From: "Frey, Nathan J." <Nathan_J._Frey@omb.eop.gov>

To: Lydia Wegman/RTP/USEPA/US@EPA

Date: 06/14/2012 06:06 PM

Subject: RE: One more edit to the Executive Summary--please review this version

Attached for your consideration please find a summary of additional interagency comments under EOs 12866 and 

13563 regarding the executive summary portion of the preamble. 

From: Lydia Wegman [mailto:Wegman.Lydia@epamail.epa.gov] 

Sent: Thursday, June 14, 2012 5:39 PM

To: Frey, Nathan J.; Mancini, Dominic J.

Cc: Beth Hassett-Sipple; martin.karen@epa.gov; hannon.john@epa.gov; Joseph-J Dougherty; Janet 

McCabe; Gina McCarthy

Subject: One more edit to the Executive Summary--please review this version

Nathan and Dom, 

I realized that there was one edit we failed to include in the last version I sent you of the Executive 

Summary related to spatial averaging. Please review this version of the revisions. Thanks. 

(See attached file: Executive Summary 06 14 12 534 pm compare to 05 29 12.docx)
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

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I. Executive Summary

A. Purpose of this Regulatory Action

Sections 108 and 109 of the Clean Air Act (CAA) govern the establishment, review, and 

revision, as appropriate, of the national ambient air quality standards (NAAQS) to protect public 

health and welfare. The CAA requires periodic review of the air quality criteria – the science 

upon which the standards are based – and the standards themselves. This proposed rulemaking is 

being done pursuant to a court order and these statutory requirements. 

In 2006, the EPA completed the last review of the PM NAAQS. In that review, it 

undertook three principal actions. (1) With regard to fine particles (generally referring to 

particles less than or equal to 2.5 micrometers (μm) in diameter, PM2.5), the EPA revised the 

level of the primary 24-hour PM2.5 standard from 65 to 35 μg/m3and retained the level of the 

primary annual PM2.5 standard. (2) With regard to the primary standards for particles less than or 

equal to 10 μm in diameter (PM10), the EPA retained the primary 24-hour PM10 standard to 

continue to provide protection against effects associated with short-term exposure to thoracic 

coarse particles (i.e., PM10-2.5) and revoked the primary annual PM10 standard. (3) The EPA 

revised the secondary standards to be identical in all respects to the primary standards. 

In subsequent litigation, the U.S. Court of Appeals for the District of Columbia Circuit 

remanded the primary annual PM2.5 standard to EPA on the ground that EPA failed to explain 

adequately why the standard provided the requisite protection from both short- and long-term 

exposures to fine particles, including protection for at-risk populations such as children. The 

Court also remanded the secondary PM2.5 standards to the EPA on the ground that the Agency
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failed to explain adequately why setting the secondary standards identical to the primary

standards provided the required protection for public welfare, including protection from PMrelated visibility impairment. The EPA is responding to the court’s remands as part of the current 

review of the PM NAAQS.

This review was initiated in June 2007. Between 2007 and 2011, EPA prepared draft and 

final Integrated Science Assessments, Risk and Exposure Assessments, and Policy Assessments. 

Multiple drafts of all of these documents were subject to review by the public and peer reviewed 

by EPA’s Clean Air Scientific Advisory Committee. This proposed rulemaking is the next step 

in the review process; as noted, the schedule for this rulemaking is subject to a court order 

requiring issuance of a proposed rule at this time.

In this rulemaking, the EPA proposes to make revisions to the suite of primary and 

secondary standards for PM to provide increased protection of public health and welfare. We 

also discuss EPA’s current perspectives on implementation issues related to the proposed 

revisions to the PM NAAQS. The EPA proposes revisions to the Prevention of Significant 

Deterioration (PSD) permitting regulations to address the proposed changes in the primary and 

secondary PM NAAQS as well as corresponding changes to ambient air monitoring, reporting 

and network design requirements The EPA also proposes an approach for implementing the PSD 

program specifically for the proposed secondary standard.

B. Summary of Major Provisions

With regard to the primary standards for fine particles, EPA proposes to revise the annual 

PM2.5 standard by lowering the level from 15.0 to within a range of 12.0 to 13.0 μg/m3so as to 

provide increased protection against health effects associated with long- and short-term 

exposures. The EPA proposes to retain the level (35 μg/m3) and the form (98th percentile) of the 
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

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24-hour PM2.5 standard to provide supplemental protection against health effects associated with 

short-term exposures. This proposed action would provide increased protection for children, 

older adults, persons with pre-existing heart and lung disease, and other at-risk populations 

against an array of PM2.5-related adverse health effects that include premature mortality, 

increased hospital admissions and emergency department visits, and development of chronic 

respiratory disease. The EPA also proposes to eliminate spatial averaging provisions as part of 

the form of the annual standard to avoid potential disproportionate impacts on at-risk 

populations.

The proposed changes to the primary annual PM2.5 standard are within the range that the 

Clean Air Scientific Advisory Committee advised the Agency to consider. These changes are 

based on an integrative assessment of an extensive body of new scientific evidence, which 

substantially strengthens what was known about PM2.5-related health effects in the last review, 

including extended analyses of key epidemiological studies, and evidence of health effects 

observed at lower ambient PM2.5 concentrations, , including effects in areas that likely met the 

current standards. The proposed changes also reflect consideration of a quantitative risk 

assessment that estimates public health risks likely to remain upon just meeting the current and 

various alternative standards. Based on this information, the Administrator proposes to conclude

that the current primary PM2.5 standards are not requisite to protect public health with an 

adequate margin of safety, as required by the CAA, and that the proposed revisions are 

warranted to provide the appropriate degree of increased public health protection. The EPA 

solicits comment on all aspects of the proposed primary PM2.5 standards.

