What is radon?

Radon is a naturally occurring radioactive gas that you can't see, taste or smell. It is produced by the breakdown of uranium in soil, rock and water. All rocks contain some uranium, although most contain just a small amount. Certain types of rock, including granites, dark shales, light-colored volcanic rocks, sedimentary rocks containing phosphate, and metamorphic rocks derived from these rocks, have higher than average uranium contents.

High levels of radon have been found in all 50 states.

Indoor radon is the second leading cause of lung cancer after smoking.

How does radon get into my home?

Radon enters homes most commonly through:

§ cracks in foundations;

§ openings around sump pumps and drains;

§ construction joints; and

§ cracks in walls.

Radon is most concentrated in the lowest level of the home.

Radon may also be present in well water and can be released into the air in your home when water is used for showering and other household uses. Radon entering homes through water may be a small risk compared to radon entering though the soil.

Is radon really a problem?

Nearly 1 in 15 homes in the U.S. is estimated to have elevated radon levels. Elevated levels have been found in every state. While radon problems may be more common in some areas, any home may have a problem. In addition, the level of radon in a nearby home or building cannot be used to predict the level of radon in your home or building. Two adjacent houses may have very different radon levels. EPA recommends that all homes below the third floor be tested for radon and that all schools be tested.

The Surgeon General, the U.S. Environmental Protection Agency, the National Academy of Sciences, the American Medical Association, the World Health Organization and the American Lung Association have all identified indoor radon as a national health problem.

What health effects are associated with exposure to Radon?

An increased risk of lung cancer is the only known health effect associated with exposures to elevated radon levels. Radon does not cause any short-term health effects, such as shortness of breath, coughing, headaches or fever.

According to the U.S. Environmental Protection Agency (EPA), radon causes an estimated 7,000 to 30,000 lung cancer deaths per year.

Radon gas decays into radioactive particles that can get trapped in your lungs when you breathe. As they break down further, these particles release small bursts of energy. This can damage lung tissue and lead to lung cancer over the course of your lifetime. Not everyone exposed to elevated levels of radon will develop lung cancer.

Your chances of getting lung cancer from radon depend mostly on:

§ How much radon is in your home

§ The amount of time you spend in your home

§ Whether you are a smoker or have ever smoked

Smokers have a higher risk of developing radon-induced lung cancer.

As with all pollutants, there is some uncertainty in estimating health risks associated with radon. Because radon risk estimates are based primarily on scientific studies of humans (mostly miners exposed to different levels of radon in their underground work), scientists are considerably more certain of radon risk estimates than they are of estimates based solely on animal studies.

I understand that radon is a concern in some areas 
but not in others. 

Does my area have a radon problem?

Elevated indoor radon levels have been found in all areas of the country. Houses next door to each other can have very different levels. Some homes in low radon potential areas have been found to have high levels of radon. Conversely, some homes in high radon potential areas have been found to have low radon levels. The only way to know if your house has an elevated radon level is to test. EPA recommends that all residences below the third floor be tested for radon.

EPA and state agencies have identified areas with greater potential for elevated radon levels -- contact your state radon office for more information.

Is radon a problem in drinking water supplies?

Radon can enter a home through well water. It can be released into residences when the water is used for household purposes such as washing dishes and showering. The risk of radon entering homes through water is small compared with that of radon entering through the soil. On average, radon in water contributes about 5% of the total indoor air concentration in homes served by wells.

Generally, radon is not a concern with public drinking water systems, where the radon likely is released to outdoor air before reaching the home faucets.

Contact your state radon office for information about having your well water tested. For additional water safety information, contact EPA's Safe Drinking Water Hotline, (800) 426-4791.