Ultra Low Sulfur Diesel (ULSD) fuel and new engines and vehicles with advanced emissions control systems offer significant air quality improvement. U.S. Environmental Protection Agency (EPA) standards designed to improve air quality have led to a major reduction in the sulfur content of diesel fuels.
To meet the EPA standards, the petroleum industry produces ULSD, a cleaner-burning diesel fuel containing a maximum of 15 parts-per-million (ppm) of sulfur. Most engine manufacturers also allow biodiesel blends in concentrations up to five percent provided those blends meet accepted fuel quality standards.
ULSD is designed to facilitate cleaner engines, and with good lubricity and corrosion inhibitors to prevent unacceptable engine wear. In combination with cleaner-burning diesel engines and vehicles, ULSD helps to improve air quality by significantly reducing emissions.
For more information: http://www.clean-diesel.org/pdf/ulsd_issue_paper.pdf