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Dr. Ellis Cowling Dr. Ellis Cowling North Carolina State University March 2, 2007 Comments on Chapter 8 and Related parts of Chapters 2 and 7 in the "Review of the National Ambient Air Quality Standards for Ozone: Policy Assessment of Scientific and Technical Information - OAQPS Staff Paper" and the "Technical Report on Ozone Exposure, Risk, and Impacts Assessments for Vegetation" What a delight it was to review Chapter 8 -Staff Conclusions and Recommendations on the Secondary 03 NAAQS -with its firm conclusions and carefully reasoned staff recommendations to the Administrator of USEPA regarding the need for a secondary (public- welfare based) standard for ozone that is: a) Biologically relevant to vegetation -including agricultural crops; seedling, sapling, and mature forest trees; and natural vegetation in natural ecosystems including natural grasslands in various parts of the United States, b) Distinct in form from the existing primary (public-health based) ozone standard, and also c) Distinct in form from the various alternative public-health-based primary standards for ozone that are proposed in Chapter 6 of this same Staff Paper! These conclusions and carefully reasoned recommendations are soundly based on the available scientific literature summarized in the 2006 Criteria Document for ozone, its carefully prepared Integrative Synthesis Chapter, and also on information presented directly in Chapters 2, 7, and 8 of the present Staff Paper or its Appendixes, and the associated "Technical Report on Ozone Exposure, Risk, and Impacts Assessments for Vegetation." It was especially satisfying to review the following conclusions with regard to the specific indicator, averaging time, statistical form, and range of levels of the secondary (public-welfare based) standard that EPA staff consider to be appropriate for consideration and implementation by the Administrator of EPA. This high degree of satisfaction was enhanced by the congruence between the following quoted paragraphs from pages 8-25 through 8-27 and the recommendations contained in CASAC's letter to Administrator Johnson dated October 26, 2006 -which was also printed as an attachment to this final OAQPS Staff Paper for ozone: (1) "It is appropriate to continue to use 03 as the indicator for a standard that is intended to address effects associated with exposure to 03, alone or in combination with related photochemical oxidants. Based on the available [scientific] information, we conclude that there is no basis for considering any alternative indicator." °., C-3