Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

Congressional research reportApr 17, 2008

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Air Quality: EPA’s 2006 Changes to the

Particulate Matter (PM) Standards

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Specialist in Environmental Policy

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Specialist in Environmental Policy

April 17, 2008

Congressional Research Service

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RL33254

CRS Report for Congress

Prepared for Members and Committees of Congress

Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

Summary

On October 17, 2006, the EPA published its final revisions to the National Ambient Air Quality

Standards (NAAQS) for particulate matter (particulates, or PM). The EPA reviewed more than

2,000 scientific studies and found that the evidence continued to support associations between

exposure to particulates in ambient air and numerous significant health problems, including

aggravated asthma, chronic bronchitis, reduced lung function, heart attacks, and premature death

in people with heart or lung disease. Based on several analytical approaches, the EPA estimated

that compliance with the new NAAQS will prevent 1,200 to 13,000 premature deaths annually, as

well as substantial numbers of hospital admissions and missed work or school days due to illness.

Although a tightening of the standards, the new 2006 particulates NAAQS are not as stringent as

recommended by EPA staff or the independent scientific advisory committee (Clean Air Scientific

Advisory Committee, or CASAC) mandated under the Clean Air Act.

The new 2006 particulates NAAQS strengthen the pre-existing (1997) standard for “fine”

particulate matter 2.5 micrometers or less in diameter (PM2.5) by lowering the allowable daily

concentration of PM2.5 in the air. The new daily standard averaged over 24-hour periods is

reduced from 65 micrograms per cubic meter (µg/m3) to 35 µg/m3. However, the annual PM2.5

standard, which is set in addition to the daily standard to address human health effects from

chronic exposures to the pollutants, is unchanged from the 1997 standard of 15 µg/m3, although

the CASAC had recommended a tighter annual standard in the range of 13 to 14 µg/m3. Nearly

90 million people live in the 208 counties designated as “nonattainment” areas for the 1997 PM2.5

NAAQS.

The 2006 particulates NAAQS also retain the 24-hour standard and revoke the annual standard

for slightly larger, but still inhalable, particles less than or equal to 10 micrometers (PM10). The

EPA abandoned its proposal to replace the particle size indicator of PM10 with a range of 10 to 2.5

micrometers (PM10-2.5), and did not follow through on its proposal to exclude any mix of particles

“dominated by rural windblown dust and soils and PM generated by agricultural and mining

sources.”

The divergence from the CASAC’s recommendation has proved controversial, as have several

other elements of the 2006 particulates NAAQS, including the decision not to exclude rural

sources from the coarse particle standard. Some have also questioned the EPA’s strengthening of

the standard for all fine particles, without distinguishing their source or chemical composition. In

December 2006, several states and industry, agriculture, business, and public advocacy groups

petitioned the U.S. Court of Appeals for the District of Columbia (D.C.) Circuit to review the new

2006 particulates NAAQS. All briefs from petitioners, EPA, and supporters were filed with the

court by March 7, 2008, but the date for oral argument has not yet been scheduled. EPA

anticipates a decision in late 2008. Congress may conduct oversight of the new 2006 particulates

NAAQS, given the potential public health and economic impacts, and concerns regarding the role

of CASAC in NAAQS reviews.

Congressional Research Service

Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

Contents

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

EPA’s 2006 Changes to the Particulates NAAQS .........................................................................2

Potential Impacts of the 2006 Particulates NAAQS .....................................................................5

EPA’s Monetized Benefits and Cost Estimates .......................................................................5

Potential Health Impacts .......................................................................................................7

Geographical Nonattainment Areas: Potential Impacts......................................................... 10

Potential Concerns and Issues ................................................................................................... 16

Fine Particulate (PM2.5) Primary (Health) Standards ............................................................ 17

Potential Health Benefits of a More Stringent PM2.5 Standard........................................ 19

Particle Size Indicator ................................................................................................... 20

Rural PM10 Sources....................................................................................................... 21

Secondary PM2.5 and PM10 Standards .................................................................................. 23

Exclusion of More Recent Research .................................................................................... 23

Synopses of Stakeholder Reaction to the New 2006 Particulates NAAQS............................ 24

Conclusions .............................................................................................................................. 25

Figures

Figure 1. Status of Current PM10 Nonattainment Areas, Based on 2004-2006 Air Quality .......... 11

Figure 2. Counties Exceeding Revised PM2.5 Standards, Based on 2003-2005

Monitoring Data..................................................................................................................... 15

Tables

Table 1. Primary (Health) NAAQS for PM2.5 and PM10: Final Revisions (2006), and

Previously Promulgated ...........................................................................................................4

Table 2. EPA’s Estimated Total Annual Monetized Benefits and Costs of Attaining

Alternative PM2.5 NAAQS in 2020...........................................................................................7

Table 3. EPA’s Predicted Reductions in Adverse Health Effects Annually in 2020

Associated with Meeting the New PM2.5 NAAQS.....................................................................9

Table 4. Counties with Monitors Identified by EPA To Be in Nonattainment for the 1997

and the New (2006) Pm2.5 NAAQS ........................................................................................ 14

Table 5. PM2.5 Primary (Health) NAAQS: Final (2006), Proposed and Alternatives, and as

Promulgated in 1997 .............................................................................................................. 17

Table 6. EPA’s Predicted Reductions in Adverse Health Effects Annually in 2020

Associated with Meeting the New PM2.5 NAAQS and a More Stringent Alternative ............... 20

Contacts

Author Contact Information ...................................................................................................... 26

Congressional Research Service

Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

Introduction

The EPA has identified and promulgated National Ambient Air Quality Standards (NAAQS)

under the Clean Air Act (CAA)1 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, 2 NOx), sulfur oxides (SOx, or, specifically, SO2), carbon

monoxide (CO), and lead (Pb). On October 17, 2006,3 the EPA published its revisions to the

NAAQS for particulates to provide protection against potential health effects associated with

short- and long-term exposure to particulate matter (including chronic respiratory disease and

premature mortality).

The EPA’s newly promulgated particulates NAAQS modify the standards established in 19874

that focused on particles smaller than 10 microns (PM10, or coarse particles) and standards for

“fine” particles smaller than 2.5 microns (PM2.5) introduced for the first time with the

promulgation of the 1997 PM2.5 NAAQS.5 The 2006 revisions to the particulates NAAQS are the

culmination of the EPA’s most recent statutorily required periodic review, 6 based on its evaluation

and analysis of more than 2,000 scientific studies available between 1997 and 2002, and on

determinations made by the Administrator. Prior to this, the most recent changes to any NAAQS,

a strengthening of the particulate matter and ozone standards, were promulgated jointly in 1997.

The EPA’s most recently completed review of the particulates NAAQS and of the scientific

criteria for setting the standards was initiated not long after the 1997 promulgation.

