A new report from the Environmental Protection Agency (EPA) shows that some regions of the United States face greater health risks from air pollution than others.

The report, based on emissions data from 2002, estimates the local and regional concentrations of 181 different air pollutants, such as benzene, methylene chloride, and acrolein. EPA scientists looked at exposure from vehicles such as buses, trains, and automobiles; industrial contaminants; as well as other sources.

Eighty of those pollutants are thought to affect cancer risk. The report also looks at pollution's effect on respiratory and neurological health.

The agency found that approximately 1 out of every 27,000 Americans would develop cancer because of breathing polluted air -- if those individuals were exposed to 2002 emissions levels 24 hours a day for 70 years.

"In other words, for every million people, air pollutants add an additional 36 people who will develop cancer over a lifetime, according to the EPA models," says Michael J. Thun, MD, MS, American Cancer Society vice president emeritus of Epidemiology and Surveillance Research. "An additional 36 is a meaningful number in terms of policy and regulation, but it comprises a very small fraction [less than one out of 10,000 cancers] of background risk."

The lifetime risk of developing cancer from air pollution is down from 41.5 cases per million people from the last analysis, which came out in 2006 and was based on 1999 emission levels.

The report also found that people living in nearly 600 neighborhoods across the country are breathing higher concentrations of toxic air than in other parts of the country. For example, the increase in risk of developing cancer from air pollution is higher in areas of Los Angeles, California, known for its smog, than in less densely populated areas such as the Dakotas, Wyoming, and Montana. View a summary of the results and a map of the United States showing areas of high risk.

Emissions from vehicles accounted for about 30% of the overall average cancer risk from air pollution; most of this is due to benzene. Local industry emissions account for about 25 percent.

These data will be used to help states shape air-quality control plans required by the Clean Air Act. The Clean Air Act gives states the responsibility for regulating air pollution. Since the 1990 Clean Air Act Amendments, toxic air emissions have decreased by 40% from all sources, according to the EPA.

Studies using data from the American Cancer Society's Cancer Prevention Studies, specifically CPS-II, have contributed to the body of evidence that has established the link between cancer risk and air pollution in the form of particulates and ozone. These studies address a wide range of potential exposures that may be associated with cancer.

For more information about air pollution and cancer risk, see our sections on Air Pollution and Chemicals. For more information about the CPS studies, click here.

Reviewed by: Members of the ACS Medical Content Staff