Effects of Fuel Sulfur Content on Predicted Ozone for Years 2005/2010 — Auto/Oil Air Quality Improvement Research Program 932728

The effect of gasoline sulfur content on urban ozone was estimated using the Urban Airshed Model (UAM) and exhaust emission measurements from the Auto/Oil Air Quality Improvement Research Program (AQIRP) Phase II sulfur study. Ozone modeling was conducted for Los Angeles in year 2010 and Dallas-Fort Worth and New York in year 2005. Reducing fuel sulfur content reduced predicted ozone formation in all three cities. The light-duty vehicle contribution to predicted peak hourly ozone was reduced by 9, 16, and 8% in Los Angeles, Dallas-Fort Worth, and New York, respectively, when fuel sulfur content was reduced from 450 to 50 ppm. This corresponds to a reduction in total peak ozone from all sources of 0.8, 0.7, and 0.5% in Los Angeles, Dallas-Fort Worth, and New York, respectively, in year 2005/2010. There is uncertainty in these predicted effects; in particular, the effect of sulfur reduction expressed as a percentage of total peak ozone from all sources may be larger.