Standards for the levels of pollutants emitted from automobiles and trucks. Congress established the first standards in the Clean Air Act of 1963. Currently, standards are set for four vehicle classes - automobiles, light trucks, heavy duty gasoline trucks, and heavy-duty diesel trucks. (DOE6)

Rules and regulations that set limits on how much pollution can be emitted from a given source. Vehicle and equipment manufacturers have responded to many mobile source emission standards by redesigning vehicles and engines to reduce pollution.

Regulatory standards that govern the amount of a given pollutant that can be discharged into the air from a given source.

Governmental regulations that establish limits on polluant released into the environment.