The 2006 particulates NAAQS are expected to continue to generate national interest and debate,

and possibly oversight in Congress, as did the previous changes to the particulates standards

promulgated in 1997. While the new 2006 particulates NAAQS generally tightened the air quality

standards for particulate matter, the action has caused considerable controversy, including

concerns that the standards are outside the range recommended by both EPA staff and by the

scientific advisory panel (Clean Air Scientific Advisory Committee, or CASAC 7) established by

the Clean Air Act (CAA). 8 Conversely, some continue to contend that available data do not

support the need for stricter standards or, in some cases, the standards as promulgated in 1997. In

December 2006, 13 states and the District of Columbia petitioned the U.S. Court of Appeals for

the District of Columbia (D.C.) Circuit to review the new 2006 particulates NAAQS. In addition,

several groups representing various industry and agriculture interests (including coal, iron, steel,

and corn refiners, oilseed processors, farmers, and cattle and pork producers), as well as

environmental and public health organizations, also filed petitions to the D.C. Circuit challenging

Sections 108-109 of the Clean Air Act.

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

71 Federal Register 61143-61233, October 17, 2006. See also EPA’s PM Regulatory Actions website at

http://epa.gov/pm/actions.html.

52 Federal Register 24634-24715, July 1, 1987.

62 Federal Register 38652-38896, July 18, 1997.

Section 109(d)(1) of the CAA. According to the statute, the EPA is required to review the latest scientific studies and

either reaffirm or modify the NAAQS every five years.

For information regarding the CASAC PM review panel and its activities and reports, see http://yosemite.epa.gov/sab/

sabpeople.nsf/WebCommittees/CASAC.

Section 109(d)(2)of the Clean Air Act.

Congressional Research Service

Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

the new 2006 NAAQS.9 Briefs from petitioners, EPA, and supporters were filed with the court by

March 7, 2008, but the date for oral argument had not yet been scheduled as of the updating of

this report. EPA anticipates a decision in late 2008.

The completion of the 2006 PM NAAQS review was followed by an EPA announcement, on

December 7, 2006, that it would modify the process for setting and reviewing NAAQS. Among

other changes, the CASAC would no longer have a role in approving the policy staff paper with

its recommendations to the Administrator. CASAC would be relegated to commenting on the

policy paper after it appears in the Federal Register, during a public comment period. The Senate

Environment and Public Works Committee included the EPA’s changes to the NAAQS review

process among the topics it considered February 6, 2007, in a hearing on “Oversight of Recent

EPA Decisions.”10 Seven Democratic members of the committee wrote EPA Administrator

Johnson on December 21, 2006, to express their strong opposition to the changes and to ask him

to “abandon” them. 11

In order to better understand EPA’s actions, this report provides an analysis of the agency’s final

2006 revisions to the particulates NAAQS, and the estimated costs and benefits of the new

standards and of more stringent alternatives analyzed. The report concludes by highlighting

concerns and issues raised regarding the revisions to the particulates standards, including those of

the science advisory committee (CASAC), and actions in Congress.

EPA’s 2006 Changes to the Particulates NAAQS

Establishing NAAQS does not directly limit emissions; rather, it represents the EPA

Administrator’s formal judgment regarding the level of ambient pollution that will protect public

health with an adequate margin of safety. Under Sections 108-109 of the CAA, Congress

mandated that the EPA set national ambient (outdoor) air quality standards for pollutants whose

emissions “may reasonably be anticipated to endanger public health (primary standards) or

welfare12 (secondary)” and “the presence of which in the ambient air results from numerous or

diverse mobile or stationary sources.” The statute further requires that every five years EPA

review the latest scientific studies and either reaffirm or modify previously established NAAQS.

The CAA is quite specific about certain steps for establishing and reviewing NAAQS, particularly

with regard to the preparation of a “criteria document” that summarizes the scientific information

and resulting criteria that the EPA Administrator will use to determine the final standard and the

procedural process for promulgating the standard. The act also established the Clean Air

Scientific Advisory Committee to review criteria and standards, and to advise the Administrator.

The CASAC augments its own resources by creating a review panel of scientists with expertise

Cases have been consolidated with American Farm Bureau Federation v. U.S. EPA, No. 06-1410 (D.C. Cir. 2006).

http://epw.senate.gov/public/index.cfm?FuseAction=Hearings.Home.

Office of Senator Barbara Boxer, “Democratic Members of Senate EPW Committee Warn EPA on Air Rollbacks,”

Press Release, December 21, 2006, at http://boxer.senate.gov/news/releases/record.cfm?id=267092. For a discussion of

issues regarding the CASAC, focusing on the statutory and historical role of CASAC and various proposals for change,

see CRS Report RL33807, Air Quality Standards and Sound Science: What Role for CASAC?, by (name redacted).

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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Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

specific to the pollutant in question. The PM review panel consisted of 22 national experts,

primarily academics and independent researchers.13 In addition to the CAA requirements, the EPA

has chosen to add the preparation of a “staff paper” that summarizes the criteria document and

lays out policy options. Traditionally, the CASAC has also formally reviewed the EPA staff

paper.14

The EPA’s most recent review found that the scientific evidence since 1997 reinforced the

associations between exposure to particulates and numerous cardiovascular and respiratory health

problems, including aggravated asthma, chronic bronchitis, reduced lung function, irregular

heartbeat, nonfatal heart attacks, and premature death. The CASAC found that the numerous

epidemiological studies EPA reviewed “have shown statistically significant associations between

the concentrations of ambient air PM2.5 and PM10 (including levels that are lower than the 1997

particulates NAAQS) and excess mortality and morbidity.”15 Further, the EPA concluded, and

most of the CASAC panel concurred, that the scientific evidence supported modifying the

particulates standards.

The primary NAAQS for both PM2.5 and PM10 include an annual and a daily (24-hour) limit. To

attain the annual standard, the three-year average of the weighted annual arithmetic mean PM

concentration at each monitor within an area must not exceed the maximum limit set by the

agency. The 24-hour standards are a concentration-based percentile form, indicating the

percentage of the time that a monitoring station can exceed the standard. For example, a 98th

percentile 24-hour standard indicates that a monitoring station can exceed the standard 2% of the

days during the year.

As modified and published in the October 17, 2006, Federal Register Notice, the primary PM2.5

and PM10 standards are as follows:

•

PM2.5: strengthens the daily (24-hour) standard, which currently allows no more

than 65 micrograms per cubic meter (µg/m3), by setting a new limit of 35 µg/m3,

based on the three-year average of the 98th percentile of 24-hour PM2.5

concentrations; retains the annual standard at 15 µg/m3.

•

PM10: retains the daily (24-hour) standard at 150 µg/m3 but changes from the 99th

percentile to no more than one exceedance per year on average over three years;

eliminates the annual maximum concentration (50 µg/m3) standard for PM10.16

For information regarding the CASAC PM review panel, see http://yosemite.epa.gov/sab/sabpeople.nsf/

WebCommittees/CASAC.

The EPA October 2004 criteria document and December 2005 staff paper, the CASAC reviews, and related

information supporting the 2006 revisions to the particulates NAAQS are available at http://www.epa.gov/ttn/naaqs/

standards/pm/s_pm_index.html.

