1 March 9, 2010
MEMORANDUM

SUBJECT: CASAC Review of the Policy Assessment for the Review of the Particulate Matter National Ambient Air Qua lity Standards -- First Ex ternal Review Draft

FROM: Lydia N. Wegman, Director /s/ Health and Environmental Impacts Division Office of Air Quality Planning and Standards

TO: Holly Stallworth Designated Federal Officer
Clean Air Sc ientific Advisory Committee EPA Science Advisory Board Staff Office

Attached is the draft document, Policy Assessment for the Revi ew of the Particulate Matter National Ambient Air Qua lity Standards - First Ex ternal Review Draft (Policy Assessment), 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 national ambient air quality standards (NAAQS) for particulate matter (PM). Th is document will be the focus of a review by the Clean Air Scientific Advisory Committee (C ASAC) Particular Matter Review Panel (the Panel), scheduled as a teleconference for April 8-9, 2010.

The attached draft Policy Assessment document presents factors relevant to EPA’s review of the current primary (health-based) standard s and secondary (welfare-based) standards for both fine and coarse particles. This dr aft document draws upon information assessed and presented in the final Integrated Science Assessment for Particulate Matter , prepared by EPA’s
National Center for Environmental Assessment after undergoing review by the Panel and the public, and the second drafts of the Quantitative Health Risk Assess ment for Particulate Matter (Risk Assessment) and the Urban-Focused Visibility Assessment for Particulate Matter (Visibility Assessment), which will be reviewed at a meetin g of the CASAC Panel sc heduled for March 10- 11, 2010 in Research Triangle Park, NC.

Following CASAC and public review of this first draft Policy Assessment, we will produce a second draft Policy Assessment for CASA C and public review, prior to preparing a final Policy Assessment in July 2010. Our re view of the PM NAAQS will conclude with Agency rulemaking. Our current schedule anticip ates that proposed and final rules will be signed in November, 2010, and July, 2011, respectively.2 Document for Review

We will send printed copies of the first draft Policy Assessment, described below, to
members of the Panel. In addi tion, we request that you forward to the Panel the electronic file containing this document. This document will also be available on the EPA website: http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_2007_pa.html . Attached to this memorandum are charge questions to guide the Panel’s review of this document.

 Policy Assessment for the Review of the Pa rticulate Matter National Ambient Air Quality Standard - First External Review Draft

Chapter 1 includes information on the purpose an d background for this review, as well as an overview of the general approach and orga nization of the policy assessment. Chapters 2 and 3 present staff observations and preliminar y conclusions related to the review of the primary standards for fine and thoracic coar se particles, respectively. Each chapter begins with a discussion of policy assessmen t approaches and focuses on evidence-based considerations based on the upda ted scientific and technical information as assessed and presented in the final Integrated Science Assessment. In addition, chapter 2 also includes a discussion of quantitative risk-based consid erations as assessed and presented in the second draft Risk Assessment. Preliminary sta ff conclusions are presented with regard to the adequacy of the current primary standard s and potential alternat ive primary standards for consideration, in terms of indicators, av eraging times, forms, and levels. Chapter 4 focuses on PM-related visibility impairme nt, and presents staff observations and preliminary conclusions with regard to th e adequacy of the current standards and potential distinct secondary standards for cons ideration, in terms of alternative indicators, averaging times, forms, and levels. This chapter focuses on the updated scientific and technical information as assessed and presented in the final Integrated Science
Assessment as well as the quantitative analyses presented in the second draft Visibility Assessment. Chapter 5 focuses on other PM-rel ated welfare effects, including effects on climate, ecological effects, and effects on ma terials, and presents staff observations and preliminary conclusions with regard to the adequacy of the current standards and the
extent to which information is available to s upport consideration of alternative standards.

