12 February 1998

The US Environmental Protection Agency (EPA) and Justice Department are investigating some American on-highway diesel engine manufacturers. Apparently, heavy-duty diesel engines produce more emissions in operation than they do during certification testing. If confirmed, it would be a violation of the Clean Air Act.

EPA said engine manufacturers may be circumventing engine-certification procedures by designing engines to run cleaner during testing than during highway operation. "EPA is working with the engine manufacturing industry and the California Air Resources Board (CARB) to fully understand and resolve the issue," the agency said.

The investigation was apparently triggered by a letter from Richard Kassel, a senior attorney for the Natural Resources Defense Council environmental group, who wrote President Clinton and EPA Administrator Carol Browner, claiming that engine manufacturers have apparently programmed engines for different emission levels in tests than on the highway and that these manufacturers may be violating the Clean Air Act be using emissions-cheating "defeat devices".

Source: Wall Street Journal