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Naturally-occurring radiation accounts for approximately 80 percent of our exposure. Most of our exposure is to indoor radon, followed by radiation from outer space and from the earth's crust.
Radon
Sixty-eight percent of our exposure to natural sources of radiation usually comes from radon. Radon is a colorless, tasteless, and odorless gas that comes from the decay of uranium found in nearly all soils. Levels of radon vary throughout the country. Radon usually moves from the ground up and migrates into homes and other buildings through cracks and other holes in their foundations. The buildings trap radon inside, where it accumulates and may become a health hazard if the building is not properly ventilated.
When you breathe air containing a large amount of radon, the radiation can damage your lungs and eventually cause lung cancer. Scientists believe that radon is the second leading cause of lung cancer in the United States. It is estimated that 7,000 to 30,000 Americans die each year from radon-induced lung cancer. Only smoking causes more lung cancer deaths and smokers exposed to radon are at higher risk than nonsmokers.
Controlling the Risks from Radon Exposure
Radon is found all over the United States. Scientists estimate that nearly one out of every 15 homes in this country has radon levels higher than four picocuries per liter, the level above which EPA recommends that homeowners take corrective action. Picocuries per liter is how radon in the air is measured. Testing your home is the only way to know if you and your family are at risk from radon.
Testing for radon is easy and only takes a few minutes of your time. There are many kinds of low-cost, "do-it-yourself" radon test kits available through the mail or from retail outlets. You can also hire a professional to do the testing.
To find a qualified professional, check with your State Radon Contact. Some states maintain lists of contractors who work in their state and states may have proficiency programs or requirements of their own. You can also contact a privately-run radon proficiency program. EPA is aware of two private programs offering proficiency in radon testing and mitigation. However, please be aware that reference to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply that the United States Government endorses, recommends, or favors them.