Not even close. Obviously, it's nicer to jog where there is little or no vehicular traffic. But the air along the Charles River is not as bad as you might think, said Douglas Dockery, chairman of the department of environmental health at the Harvard School of Public Health.
The biggest pollution hazard along roadways comes not from gasoline-burning cars but from trucks that burn diesel fuel, said Bruce Hill, a senior scientist and air quality specialist at the Clean Air Task Force, a nonprofit, Boston-based group dedicated to restoring clean air through scientific research.
Storrow Drive and Memorial Drive, which run along the Charles, are classified as parkways, which means that commercial vehicles are not allowed to use them. But smaller diesels - and cheaters - do use those roads, he said, so the air along the river is not pristine.
"Diesel particles are eight times more toxic in terms of lung cancer than all other air toxin pollutants combined," Hill said. These particles are also tiny, which means they can easily penetrate lungs and other organs. "Anything that burns fuel causes air pollution," he said. "But the quantity of particles from diesel engines swamps that from gasoline," he added.
It is true that on days when air pollution is really bad there are spikes in the heart attack rate, Dockery said. "But these risks are very small.
"Clearly, the benefits of exercise far outweigh the risks from air pollution," he said. "The worst risk of all is not exercising."
E-mail health questions to foreman@globe.com.
