September 16, 2009 

MEMORANDUM

SUBJECT: CASAC Discussion of Policy Assessment for the Review of the Particulate Matter 

National Ambient Air Quality Standards: Preliminary Draft

FROM: Lydia N. Wegman, Director /s/ 

Health and Environmental Impacts Division (C504-02) 

Office of Air Quality Planning and Standards 

United States Environmental Protection Agency 

TO: Holly Stallworth 

Designated Federal Officer 

Clean Air Scientific Advisory Committee 

EPA Science Advisory Board Staff Office 

Attached is a very preliminary draft document, Policy Assessment for the Review of the

Particulate Matter National Ambient Air Quality Standards: Preliminary Draft (Policy 

Assessment). This document will be the focus of a presentation for and discussion with the 

Clean Air Scientific Advisory Committee (CASAC) PM NAAQS Review Panel (the CASAC 

PM Panel) at a public meeting to be held in Chapel Hill, NC on October 5–6, 2009. This 

preliminary draft Policy Assessment has been prepared by the Environmental Protection 

Agency’s (EPA) Office of Air Quality Planning and Standards (OAQPS) staff as part of EPA’s 

ongoing review of the primary (health-based) and secondary (welfare-based) national ambient air 

quality standards (NAAQS) for particulate matter (PM). I am requesting that you forward this 

preliminary draft document to the CASAC PM Panel to prepare for our discussion at the October 

meeting. 

Preparation of a Policy Assessment by OAQPS staff reflects Administrator Jackson’s 

decision to modify the NAAQS review process by reinstating the use of a policy assessment 

document in lieu of issuing a policy assessment in the form of an advance notice of proposed 

rulemaking (see http://www.epa.gov/ttn/naaqs/review.html). We are releasing a very 

preliminary draft Policy Assessment prior to the upcoming CASAC meeting for informational 

purposes and to facilitate discussion with the CASAC PM Panel on the overall structure, areas of 

focus, and level of detail to be included in an external review draft Policy Assessment, which we 

plan to release for CASAC review and public comment later this year. 

This preliminary draft document, which is clearly a work in progress, draws from the 

information and conclusions presented in the Integrated Science Assessment for Particulate 

Matter: Second External Review Draft (ISA, July 2009) prepared by EPA’s National Center for 
Environmental Assessment, Research Triangle Park, NC (NCEA-RTP) and two draft assessment 

documents prepared by OAQPS: (1) Risk Assessment to Support the Review of the PM Primary 

National Ambient Air Quality Standards -- External Review Draft (September 2009) and (2) 

Particulate Matter Urban-Focused Visibility Assessment – External Review Draft (September 

2009). These draft documents will be the subject of review by the CASAC PM Panel at the 

October meeting. 

Following an introductory chapter, this preliminary draft Policy Assessment includes 

early draft chapters addressing the following: a characterization of ambient PM (Chapter 2), an 

overview of the policy-relevant health effects evidence (Chapter 3), and an overview of the 

policy-relevant evidence of PM-related welfare effects and the assessment of PM-related 

visibility impairment (Chapter 6). Chapter 4, which will present an overview of the health risk 

assessment, is previewed by way of an annotated outline. Chapters 5 and 7, which will present 

staff conclusions on a range of policy options for the Administrator to consider concerning 

whether, and if so how, to revise the primary and secondary PM NAAQS, are previewed only by 

way of the organization shown in the draft table of contents. These two chapters will discuss 

both evidence- and risk-based approaches to informing consideration of the basic elements of 

each of the PM NAAQS: indicator, averaging time, form, and level. 

As noted above, this preliminary draft Policy Assessment is a work in progress. For 

example, we are still working to identify and potentially adapt figures from the ISA to sharpen 

our focus and discussion of the health effects evidence presented in Chapter 3. Additionally, we 

are continuing our efforts to obtain relevant air quality data from epidemiologic study authors to 

aid in our evidence-based approach for evaluating the current and potential alternative primary 

standards. We are also continuing to consider how to focus our presentation of the scientific 

evidence and quantitative analyses in a manner that will most directly help to address the key 

policy-relevant questions that frame this review. Staff will consider CASAC review and public 

comments on the second draft ISA and the two draft assessment documents, as well as CASAC 

discussion of this preliminary draft Policy Assessment, in subsequently preparing a complete 

external review draft Policy Assessment. 

We look forward to discussing the preliminary draft Policy Assessment with the CASAC 

PM Panel at our upcoming meeting. Should you have any questions regarding the preliminary 

draft Policy Assessment or the PM NAAQS review in general, please contact Dr. Karen Martin 

(919-541-5274; email martin.karen@epa.gov) or Ms. Beth Hassett-Sipple (919-541-4605; email 

hassett-sipple.beth@epa.gov). 

Attachments 

cc: Vanessa Vu, SAB, OA 

Karen Martin, OAQPS/HEID 

Neal Fann, OAQPS/HEID 

Beth Hassett-Sipple, OAQPS/HEID 

Bryan Hubbell, OAQPS/HEID 

Meredith Lassiter, OAQPS/HEID 

Phil Lorang, OAQPS/AQAD 

2
3

Zach Pekar, OAQPS/HEID 

Marc Pitchford, OAQPS/HEID 

Pradeep Rajan, OAQPS/HEID 

Harvey Richmond, OAQPS/HEID 

Mary Ross, ORD/NCEA-RTP 

Vicki Sandiford, OAQPS/HEID 

Lindsay Stanek, ORD/NCEA-RTP 

Susan Stone, OAQPS/HEID 

 John Vandenberg, ORD/NCEA-RTP