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Dr. Paul J. Hanson Comments on Chapters 8 of the Review of the National Ambient Air Quality Standards for Ozone: Policy Assessment of Scientific and Technical Information OAQPS Staff Paper Final Comments from Dr. Paul J. Hanson: 06 March 2007 1 commend the EPA staff for their comprehensive modifications to both Chapters 7 and 8 of the Staff Paper and the attention they paid to panel comments submitted in August of 2006. In my opinion EPA staff has done a very good job of laying out the rationale and justifications for their recommendations for a change to the secondary NAAQS for ozone. Good justification:exists for the promulgation of a secondary standard for the protection of human welfare effects different from the primary standard designed to protect human health. The key change is the recommended alteration of the form of the secondary standard to a cumulative exposure index that better describes the true nature of tropospheric ozone's interaction with vegetation and materials in the natural world. The recommended averaging time (12 daylight hours and 3 month growing season) and levels for a W 126-based secondary standard represent a logical choice driven by the need to propose a single standard representing a compromise across a wide range of sensitivities exhibited by important agricultural, forest, and natural species present throughout the United States. Mr. Richard L. Poirot's verbal and written comments on setting the level of the secondary standard offered during the OS March 2007 teleconference provide additional logical input to be considered in selecting a specific level for the secondary ozone standard. A few comments on the text of Chapters 7 and 8 are offered below for EPA's consideration: Pages 7-40 to 7-43 I found the EPA Staffl s justification of the extensive use of historical open-top chamber data for the analysis of crop responses to ozone (i.e., NCLAN results) to adequately address the CASAC-Ozone Panel's concerns about the utility of the methods and the applicability of those data to current crop varieties currently in use throughout the Uriited States. Page 7-62 The figure appears to have an unneeded subtitle -- "Is Foliar injury present or absent?, 2001". Page 8-13 lines 3 and 4 I'm not certain that EPA Staff can adequately support the eg neral statement that "the results of these impairments (e.g., loss in vigor) maybe premature pant death". While this .statement maybe true for some sensitive species it is not likely to be a logical conclusion for all C-15