This summary describes a government and industry cost-shared project to determine the impact of fuel sulfur levels on emission control systems that could be used to lower emissions of nitrogen oxides (NOx) and particulate matter (PM) from compression ignition, direct injection (CIDI) diesel-cycle vehicles. The sulfur in diesel fuel adversely affects the operation of diesel exhaust emission control systems. Tests were conducted and data were collected and analyzed for various combinations of fuel sulfur levels, engines, and exhaust emission control systems.

Diesel engines are used to power most heavy vehicles, as well as some light trucks, minivans, and automobiles. Engine exhaust emission standards will be more stringent for all vehicles, including light trucks and sport utility vehicles (SUVs) as new federal regulations are implemented. The U.S. Environmental Protection Agency (EPA) has announced emission standards for heavy-duty trucks that manufacturers will have to meet starting in 2007. These standards require that NOx emissions be reduced by 75%–90% and PM emissions by 80%–90%, compared with current standards. EPA also announced lower emission standards for passenger vehicles, requiring that their emissions be 77%–95% cleaner than current emissions and that sulfur in gasoline be reduced by as much as 90% from today’s level. These new standards are to be phased in beginning in 2004.

Download the report here: Diesel emissions control – Sulfur effects project (DECSE)