WASHINGTON (May 6, 2002) — The U.S. Court of Appeals unanimously upheld U.S. Environmental Protection Agency regulations that would reduce pollution by heavy trucks and buses and remove 97% of the sulfur from diesel fuel by 2007.

A group of oil refiners, auto makers, and diesel-engine manufacturers had argued that the rules and the deadline in particular were unreasonable. But the three-judge panel said the EPA didn’t have to explore “every engineering problem” that might be created by the changes as long as it gave industry time to solve them.

The regulations require diesel-engine manufacturers to reduce emissions by 95% over current levels by 2007. The removal of most of the sulfur from diesel fuel will allow them to use large catalytic converters to reduce pollutants in the vehicles’ exhaust stream. Fuels containing sulfur tend to interfere with the catalytic reaction.