CASAC Particulate Matter (PM) review of EPA’s Review of the National Ambient Air Quality Standards for

Particulate Matter: Policy Assessment of Scientific and Technical Information (Second Draft PM Staff Paper, January

2005, EPA-SAB-CASAC-05-007, June 6, 2005), available on the EPA CASAC website, see “Final Reports by Fiscal

Year” at http://yosemite.epa.gov/sab/sabproduct.nsf/WebReportsbyYearCASAC.

Based on the findings in the EPA PM criteria document and staff paper, and the CASAC’s concurrence, that the

studies reviewed do not provide sufficient evidence regarding long-term exposure to warrant continuation of an annual

standard, see 71 Federal Register 2653, Section III. Rationale for Proposed Decision on Primary PM10 Standards,

January 17, 2006.

Congressional Research Service

Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

For PM2.5 and PM10, the secondary (welfare) NAAQS are the same as the primary standards.

Table 1 below provides a comparison of the newly revised primary NAAQS with those

previously promulgated for both PM2.5 and PM10.

Table 1. Primary (Health) NAAQS for PM2.5 and PM10: Final Revisions (2006), and

Previously Promulgated

Previous NAAQS

EPA Final Rule (2006)

PM2.5 (Fine)

24-Hour Primary Standard

65 μg/m3

35 μg/m3

Annual Primary Standard

15 μg/m3

PM10 (Coarse)

24-Hour Primary Standard

150 μg/m3

Annual Primary Standard

50 μg/m3

Revoked

Source: Prepared by the Congressional Research Service (CRS), with information from the EPA’s final particulates

NAAQS (71 Federal Register 61143-61233, Oct. 17, 2006), and related technical documents,17 available at

http://www.epa.gov/air/particles/actions.html.

EPA’s final revisions to the standards for fine particulates (PM2.5) are the same as the agency had

proposed in January 2006. However, the final 2006 EPA revisions to the PM2.5 NAAQS, while

tightening the standards, are not as stringent as those recommended by the CASAC and by the

EPA staff. With regard to coarse particulates, the EPA had proposed replacing the current particle

size indicator of PM10 with a range of 10 to 2.5 micrometers (PM10-2.5), referred to as inhalable (or

thoracic) coarse particles, and setting a PM10-2.5 daily standard of 70 µg/m3 rather than the current

PM10 daily standard of 150 µg/m3. The proposal also included narrowing the focus of the PM10-2.5

standard to “urban and industrial” sources and excluding particles typical to rural areas, including

“windblown dust and soils and particulates generated by agricultural and mining sources.” The

range of alternative standards considered and proposed and issues associated with the EPA’s final

decisions are discussed later in this report.

Promulgation of NAAQS sets in motion a process under which the states and the EPA first

identify geographic nonattainment areas, those areas failing to comply with the NAAQS based on

monitoring and analysis of relevant air quality data. The 2006 tightening of the PM2.5 standards is

expected to increase the number of areas (typically defined by counties or portions of counties) in

nonattainment. EPA expects to finalize the nonattainment designations (based on 2005-2007

monitoring data) for the new 2006 PM NAAQs by the end of 2008 with an effective date of April

2009.18 Following formal designation, the states have three years (until April 2012) to submit

State Implementation Plans (SIPs), which identify specific regulations and emission control

requirements that will bring an area into compliance.

EPA’s final PM staff paper and the CASAC review of the EPA staff paper http://www.epa.gov/ttn/naaqs/standards/

pm/s_pm_index.html.

See EPA’s guidance on its website “Area Designations for 2006 24-Hour PM2.5 NAAQS - Technical Information,”

http://www.epa.gov/ttn/naaqs/pm/pm25_2006_techinfo.html.

Congressional Research Service

Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

The EPA is not requiring new nonattainment designations for PM10 and it does not anticipate any

significant incremental cost impacts of this action. A discussion of the potential benefits and cost

impacts associated with implementation of the new particulates NAAQS follows.

Potential Impacts of the 2006 Particulates NAAQS

As discussed above, in setting and revising the NAAQS, the CAA directs the EPA Administrator

to protect public health with an adequate margin of safety. This language has been interpreted,

both by the agency and by the courts, as requiring standards based on a review of the health

impacts, without consideration of the costs, technological feasibility, or other non-health

criteria.19 This being the case, costs and benefits were not to play a central role in setting the

particulates NAAQS. Costs and feasibility are generally taken into account in NAAQS

implementation (a process that is primarily a state responsibility).

Nevertheless, the EPA released a regulatory impact analysis (RIA) on October 6, 2006,20 to meet

its obligations under Executive Order 12866 and in compliance with guidance from the White

House Office of Management and Budget.21 The RIA only analyzed the benefits and costs of

implementing the PM2.5 NAAQS. Citing time, data, and modeling limitations, the EPA did not

analyze the benefits and costs of retaining the PM10 standard. 22

The EPA emphasized that the October 2006 RIA differs from typical RIAs in that it does not

analyze the regulatory impact of an action and that it is primarily for illustrative purposes. The

basis for the benefits calculations are reductions in ambient concentrations of PM2.5 resulting

from a reasonable, but speculative, array of cost-effective state implementation strategies selected

by the EPA for purposes of analysis. The analysis does not model the specific actions that each

state will undertake in implementing the new PM2.5 NAAQS. The EPA includes a detailed

discussion of the limitations and uncertainties associated with the analyses.

EPA’s Monetized Benefits and Cost Estimates23

The EPA estimated incremental costs of attaining the new PM2.5 standard based on a set of

assumptions and extrapolations regarding currently designated nonattainment areas, likely control

strategies and technologies and their associated engineering costs, emissions inventories and

sources, and regional variability. The EPA emphasizes that the technologies and control strategies

selected for analysis only illustrate one way for nonattainment areas to reach attainment, and that

states will compile and evaluate a variety of programs and adopt those attainment strategies best

With regard to the non-relevance of cost considerations, see generally Whitman v. American Trucking Associations,

531 U.S. 457, 465-472, 475-76 (2001).

EPA’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality Standards for Fine Particle

Pollution (PM2.5), available on EPA’s website at http://www.epa.gov/ttn/ecas/ria.html.

58 Federal Register 51735, October 4, 1993. See the White House OMB website, Regulatory Matters at

http://www.whitehouse.gov/omb/inforeg/regpol.html#rr.

The EPA did not release an RIA assessing the costs and benefits at the time of its January 17, 2006, proposal, but

conducted interim and “provisional” analyses regarding certain aspects of potential risk reductions in specific locations

associated with an array of PM2.5 standards. http://www.epa.gov/air/particlepollution/actions.html.

EPA’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality Standards for Fine Particle

Pollution (PM2.5), available on EPA’s website at http://www.epa.gov/ttn/ecas/ria.html.

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Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

suited for their specific local conditions. For purposes of comparing costs with monetized

benefits, the EPA estimated that the total annual mean social cost of attainment of the new PM2.5

NAAQS incremental to attainment of the 1997 standards would be $5.4 billion in 2020.

