There also is increasing evidence that diesel exhaust may cause lung cancer in humans. This proposal would cut 2.8 million tons of smog-causing nitrogen oxides emissions each year once the program is fully implemented. Emissions of soot would be reduced by 110,000 tons each year. To date, most diesel trucks and buses have not used pollution control devices such as catalytic converters, similar to the devices that have been used on cars for the last 25 years. To enable pollution-control technology to be effective on trucks and buses, diesel fuel must be significantly cleaner than it is today.
Diesel engines are more durable and have higher fuel economy than gasoline engines.
With lower-sulfur fuels and advanced technology, they also will be able to burn more cleanly as well.