1997 Data Radon Radon is a naturally-occurring radioactive gas that is the second leading cause of lung cancer in the United States.
Radon is by far the greatest single source of radiation to the general public.
Since radon is a gas, it can easily enter homes and other buildings. While radon in outdoor air is diluted to very low levels, radon inside homes may accumulate to dangerous levels. Homes with ground contact, that is, homes with basements, walkouts, or crawl spaces, or those built on slabs, are more likely to have elevated radon levels, subjecting residents to higher exposures. Individuals who smoke and who are also exposed to radon are at an even higher risk of developing lung cancer. The only way to know whether you and your family are being exposed to radon is to test your home for radon.