Review of the Air Quality Criteria Document for Particulate Matter

given mass, as demonstrated in Table 8-9. However, it is clear, given the distributions ofparticle mass, particle surface area and particle number by particle size in ambient air,that particle mass falls dramatically as one enters the ultrafine size range: so much so, infact, that surface area begins to fall before getting down to the ultrafine range, and thenfalls dramatically once the ultrafine range is reached (as shown in the Whitby plot on p.2-7, Fig. 2-1). I would drop Table 8-9. It is conceivable that the Whitby plot is outdated,since it is at least 23 years old. It might be useful to have similar work repeated formodern-day atmospheres.8-82 The first paragraph describes a clinical study that has no place here. One couldalternatively note that, “Clinical studies have observed....”. Here is what thetoxicological studies show:.....SummaryThis summary, as I noted above, is excellent.Chapter 9. Integrative synthesis.I would recommend that this chapter, as the title suggests, serve the primary purpose ofan integrative synthesis rather than a stand-alone summary of the CD. Of course it is possiblefor it to partially serve as a summary, while still serving primarily as a synthesis, but this wouldtake considerable thoughtfulness.In terms of organization, I would like to see the chapter focus on the big issues that werelargely unresolved at the time of the 1996 CD, and then proceed to addressing how muchprogress has been made in answering these questions. This should take the form of integratingnew findings across discipline. For example, in addressing the issue of coarse fraction effects,the epidemiological findings in isolation would suggest that there are effects of the coarsefraction, apart from those due to the fine fraction, and that strong consideration should be givento setting a coarse particle standard of some form. However, this course is tempered somewhatwhen information on coarse PM measurement issues and exposures are also considered.The chapter could end with posing questions that remain unanswered, and which stillneed further work.Barbara Zielinska, PhDChapter 2: Physics, Chemistry, and Measurement of Particulate MatterIn my opinion, this chapter requires more work. At present, the chapter makes theimpression on the reader that it was written by several independent authors, without any attemptto integrate it into one consistent document. Following are the specific examples:1. On page 2-47, line 19-21 (Section 2.2.3), the authors state discussing the experimentswith two quartz fiber filters deployed in series in order to examine the artifacts connectedwith SVOC partitioning: “Unless the individual compounds are identified, theinvestigator does not know what to do with the loading value on the second filter (i.e. toadd or subtract from the first filter loading value)”. I agree with this statement -moreover, even if the individual compounds were identified on back-up filter, thedecision concerning adding or subtracting back-up filter loading would not bestraightforward. However, the authors discuss subsequently in detail (page 2-51 to 2-62)in several places throughout the Section 2.2.3 several experiments with Teflon-quartz orquartz-quartz back-up filters that produced conflicting results. The references of Turpinet al., 2000, and Kirchsteller et al, 2000, are discussed on p. 2-52 – 2-53 and again on p.2-61 – 2-62 (in addition, the reference of Turpin et al., 2000, is missing). This would beconfusing to the reader who is not very familiar with the problem of positive andnegative sampling artifacts. It would be desirable to organize the discussion in moreconsistent manner, shorten it significantly, and not scatter it throughout the wholeSection 2.2.3A - 17