Programs

Most heavy-duty vehicles are powered by diesel engines that, without pollution controls, can emit high levels of other pollutants that contribute to global warming  and local air pollution.  For example, uncontrolled diesel vehicles produce high levels of particulate matter, a fraction of which has a warming effect, and nitrogen oxides, which are an ingredient of ozone (also known as smog), an important greenhouse gas. These pollutants are associated with bronchitis, asthma, and other lung diseases, and are responsible for millions of premature deaths worldwide. A number of scientific agencies, including the World Health Organization, the U.S. Environmental Protection Agency, and the California Air Resources Board, have determined that diesel exhaust is a likely or probable human carcinogen.