Attaining the 8-hr Ozone Standard in East Texas: A Tale of Two Cities

摘要

The HGB and DFW 8-hr ozone SIPs are due to EPA by June 15, 2007, and must demonstrate attainment by 2010. Successful attainment demonstration may require a number of issues to be resolved, some unique to Texas and others applicable to other areas of the United States. In Houston, the combination of HRVOCs emissions and the sea breeze makes ozone attainment difficult. At issue are the relative importance of emissions events and sea breeze trapping of routine emissions. Model ozone predictions are also highly sensitive to the choice of chemical mechanism. Because of these factors, an ozone attainment demonstration for Houston needs to have much finer and more accurate representations of industrial emissions, meteorology, and ozone chemistry than for other nonattainment areas. Even if current 1-hr SIP measures for HGB were successfully implemented, remaining NO_x emissions would still resemble current DFW emissions (see Tables 1 and 2), requiring fur-ther reductions across all source categories. Ozone nonattainment is further exacerbated by the late effectiveness of federal measures for motor vehicles.