February 27, 2009

MEMORANDUM

SUBJECT: CASAC Consultation on Particulate Matter National Ambient Air Quality

Standards: Scope and Methods Plan for Health Risk a nd Exposure Assessment

and Particulate Matter National Ambient Air Quality Sta ndards: Scope and Methods Plan for Urban Visibility Impact Assessment

FROM: Lydia N. Wegman, Director

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 are two planning documents, (1) Particulate Matter National Ambient Air Quality Standards: Scope and Methods Plan for Heal th Risk and Exposure Assessment (Health Assessment Plan), and (2) Particulate Matter National Ambient Air Quality Sta ndards: Scope and Methods Plan for Urban Visibility Impact Assess ment (Welfare Assessment Plan), prepared by the Environmental Protection Agency’s (EPA) Offi ce of Air Quality Planning and Standards (OAQPS) staff as part of EPA’s ongoing review of th e primary (health-based) and secondary (welfare-based) national ambient air quality standa rds (NAAQS) for particulate matter (PM). These plans will be the focus of a consultation by the Clean Air Scientific Advisory Committee (CASAC) PM NAAQS Review Panel (the CASAC PM Panel), scheduled for a public meeting to be held in Chapel Hill, NC, on April 2, 2009. I am requesting that you forward these planning documents to the CASAC PM Panel to prepare for that consultation.

The purpose of the Health Assessment Plan is to out line the scope and approaches that staff is planning or considering to use to conduct a human health risk assessment and an exposure assessment for fine particles and a health risk assessment for thoracic coarse particles. The purpose of the Welfare Assessment Plan is to ou tline the scope and approaches that staff is planning to use to conduct a quantitative assessmen t of urban visibility impairment and qualitative assessments of other welfare-related ef fects. In addition, the plans highlight key issues involved in these assessments. These plans a re intended to provide enough specificity to facilitate consultation with CASAC, as well as for public review, in order to obtain advice on the overall scope, approaches, and key issues in advanc e of the conduct of the risk and exposure2

analyses and presentation of results in the first d raft Risk and Exposure Assessment (REA). The plans draw upon information presented in Integrated Science Assessment for Particulate Matte r: First External Review Draft (PM ISA, December 2008) prepared by EPA’s National Center for Environmental Assessment, Research Triangle Park, NC (NCEA-RTP). CASAC consultation on these plans coincides with their review of the firs t draft PM ISA. CASAC and public comments on the plans will be taken into consideration in th e development of the first draft REA, the preparation of which will coincide with and draw fr om the second draft ISA. The second draft

REA will draw on the final ISA and will reflect con sideration of CASAC and public comments

on the first draft REA. The final REA will reflect consideration of CASAC and public

comments on the second draft REA.

EPA’s overall plan and schedule for this PM NAAQS re view was presented in the Integrated Review for the National Ambient Air Qual ity Standards for Particulate Matter , which was the subject of a consultation by the CASAC PM P anel on November 30, 2007 (see http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_2007 _pd.html ). That plan outlines the Clean Air Act (CAA) requirements related to the establish ment and reviews of the NAAQS, the process and schedule for conducting the current PM NAAQS review, and plans for the key components in the NAAQS review process including th e ISA, REA, and policy assessment and rulemaking documents. It also lays out key policy- relevant issues to be addressed in this review as a series of policy-relevant questions that frame our approach to determining whether the current primary and secondary NAAQS for PM should b e retained or revised. An updated schedule for completing the REA is outlined in the attached plans. Currently, our schedule calls for completion of the PM ISA by December 2009, comp letion of the REA by July 2010, and proposed and final rules to be issued in 2011.

Documents for Consultation

The following documents are being made available to the CASAC PM Panel in the form

of an attached electronic file. The documents are also available from the EPA website at http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_2007 _pd.html . Printed copies of this

document will be sent to Panel members via Federal Express.

 Attachment: Particulate Matter National Ambient Air Quality Sta ndards: Scope and Methods Plan for Health Risk and Exposure Assessmen t (Health Assessment Plan, February 2009)

Following an introductory section, this document di scusses air quality considerations that are relevant to both the planned human health risk and exposure assessments. The next two sections present the planned scope and approach for the health risk assessment and exposure analysis, respectively. Throughout these sections, key issues are discussed and staff’s plans for addressing these issues are noted. The final secti on summarizes the schedule and interim

milestones related to these assessments.

