Radon is a naturally occurring, odorless, tasteless, radioactive gas produced by the breakdown of uranium in rocks and soil. It is harmlessly dispersed in outdoor air, but when trapped in buildings, can be harmful, especially at elevated levels.
Radon is the second leading cause of lung cancer, after smoking.
Radon comes from the soil surrounding and beneath the house, especially soil that contains uranium. It typically moves up through the soil into the air above and then into your home through cracks in foundations and walls, openings around sump pumps and drains, and construction joints. The highest concentrations of radon can be found in the lowest levels 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. The risk of radon entering homes through water is small compared with that of radon entering through the soil.