(CASAC) Peer Review of EPA's Integrated Science Assessment

Specific CommentsPage; lines2-3; 10 &12 Define terminology (OH for hydroxyl free radical and HO 2 forhydroperoxyl radical) immediately after the equation in which they first appear.2-9; 3-4 How large a difference between monitored concentrations is a variation of 2-15m difference in monitor height likely to introduce? How does this difference depend ondistance to the point source?2-14; 1 Make sure that SLAMS and NAMS acronyms have been previously defined.2-23; 9 I assume that you mean “the Pearson correlation coefficients (r) forconcentration data from multiple monitors taken as pairs in these CMSA’s…”2-26; 9-11 104 sites +15 sites is greater than the total of 108 sites mentioned in theprevious sentence.2-41; 5 Given the importance of exercise in promoting health effects in asthmatics, it isimportant that this be included as a personal activity in this list.2-41;17-21 Incomplete, run-on, sentence.2-58; 14 For clarification, it would be helpful to add a phase indicating that the Henry’sLaw constant is inversely proportional to solubility.One-way flow versus cyclic flow---2-59; 4-5 What the text refers to as “total respiratory tract absorption” is presumably theretained dose of SO2 over a complete respiratory cycle.2-59; 18-20 In these experiments, the upper airways were isolated from the lowerrespiratory tract, and absorption was measured during one-way flow (as opposed to thebidirection flow that occurs during a complete respiratory cycle). This was also the casefor other investigations that are cited later on pages 2-59 and 2-60.2-63; 6-8 It is precisely because of desorption during exhalation that cyclic flowexperiments report smaller absorption efficiencies than one-way flow experiments. Thisexplanation should be worked into the discussion.52