Chapter 6: Incremental Benefits of Attaining Alternative Ozone Standards Relative to the Current 8-hour Standard (0.08 ppm) Synopsis

Based on projected emissions and air quality modeling, in 2020, 28 counties in the U.S. with ozone monitors are anticipated to fail to meet an alternative ozone standard of 0.075 ppm for the 4th highest maximum 8-hour ozone concentration. This number falls to 11 for an ozone standard of 0.079 ppm, and increases to 89 for a standard of 0.070 ppm, and increases to 231 for an alternative standard of 0.065 ppm (see Figure 3.4 in Chapter 3). We estimated the health benefits of attaining these alternative ozone standards across the nation using the EPA Environmental Benefits Modeling and Analysis Program (BenMAP) using a two-stage analysis. In the first stage, we estimated the benefits associated with improving modeled air quality using known control technologies. These control strategies were sufficient to bring some, but not all, areas into attainment with the alternative standards. Thus, for some areas, the benefits computed during this first stage only represented partial attainment. In the second stage, we estimated the benefits of fully attaining the standards in all areas by using a “rollback ” method. This method reduced ozone concentrations at nonattaining monitors to a level that would just meet the standards. To estimate the benefits for the 0.075 ppm and 0.079 standards, we deviated from this two-stage approach. Instead, we used an interpolation technique (please see Appendix 6a fo