

Interstate Air Quality Rule.

CRS Report RL32273, Air Quality: EPA’s Proposed Interstate Air Quality Rule, p. 11.

CRS-30

meeting because some of the studies supporting the standard had used the faulty

software. At the meeting, CARB unanimously approved the three other particulate

matter standard recommendations. Following the required administrative law

review, the standards became effective July 5, 2003. Table 3 compares California’s

1982 standards, California’s 2002 standards, and EPA’s 1997 PM NAAQS.

Table 3. California’s State Particulate Matter Standards and the 1997

National Primary Particulate Matter Standards

California’s 1982 State

Standard

California’s 2002 State

Standard

1997 National Primary

Standard

PM10

PM10 and PM2.5

24-hour average (not to

be exceeded)

24-hour average (not to

be exceeded)

24-hour average (concentrationbased percentile)

Annual geometric mean

(not to be exceeded)

Annual arithmetic mean

(not to be exceeded)

Annual arithmetic mean

24-hour

NAAQS

50 :g/m3

PM10: 50 :g/m3

PM2.5: none

PM10: 150 :g/m3 (99th percentile)

PM2.5: 65 :g/m3 (98th percentile)

Annual

NAAQS

30 :g/m3

PM10: 20 :g/m3

PM2.5: 12 :g/m3

PM10: 50 :g/m3

PM2.5: 15 :g/m3

Indicator

Form

Source: Prepared by the Congressional Research Service.

California is currently considering amendments to its designation criteria, and

current area designations to account for the particulate standards adopted in June

2002. Legislation signed by the governor on October 8, 2003, required additional

specific requirements for PM10 and PM2.5 nonattainment areas. California Senate Bill

656 (SB 656)90 requires the development and adoption of a list of the “most readily

available, feasible, and cost-effective control measures to reduce PM10, PM2.5, and

their precursor emissions,” by January 1, 2005.

California’s decision on particulate matter may have national ramifications,

although no other states have set particulate matter standards different from the

federal standards. How California’s actions regarding particulate matter might impact

EPA’s decision upon conclusion of its current review is unclear.

International Particulate Matter Standards. Several countries have

established relatively comparable air quality standards for a number of the same

pollutants as the U.S., including particular matter. A recent study91 compared various

aspects of the U.S. air quality and water quality standards with those of other

countries. According to the study, the U.S. standards for PM10 are less stringent than

For more information, see the California Air Resources Board website at [http://www.

arb.ca.gov/pm/pmmeasures/pmmeasures.htm].

Timothy Benner, “Brief Survey of EPA Standard-Setting and Health Assessments,”

Environmental Science and Technology, vol. 38, no. 13, 2004. Published on the American

Chemical Society website at [http://pubs.acs.org/].

CRS-31

64% of the countries identified. Canada is the only other country that currently has

standards for PM2.5; their 24-hour standard is more stringent (30 µg/m3) than the U.S.

24-hour standard (65 µg/m3) . Several countries include standards for total suspended

particulates (TSP), which U.S. EPA discontinued regulating in 1987 when the agency

focused attention on PM10.

For purposes of illustration, Table 4 (below) presents comparisons of U.S. PM10

and PM2.5 standards with standards in other selected countries as reported in the

study. The comparisons of the various countries’ particulate matter standards in this

survey introduce interesting insights and raise empirical questions about why they

differ. The significance of these differences requires a more complete understanding

of the individual statutory authority, the data and interpretations of the data, and other

factors each country used in establishing their standards, as well as their intended

outcomes in terms of particulate matter emissions.

Table 4. PM10 and PM2.5 Air Quality Standard Comparison of United States

and Selected Countries

Brazil

China

France

Germany

India

Mex.

N.Z.

S.Africa

Spain

PM10 (µg/m3)

24-hour

150

100

150

180

Annual

20a

100

20a

Source: Prepared by the Congressional Research Service based on “Brief Survey of EPA Standard-Setting and Health

Assessment,” by Timothy Benner, U.S. Environmental Protection Agency, Office of Research and development, Office

of Science Policy. Published by the American Chemical Society May 28, 2004. As printed in Environmental Science

and Technology, vol. 38, no. 13, 2004.

