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

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

Date: 06/14/2012 09:56 AM

Subject: Summary of Interagency Comments under EOs 12866 and 13563

Attached please find a summary of some additional interagency comments under 

EOs 12866 and 13563 regarding the National Ambient Air Quality Standards for 

Particulate Matter proposed rule: RIN 2060-AO47.

Please let me know if you have any questions.
Summary of Interagency Working Comments on Draft Language under 

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

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. 

In direct response to a court order, explicitly requiring the issuance of this proposed rule, 

and to statutory requirements, 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, 

respectively, and to make corresponding revisions to the data handling conventions for PM and 

ambient air monitoring, reporting, and network design requirements.

In this proposed rule, we 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. The EPA also proposes an approach for 

implementing the PSD program specifically for the proposed secondary standard.

In 2006, the EPA completed the last review of the PM NAAQS. With regard to fine 

particles (generally referring to particles less than or equal to 2.5 micrometers (μm) in diameter, 

PM2.5), at that time, 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. 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 
Summary of Interagency Working Comments on Draft Language under 

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

PM10 standard. The EPA also 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 because 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 remanded 

the secondary PM2.5 standards to the EPA because the Agency failed to explain adequately why 

setting the secondary standards identical to the primary standards provided the required 

protection for public welfare, including protection from PM-related visibility impairment. The 

EPA is responding to the court’s remands as part of the current review of the PM NAAQS.

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 a range of 12.0 to 13.0 μg/m3and by

eliminating spatial averaging provisions as part of the form of the standard, so 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 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 proposed changes to the primary annual PM2.5 standard are within the range 

recommended by the Clean Air Act Advisory Committee and are based on an integrative 
Summary of Interagency Working Comments on Draft Language under 

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

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. The proposed changes reflect 

consideration of a quantitative risk assessment that estimates public health risks likely to remain 

even after meeting the current standards. The risk assessment then considered the increased 

protection that would be afforded by alternative standards. Based on this information, the 

Administrator provisionally concludes 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 alternative combinations of primary PM2.5 standards 

including: (1) an annual standard level of 12.0 or 13.0 μg/m3as proposed here, but in 

conjunction with an alternative 24-hour standard level down to 30 μg/m3; (2) an annual standard 

level down to 11.0 μg/m3in conjunction with retaining the 24-hour standard level at 35 μg/m3; 

or (3) other combinations of annual and 24-hour 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, 

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 proposed decision, the Administrator concludes 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 
Summary of Interagency Working Comments on Draft Language under 

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

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 add a new standard for 

PM2.5 to address PM-related visibility impairment. More specifically, the EPA proposes to 

establish a new 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 new 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 provisionally concludes that the current secondary

PM2.5 standards are not sufficiently protective of the public welfare with respect to visual air 

quality. The EPA solicits comment on all aspects of the proposed new 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 
Summary of Interagency Working Comments on Draft Language under 

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

(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.

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 
Summary of Interagency Working Comments on Draft Language under 

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

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 

the requirements of Executive Order 12866 as discussed below in section X.A, which includes a 

summary of the estimated costs and benefits from the RIA.