Radon is the second leading cause of lung cancer after cigarette smoking. If you smoke and live in a home with high radon levels, you increase your risk of developing lung cancer. Having your home tested is the only effective way to determine whether you and your family are at risk of high radon exposure.

Radon is a radioactive gas that forms naturally when uranium, thorium, or radium, which are radioactive metals break down in rocks, soil, and groundwater. People can be exposed to radon primarily from breathing radon in the air that comes through cracks and gaps in buildings and homes. Because radon comes naturally from the earth, people are always exposed to it.