 Attachment: Particulate Matter National Ambient Air Quality Sta ndards: Scope and Methods Plan for Urban Visibility Impact Assessment (Welfare Assessment Plan, February 2009)3

Following an introductory section, two sections of this document discuss the planned scope and approach for assessing visibility impairm ents in urban areas. The final section

summarizes the schedule and interim milestones rela ted to these assessments. Attachment A outlines issues related to planned qualitative asse ssments of other welfare effects.

Charge to the CASAC PM Review Panel

We ask the CASAC PM Panel to focus on the charge qu estions listed below in their consultation on these planning documents.

A. Health Assessment Plan

Chapter 1 – Introduction/Overarching Questions

The introductory section presents an overview of th e goals and planned approaches for conducting the health risk and exposure assessments

.

1. What are the Panel members’ views on the general st ructure and overall design of the planned analyses?

2. Is the plan clear and transparent in its descriptio n of the proposed approaches? Are the various assumptions and judgments that must be made in carrying out the planned risk analyses clear and transparent?

3. What are the Panel members’ views on the goals iden tified for the risk and exposure

assessments?

4. Given the goals set forth for the planned analyses, has the plan appropriately drawn from the existing scientific and technical information i n developing the overall approach? Are

there relevant features that should be added or mod ified in the planned approach?

Chapter 2 - Air Quality Considerations :

1. Do Panel members generally agree with the planned a pproach for obtaining and analyzing the air quality data that will be used in the risk and assessments?

2. With regard to approaches for simulating air qualit y that just meets the current or

alternative standards under consideration:

a. What are the Panel members’ views on the planned us e of a proportional (i.e., linear) approach to adjusting air quality (proporti onal rollback)?

b. What are the Panel member's views on also consideri ng the alternative rollback approach being considered for PM 2.5 (model-based rollback)?4

3. What are the Panel members’ views on the planned ap proach for estimating and using policy-relevant background concentrations?

Chapter 3 – Scope and Approach for the Health Risk Assessment

1. Regarding selection of health effects endpoints to model in the risk assessment:

a. To what extent are the Panel members supportive of EPA’s planned approach to focus on selected health effects endpoints (e.g, em ergency department visits and hospitalizations for ischemic heart disease) within broader health effect categories (e.g, cardiovascular morbidity) initially classifie d in the first draft ISA as having a causal or likely-causal association with ambient PM 2.5 ?

b. What are the Panel members’ views regarding EPA’s p lans to consider for inclusion additional health effects endpoints (e.g, birth outcomes) for PM 2.5 that are within broader health effect categories (e.g, r eproductive, developmental, prenatal and neonatal outcomes) that have been init ially classified in the first draft ISA as having suggestive evidence of a causal assoc iation? What are the Panel members’ views with respect to addressing the chall enges in designing a quantitative risk assessment to appropriately consi der birth outcome endpoints?

c. Are the Panel members generally supportive of EPA's planned approach to

conduct a risk assessment for PM 10-2.5 considering health effect endpoints within broader health effect categories that have been ini tially classified in the first draft ISA as having suggestive evidence of a causal assoc iation?

2. Regarding specification of concentration-response f unctions for use in the risk

assessment:

a. In modeling health impacts associated with short-te rm ambient PM, to what extent are Panel members supportive of EPA’s planne d approach to place emphasis on distributed lags, where they are availa ble, with additional lags (e.g., 0, 1 day lags) being included as part of sensitivit y analyses, based on consideration of the degree of biological support f or these lags?

b. What are the Panel members' views on EPA’s planned approach to place emphasis on multi-city studies which provide city-s pecific effect estimates, particularly Empirical Bayes adjusted effect estima tes which consider both the regional signal as well as the local (city-specific ) signal in deriving adjusted cityspecific effect estimates?

c. What are the Panel members’ views regarding EPA's p lanned approach to place equal weight on single and multi-pollutant models i n recognition of the competing advantages and disadvantages provided by both types of models?5 d. Based on information provided in the first draft IS A regarding potential population thresholds, EPA is planning to place pri mary emphasis on modeling risk down to policy-relevant background or the lowe st reported measured level in the epidemiological studies. In contrast to the pr ior review, EPA is planning to place less emphasis on consideration of hypothetica l population thresholds. What are the Panel members’ views on this approach or alternative approaches

that could be considered?