With regard to the primary standard for coarse particles, EPA proposes to retain the 

current 24-hour PM10 standard, with a level of 150 μg/m3and a one-expected exceedance form, 
Summary of Interagency Working Comments on Draft Language under 

EO12866/13563 Interagency Review. Subject to Further Policy Review.

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to continue to provide protection against effects associated with short-term exposure to PM10-2.5, 

including premature mortality and increased hospital admissions and emergency department 

visits. In reaching this decision, the Administrator proposes to conclude that the available health 

evidence and air quality information for PM10-2.5, taken together with the considerable 

uncertainties and limitations associated with that information, suggests that the degree of public 

health protection provided against short-term exposures to PM10-2.5 does not need to be increased 

beyond that provided by the current PM10 standard. The Administrator welcomes the public’s 

views on these approaches to considering and accounting for the evidence and its limitations and 

uncertainties.

With regard to the secondary PM standards, the EPA proposes to revise the suite of 

secondary PM standards by adding a distinct standard for PM2.5 to address PM-related visibility

impairment. More specifically, the EPA proposes to establish a secondary standard defined in 

terms of a PM2.5 visibility index, which would use speciated PM2.5 mass concentrations and 

relative humidity data to calculate PM2.5 light extinction, similar to the Regional Haze Program; 

a 24-hour averaging time; a 90th percentile form, averaged over 3 years; and a level set at one of 

two options – either 30 deciviews (dv) or 28 dv. The EPA also proposes to rely upon the existing 

Chemical Speciation Network (CSN) to provide appropriate monitoring data for calculating 

PM2.5 visibility index values. 

The proposed secondary standard is based on the long-standing science characterizing the 

contribution of PM, especially fine particles, to visibility impairment and on air quality analyses, 

with consideration also given to a reanalysis of public perception surveys regarding people’s 

stated preferences regarding acceptable and unacceptable visual air quality. Based on this 

information, the Administrator proposes to conclude that the current secondary PM2.5 standards 
Summary of Interagency Working Comments on Draft Language under 

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are not sufficiently protective of the public welfare with respect to visual air quality. The EPA 

solicits comment on all aspects of the proposed secondary standard. 

To address other non-visibility welfare effects including ecological effects, effects on 

materials, and climate impacts, the EPA proposes to retain the current suite of secondary PM 

standards generally, while proposing to revise only the form of the secondary annual PM2.5

standard to remove the option for spatial averaging consistent with this proposed change to the 

primary annual PM2.5 standard. 

The proposed revisions to the PM NAAQS would trigger a process under which states 

(and tribes, if they choose) will make recommendations to the Administrator regarding 

designations, identifying areas of the country that either meet or do not meet the proposed new or 

revised NAAQS for PM2.5. States will also review, modify and supplement their existing state 

implementation plans. The proposed NAAQS revisions would affect the applicable air permitting 

requirements and the transportation conformity and general conformity processes. This notice 

provides background information for understanding the implications of the proposed NAAQS 

revisions for these implementation processes and describes and requests comment on EPA’s 

current perspectives on implementation issues. In addition, the EPA proposes to revise its PSD 

regulations to provide limited grandfathering from the requirements that result from the revised 

PM NAAQS for permit applications for which the public comment period has begun when the 

revised PM NAAQS take effect. The EPA also proposes to implement a surrogate approach that 

would provide a mechanism for permit applicants to demonstrate that they will not cause or 

contribute to a violation of the proposed secondary PM2.5 visibility index NAAQS. It is the 

EPA’s intention to finalize any time-sensitive revisions to its PSD regulations at the same time as 

any new or revised NAAQS are finalized.
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With regard to implementation-related activities, the EPA intends to promulgate rules or 

develop guidance related to NAAQS implementation on a schedule that provides timely clarity

to the states, tribes, and other parties responsible for NAAQS implementation. The EPA solicits 

comment on all implementation aspects during the public comment period for this notice and 

will consider these comments as it develops future rulemaking or guidance, as appropriate.

On other topics, the EPA proposes changes to the Air Quality Index (AQI) for PM2.5 to 

be consistent with the proposed primary PM2.5 standards. The EPA also proposes revisions to the 

data handling procedures consistent with the proposed primary and secondary standards for 

PM2.5 including the computations necessary for determining when these standards are met and 

the measurement data that are appropriate for comparison to the standards. With regard to 

monitoring-related activities, the EPA proposes updates to several aspects of the monitoring 

regulations and specifically proposes to require that a small number of PM2.5 monitors be 

relocated to be collocated with measurements of other pollutants (e.g., nitrogen dioxide, carbon 

monoxide) in the near-road environment.

C. Costs and Benefits

In setting the NAAQS, the EPA may not consider the costs of implementing the 

standards. This was confirmed by the Supreme Court in Whitman v. American Trucking 

Associations, 531 U.S. 457, 465-472, 475-76 (2001), as discussed in section II.A of this notice. 

As has traditionally been done in NAAQS rulemaking, the EPA has conducted a Regulatory

Impact Analysis (RIA) to provide the public with information on the potential costs and benefits 

of attaining several alternative PM2.5 standards. In NAAQS rulemaking, the RIA is done for 

informational purposes only, and the proposed decisions on the NAAQS in this rulemaking are 

not in any way based on consideration of the information or analyses in the RIA. The RIA fulfills 
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the requirements of Executive Orders 13563 and 12866..

The summary of the RIA, which is discussed in more detail below in section X.A.,

estimates benefits ranging from $88 million to $220 million (for 13.0 μg/m3) and from $2.3 

billion to $5.9 billion per year (for 12.0 μg/m3) in 2020 and costs ranging from $2.9 million (for 

13.0 μg/m3) to $69 million (for 12.0 μg/m3) per year.