AG 2007 10 15 - Laserfiche WebLink

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The important effects of ozone and other oxidants on human health occur in spite of the fact that most people spend most days of their lives inside home, school, office, and/or factory buildings where ozone exposures are a small faction of the ambient air concentrations of ozone that occur in the ambient air. By contrast, almost all plants spend their entire lives in the great outdoors -where they aze exposed to ambient concentrations of ozone 24 hours of every day, 7 days of every week, and in all seasons of the year; these continuous exposures occur for all the weeks, months, years, decades, or sometimes even centuries of the functional lives of the plant, animals, insects, and microorganisms that inhabit the managed or unmanaged ecosystems in all parts of the United States. Thus, many plant pathologists, plant physiologists and ecologists like me are prone to assert, somewhat factiously, that: "Plants do not worry about a bad Tuesday, but they do worry about bad ozone seasons." Furthermore, we plant scientists also aze well aware that the injurious effects of ozone often carry over from one year to the next. For all of the above reasons, plant pathologists, physiologists, and ecologists concerned with the injurious effects of ozone and other photochemical oxidants on plants recommend that the "averaging time" of03 exposure necessary to avoid or decrease injury to crop plants, trees, and natural ecosystems should extend over the whole growing season rather than just a few hours. Hence the "ozone indices" recommended by EPA staff and CASAC to avoid or decrease injury or damage to plants have been of a cumulative form -such as W 126 as was recommended by both EPA staff and CASAC in 2007 or SUM06 as was recommended by EPA staff and the Administrator of EPA as well as CASAC in 1997. Significant injury and damage to vegetation continues to occur in many parts of the United States that are not in violation of the current 8-hr ozone standazd. The maps and charts shown on pages 7-28 of the staff paper and pages 7B-4 and 7B-5 of Appendices, as well as the discussion on pages 7-17 and 7-19 of the staff paper indicate the geographical locations and numbers of counties in which visible foliar injury and other welfare effects occur in azeas that meet the current 8-hr standard for ozone. On March 21, 1996, I presented the attached statement to the CASAC of that time regarding the need for a secondary standard for ozone that is different in form from the primary standard. That statement was titled "Avoiding the Necessity for a Second NRC Report on `Rethinking the Ozone Problem in Urban and Regional Air Pollution' during the Years Between 2002 and 2017."' After careful study of Chapters 2, 7, and 8 in the current EPA Staff Paper on ozone, rereading again the 1991 NRC "Rethinking" report as mentioned above, and finally, once again rereading my 1996 statement to CASAC as shown on pages 5-9 of these comments, I am even more convinced (and for the same general and specific reasons outlined in all of these ~;_ . i. '~ C-6