3. Regarding selection of urban study areas:

a. EPA plans to include 15 to 20 urban study areas in the PM 2.5 health risk assessment, with areas selected based on applicatio n of the criteria presented in the plan. What are the Panel members’ views on the planned criteria for selecting urban study areas?

b. The scope of the planned assessment for PM 10-2.5 is much more limited. What are the Panel members’ views regarding the overall appr oach and, specifically, on the criteria for selecting study areas for evaluating t he health impacts associated with ambient thoracic coarse particles?

4. Regarding the approach for addressing uncertainty a nd variability:

a. In the plan, EPA describes an uncertainty analysis approach based on the application of single and multi-element sensitivity analysis. What are the Panel members' views on this planned approach for address ing uncertainty in the risk

assessment?

b. Do Panel members generally agree that the planned a pproach sufficiently captures key sources of variability related to PM-related ri sk? Are there any important sources of variability which are not captured by th e proposed risk assessment approach and, if so, what are the Panel members’ vi ews regarding how these sources of variability could be incorporated into t he analyses?

5. Regarding analyses being considered to place the ur ban study area risk results in a broader context with regard to national patterns of risk and risk-related indices:

a. EPA is considering conducting a national-scale heal th impact assessment of the mortality impacts in the U.S. population associated with long-term exposure to

ambient PM 2.5 under recent air quality conditions to support interpretation of the risk estimates generated for the urban study areas. What are the Panel members’ views related to including such a national-sale ana lysis in the risk assessment? What are the Panel members’ views regarding the gen eral structure and overall design of this analysis?

b. EPA’s planned approach also includes analyses to co mpare the information for the selected urban study areas with national statis tics for a set of key PM risk-6 related indices (e.g., baseline incidence rates for health effects modeled in the risk assessment, rates of air conditioner use, housing s tock). What are the Panel members’ views on this planned comparison?

Chapter 4 – Scope and Approach for Population Expos ure Analysis

1. What are the Panel members’ views on the general st ructure and overall design of the exposure assessment to provide insight on populatio n exposures with respect to informing the interpretation of available epidemiol ogic studies?

2. What are the Panel members’ views regarding the pla nned measures of exposure?

3. EPA is planning to focus the exposure assessment on a subset of the urban study areas

evaluated in the risk assessment. What are the Pan el members’ views regarding the selection of these study areas and the planned time periods to be modeled?

4. Regarding the approach for addressing uncertainty a nd variability, are Panel members generally supportive of the planned approach?

B. Welfare Assessment Plan

Chapter 1 – Introduction

The introductory section presents an overview of th e goals and planned approaches for conducting urban visibility assessments.

1. What are the Panel members’ views on the general st ructure and overall design of the planned analyses?

2. Is the plan clear and transparent in its descriptio n of the planned approaches? Are the various assumptions and judgments that must be made in carrying out the planned assessments clear and transparent?

3. Given the goals set forth for the planned analyses, has the plan appropriately drawn from the existing scientific and technical information i n developing the overall approach? Are

there relevant features that should be added or mod ified in the planned approach?

4. In addition to the sub-daily PM 2.5 alternative standard considered in the last PM NAA QS review and summarized in this chapter, an alternati ve standard structure is being

considered in this review. This alternative struct ure would use daylight hourly PM light extinction, which can be measured either by a combi nation of instruments (nephelometer – PM light scattering and aethalometer – PM light a bsorption) or calculated from PM speciation and concurrent relative humidity data us ing a linear algorithm.7 a. What are the Panel members’ views regarding this al ternative structure and its utility in the context of this PM NAAQS review?

b. What are the Panel members’ views regarding advanta ges and disadvantages of this alternate structure compared to the sub-daily PM mass concentration approach?

