On the Assessment of Ozone Control Policies for the Northeastern United States

Abstract

Currently, increased attention is being paid to the nation’s smog problem in major urban areas because of the lack of a sustained improvement in meeting and maintaining the National Ambient Air Quality Standard (NAAQS) for ozone. The efficacy of various emission control policies at the urban and regional scale can be examined through the application of grid-based photochemical models (NAS, 1991). In this paper, we report on the use of the Regional Oxidant Model (ROM) in the eastern United States for two ozone conducive events in examining the response of ozone concentrations to NOx- and VOC- focussed emission control strategies. As expected, the results indicate that the predicted peak ozone levels decrease as emissions are reduced, but the amount of improvement in ozone concentration levels is strongly dependent upon the prevailing meteorological conditions. ROM simulations reveal that NOx-focussed controls are more effective in reducing the areal extent of the ozone exceedances than VOC- focussed controls. Further, the improvement in the peak ozone levels over urban areas from the base case for the VOC-focussed scenario is found to be comparable to that of the NOx-focussed scenario. However, the peak ozone in rural areas are found to respond more favorably to NOx- focussed controls rather than to VOC-focussed controls. These results demonstrate the need for region-wide NOx and urban-specific VOC control strategies to attain the ozone NAAQS throughout the eastern United States.