Radon is an odorless, tasteless and invisible gas produced by the decay of naturally occurring uranium in soil and water. Radon can seep into buildings from the surrounding soil. Radioactive particles from radon can damage cells that line the lungs and lead to lung cancer.

Radon is the second leading cause of lung cancer in the United States and is associated with 15,000 to 22,000 lung cancer deaths each year. Testing in existing buildings is recommended, and may be required for new construction.