Review of the Air Quality Criteria Document for Particulate Matter

32. Page 4-147, lines 10 -14. I believe that “the range of Rocky Mountain spotted tick vectors”already extends into the northern US states and southern Canada in the west.33. Page 4-148, line 27. Should read “–with A. aegypti or –“.Paul J. Lioy, PhDChapter 3Most of the information and analyses presented in Chapter 3 are typical of those presented inprevious criteria documents on Particulate Matter (PM). Further, the analyses completed for thePM 2.5 concentrations collected with the new standard reference method are valuable as an initialassessment of annual or daily exceedences.My major concerns are with the emissions and source apportionment sections. The focus of theemissions section is on sources of primary particulate matter. This is a good start, but isdeficient with respect to sources of secondary particulate matter. The source apportionmentassessment also provides more information on the nature of primary particle sources. At thesame time the source apportionment analyses also point out the significant contributions ofsecondary particulate matter to the mass of PM 2.5 , known as accumulate mode particles.The source apportionment analyses can do an effective job investigating the percentage ofcontributions of secondary particles to the mass. They do not, however, provide quantitativeinformation on the levels and types of precursor emissions which contribute to the formation ofthe mass.In addition, there is no discussion on the chemistry that leads to the formation of secondaryparticles, and the residence time for fresh or aged secondary particles in the atmosphere. Theonly statement made that comes close to discussing secondary particles is on chapter 3, page 51.However, it states on line 26, that gaseous emissions “cannot be translated directly intoproduction rates for PM.” Based upon the many years of particle formation modeling that hasbeen completed by many laboratories, this statement is not accurate.The lack of information or predictions for secondary particle formation is serious. This is basedon the information presented in the current criteria document, and many papers published since1976, which indicate that a large quantity of the mass of PM 2.5 in many urban suburban areasincludes secondary particles.The above deficiency requires that a section be added to the chapter that specifically addressesparticle formation by photochemical smog or wintertime reducing smog processes. Modelingactivities that include assessments of emissions inventories and a number of chemical processes,e.g., developed by Caltech, EOHSI, and other investigators, need to be described in the section.They are necessary to establish the types and levels of precursors that lead to the formation ofsecondary aerosol. The section could also provide a context for coupling the efforts forcontrolling ozone and other pollutants, to reducing formation and accumulation of particles.Thus, I recommend that a section be added that focuses specifically on particle formation inphotochemical smog by dark phase and sunlight phase processes. It should be developed toprovide the proper context for evaluating the peak concentrations observed in the summertime.Condensation and heterogeneous chemical processes and aerosol production will assist inunderstanding wintertime chemistry. The section should also have a discussion on products,lifetimes, concentrations, and neutralization.The new section will provide a framework for discussion about the significance of both “soot “and “secondary particles” in causing PM air pollution. It is essential that during thedevelopment of the SIP, we do not focus on sources that will provide marginal gains in particleA - 35