EPA’s estimates of the monetized benefits of complying with the new PM2.5 standard reflect the

valuation associated with predicted reductions in the incidence of certain health and social

welfare effects. In the RIA, the EPA presents a variety of benefits estimates based on several

published epidemiological studies, including an American Cancer Society (ACS) Study24 used in

previous RIAs, and the Harvard Six Cities Study,25 as well as an expert elicitation study

conducted by the EPA in 2006.26 The EPA estimated the total annual monetized benefits of

attaining the new PM2.5 NAAQS would range from $15 billion to $17 billion based on the

mortality function from the ACS study and morbidity function from the published studies. Using

the mortality function developed using the expert elicitation in conjunction with the morbidity

function from the published studies, the EPA’s total annual benefits are estimated to range from

$8 billion to $76 billion in 2020. The EPA’s estimated monetized benefits for 2020, like the cost

estimates, are based on the EPA’s projected compliance schedule and are incremental to

compliance with the 1997 PM2.5 NAAQS by 2015.

According to the October 6, 2006, RIA, the estimated total annual health and welfare net benefits

(subtracting social costs from the monetized benefits) in 2020 of attaining the new PM2.5 NAAQS

range from $9 billion to $12 billion, based on modeling of morbidity and mortality using

published epidemiology studies, and from $2.4 billion to $70 billion, based on derivation from

expert elicitation.

The EPA’s benefits and cost estimates are in terms of 1999 dollars and are incremental to the

agency’s modeled attainment strategy for the 1997 PM2.5 NAAQS by 2015. The baseline case

incorporates expected impacts associated with implementation of recent national regulations

addressing emissions from the power generation sector (e.g., the Clean Air Interstate Rule

[CAIR]27), as well as various mobile sources, that contribute to lowering PM2.5 concentrations in

future years. below presents a range of the EPA’s cost and monetized benefits estimates.

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.

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. See also the 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 November 1, 2001 errata sheet), p. I.

(http://pubs.healtheffects.org/getfile.php?u=271).

See Chapter 5 of the EPA’s October 6, 2006, RIA http://www.epa.gov/ttn/ecas/ria.html.

70 Federal Register 25162, May 12, 2005.

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Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

Table 2. EPA’s Estimated Total Annual Monetized Benefits and Costs of Attaining

Alternative PM2.5 NAAQS in 2020

(1999 $ billions)

2006 PM2.5 NAAQS (15/35 μg/m3)

Discount Ratea

Benefits

Cost

Net Benefits

Benefits based on American Cancer Society Study Mortality Function and Published Scientific Literature Morbidity Functions

$17

$5.4

$12

$15

$5.4

Benefits Range based on Expert Elicitation Derived Mortality Function and Published Scientific Literature Morbidity Functions

Low Mean

High Mean

$76

$54

Low Mean

High Mean

$5.4

$3.5

$70

$5.4

$2.4

$59

Source: Prepared by the Congressional Research Service from the Environmental Protection Agency’s

Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality Standards for Fine Particle Pollution (PM2.5),

Table ES-1, p. ES-7, available on the EPA’s website at http://www.epa.gov/ttn/ecas/ria.html. Estimates and results

have been rounded.

Note: Estimates (costs and benefits) reflect attainment in 2020, which includes implementation of several

national programs and are incremental to compliance with the 1997 PM2.5 NAAQS.

The discount rates are as recommended in the EPA’s Guidelines for Preparing Economic Analyses (2000) and

OMB Circular A-4 (2003).

In addition to the monetized health benefits estimates, the EPA estimated the monetary benefits

associated with improvements in visibility in selected Class I national parks and wilderness

areas.28 The EPA primarily used a stated preference approach which estimates values based on

sampling surveys asking people what amount of compensation would be equivalent to a defined

improvement in environmental quality. Extrapolating the results of a study based on a 1988

survey on recreational visibility value, the EPA estimated visibility “willingness to pay” benefits

to be $530 million in 2020 with attainment of the new PM2.5 NAAQS.29

EPA estimated the cost and benefits of a more stringent alternative PM2.5 for purposes of

comparative analysis. The comparative results are discussed in the “Potential Concerns and

Issues” section of this report.

Potential Health Impacts

According to the January 2008 EPA report entitled, Latest Findings on National Air Quality

Status and Trends Through 2006,30 nationally, annual PM2.5 concentrations declined by 14%

between 2000 and 2006. Between 1990 and 2006, nationally, PM10 concentrations declined by

30%. For PM2.5 the areas that showed the greatest improvement were the ones that had the

Defined as areas of the country such as national parks, national wilderness areas, and national monuments that have

been set aside under Section 162(a) of the Clean Air Act to receive the most stringent degree of air quality protection.

See Appendix I Visibility Benefits Methodology of the EPA’s October 6, 2006, RIA http://www.epa.gov/ttn/ecas/

ria.html.

EPA-454/R-07-007, January 2008 http://www.epa.gov/air/airtrends/2007/.

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Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

highest concentrations in the earlier years. Decreasing concentrations in southern California were

largely the result of decreasing levels of nitrate particles; organic carbon levels remained

relatively unchanged and have been the largest component of PM2.5 in southern California. The

Southeast had little change in PM2.5. The industrial Midwest and the Northeast showed

decreasing concentrations, mostly due to reductions in nitrates and sulfates. Despite this progress,

in 2006 nearly 67 million people lived in counties with measured concentrations exceeding the

annual PM2.5 national air quality standard (based on one-year metric, not the three-year

average).31

A report released by the American Lung Association (ALA) in April 2007 indicated higher

average concentration levels of year-round PM2.5 in densely populated areas of the eastern

United States during 2003-2005, compared with 2002-2004. The report noted that outside of the

eastern United States, particle levels continued to drop during the same time period, even in areas

that the ALA has historically ranked as high in particle pollution. 32

For purposes of illustration, Table 3 summarizes the EPA’s predicted reductions in the incidence

of a range of adverse health effects annually in 2020 for the new PM2.5 NAAQS (15/35 µg/m3),

as reported in its RIA. The range of the estimated mean number of reductions in premature deaths

is based on the EPA’s derivations using the ACS and the Harvard Six-City studies. EPA’s mean

estimates for the remaining adverse health effects are based on various epidemiology studies. The

EPA health effects estimates were a primary component of its derivations of the monetized

benefits discussed above.

Refers to trends in the measured PM2.5 concentrations relative to their air quality standards in those areas where

monitors are located across the country, and does reflect all designated nonattainment areas. The combined population

residing in EPA’s final PM2.5 nonattainment designation areas, consisting of 208 counties in 20 states and the District

of Columbia, is almost 90 million.

Estimates are based on air quality data obtained from the U.S. Environmental Protection Agency’s Air Quality

System, formerly called Aerometric Information Retrieval System (AIRS). American Lung Association, State of the

Air: 2007, released April 2007, http://lungaction.org/reports/stateoftheair2007.html.

