Free radicals are electrically charged atoms or molecules that are known to cause cell damage and have been linked to a variety of health conditions including heart disease and cancer. While scientists have long known that combustion produces free radicals, until now they had believed that the particles were unstable and persisted for no more than a second. In the current study, however, the researchers found that when released along with air pollutants from exhaust pipes, chimneys or smokestacks, free radicals bind to those pollutants and continue to exist over the long term.
"What I found out is that combustion-generated particles contain environmentally persistent free radicals," researcher Barry Dellinger said. "When the radicals are associated with particles, they can apparently exist indefinitely."
Air pollution that contains metals such as iron or copper is much less likely to dissipate or be filtered out of the atmosphere, and is therefore able to carry the so-called persistent free radicals for vast distances.
When persistent free radicals are inhaled, they directly damage lung tissue in ways that researchers believe could lead to asthma, emphysema, lung cancer or other diseases. Strikingly, the free radicals found in air pollution are nearly identical to those in cigarette tar.
"The implication is you can have the same environmentally related diseases by exposure to airborne fine particles that you can get from cigarettes," Dellinger said.
The existence of persistent free radicals might partially explain why lung diseases such as cancer or emphysema are not limited to smokers, he added.
Sources for this story include: www.washingtonpost.com.