Review of the Air Quality Criteria Document for Particulate Matter

P 8-81, L 9: “Interaction” should be “interactions”.P 8-82, L 16 to P 8-83, L 8: It is astonishing that these field studies of whole air (urban andotherwise) are cited as contributing to our understanding of the co-pollutant issue, while wellcharacterizedcombustion emission studies are not cited at all! These studies provide very littleuseful information. With regard to the topic of the section, they are basically ecologicalepidemiology studies with very few subjects of the wrong species. In line 26-27, it is stated that“extrapolation is hampered” by a lack of exposure characterization. What an understatement!Considering all the problems with these studies, it is questionable whether they merit inclusion atall. As in all air pollution studies, but especially true for studies of co-pollutant interactions, ifyou don’t know the exposure, you don’t know anything.P 8-83, L 21-22: I disagree with this statement. The key to plausibility is not knowing thecomponents and the individuals at risk. The key is to plausibility is understanding the linkagebetween the two (ie, a plausible mechanism).P 8-85, L 13-14: This sentence contrasts with the earlier statement on page 8-63 that metalshave been established as a key (it actually implied metals were the only key) contributor tohealth impacts of PM via reactive oxygen species. It is stated that the ROFA studies haveimportant implications, but it doesn’t state what the implications are.P 8-86, L 5-14: This section on “bioaerosols” only talks about endotoxin. What about all theother bioaerosols? Endotoxin is seldom, if ever, actually a “bioaerosol”. It is a contaminant ofairborne PM. Pollen proteins, plant debris, and many other airborne materials of biologicalorigin are not mentioned.P 8-86, L 20: First, “PM is responsible” should be PM are the responsible”. Second, there otherhealth effects of concern for diesel PM in addition to the adjuvant effect. Why not mention themin this chapter?8-87, L 29: It should say “animals with certain types of compromised health”, or “animals withcompromised cardiorespiratory health” or some such wording. Not all types of compromisedhealth would be expected to affect susceptibility to inhaled PM (a broken toe, as an extreme, butillustrative example).P 8-88, L 3-6: This closing statement needs work. First, validation of animal models is asimportant as identification, and this important point is overlooked in the section, and too oftenoverlooked by researchers. Second, what is the connection between making “solid progress” andthe fact that large numbers of people are needed for epidemiology studies? Would our progressbe less solid if fewer numbers of people sufficed for epidemiologists? The author probably has acouple of good thoughts here, but it’s not clear that they belong in the same sentence.P 8-88, L 12-13: This sentence is trite. I think we can go beyond saying that there “may be”multiple mechanisms to state that research to date clearly indicates that there “are” multiplemechanisms.Chapter 9 Integrative Synthesis - General Comments:In general, the chapter is well-developed, and with some modest editing, will serve well as anintegrated synthesis. With minor editing, it will hit approximately the right level of detail, andgive appropriate attention to making the major points and drawing conclusions.Some additional attention needs to be given to this chapter to accommodate the fact that manypeople will read only this chapter. It proposes to be a synthesis of all of the Criteria Documentexcept the environmental effects. First, one wonders why the environmental effects couldn’tA - 29