Review of the Air Quality Criteria Document for Particulate Matter

multiple pollutants. In presenting the results, it would also be useful to complement informationon pollutant effects estimators with information on actual pollutant levels so that the role of theindividual pollutants would be more apparent.Page 6-42, line 7 and page 6-43, line 6. It would be useful for the CD to include an expandeddiscussion of the handling of county-specific variables and co-pollutants in the NMMAP studies.Specifically, it would be useful to include one or more tables that present specific data on theeffects estimators used for other pollutants such as NO 2 , O 3 , SO 2 , and CO and for temperature(both elevated and reduced). This would be helpful in understanding the total air pollution effectand the relative importance of PM. It is not sufficient (as in page 6-44, line 2-3) to relate that thePM 10 effect on mortality "did not appear to be affected by other pollutants in the model."In presenting the NMMAPS results it would be useful to include a graphical display that conveysthe slope of the effects estimators for the 90 cities. At a minimum, the regional data could beplotted relative to the measured range of PM 10 values used to derive the effects estimators. Thelatter values might be the 25 th to 75 th or 10 th to 90 th percentile of the PM 10 values that were usedin the analyses plotted on the horizontal and the mortality rate on the vertical.Page 6-49, section 6.2.2.4 (The Role of Particulate Matter Components). This section shouldeither begin with or end with a discussion of the challenge of characterizing the role of specificparticulate matter components. Two major issues should be covered. First, epidemiologicalanalyses can only be carried out on the components that have been measured. In that regard, amajor problem relates to the past excessive domination of monitoring by concern for regulatorycompliance, with a progression in the U.S. from TSP to PM 10 and most recently to PM 2.5measurements and with measurements of PM indicators made only every 6 th day. The ability totest for the role of other components that may be significant will continue to be dependent uponhaving long-term measurements of these components. The second issue is the challenge ofteasing out very small relative risks. It is apparent, and especially from the staff paper, that largestudy sizes are needed to obtain relatively stable and statistically significant results—studies forwhich the product of number of mortality/morbidity events per day multiplied by the number ofdays monitored is at least 10,000.Page 6-58, lines 19-20: The statement indicating that wind-blown endotoxins and molds arecontributing to PM10-2.5 fraction effects in the Phoenix area needs to be supported byreferences or omitted if it is mere speculation.Page 6-58, line 2.7. In view of the role of SO 2 in the Wichmann, et al (2000) study, it would beappropriate to give an indication of the SO 2 levels measured and how they compare to levelsmeasured in the eastern U.S.Page 6-67, Source-Disputed Evaluation: It would be useful to review the analyses done by theNMMAPS investigators (perhaps even unpublished analyses) to determine if any of the resultsprovide any insights into source-oriented impacts. For example, did the NMMAPS investigatorsexplore any weekday versus weekend effects that might give insights into mobile source relatedeffects?Page 6-72, line 1: Show the Confidence Interval for excess other deaths; i.e., 1.3% increase per50 :g/m 3 PM 10 . It would also be appropriate to expand the discussion of other deaths to considerregional differences.Page 6-73, lines 28-30: It would be useful to expand the discussion of sample size issues forsub-categories of disease. This could be done using the study size calculations in the staff paperfor the NMMAP study showing how the study size decreases progressing from total mortality tocardiac to respiratory causes because of decreases in number of events. This discussion could beA - 59