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Table 3. EPA’s Predicted Reductions in Adverse Health Effects Annually in 2020

Associated with Meeting the New PM2.5 NAAQS

Adverse Health Effect

Premature deaths in individuals with preexisting

cardiovascular and respiratory disease

Predicted Reductionsa

(estimated mean)

2,500 to 5,700b

Cases of chronic bronchitis (age >25)

2,600

Cases of acute bronchitis (age 8-12)

7,300

Nonfatal heart attacks (age >71)

5,000

Hospital admissions for cardiovascular or respiratory

symptoms (age >17)

1,630

Emergency room visits for asthma (age <19)

1,200

Cases of aggravated asthma (asthmatics age 6-18)

51,000

Cases of upper and lower respiratory symptoms (asthmatics age 6-18)

97,000

Days when individuals miss work (age 18-75)

350,000

Days when individuals must restrict their activities because

of symptoms related to particle pollution (age 18-65)

2,000,000

Source: Prepared by the Congressional Research Service with data based on epidemiology studies presented in

Chapter 5 of the Environmental Protection Agency Regulatory Impact Analysis of the 2006 National Ambient Air Quality

Standards for Fine Particle Pollution (PM2.5) Oct. 6, 2006, and available on the EPA’s website at http://www.epa.gov/ttn/

ecas/ria.html. Estimates are rounded by EPA to two significant digits.

For consistency with the emissions and benefits modeling, the EPA used national population estimates based

on the U.S. Census Bureau projections. U.S. Bureau of Census. 2000. Population Projections of the United

States by Age, Sex, Race, Hispanic Origin and Nativity: 1999 to 2100. Population Projections Program,

Population Division, U.S. Census Bureau, Available at http://www.census.gov/population/projections/nation/

summary/np-t.txt.

The range of estimates reflects the mean estimates derived from the American Cancer Society study and

the Harvard Six-City Study, respectively.

In addition to the expected improved health benefits based on the epidemiology studies, the EPA

estimated reductions in premature mortality based on the expert elicitation approach discussed

above. The estimates were variable from expert to expert, ranging from a mean of 1,200 to 13,000

avoided premature deaths annually in 2020 resulting from attainment of the new standards (15/35

μg/m3) incremental to the EPA’s baseline strategy for the 1997 PM2.5 NAAQS (15/65 μg/m3).

When promulgating the 1997 PM2.5 NAAQS, the EPA estimated that compliance would result in

the annual prevention of 15,000 premature deaths, 75,000 cases of chronic bronchitis, and 10,000

hospital admissions for respiratory and cardiovascular disease, as well as other benefits. These

estimates have been the subject of significant debate and re-analysis. Since 1998, with dedicated

funding from Congress, the EPA accelerated its research and re-analysis on PM2.5 to better

understand the potential associated health effects and to develop ways to reduce risks.33 The

Congress increased EPA’s appropriations for particulate matter research from $18.8 million in FY1997 (H.Rept. 104812) to $49.6 million in FY1998 (H.Rept. 105-297). PM research appropriations averaged more than $60 million per

year from FY1999 through FY2004, and Congress provided $60.5 million for FY2005. Congress did not identify PM

research funding in EPA’s FY2006 appropriation but included $66.8 million for NAAQS research (H.Rept. 109-465).

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funding supported EPA intramural and extramural PM research projects and the establishment of

five university-based PM research centers around the country. The EPA’s most recent review has

increased its confidence in earlier findings associating exposure to PM2.5 with increases in

respiratory health problems, hospitalizations for heart and lung disease, and premature death,

particularly for children, the elderly, and those with preexisting heart and lung disease. 34

Geographical Nonattainment Areas: Potential Impacts

As described earlier, the Clean Air Act has been interpreted to exclude consideration of the costs,

technological feasibility, and other non-health criteria when setting and revising the NAAQS.

Nevertheless, costs and feasibility associated with the NAAQS implementation (primarily a state

responsibility) are key elements of the debate regarding the new 2006 particulates NAAQS. The

proposed tightening of the PM2.5 standards is expected to increase the number of areas (typically

defined by counties or portions of counties) in nonattainment, and subsequently result in

increased costs to achieve compliance.

The current PM10 daily (24-hour) standard has been retained at the 1987 level and the annual

standard revoked. The EPA is not requiring new nonattainment designations for PM10, and it does

not anticipate any significant incremental cost impacts of this action. The Agency has designated

87 areas as nonattainment with the PM10 NAAQS since 1990. As of March 2008, 40 of the

original 87 PM10 areas have been redesignated to attainment. Of the remaining 47 nonattainment

areas (46 counties with a population of 28.5 million), 18 areas are currently not meeting the 1987

standard based on 2004-2006 data. The remaining counties have submitted the required SIPs for

PM10 but have not yet been formally redesignated to attainment. Figure 1, below, shows the

status of nonattainment of the 1987 PM10 NAAQS.35

EPA criteria and technical documents in support of the October 17, 2006, final particulates NAAQS, the December

20, 2005, proposal, and the 1997 NAAQS, are available at http://www.epa.gov/ttn/naaqs/standards/pm/

s_pm_index.html.

See EPA’s PM10 designations at http://www.epa.gov/air/oaqps/greenbk/pindex.html.

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Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

Figure 1. Status of Current PM10 Nonattainment Areas, Based on 2004-2006 Air Quality

Source: U.S. EPA http://www.epa.gov/particles/pdfs/20061025_graphsmaps.pdf.

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Designation of geographical areas and the associated impacts on specific areas would be

speculative at best, because implementation of the 2006 revised PM NAAQS is several years off.

The tightening of the PM2.5 standards36 is expected to increase the number of areas (typically

defined by counties or portions of counties) in nonattainment. States provided recommendations

to EPA in December 2007 for nonattainment boundaries for the 2006 PM2.5 standards based on

2004-2006 monitoring data. EPA expects to finalize these nonattainment designations (based on

2005-2007 monitoring data) by the end of 2008 with an effective date of April 2009, and state

implementation plans (SIPs) would be due three years later in April of 2012.37 SIPs identify

specific regulations and emission control requirements that will bring an area into compliance. If

new or revised SIPs for attainment establish or revise a transportation-related emissions

allowance (“budget”), or add or delete transportation control measures (TCMs), they will trigger

“conformity” determinations. Transportation conformity is required by the CAA, Section

176(c),38 to prohibit federal funding and approval for highway and transit projects unless they are

consistent with (“conform to”) the air quality goals established by a SIP, and will not cause new

air quality violations, worsen existing violations, or delay timely attainment of the national

ambient air quality standards.

Under the Clean Air Act, states are required to meet the new 2006 PM2.5 standard “as

expeditiously as practicable,” but no later than five years from the date of designation—April

2014. An extension of one to five years may be obtained if a state demonstrates severe air quality

conditions prevent achieving attainment within the five years after designation. 39

With regard to the 1997 PM2.5 NAAQS, States are required to submit their SIPs for how the

designated nonattainment areas will meet the 1997 PM2.5 NAAQS by April 2008. EPA expects

that about half of the 58 SIPs (there are 39 areas but some have multiple states submitting

individual SIPs) to be submitted before July 2008, and the remainder to be submitted in the

following months.40 States with nonattainment areas must be in compliance with the 1997 PM2.5

NAAQS by April 5, 2010, unless they are granted a five-year extension.41 The EPA published its

final “PM2.5 implementation” rule on April 25, 2007, which describes the requirements that states

and tribes must meet in their implementation plans to achieve and maintain attainment of the

1997 PM2.5 NAAQS.42 The rule also provides guidance and procedures for establishing controls

The new daily standard averaged over 24-hour periods is reduced from 65 micrograms per cubic meter (µg/m3) to 35

µg/m3 (71 Federal Register 61143-61233, October 17, 2006).

