HEI-sponsored study indicates drastic reduction in diesel PM emissions from vehicles

Diesel Fuel News, April 15, 2002

A Health Effects Institute study (see: www.healtheffects.org/Pubs/GertGros.pdf) shows that diesel [PM.sub.2.5] emissions from diesel trucks are only 10% of 1975 levels, while is only 40% of 1993 levels, according to measurements from the Tuscarora Mountain Tunnel in Pennsylvania, one of the few places to measure gasoline and diesel emissions side-by-side.

Meantime, diesel PM emissions are declining more rapidly than gasoline PM emissions. "Although gasoline engines emitted 10% less [PM.sub.2.5] than diesel engines, the [study] authors suggest that because gasoline-engine vehicles dominate the overall driving fleet, their contribution may exceed that of diesel engines," HEI's Spring 2002 newsletter noted. However, nitrogen oxides (NOx) emissions aren't declining, which "suggests that newer diesel engines designed to reduce NOx emissions are in fact being operated to improve fuel economy at the cost of NOx emissions," HEL said.