Assessment of Research Studies in Addressing Key Reactivity Policy-Relevant Questions

Question UCR -Carter GT -Russell MCNC -Arunachulam Reviewer's Comments 1 What is the hypothesis that we want to test? It is possible to develop a means to quantify differences in ozone impacts of the major classes of emitted VOCs sufficiently well that these relative ozone impact quantifications can be effectively used in VOC regulations to reduce ambient ozone levels. For this to be the case, it is necessary to show the following: • That VOC regulations, either by themselves or on conjunction with NOx controls, are effective in reducing ground level ozone at least in some regions that are of concern to policy makers; • That relative ozone impacts of the major classes of VOCs are not so variable over time and space that it is not possible to derive a meaningful relative ozone impact quantification; and • That differences in ozone impacts among the major classes of VOCs are sufficient to make the effort of researching and implementing reactivity-based regulations worthwhile. The hypothesis is whether or not reactivity scales that are calculated through threedimensional regional air quality modeling, can offer a quantitative measure to rank different organic species, based on their relative importance in photochemical ozone production, and if such scale could prove useful and applicable in developing and evaluating VOCbased pollution control strategies. In particular: • Are VOC reactivity scales stable and robust? * With respect to different regions? * With respect to varying meteorologies? * With respect to changing emissions? • Are species’ reactivities different enough from each other to warrant using a regulatory mechanism to account for the variations in reactivities? • Are multi-dimensional air quality models the appropriate tools to develop reactivity scales? While the overall objective of this project is to generate scientific evidence in support of EPA’s reactivity policy with respect to emissions controls for attainment of the air quality standards, the specific goal is to: • Perform modeling and analyses using existing state-of-the-art systems like MAQSIP and SMOKE to provide data on the effectiveness of substituting less reactive organic emissions for more reactive ones Thus, the hypothesis that we want to test is: “Can we can develop methods and means to assess individual reactivities of volatile organic compounds (VOCs) in quantifying changes in ozone related metrics?”