Radon is a colorless, odorless, tasteless and chemically inert radioactive gas. Unless you test for it, there is no way of telling how much is present. Radon is formed by the natural radioactive decay of uranium in rock, soil, and water. Naturally existing, low levels of uranium occur widely in Earth's crust. It can be found in all 50 states.

The Surgeon General has warned that radon is one of the leading causes of lung cancer in the United States, second only to smoking. There are currently no conclusive data on whether children are at greater risk from radon than adults. If you smoke and you are exposed to elevated radon levels, your risk of lung cancer is especially high.

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, and the amount of time between exposure and the onset of the disease may be many years. In 1998, the National Academy of Sciences (NAS) released the Biological Effects of Ionizing Radiation (BEIR VI) Report, "The Health Effects of Exposure to Indoor Radon." The study reviewed and evaluated data from many prior studies and drew conclusions. It fully supports estimates by EPA that radon causes about 15,000 lung cancer deaths per year.

The National Safety Council offers low-cost short- and long-term radon test kits through its National Radon Hotline to people who want to test their homes. The price includes lab analysis and return postage. The kits need only be used according to directions on the package and then sealed and promptly returned to the lab for analysis. Results are provided within a few weeks, along with information on how to reduce radon risks, if necessary. For more information and a coupon for radon test kits, visit the Web site of the National Safety Council.