The metropolitan area of Mexico City is the urban area of the country that presents the mast critical environmental problem due to fuel consumption. Attempting to reduce the ambient concentration of pollutants, the environmental program adopted consisted of a broad series of strategies designed to improve the air quality. Modification of fuel formulation, which include composition and physical properties, provide a particularly effective way to reduce emissions. The reformulated gasoline in Mexico has reduced aromatics, olefins, and benzene contents as well as a lower Reid Vapor pressure. The regulated emissions (carbon monoxide, total hydrocarbons, and nitrogen oxides) were evaluated for each vehicle as well as the speciated hydrocarbons present in the exhaust emission. With these data, we estimated the ozone-forming potential of the fuels and correlate the results with the technology of the vehicles. When these data are compared with those obtained in United States, there is an important difference in the technological devices related to emission control in vehicles of the Mexican market. Moreover, our results strongly suggest that emission standards for new vehicles said in Mexico must be tighten further in order equal those demanded in other countries.