5. The public’s preferences for urban visual air quali ty (VAQ) levels were assessed in the last review in part by considering results from pas t western U.S. urban preference studies that used scenes with distant mountain backdrops.

a. What are the Panel members’ views on the usefulness of the planned approach to conduct a focus group study in different regions of the country with different scene types to enhance our understanding of the app licability of this earlier body of work to U.S. urban areas in general?

b. What are the Panel members’ views regarding the sco pe and approach envisioned for this effort, given the time available in this r eview?

Chapter 2 – Assessment of Urban Visibility Conditio ns

1. Visibility impairment is caused by both PM 2.5 and PM 10-2.5 , though the latter is less effective on a per unit concentration basis and the re is less available PM 10-2.5 data

available in urban areas with which to conduct an a ssessment. PM in the atmosphere includes liquid water which contributes to light ex tinction but is removed when filter samples are desiccated prior to mass and compositio n analysis.

c. What are the Panel members’ views regarding to what degree and using what approaches EPA should assess the role of PM 10-2.5 in urban light extinction?

d. What are the Panel members’ views regarding the adv antages and disadvantages of using direct measurements of ambient PM light ex tinction (e.g., nephelometer plus aethalometer, or transmissometer) compared to using a linear algorithm that includes particle composition and concurrent relati ve humidity to calculate (reconstitute) PM light extinction?

e. What are the Panel members’ views regarding the imp ortance of refining the IMPROVE algorithm so that it is optimized for urban areas in order to estimate PM light extinction for use in this assessment?

2. This plan anticipates using the same approach to es timate policy-relevant background PM

levels as in the health risk assessment. What are the Panel members’ views on this planned approach and its use in the context of the urban visibility conditions assessment?

3. The planned approach includes consideration of high time resolution PM mass and component concentrations as well as PM light extinc tion data, together with relative8

humidity values, to assess recent air quality as we ll as air quality simulated to just meet

current and alternative standards under considerati on. However, such high time resolution data are not broadly available.

a. What are the Panel members’ views on this planned a pproach or on other approaches or data sources that might be explored?

b. What are the Panel members’ views regarding useful approaches for characterizing the uncertainties associated with th e urban visibility conditions

assessment?

Chapter 3 – Quantitative Visual Air Quality Impact Assessment

1. EPA plans to conduct public preference studies to s upplement the information from past studies concerning VAQ levels that impact public we lfare. The planned approach is to conduct an investigative focus group in one locatio n to develop the approach that will then be used in group interviews in four urban area s. The proposed approach would ask participants to view an urban-specific iconic scene and a generic scene in each study location, all selected to be sensitive to changes i n PM light extinction using WinHaze superimposed haze levels.

a. What are the Panel members’ views regarding the app ropriateness of EPA’s preference study approach and its adequacy to accom plish the goals outlined in the plan?

b. What are the Panel members’ views with respect to a lternative approaches that could be considered in this review to acquire this and/or additional relevant

information?

2. EPA is not planning to include monetary valuation s tudy questions (e.g. willingness to pay, conjoint analysis) in the studies conducted fo r this review.

a. What are the Panel members’ views regarding the use fulness of adding valuation questions to the proposed four urban-areas group in terview surveys and the adequacy of such limited information to inform esti mate of the value of improved visibility in the broader nationwide context?

b. What are the Panel members’ views with respect to p ossible approaches for estimating monetary values associated with improved visibility that should be

considered?

We look forward to discussing these issues with the CASAC PM Panel at our upcoming meeting. Should you have any questions regarding t hese planning documents, 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 ) regarding the Health Assessment Plan or Ms.9

Vicki Sandiford (919-541-2629; email sandiford.vicki@epa.gov ) regarding the Welfare

Assessment Plan.

Attachments

cc: Vanessa Vu, SAB, OA Karen Martin, OAQPS/HEID John Vandenberg, ORD/NCEA-RTP Mary Ross, ORD/NCEA-RTP Lindsay Stanek, ORD/NCEA-rTP Beth Hassett-Sipple, OAQPS/HEID Vicki Sandiford, OAQPS/HEID Harvey Richmond, OAQPS/HEID Zach Pekar, OAQPS/HEID John Langstaff, OAQPS/HEID Pradeep Rajan, OAQPS/HEID Susan Stone, OAQPS/HEID Meredith Lassiter, OAQPS/HEID Bryan Hubbell, OAQPS/HEID Marc Pitchford, OAQPS/HEID