US Environmental Protection Agency (EPA)

National Clean Diesel Campaign

Building on the successes of EPA’s regulatory and voluntary efforts to reduce emissions from diesel engines, EPA created the National Clean Diesel Campaign (NCDC) to work aggressively to reduce the pollution emitted from diesel engines across the country through the implementation of varied control strategies and the aggressive involvement of national, state, and local partners.

EPA Sector Programs

EPA currently has programs focusing on Clean School Bus, Ports & Marine, Clean Construction, SmartWay Transport, and Clean Agriculture.

Smartway Transport

A voluntary program between EPA and the freight industry that will increase the energy efficiency while significantly reducing air pollution and greenhouse gases.

Truck and Bus Engine Emissions Standards

Guidance, regulations, and general information on emission standards for heavy-duty highway diesel engines and vehicles.

Nonroad Engine Emission Standards

General information, reports, and proposals for nonroad engine emission standards (e.g., marine diesel engines).

US Department of Energy (DOE) Clean Cities

National Idling Reduction Network News

Vehicle Technologies Program

Alternative Fuels Data Center

Custom Alternative Fuels Comparison Chart (PDF)


US Department of Transportation (DOT)

Federal Highways Administration Air Quality Website

U.S. Department of Transportation's Congestion Mitigation Air Quality CMAQ Program

Transportation & Toxic Air Pollutants