EPA data shows that exhaust from diesel engines accounts for 78 percent of the total cancer risk from all hazardous outdoor air pollutants combined, according to an analysis by Environmental Defense.
The analysis is based on a massive EPA study, which provides detailed estimates of the levels of 41 top hazardous air pollutants in every community in the United States.
EPA''s previous version did not include information on diesel particulate emissions.
"The dominance of diesel in the unhealthiness of our air is a revelation," said David Roe, Environmental Defense senior attorney. "It couldn''t be seen before, only because studies weren''t trying to look for it."
Environmental Defense''s Web site, www.scorecard.org, is able to translate quantities of hazardous air pollutants into cancer risks, both nationally and at the local level. For any locality, see: www.scorecard.org/env-releases/hap/community.tcl.
"The bad news is that cancer risks from air toxics are much higher than the public has been told before. The good news is that a great deal of the air toxics problem can by addressed by focusing on just this one pollutant," said Roe. "Cutting diesel exhaust has to be priority number one for everyone concerned about the health of our air."
Diesel''s predominance leads to surprising results. For example, San Francisco shows a risk level of 2,600 additional cancer cases per million, with 90 percent of the risk coming from diesel emissions.
The goal set in the Clean Air Act for air toxics is a maximum of one additional case per million.
The air pollution comes both from diesel vehicles on the roads, like trucks and buses and from off-road equipment like bulldozers and heavy construction machinery.
"Offroad diesel equipment is a big part of the problem that most people don''t realize, and that is long overdue for emission controls," Roe said.
by Virginia Sutcliffe