(The following story by Chris Bowman appeared on the Sacramento Bee website on November 28.)
SACRAMENTO, Calif. — Air pollution tests results released Wednesday confirm that residents living just downwind of the Roseville train yard face a sharply higher cancer risk from diesel exhaust than those living along nearby Interstate 80, a stretch traveled by an average 10,000 big rigs a day.
Leaders of the study said the exhaust from idling Union Pacific locomotives contains five to six times more of the most potent cancer-causing particles than emissions from diesel-powered trucks on freeways.
And those particles are smaller, allowing for easier passage to the deepest recesses of the lungs where they can cause the greatest harm, the scientists said.
The toxic exhaust components of greatest concern are polycyclic aromatic hydrocarbons, a group of compounds known to cause cancer. The scientists traced the source of these compounds to the burning of locomotive engine oil, rather than the combustion of the diesel fuel.
The air samplers also picked up unexpectedly high levels of toxic metals such as lead. The researchers said the metals most likely came from the dirt surfaces of the train yard, where locomotives across the West have been serviced for decades.
The peer-reviewed study was conducted by Thomas A. Cahill, retired atmospheric physics professor at the University of California, Davis, and his son, Thomas M. Cahill, an assistant professor of environmental toxicology at Arizona State University.
The Cahills did the work as volunteers on behalf of the Sacramento area chapter of Breathe California, a clean-air advocacy group.
The pair recommended several ways to lower residents’ health risks. Paving the yard would cut down toxic dust. Planting rows of tall trees along the edges of the yard would filter out a good portion of the diesel exhaust particles, as would installation of electrostatic air filters in homes.