Review of the Air Quality Criteria Document for Particulate Matter

P 7- 40, L 18: You need to explain what “mechanisms such as two-phase gas-liquid interaction”means.P 7- 40, L 20: Do you mean that transport is more effective (ie, more rapid)?P 7-41, L 13: It should read “—those obtained”.P 7- 41, L 21: I doubt this statement. I’d wager that more coughs occur in the U.S. annuallybecause of internal reasons (viral infections, chronic bronchitis, etc.) than from an “inhaledstimulus”.P 7- 42, L 29: Again, there is confusion between deposition and retention. The 1 mg value is anamount of retained PM, not deposited PM. If you deposit that amount slowly enough, there willbe no overload from the deposition.P 7- 44, L 16: Do you really mean “random” here, or do you mean “uniform”? I think the latterwould be a better term.P 7-46, L 18: It should read “The model results were in good agreement”, not that the “model”was in good agreement. “Models” don’t agree with anything, but good ones produce “results”that do.P 7- 47, L 7: Any results or validation here?P 7- 47, L 15: Again, any validation?P 7- 47, L 27: Once again, any validation?P 7- 47, L 29: Please explain what “general dynamic equation for size evolution” is. I don’tunderstand this, and there may be others like me.P 7- 48, L 9-10: I think you are saying that the combined effects yield a narrower sizedistribution. If so, why not just say that, instead of saying “decrease the size nonuniformity” and“variance”?P 7-50, L 16: It should read “—data are”. Data is a plural word.P 7-50, L 21: Define “acinar airways”. That’s a new term for this chapter.P 7- 52, L 25: It should read “—rats and monkeys exposed—“. The statement talks about twospecies, but you only name one.Chapter 8: Toxicology of Particulate Matter - General Comments:The chapter is a good draft, but needs considerable editorial clean-up of both text andtables, and some additional attention to content and conclusions. The former is addressed bynumerous of the following specific comments. The latter pertains to the several places wheresentences that portray conclusions (although not necessarily marked as such) that are unclear,misleading, or in conflict with one another. These are also addressed in the specific commentsbelow.The chapter could be better balanced in its treatment of the types of PM that are emphasized. Asone example, it contains greater emphasis on ROFA than is warranted. Granted, there has been atremendous investment in ROFA research, but aside from demonstrating the importance ofsoluble transition metals (which is important), the extension of this work to other ambient PM islimited. As one contrast, very little attention is given to “bioaerosols”, and what informationA - 23