New Diesel Engines Emit 90 Percent Less Soot, Smog

A new generation of diesel engines for trucks and buses has slashed harmful exhaust, including soot and smog-causing hydrocarbons, by more than 90 percent, according to a new study. Conducted by the Boston-based nonprofit Health Effects Institute, the study showed that the new diesel engines — some of which are already in use — have so sharply reduced harmful pollution that they far exceed emissions reductions targets set by the U.S. Environmental Protection Agency. The study said that ultra-fine particulates — the tiny pieces of soot that can lodge in lungs and cause respiratory and heart problems — are 99 percent lower in 2007-model trucks and buses than in 2004 models. Smog-causing hydrocarbon emissions in the new “clean-diesel” engines are 95 percent lower than in older models. The new engines are so much cleaner, the study said, that it would take 60 of the new truck or bus models to emit the same soot as one 1988 model. The spread of the new clean-diesel engines is expected to improve public health in major metropolitan areas, such as Los Angeles and New York, that have high levels of particulate air pollution caused by older diesel engines.