CAMx simulations of the control of anthropogenic emissions on the reduction of ozone formation in Southeast Texas of USA

Abstract

The elevated point and on-road emission sources have been identified to be the dominant anthropogenic categories contributing to ozone formation in Southeast Texas of USA. In this study, additional CAMx simulations were carried out to quantify the reductions of ozone concentration in response to the reductions of the two emission sources in the amount of 25, 50 and 75% from the Southeast region based on the summertime Ozone Episode provided by the Texas Commission on Environmental Quality (TCEQ). The simulation results were analyzed and reported in the form of Empirical Kinetics Modeling Approach (EKMA) diagrams and further confirmed through additional Ozone Source Apportionment Technology (OSAT) simulations available in CAMx. While the results are observed to be highly depending on the monitor station, they have indicated that the control of elevated point emissions is slightly more effective in ozone reduction than that of on-road emissions. Averagely, a sole reduction of 48.3% from the elevated point source, or a sole reduction of 61.0% from the on-road source, or a combined reduction of 30.0% each from the two sources are required to meet a potential future 8-h ozone NAAQS of 65 ppb. The current study has demonstrated that CAMx simulations are powerful for the practice and the developed methodology is beneficial to potential future practice when new ozone episodes become available.