Review of the Air Quality Criteria Document for Particulate Matter

old and young rats and mice used only ultrafine carbon particles, see also the publications byElder et al. (2000, 2001) which were mentioned earlier in my comments.Page 8-72, line 11: Replace “properties” with “area”.Page 8-73, lines 5-8: One has to be careful to characterize ambient PM as ROFA whichhas been used in a number of animal and in vitro studies. The ROFA that was used wascollected from a bag house, and – as was pointed out earlier in this document – has a differentmetal content than the fly ash which is actually released into the environment, also metalsolubilities are different. Furthermore, the high doses that were used in the ROFA studies needto be mentioned here as well.Page 8-74, Section 8.5.5.2: This section reiterates studies that have been describedbefore in this document. It should be remembered that the studies which are used here todemonstrate a specific mechanism to cause systemic effects have been run at very high doses orexposure concentrations, and thus, one needs to be very cautious to extrapolate these responsesto relevant ambient concentrations of PM. What the studies do is show that the concept of aspecific pathway or mechanism is valid in principle, but this needs to be validated and verifiedby additional studies using relevant exposures.Page 8-81, line 26: Include (Elder et al., 2001).Page 8-83, Section 8.7 Summary: This section provides a good summary of our presentstate of knowledge. There should be a few clarifications:Page 8-85, line 14: Implications for what? The implication I see here is to conductfurther studies on the importance of metals, and that the ROFA studies have pointed out theimportance of the metal concept for PM toxicity in general.Page 8-87, line 16: Another ultrafine ambient PM concentrator was developed byKoutrakis and colleagues.Section 8.7.1.2, Susceptibility: Among the susceptibility factors, not onlygenetically or induced compromised health should be listed but also age as a factor.Robert Rowe, PhDBelow are revised comments on the second draft CD and draft Staff Paper for the PMNAAQS. The EPA staff are to be commended for the work to date, especially recognizing thesignificant growth in literature relevant to the PM standard. My comments focus on economicand visibility perception portions of the materials provided.Visibility Impairment AssessmentThe Staff Paper Section 5.2.5, and a supplemental paper, address a proposed approach to addressvisibility impairment in terms of human judgement. I encourage EPA to pursue this perceptions,preference and economic valuation work as important to setting the secondary standard.However the work completed to date should be seen as being only very preliminary. It isimportant that a more comprehensive workplan be developed, including how the results may beused as input to decisions about the secondary national standard, and that the type and level ofwork effort be consistent with the expected use of the work.My key recommendations are that:1. EPA should conduct several additional focus groups in the Washington, D.C. area to addressbasic issues in the research.2. EPA should then conduct similar preliminary analyses in another city that is diverse fromWashington, D.C.3. Based on the above, EPA should develop a more comprehensive workplan on the issues andobjectives, data to be collected and its uses, steps to be performed, survey instruments, andtime schedule. I recommend a peer review at this stage.4. EPA should develop a plan that will provide a sound sampling strategy, and not just one ortwo focus groups in a variety of locations. This may require OMB approval.A - 70