Radon is a naturally occurring radioactive gas. It’s produced when uranium, thorium, and radium break down in soil, rock, and water. It’s then released into the air. Radon is odorless, tasteless, and invisible.

Radon gas can damage cells in your lungs, which can lead to cancer. Radon is responsible for about 21,000 lung cancer deaths each year in the United States, though it usually takes 5 to 25 years to develop.