See EPA’s guidance on its website”Area Designations for 2006 24-Hour PM2.5 NAAQS—Technical Information,”

http://www.epa.gov/ttn/naaqs/pm/pm25_2006_techinfo.html.

42 U.S.C. 7506(c).

Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the initial attainment date for one

to five years (in no case later than 10 years after the designation date for the area). A state requesting an extension must

submit an implementation plan (SIP) by the required deadline that includes, among other things, sufficient information

demonstrating that attainment by the initial attainment date is “impracticable.”

U.S. EPA Office of Air Quality Planning and Standards (OAQPS) based on information received from the EPA

Regions regarding expected SIP submittal dates.

Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the initial attainment date for one

to five years (in no case later than 10 years after the designation date for the area). A state requesting an extension must

submit an implementation plan (SIP) by the required deadline that includes, among other things, sufficient information

demonstrating that attainment by the initial attainment date is “impracticable.”

The rule addresses attainment demonstration and modeling; local emission reduction measures, including reasonably

available control technology (RACT), reasonably available control measures (RACM), and reasonable further progress

(RFP); regional emission reduction strategies; innovative program guidance; emission inventory requirements;

transportation conformity; and stationary source test methods.

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to achieve and maintain attainment. Six petitions for review of EPA’s implementation rule have

been filed with the U.S. Court of Appeals for the District of Columbia (D.C.) Circuit,43 and two

petitions for reconsideration have been filed with EPA.44

Implementation of the 1997 PM2.5 NAAQS—delayed several years by litigation, the lack of

monitoring capability, and other factors—is ongoing. The EPA’s final designation of 39

geographical areas, composed of 208 counties in 20 states and the District of Columbia, in

nonattainment with the 1997 PM2.5 NAAQS (those areas with or contributing to air quality levels

exceeding the annual and 24-hour standards) became effective on April 5, 2005. A direct national

comparison of nonattainment areas for the 1997 PM2.5 NAAQS and the 2006 revised PM2.5

NAAQS is not currently available. However, using 2003-2005 monitoring data, the EPA

identified 143 of those counties with monitors that exceed the new PM2.5 NAAQS. Although the

actual nonattainment designations would be based on monitoring data45 from later years (EPA

expects to use 2005-2007 monitoring data,46 comparatively the counties identified reflect an

increase from 73 counties with monitors within the total 208 counties that were designated by

EPA as in nonattainment (exceeding) the 1997 PM2.5 NAAQS. presents the geographic

distribution of counties with monitors exceeding new 2006 PM2.5 NAAQS identified by EPA, and

those exceeding the 1997 PM2.5 NAAQS.

The six petitions are: Earthjustice on behalf of American Lung Association, National Resources Defense Council,

Sierra Club and Medical Advocates for Healthy Air (American Lung Association v. EPA, No. 07-1233 (D.C. Cir. June

26, 2007); National Environmental Development Association’s Clean Air Project; National Petrochemical & Refiners

Association; State of New York; State of New Jersey; National Cattlemen’s Beef Association.

Earthjustice, Petition for Reconsideration, Final Clean Air Fine Particle Implementation, filed before the

Administrator of the U.S. Environmental Protection Agency, June 25, 2007, (Docket #EPA-HQ-OAR-2003-0062-0256

available at http://www.regulations.gov); and petition by the National Cattlemen’s Beef Association (based on

information received by CRS from EPA’s Office of Air Quality Planning and Standards, March 19, 2008).

Revisions to Ambient Air Monitoring Regulations, final rule, 71 Federal Register 61235-61328, October 17, 2006.

In a separate but related action, EPA amended its national air quality monitoring requirements, including those for

monitoring particle pollution, to help federal, state, and local air quality agencies “improve public health protection and

inform the public about air quality in their communities” by taking advantage of improvements in monitoring

technology. Information on the changes is available at http://www.epa.gov/air/particlepollution/actions.html.

See EPA’s guidance on its website “Area Designations for 2006 24-Hour PM2.5 NAAQS—Technical Information,”

http://www.epa.gov/ttn/naaqs/pm/pm25_2006_techinfo.html.

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Table 4. Counties with Monitors Identified by EPA To Be in Nonattainment for the

1997 and the New (2006) Pm2.5 NAAQS

PM2.5 NAAQS (annual/24-hour μg/m3)

1997 Standard

15/65 μg/m3

National

West

New 2006 Standard

15/35 μg/m3

East

National

West

East

Number of counties with monitors

Total exceeding the standard

143

111

Exceeding the 24-hour and annual standards

Exceeding the 24-hour standard only

Exceeding the annual standard only

Source: Prepared by the Congressional Research Service with data provided by EPA Office of Air Quality Planning

and Standards, Office of Air and Radiation.

Note: By December 2007, EPA received States recommendations for nonattainment area boundaries for the 2006

PM2.5 NAAQS based on 2004-2006 monitoring data. EPA expects to finalize the nonattainment area designations for

the 2006 PM2.5 NAAQS in December 2008 based on 2005-2007 monitoring data, with an effective date in April

2009.47

Observed on the map in Figure 2 below, the identified areas can seem small compared with the

approximately 3,000 counties in the United States. However, taking into account those areas

without monitors but contributing to air quality levels exceeding the new 2006 PM2.5 and other

factors considered by the agency when determining the designations, the total number of counties

in nonattainment, and the potential impacts with the new PM2.5 NAAQS, is likely to be even

larger. The number of counties where emissions will need to be controlled may be two or three

times the number of those exceeding the standard, because “nonattainment areas” include both

counties where pollutant concentrations exceed the standard and those that contribute to

exceedance of the standard in adjoining counties. Entire metropolitan areas tend to be designated

nonattainment, even if only one county in the area has readings worse than the standard. In

addition, the nonattainment counties tend to have larger populations than those in attainment:

nearly 90 million people (about 30% of the U.S. population) live in the 208 counties designated

nonattainment for the current standard. The new standard may affect an even larger percentage of

the population.

Ibid.

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Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

Figure 2. Counties Exceeding Revised PM2.5 Standards, Based on 2003-2005 Monitoring Data

Source: U.S. EPA http://www.epa.gov/particles/pdfs/20061025_graphsmaps.pdf

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Potential Concerns and Issues

Congress and a wide variety of stakeholders have closely followed the development of the new

2006 particulates NAAQS since EPA’s review began nearly 10 years ago. During the 109th

Congress the Senate Committee on Environment and Public Works and the committee’s

Subcommittee on Clean Air, Climate Change, and Nuclear Safety held hearings regarding

implementation and review of the particulates NAAQS.48 Well before the EPA formally proposed

revising the particulates NAAQS, stakeholders were providing evidence and arguments at public

hearings and other forums for their preferred recommendations. In general, business and industry

oppose more stringent standards, and public health and environmental interest groups advocate

tighter standards. The EPA received thousands of comments during various stages of development

of the particulates criteria document and in response to drafts of the EPA particulates staff paper.

