The U.S. surgeon general is warning the American public about the health dangers of breathing indoor radon (search).

Richard H. Carmona, MD, MPH, FACS, has issued a national health advisory on the radioactive gas, which can seep into homes and buildings and reach dangerous levels.

Americans should test their home's air for radon every two years, after a move, or when changes are made to the home, says the advisory.

Carmona issued the advisory during a two-day workshop on healthy indoor environments. A public service announcement about radon was also released to TV stations, since January is National Radon Action Month.

Radon is a well-established health risk. It’s America’s second-leading cause of lung cancer and is responsible for 20,000 lung cancer deaths per year in the U.S. Breathing the invisible, odorless, and tasteless gas over a period of time can increase the risk of lung cancer. Lung cancer would usually occur years after exposure.

There is no evidence that lung diseases such as asthma are caused by radon exposure, and there is no evidence that children are at greater risk of radon-induced lung cancer than adults.

Smokers have a much higher lung cancer risk if they also breathe too much radon.

Millions of homes have elevated radon levels, says a Department of Health and Human Services (HHS) news release. Radon levels are at or above the recommended level in 1 out 15 homes, according to the Environmental Protection Agency.

Radon occurs naturally in soil. Indoor radon can be detected with simple test kits. The EPA recommends that homeowners make radon-reducing alterations to homes if the radon level is 4 pCi/L (pico-Curies per liter) or more.

Different methods can be used to reduce radon in homes. Sealing cracks and other openings in the foundation is a basic part of most approaches to reduce indoor radon levels. In most cases, a system with one or more vent pipes and fans is used to reduce radon levels.

A radon level of 4 pCi/L or more should be fixed as soon as possible, says the HHS. But installing a venting system is not considered a do-it-yourself chore. “Repairs to decrease radon levels should be made by an EPA or state-certified contractor,” says the American Lung Association.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: News release, U.S. Department of Health and Human Services. American Lung Association.