We look forward to discussing this first draf t Policy Assessment w ith the Panel at our upcoming teleconference in April. At the Pane l’s request, we will provide a brief overview of this document at the meeting on March 10-11 to pr ovide context for the Pa nel’s review of the
second drafts of the Risk Assessment and Visi bility Assessment at that meeting. Should you have any questions regarding this first draft Policy Assessment, please contact Ms. Beth HassettSipple (919-541-4605; email ha ssett-sipple.beth@epa.gov).

cc: Vanessa Vu, SAB, OA Holly Stallworth, SAB, OA John Vandenberg, ORD/NCEA-RTP Debra Walsh, ORD/NCEA-RTP Mary Ross, ORD/NCEA-RTP Lindsay Stanek, ORD/NCEA-RTP3 Jason Sacks, ORD/NCEA-RTP Beth Hassett-Sipple, OAQPS/HEID Zachary Pekar, OAQPS/HEID Pradeep Rajan, OAQPS/HEID Susan Lyon Stone, OAQPS/HEID Scott Jenkins, OAQPS/HEID Vicki Sandiford, OAQPS/HEID Meredith Lassiter, OAQPS/HEID Marc Pitchford, OAQPS/HEID Karen Martin, OAQPS/HEID Rosalina Rodriquez, OAQPS/HEID

Attachment: Charge to the CASAC PM Review Panel for Review of the Draft PM Policy AssessmentUpdate

1

Charge to the CASAC PM Review Panel for Re view of the First Draft Policy Assessment
for the Review of the Particulate Matter NAAQS

The first draft Policy Assessment (PA), conv eyed to the CASAC PM Panel on March 9, 2010, includes staff’s preliminary evaluation of the policy implications of the scientific assessment of the evidence presented in the Integrated Science Assessment (ISA) and the results of quantitative assessment based on analyses pres ented in the second draft Risk and Exposure Assessments (REAs). Consistent with CASA C’s comments on a prel iminary draft Policy Assessment (September 2009) that encouraged th e development of a document focused on key policy-relevant issues that draw s from and is not re petitive of information in the ISA and REAs, staff has organized the discussion in the Policy Assessment around answering a series of policyrelevant questions. Taken together, staff’s respon ses to these questions support preliminary staff
conclusions and the identification of policy options for considerati on in our review of the primary and secondary PM NAAQS.

We ask the CASAC PM Panel to focus on the charge questions below in their review of the first draft Policy Assessment, but we would appr eciate comments on any ot her topics as well.

Overarching Questions (related to Chapters 2, 3, 4, 5)

1. Organizational Structure

a. Does the Panel find the introductory and backgr ound material, including that pertaining to previous reviews of the PM standards and th e current review, to be clearly communicated and appropriately characterized?

b. To what extent does the Panel find that th e questions posed appropriately reflect the important policy-relevant issues for this re view? Are there additional policy-relevant questions that should be addressed?

c. What are the Panel’s views regarding the level of detail used to address these policyrelevant questions? Please comment on th e extent to which the discussions are appropriately focused in addressing the questions.

2. Technical Content

a. Do the discussions accurately reflect and clearly communicate the currently available
health and welfare effects evid ence, including important uncert ainties, as characterized in
the final ISA?

b. Do the discussions accurately reflect and cl early communicate policy-relevant information from the human health risk and visibility asse ssments, including importa nt uncertainties, as
characterized in the second draft REAs?

Review of the Primary Standards for Fine Particles (Chapter 2)

3. Approach (section 2.1.3): Various approaches are describe d for translating different air quality metrics from epidemiolo gical studies into the basis for reaching preliminary staff conclusions on the adequacy of the current PM 2.5 standards and on alternative standards forUpdate

2 consideration. What are the Pane l’s views regarding the appropriate weight to place on these various approaches; should specific approaches be afforded more or less weight? Are there additional approaches that should be considered?

4. Adequacy of current suite of PM 2.5 standards (section 2.2):

What are the Panel’s vi ews on the following:

a. The appropriateness and characterization of the sets of long- and short-term PM 2.5 exposure studies highlighted? (section 2.2.1)

 Are there specific studies that should be given more or less emphasis?