The agency reported receiving more than 120,000 comments in response to the January 2006

particulates NAAQS proposal.

The Administrator’s proposed and final decisions represent the first time in CASAC’s nearly 30year history that the promulgated standards fall outside of the range of the scientific panel’s

recommendations.49 In letters dated March 21, 2006, and September 29, 2006, the CASAC raised

its concerns and objections regarding both PM10 and PM2.5 proposed standards.50 The

Administrator is not required by statute to follow CASAC’s recommendations; the act (in Section

307(d)(3)) requires only that the Administrator set forth any pertinent findings, recommendations,

and comments by CASAC and the National Academy of Sciences, and, if his proposal differs in

an important respect from any of their recommendations, provide an explanation of the reasons

for such differences. Courts, in reviewing EPA regulations, also generally defer to the

Administrator’s judgment on scientific matters, focusing more on issues of procedure,

jurisdiction, and standing. Nevertheless, CASAC’s detailed objections to the Administrator’s

decisions and its description of the process as having failed to meet statutory and procedural

requirements could play a role litigation challenging the standards.

At the time of its January 2006 proposal, the agency solicited comment regarding its supporting

analysis and a variety of alternative particulates NAAQS. In addition to soliciting written

comments, the EPA held public hearings in early March 2006 in Philadelphia, Chicago, and San

Francisco. As presented in its rationale for the final standards throughout the preamble of the final

rule, in some cases the EPA has revised elements of its proposal based on certain comments; in

U.S. Senate Committee on Environment and Public Works, full Committee, The Science and Risk Assessment Behind

the EPA’s Proposed Revisions to the Particulate Matter Air Quality Standards, July 19, 2006; Subcommittee on Clean

Air, Climate Change, and Nuclear Safety, EPA’s Proposed Revisions to the Particulate Matter Air Quality Standards,

July 13, 2006, and Implementation of the Existing Particulate Matter and Ozone Air Quality Standards, November 10,

2005.

For a discussion of recent issues regarding the CASAC, focusing on the statutory and historical role of CASAC and

various proposals for change, see CRS Report RL33807, Air Quality Standards and Sound Science: What Role for

CASAC?, by (name redacted).

Letter of Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to the Hon. Stephen Johnson,

Administrator, U.S. EPA, March 21, 2006, EPA-CASAC-LTR-06-002, available at http://yosemite.epa.gov/sab/

sabproduct.nsf/CD706C976DAC62B3852571390081CC21/$File/casac-ltr-06-002.pdf; and letter of Dr. Rogene

Henderson, Chair of the Clean Air Scientific Advisory Committee, et al. to Hon. Stephen L. Johnson, EPA

Administrator, September 29, 2006, EPA-CASAC-LTR-06-003, available at http://yosemite.epa.gov/sab/

sabproduct.nsf/1C69E987731CB775852571FC00499A10/$File/casac-ltr-06-003.pdf.

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other cases the EPA lays out its reasoning for disagreeing. EPA’s final modifications to the

existing particulates NAAQS have sparked interest and conflicting concerns among a diverse

array of stakeholders and in Congress. The following sections highlight several areas of interest.

Fine Particulate (PM2.5) Primary (Health) Standards

The final 2006 revised PM2.5 NAAQS, which are the same as proposed, are not as stringent as the

levels recommended by the independent CASAC and those recommended by EPA professional

staff, as noted above. EPA staff and CASAC recommendations for PM2.5 included a range of

levels more stringent than those proposed in January and finalized September of 2006. In

particular, the majority of the CASAC panel “did not endorse the option of keeping the annual

standard at its present value.” According to the CASAC:

Of the options presented by EPA staff for lowering the level of the PM standard, based on

the above considerations and the predicted reductions in health impacts derived from the risk

analyses, most Panel members favored the option of setting a 24-hour PM2.5 NAAQS at

concentrations in the range of 35 to 30 μg/m3 with the 98th percentile form, in concert with

an annual NAAQS in the range of 14 to 13 μg/m3. 51

Table 5 below compares the CASAC and EPA staff recommendations for PM2.5 primary

standards, the 1997 standards, and 2006 standards as proposed and promulgated.

Table 5. PM2.5 Primary (Health) NAAQS: Final (2006), Proposed and Alternatives,

and as Promulgated in 1997

PM2.5 NAAQS Options

24-hour Primary

(98th percentile)

Annual Primary

(arithmetic mean)

1997 NAAQS

65 μg/m3

15 μg/m3

EPA staff paper (December 2005)

mid to lower range of 35-25 μg/m3

15 μg/m3

mid to lower range of 40-30 μg/m3

14-12 μg/m3

CASAC (December 2005)

35-30 μg/m3

14-13 μg/m3

EPA Proposed Rule (January 2006)

35 μg/m3

15 μg/m3

EPA Final Rule (October 2006)

35 μg/m3

15 μg/m3

Source: Prepared by the Congressional Research Service (CRS), with information from the EPA’s final 2006

particulates NAAQS (71 Federal Register 61143-61233, Oct. 17, 2006), the EPA’s proposed particulates NAAQS (71

Federal Register 2620, Dec. 20, 2005), and related technical documents,52 available at http://www.epa.gov/air/particles/

actions.html.

In response to the discrepancies between the proposal and the CASAC recommendations, EPA

Administrator Stephen Johnson indicated that his decision required consideration of a number of

factors and “judgment based upon an interpretation of the evidence.” The Administrator relied on

the evidence of long-term exposure studies as the principal basis for retaining the annual PM2.5

CASAC PM Review Panel report, p. 7, June 2005 http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html.

EPA’s final PM staff paper and the CASAC review of the EPA staff paper (see references earlier in this report).

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standard.53 CASAC strongly disagreed with the Administrator’s decision regarding the PM2.5

annual standard and took the unprecedented step of urging reconsideration of the proposal.54

Many public comments received on the EPA’s proposed revisions to the PM2.5 standards, most

frequently from environmental and public health organizations, medical doctors and researchers,

and the association representing state air quality regulators,55 argue for standards as stringent or

more stringent than those recommended by CASAC. In contrast, another group of commenters,

generally representing industry associations and businesses, opposed revising the 1997 PM2.5

standards, in some cases highlighting different aspects of the same research cited by the CASAC

and others supporting tighter standards.56 Some who opposed more stringent particulates NAAQS

called attention to more recent studies of health effects attributable to particulates that

demonstrate risk estimates are lower and less statistically significant than they were in 1997,

when the last standard was set.57

In Section II of the preamble of the final October 2006 revisions, “Rationale for Final Decisions

on Primary PM2.5 Standards,” the EPA discusses its final decision with respect to the CASAC

recommendations regarding the PM2.5 annual standard. The Administrator differs with the

CASAC with regard to the level of uncertainty associated with the agency’s quantitative risk

assessment and whether the results appropriately serve as a primary basis for a decision on the

level of the annual PM2.5 standard. The Administrator further stressed the emphasis placed on the

long-term means of the levels associated with mortality effects in the two key long-term studies58

in determining the level of the annual standard. CASAC considered the evidence from specific

short-term exposure studies as part of the basis for its recommendation for a lower annual

standard level. As noted above, the CASAC expressed its objections to the EPA’s final 2006

particulates NAAQS in its September 29, 2006, letter to Administrator Johnson.59

With regard to PM2.5, the letter stated: “CASAC is concerned that the EPA did not accept our

finding that the annual PM2.5 standard was not protective of human health and did not follow our

recommendation for a change in that standard.”60 The letter noted that “there is clear and

convincing scientific evidence that significant adverse human-health effects occur in response to

For the EPA Administrator’s rationale for proposing to retain the current level for the annual PM2.5 standard and

recognition of the CASAC’s recommendation not endorsing this approach, see 71 Federal Register 2650-2653, January

17, 2006.

