Vehicular air pollution: heavy-duty vehicles.

Existing law imposes various limitations on emissions of air contaminants for the control of air pollution from vehicular and nonvehicular sources. Existing law generally designates the State Air Resources Board as the state agency with the primary responsibility for the control of vehicular air pollution. Existing law defines a heavy-duty vehicle as having a manufacturer's maximum gross vehicle weight rating of 6,001 or more pounds, a light-duty vehicle as having a manufacturer's gross vehicle weight rating of under 6,001 pounds, and a medium duty vehicle as a heavy-duty vehicle having a manufacturer's gross vehicle weight rating under a limit established by the state board.