 Are there additional studies that should be focused on?

 Does the Panel generally supp ort placing greater weight on multi-city vs. single-city short-term exposure studies?

 Does the Panel agree with the characterizations of PM 2.5 air quality at which
associations have been observed?

b. The focus on persons with lower socioeconom ic status as a susceptible population in addition to consideration of newly available evidence for susceptible populations identified in previous reviews (e.g., children, older adults, persons with pre-existing cardiac and respiratory disease)? (section 2.2.1)

c. The preliminary staff conclusion that the estima ted risks remaining upon simulation of just meeting the current suite of standards can r easonably be judged to be important from a public health perspective? (section 2.2.2)

d. The relative roles of the annual and 24-hour st andards in providing public health protection as informed by the quantitative risk assessment , specifically in focusi ng on simulation of estimated risks remaining upon ju st meeting the current suite of standards? (section 2.2.2)

e. The integration of evidence-based and risk-bas ed considerations to inform the preliminary
staff conclusion that the available information clearly calls into question the adequacy of
the current suite of PM 2.5 standards and provides strong s upport for giving consideration to revising the current standards to provide increas ed public health protection? (section 2.2.3)

5. Indicator (section 2.3.1):

What are the Panel’s vi ews on the following:

a. The preliminary staff conclusion that it is reasonable to retain PM 2.5 as an indicator for fine particles?

b. The preliminary staff conclusion that the current ly available informatio n is too limited to support a distinct PM standard for ultrafine particles?

c. The preliminary staff conclusion that the currently available information is not sufficient to support consideration of a separate indicator for a specific PM 2.5 component or for the mix of fine particles from any specific source category, and that data are too limited to consider eliminating any component or source category from the mix of fine particles included in
the PM 2.5 mass-based indicator?Update

3 6. Averaging Times (section 2.3.2):

What are the Panel’s vi ews on the following:

a. The preliminary staff conclusion that it is reasonable to retain annual and 24- hour averaging times?

b. The preliminary staff conclusions that the curre ntly available evidence is too limited to support additional averaging times to address s ub-daily exposures or seasonal exposures?

7. Forms (section 2.3.3): What are the Panel’s views on the utility of additional analyses to inform consideration of eliminating provisions included in the current form of the annual standard that allow for spatial averaging acro ss monitors, specifically with regard to the potential for disproportionate impacts on suscep tible populations with lower socioeconomic
status?

8. Levels (sections 2.3 .4, 2.3.5, and 2.3.6):

What are the Panel’s vi ews on the following:

a. The preliminary staff conclusions regarding alte rnative standard levels that are appropriate for consideration, and the rationale upon which those conclusions are based?

b. The insights that can be gain ed from the quantitative risk assessment to inform our understanding of the roles that the annual and 24-hour standards play in providing public health protection, specifically in focusing on simulations of estimated risks remaining upon just meeting alternative suites of stan dards? (sections 2 .3.4.2 and 2.3.5.2)

c. The policy implications of th e uncertainties associated with estimating risks, including potential underestimation of risk, in reaching conclusions regarding standards that would provide public health protection with an adequate margin of safety?

d. A policy approach for identifying a suite of stan dard levels in which the annual standard would be the “generally controlling” standa rd to provide protection for both long- and
short-term PM 2.5 exposures, in conjunction with a 24-hour standard set to provide supplemental protection against days with hi gh peak concentrations associated with localized “hotspots” and risk arising from seasonal emission th at might not be controlled by a national annual standard? (section 2.3.6)

e. Additional considerations that could inform our conclusions related to alternative suites of fine particle standards?

Review of the Primary Standard for Thoracic Coarse Particles (Chapter 3)

9. Adequacy of the current 24-hour PM 10 standard (section 3.2):

What are the Panel’s vi ews on the following:

a. The preliminary staff conclusion that the availa ble scientific evidence supports maintaining a standard that provides protection against health effects associated with exposure to thoracic coarse particles?Update

4 b. The various approaches described for translati ng the evidence and related uncertainties into
the basis for conclusions on th e adequacy of the current PM 10 standard?

c. The adequacy of the public health protection afforded by the current PM 10 standard against exposures to thoracic coarse particles?

