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said, Staff does not appear to appreciate the potential for propagation of error/uncertainty other <br />than to qualitatively describe and identify where uncertainty exists. It is still my view that the <br />analyses provided by Abt Associates Inc. (2006 and 2007) represent a "house of cards" with an <br />unstable foundation. <br />Specific Comments: <br />1. The case has not been made by Staff that the results of ozone/vegetation exposure experiments <br />carried out in open-top chambers (OTC) can be extrapolated to reflect what occurs in the <br />ambient environment. <br />2. The case has not been made by Staff that one can use the same concentration-response (C-R) <br />functions today which were developed in the 1980's using controlled ozone exposures in OTCs <br />during the National Crop Loss Assessment Network (NCLAN) Program for selected agricultural <br />crop species cultivars and the EPA's National Environmental Effects Research Laboratory- <br />Western Ecology Division (NEERL-WED) for selected tree species seedlings. <br />3. The case is not made by Staff that the current crop species cultivars in use in 2002 have the <br />same ozone sensitivity as the crop species cultivars used in NCLAN in the 1980's which were <br />developed in the 1970's. <br />4. The case is not made by Staff that the ozone exposure indices SUM06 and W 126 have a <br />biological basis as has been implied. The only thing which can be said is that these two exposure <br />indices are simply mathematical expressions of exposure which have been related to an endpoint <br />such as yield in controlled ozone exposure OTC experiments. <br />C-18 <br />