Impact of sulfur-in-gasoline on motor vehicle emissions in the metropolitan area of Mexico City

Light duty gasoline vehicles account for most of CO, hydrocarbons and NOx emissions to the urban environment in Mexico City. From the beginning of year 2001, vehicles comply with Tier I emissions standards. Two types of Regular gasoline are available in the country. In those ozone non-attainment areas Regular oxygenated gasoline with an average of 450 ppm S is available, while on the rest of the country, a gasoline of 750 ppm S, is sold. It is anticipated then that many or all Tier I vehicles in ozone non-attainment zones would be occasionally or regularly fueled with high sulfur gasoline. In this work we evaluate the impact of sulfur on new, and in-use vehicles model years 1993-2001 with gasoline ranging from 90 to 815 ppm S. It is interesting to note that for Tier 0 vehicles, CO emissions are above the standard limits at all sulfur levels, while Tier I vehicles are very close to the limits for NOx emissions. (C) 2003 Elsevier Science Ltd. All rights reserved.