10. Indicator (sections 3.3.1 , 3.3.2, and 3.3.3):

What are the Panel’s vi ews on the following:

a. The preliminary staff conclusion that it is appr opriate to maintain a standard that provides protection against all thoracic coarse particles, regardless of their source of origin or composition?

b. The appropriateness of maintaining an indicator that allows lower PM 10-2.5 concentrations
in urban areas than non-urban areas?

c. The appropriateness of either a PM 10 or PM 10-2.5 indicator for a standard meant to protect against exposures to thoraci c coarse particles?

11. Averaging Time (section 3.3.4): What are the Panel’s views on the preliminary staff conclusions that the currently available eviden ce supports maintaining a 24-hour standard to protect against health effects associated with shor t-term exposures to thoracic coarse particles, and does not support consideration of a long -term thoracic coarse particle standard?

12. Form (section 3.3.6): What are the Panel’s vi ews on the preliminary staf f conclusion that it is appropriate to consider a 98 th percentile form for a revised 24- hour standard meant to protect against short-term exposures to thoracic coarse particles?

13. Level (section 3.3.7): What are the Panel’s views on th e appropriateness of considering 98 th percentile, 24-hour PM 10 or PM 10-2.5 concentrations in epidemio logical study locations for identifying a range of potential alternative sta ndard levels for consideration, recognizing the more limited air quality in formation available for PM 10-2.5 ?

Review of the Secondary PM 2.5 Standards for Visibility-Re lated Effects (Chapter 4)

14. Adequacy (section 4.2): What are the Panel’s views on the preliminary staff conclusion that the currently available information clearly calls into question the adequacy of the current suite
of PM 2.5 standards to provide public welfare protection from unaccept able levels of visibility impairment, primarily in urban areas, and suppor ts consideration of a lternative standards to provide appropriate protection?

15. Indicator (section 4.3.1) :

What are the Panel’s vi ews on the following:

a. The appropriateness of considering PM light extinction and PM 2.5 mass as indicators for a distinct secondary PM standard for visibility protection, and the relative advantages and disadvantages associated with each indicator?Update

5 b. The appropriateness of considering the contribut ion of coarse particles with respect to a potential PM light extinction indicator?

16. Averaging times (section 4.3.2):

What are the Panel’s vi ews on the following:

a. The preliminary staff conclusion that consider ation should be given to a 1-hour averaging
time?

b. The advantages and disadvantages of focusing on a 1-hour daily maxi mum or each 1-hour average concentration duri ng all daylight hours?

17. Levels and Forms (section 4.3.3):

What are the Panel’s vi ews on the following:

a. The preliminary staff conclusions regarding ranges of options with varying levels and
forms in combination with differen t indicators (light extinction and PM 2.5 mass-based indicators) and averaging times (1-hour daily maximum or each 1-hour average concentration during all daylight hours)?
b. Additional approaches that could help inform our consideration of alternative levels and
forms?

Review of the Secondary Standards for Ot her Welfare-related Effects (Chapter 5)

18. Climate (section 5.2): What are the Panel’s views on the preliminary staff conclusion that
there is insufficient informatio n to base a standard on climate impacts associated with current
ambient PM concentrations?

19. Ecological effects (section 5.3): What are the Panel’s views on the preliminary staff conclusion that data are insufficient to support establishing a distinct standard for ambient PM based on ecosystem effects not addressed in the ongoing NOx/ SOx secondary NAAQS
review?

20. Material effects (section 5.4): What are the Panel’s views on the preliminary staff conclusion that no new evidence calls into question the ade quacy of the protection afforded by the current suite of PM standards, and that there continue s to be support for retaining an appropriate degree of control for both fine and coarse particles to provide protection against materials damage and soiling?