Final 2010.

Some of the differences are likely to be the result of different interpretation of

the same data. In addition, the U.S. was among the first to establish standards for

particulate matter; several other countries are only now considering comparable PM2.5

standards. The lag in establishing particulate matter standards by other countries may

be part of the reason for the comparable stringency in the PM10 standards. Other

countries that established these standards later than the U.S. had the advantage of

expanded information. As noted in the study, an important consideration with regard

to this type of comparison is the implementation and adequacy of enforcement

regulations for actually achieving improved air quality. According to the study,

although it varies from country to country, EPA’s implementation and enforcement

appears to be more successful than most other countries.

The level at which other countries are setting their particulate matter standards

might be indicative of an emerging international agreement regarding the scientific

knowledge about particulate matter health effects. However, it is not clear if the

comparison of the U.S. particulate matter standards to those of other countries will

be a factor as EPA continues the simultaneous review and implementation of the

current PM NAAQS.

CRS-32

Conclusions

Particulate matter standards have been a source of significant controversy.

EPA’s promulgation of standards for both coarse and fine particulate matter in 1997

prompted critics to charge EPA with over-regulation and spurred environmental

groups to claim that EPA had not gone far enough. Not only was the science behind

the PM NAAQS challenged, but EPA was also accused of unconstitutional behavior.

However, EPA’s decision to issue these standards was upheld, for the most part, and

the science behind the standards was generally vindicated by an HEI review.

EPA is proceeding with its review of new information to determine whether

further revision of the PM NAAQS is necessary. Congress’s provision of

significantly more funding for particulate matter research has resulted in an increased

number of ongoing studies to determine particulate matter health effects. Recent

scientific findings in the NMMAPS and other related research have prompted further

concern about the health effects of particulate matter. However, a number of

stakeholders still contend that the scientific does not adequately support the PM

NAAQS.

As EPA evaluates the need to revise current PM NAAQS, stakeholder interest

remains high. PM2.5 standards are expected to affect numerous areas, including some

that have not previously been designated nonattainment for a NAAQS. This has

raised concerns regarding the potential impacts, and triggered numerous questions

regarding the specifics of the implementation process. EPA projects that federal

measures, such as recent auto and truck emission standards and controls on power

plants, will be sufficient to demonstrate attainment in a large portion of monitored

nonattainment counties by 2015, and help alleviate the development and

implementation of local measures. Some Members of Congress, and others, have

questioned the agency’s predictions regarding the relative magnitude of the emission

reductions associated with existing and proposed air quality controls.

If EPA decides to tighten the PM NAAQS again based on the results of its

review, more areas could be classified as nonattainment and need to implement new

controls on particulate matter. This would require states and local governments to

develop and implement new plans for addressing emissions in those areas that do not

meet any new standards. A stricter standard may mean more costs for these

transportation and large industries, including utilities, refineries, and the trucking

industry, impacted by particulate matter controls. In terms of public health, a stricter

standard may mean fewer health effects for the general population and particularly

sensitive populations such as children, asthmatics, and the elderly. Because both the

health and economic consequences of particulate matter standards are so potentially

significant, the PM NAAQS are likely to remain a prominent issue of interest to

many, including Members of Congress.

Actions following the release of the 8-hour ozone designations will likely affect

certain decisions and the schedule regarding PM2.5. In addition, California and several

countries have established particulate matter standards that are more stringent than

the current U.S. standards. Whether these actions can be considered indicative of

what EPA will decide to do in its current review of the PM NAAQS is unclear.

CRS-33

The agency’s previous review and establishment of PM NAAQS was the subject

of litigation and challenges, including a Supreme Court decision in 2001. It would

not be surprising if interested parties return to the courts or initiate challenges under

the 2000 Data Quality Act in the months ahead, as the agency continues its review

and implementation of the PM NAAQS. Thus, the final form of the current efforts

to implement the PM2.5 standards, and EPA’s response to the current review of PM

NAAQS and the science information, may not be known for some time. It could be

some time before the final form of the PM NAAQS resulting from the current EPA

review is known. Likewise, the EPA’s current PM2.5 implementation efforts could

also potentially be delayed.

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.