Radon is a colorless, odorless, radioactive gas that occurs naturally in soil, rocks, underground water supplies, and in the ambient air. According to the U.S. Environmental Protection Agency (EPA) and other scientific organizations, naturally-occurring radon gas has been associated with an increased risk of developing lung cancer. The chance of developing lung cancer from radon exposure is dependent on several factors, including individual susceptibility and, perhaps more importantly, the dose and duration of exposure. The EPA and other major national and international scientific organizations have concluded that radon is a human carcinogen and a serious environmental health problem. Radon gas typically moves up through the ground into the air in buildings through subsurface wall and/or floor cracks, floor drains, and construction joints and pipes. The water supply may also be a source of radon exposure.
The EPA and the Minnesota Department of Health (MDH) advise schools to test for radon after any renovation to the building or HVAC system, or periodically, such as every 5 years and to reduce levels to below 4 picoCuries per Liter (pCi/L).