Letter of Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to the Hon. Stephen Johnson,

Administrator, U.S. EPA, March 21, 2006, EPA-CASAC-LTR-06-002, available at http://yosemite.epa.gov/sab/

sabproduct.nsf/CD706C976DAC62B3852571390081CC21/$File/casac-ltr-06-002.pdf; or from the federal docket for

the proposed rule Docket ID No. EPA-HQ-OAR-2001-0017, on the Federal Docket website

http://www.regulations.gov.

CRS communication with Mr. William Becker, Executive Director, State and Territorial Air Pollution Program

Administrators/Association of Local Air Pollution Control Officials (STAPPA/ALAPCO), January 5, 2006.

For EPA’s discussion and response to several of these comments, see 71 Federal Register 61143-61233, October 17,

2006, Part II Rationale for Final Decisions on Primary PM2.5 Standards, Sections B and F, on EPA’s website at

http://epa.gov/pm/actions.html.

Communication with Mr. Frank Maisano, Media Contact for the Electric Reliability Coordinating Council, January

17, 2006.

71 Federal Register at 2651, January 17, 2006.

Letter of Dr. Rogene Henderson, Chair of the Clean Air Scientific Advisory Committee, et al. to Hon. Stephen L.

Johnson, EPA Administrator, September 29, 2006, available at http://yosemite.epa.gov/sab/sabproduct.nsf/

1C69E987731CB775852571FC00499A10/$File/casac-ltr-06-003.pdf.

Ibid.

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short-term and chronic particulate matter exposures at and below 15 µg/m3,” and noted that 20 of

the 22 Particulate Matter Review Panel members, including all seven members of the statutory

committee were in “complete agreement” regarding the recommended reduction. “It is the

CASAC’s consensus scientific opinion that the decision to retain without change the annual PM2.5

standard does not provide an adequate margin of safety … requisite to protect the public health’

(as required by the Clean Air Act)....”61

Potential Health Benefits of a More Stringent PM2.5 Standard

In its RIA, the EPA estimated the nationwide monetized human health and welfare benefits of

attaining two suites of PM2.5 NAAQS: (1) the newly revised PM2.5 NAAQS, which include the

new 35 µg/m3 daily (24-hour) standard and the unchanged 15 µg/m3 annual standard, and (2) an

alternative standard similar to the least stringent of the CASAC recommendations that includes a

tighter annual standard of 14 µg/m3 and the same 35 µg/m3 daily (24-hour) standard. As discussed

previously, the EPA presented a variety of benefits estimates based on several epidemiological

studies, the American Cancer Society (ACS) Study62 used in previous RIAs, the Harvard SixCities Study,63 and expert elicitation study conducted by the EPA in 2006.64

The EPA estimated that attainment of the more stringent alternative PM2.5 NAAQS would result

in $26 billion to $30 billion of total annual benefits in 2020, based on the ACS mortality function.

This compares to a range of $15 billion to $17 billion estimated for compliance with the newly

promulgated PM2.5 NAAQS (see Table 2 and discussion earlier in this report). EPA’s estimate of

annual benefits derived using the expert elicitation ranged from $15 billion to $140 billion for the

more stringent alternative, compared to the agency’s estimates of $8 billion to $76 billion for

compliance with the new standard. EPA also estimated the monetary benefits (“willingness to

pay”) associated with improvements in visibility in selected Class I national parks and wilderness

areas would be $1.2 billion in 2020 with attainment of the more stringent alternative PM2.5

standard analyzed, compared to $530 million with attainment of the newly revised PM2.5

NAAQS.65 EPA estimated the total annual cost associated with attainment of the alternative PM2.5

NAAQS analyzed would be $7.9 billion in 2020, compared to $5.4 billion.

As discussed previously, a key component of the EPA’s monetized benefits estimates are the

agency’s predicted reductions in the incidence of premature deaths and a range of adverse health

effects annually in 2020 associated with compliance of the new 2006 PM2.5 NAAQS. For

example, for the more stringent attainment strategy analyzed (14/35 µg/m3), the EPA estimated

2,200 to 24,000 fewer premature deaths based on the expert elicitation. For purposes of

illustration, Table 5 provides a comparison of EPA’s predicted reductions annually for the new

Ibid.

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.

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. See also the 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 November 1, 2001 errata sheet), p. I.

(http://pubs.healtheffects.org/getfile.php?u=271).

See Chapter 5 of the EPA’s October 6, 2006, RIA for more detail http://www.epa.gov/ttn/ecas/ria.html.

See Appendix I Visibility Benefits Methodology of the EPA’s October 6, 2006, RIA http://www.epa.gov/ttn/ecas/

ria.html.

Congressional Research Service

Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards

PM2.5 NAAQS (15/35 µg/m3) with a more stringent alternative analyzed (14/35 µg/m3), based on

data from the ACS and Harvard Six-City studies, and various epidemiology studies.

Table 6. EPA’s Predicted Reductions in Adverse Health Effects Annually in 2020

Associated with Meeting the New PM2.5 NAAQS and a More Stringent Alternative

Adverse Health Effect

Predicted Reductionsa

(estimated mean)

PM2.5 NAAQS

(15/35 µg/m3)

More Stringent Alternative

(14/35 µg/m3)

2,500 to 5,700

4,000 to 9,000b

Cases of chronic bronchitis (age >25)

2,600

4,600

Cases of acute bronchitis (age 8-12)

7,300

13,000

Nonfatal heart attacks (age >71)

5,000

8,700

Hospital admissions for cardiovascular or

respiratory symptoms (age >17)

1,630

3,080

Emergency room visits for asthma (age <19)

1,200

3,200

Cases of aggravated asthma (asthmatics age 6-18)

51,000

79,000

Cases of upper and lower respiratory symptoms

(asthmatics age 6-18)

97,000

153,000

Days when individuals miss work (age 18-75)

350,000

550,000

2,000,000

3,300,000

Premature deaths in individuals with preexisting

cardiovascular and respiratory disease

Days when individuals must restrict their activities

because of symptoms related to particle pollution (age 18-65)