While scientists have known that breathing bad air such as Sacramento sometimes experiences is harmful, they have never pinpointed what it is in fine particles that causes conditions usually associated with smoking such as lung disease.

Now a piece of the pollution puzzle has snapped into place with new findings from Louisiana State University.

Led by chemist H. Barry Dellinger, LSU researchers have discovered that free radicals, similar to those in cigarettes, exist in polluted air. Furthermore, they found that free radicals often persist for days or even indefinitely.

Kent Pinkerton, director of the University of California, Davis, Center for Health and the Environment, said the LSU study is significant in changing scientific perceptions of free radicals as being short-lived.

"If certain forms of free radicals are actually persistent, that increases chances they may interact with biological cells to create damage," Pinkerton said.

Even a day of air that meets federal standards set by the Environmental Protection Agency exposes people to as many harmful free radicals as smoking one cigarette, the researchers learned. But breathing heavily polluted air could expose a person to 100 cigarettes' worth of free radicals in one day, researchers said.

LSU researcher Dellinger said this is the first time that free radicals have been proved to exist in fine airborne particles, and the first time that scientists have seen them persist in air for days or even indefinitely. Particles that contain metals such as copper or iron are most likely to have persistent free radicals, Dellinger said.

Free radicals are atoms, molecules and ions with unpaired electrons that form during combustion and other chemical processes. Because they seek electrons, they are usually unstable and highly reactive. When they enter the body and come into contact with cell membranes, they undergo reactions and cause these membranes to become leaky, Pinkerton said.

Damage can reach a point at which it is irreversible and leads to cell death. A cascade of events takes place that under normal circumstances help remove dead cells from the body, but when the process gets out of control, injury occurs, according to Pinkerton.

The LSU research suggests that free radicals in airborne fine particles may cause diseases like asthma and heart disease. The discovery may also help explain why nonsmokers get tobacco-related diseases such as lung cancer, Dellinger said.

Sacramento is not the only place where free radicals are a concern. "There will always be some particles present in air, regardless of where you're at," Pinkerton said.

However, with air quality often poor, the Sacramento region may present greater exposure to free radicals than other places.

"There are many instances where if we have a bad air quality day, that concentration in air could be similar to a home where smoking is taking place," Pinkerton said.

Dellinger used the technique called electron paramagnetic resonance to determine free radicals existed in air particles. As he measured each sample, he found free radicals every time, at concentrations varying from the equivalent of smoking one cigarette per day to smoking 100 cigarettes per day.

Dellinger presented his team's findings Sunday at the American Chemical Society meeting.

Now that his team has proved persistent free radicals exist in polluted air, Dellinger believes the next step is a large study of the human health effects from exposure to free radicals. Though many studies have shown fine particles cause deaths, there has been little success correlating particle components with effects, he said.

"Now we have something we can measure," Dellinger said.

Call The Bee's Jane Liaw, (916) 321-1074.