Review of the Air Quality Criteria Document for Particulate Matter

Günter Oberdörster, PhDChapter 7 Dosimetry of Particulate MatterOverall, this chapter summarizes well what has been presented in previous EPAdocuments and gives additional useful new information. However, there are several ratherdogmatic statements which are unsupported and need either to be referenced or to be labelled asspeculative. Some sections are also rather simplistic by stating the obvious, a bit more depthwould help. This review summarizes on a page-by-page basis some suggestions for changes,deletions, additions.Page 7-7, line 7: In addition to defining the term "inhalability" it would also be useful todefine "respirability" since later on there appears to be some confusion as to which term shouldbe usedṖage 7-9, line 2: CMD is not necessary, it implies a size distribution whereas here theupper limit is meant.Line 4: The Frampton et al. study had both male and female subjects.Line 9: Add after “diameter” the sentence: There was no gender difference.Line 10: A statement could be added that this result compares favorably with theICRP 1994 model.Line 13: A sentence should be added here listing some of the values of the Jaquesand Kim study, rather than giving the results only in relative terms.Line 24: A sentence should be added here stating that at the same time, there is ashift in deposition sites from more peripheral to central or extrathoracic regions.Page 7-11, lines 18-20: 94 - 99 percent is not consistent with the result reported in theprevious paragraph (Yu et al.) where only 54% deposition was found for 1 nm particles, andthese have the highest deposition efficiency.Page 7-12, lines 7-11: The efficiency of the nose as a filter for ultrafine particles has tobe seen in the context of the size within the ultrafine range. Whereas it can be very high fornanoparticles below 10 nm, the filtering capacity becomes less for ultrafine particles of 20 nmand greater.Page 7-14, lines 10: Change "fine" to "ultrafine". In this paragraph again it would behelpful to give some of the values that were found by Kim and Jacques in their studies in termsof deposition efficiencies. A statement comparing their results with the ICRP model would alsobe helpful, for example, the total deposition in the alveolar region found by Kim and Jacques for40 and 60 nm particles of ~33 and ~27 percent, respectively, are in excellent agreement with theICRP model.Line 30: To understand the modeling result it would be helpful to provide data onthe size distribution of the environmental aerosols in terms of MMADs and geometric standarddeviations.Page 7-15, line 1: What kind of mathematical model was used? A brief descriptorwould be helpful.Lines 4-6: If 36 of the inhaled coarse particles were deposited in the lung, thatdoesn't add up if only 4 percent were in the tracheobronchial region and 2 percent in the alveolarregion. Please check. Likewise, 9 percent of the fine particles deposited in the lung is notexplained by 6 percent in the alveolar and a small fraction in the tracheobronchial region.Lines 13-14: Here again 18 percent deposition in the lung is not explained by 2percent in tracheobronchial and 3 percent in alveolar regions.Line 23: I assume the cautionary note refers to the numbers (10 3 , 10 5 , etc.) butthe general trend of differences between coarse and fine particle surface area and cell doses canalso be derived from other models, i.e., ICRP, MPP Dep model.Page 7-17, lines 24-26: I suggest to add here also that exercising will cause a shift indeposition sites from peripheral to more central airways as had been modeled by Martonen.Page 7-18, lines 2: When differences in deposition between females and males aredescribed here, these results as well as those from other studies comparing the gender-relateddeposition efficiencies should be critically evaluated: Both men and women breathed at theA - 64