- US EPA Heavy-Duty Highway Engines page
- EPA information on truck and bus emissions. Includes heavy-duty engine emission regulations, fact sheets, Urban Bus Retrofit/Rebuild notices.
- US EPA Heavy-Duty Highway Diesel Program
- EPA information on the 2007 diesel emission and diesel fuel regulation.
- US EPA HD Highway Engines Consent Decrees
- Information on Consent Decrees reached in 1998 between the EPA and US HD engine manufacturers on the issue of off-cycle NOx emissions (see Decrees dated 10/22/1998).
- “Asleep at the Wheel”
Committee on Commerce, US House of Representatives, March 2000A report outlining the history of events leading to the EPA - engine manufacturers Consent Decree and charging the EPA with failure to enforce emission standards for heavy-duty diesel trucks.
- US EPA Nonroad Diesel Engines
US EPAInformation on nonroad diesel engine emission regulations.
- Nonroad Engines, Equipment, and Vehicles
US EPAInformation on emission legislation fro nonroad diesel engines.
- California Urban Transit Bus Regulations
California Air Resources BoardInformation and regulatory documents on California emission regulations for urban buses.