Cleaning Up Diesel Emissions in Mexico City
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
Mexico City's air pollution, with ground-level ozone and particulate matter exceeding national standards for 80 percent of the year, affects the health and quality of life of all its residents. Heavy-duty diesel vehicles-buses, trash trucks, commercial vehicles-contribute up to 38 percent of the nitrogen oxides and more than 50 percent of the fine particulates in the air, despite comprising only 5.5 percent of the entire vehicle fleet. Emissions from diesel trucks and buses pose serious public health concerns, ranging from asthma to cardiovascular disease to cancer.
Working with the U.S. Agency for International Development (USAID) and EMBARQ (the World Resources Institute's Center for Transport and the Environment), EPA initiated the Mexico City Diesel Retrofit Project in June 2004. The project was designed to demonstrate how the combined use of low-sulfur fuels (15 parts per million) and diesel retrofit technologies on urban buses can improve air quality and reduce adverse effects on human health. The project is similar to diesel retrofit projects now underway in several U.S. cities that have committed to retrofit more than 150,000 diesel vehicles. The Mexico City Diesel Retrofit Project is the first international retrofit project of the United States; already it is serving as a model for EPA projects in other areas of the world.
The technologies used for the demonstration project are diesel particulate filters and diesel oxidation catalysts that have been performance verified under EPA's Environmental Technology Verification program. The project developed key information on costs and emissions reductions and is leading to policy recommendations for reducing emissions from other fleets in Mexico City and other cities in Mexico. It also was a concrete demonstration for the benefits of ultra low-sulfur fuel. Mexico has since passed a regulation requiring ultra low-sulfur fuel for the U.S.-Mexico border and for the nation.
Ultra low-sulfur diesel fuel was provided by a U.S. refinery for 20 buses involved in the demonstration. The buses were retrofitted, labeled, and operated on the streets of Mexico City. The Centro de Transporte Sustentable performed baseline emissions testing and then tested one month after the retrofits were installed and at the end of the demonstration (after about 11 months of operation). The testing determined how much the emissions were reduced by the cleaner fuels and cleaner vehicle technologies.
Test results show reductions of 86 to 92 percent in the particulate emissions from the newer vehicles using diesel particulate filters and ultra low-sulfur fuel and 10 to 23 percent reduction from the older vehicles using diesel oxidation catalysts (a technology most useful for older buses). Although the project size was limited, the potential is great-there are more than 3,000 buses in Mexico City.