EPA has proposed setting more stringent quality requirements for diesel fuel. With the exception of routine auditing of new engine certification, the federal government does not generally regulate emissions from diesel engines once they are sold to the end user. However, in 1993, new requirements issued by EPA became effective for one category of heavy-duty highway diesel engines used in urban bus applications. An increasing number of states have regulations and enforcement programs that target excessive smoke from diesel engines. In these states, operators of diesel engines suspected of emitting excessive smoke emissions are required to undergo a roadside smoke emissions check.
Some states require the same type of test be administered on an annual basis.
Diesel fuel used for nonroad applications has sulfur levels of roughly 3300 ppm. Reg at 26148. All Rights Reserved.