Radon is a naturally occurring radioactive gas, and you cannot see, smell or taste it, the Environmental Protection Agency says. Testing is the only way to know your level of exposure, and the EPA says all homes should be tested.

The gas comes from the decay of naturally occurring uranium in soil and water, according to the EPA. Exposure to radon is the second leading cause of lung cancer after smoking, the agency says, and it can have a big impact on your health and indoor air quality.

The EPA's advice is short: test, fix and save a life. Its website points readers to a radon test kit and to a page on risks and solutions that explains how to reduce exposure.

The site also lets you find out which radon zone you live in and connect with regional, state and tribal radon programs for local information. The EPA lists technical standards for radon professionals, answers to common questions and a customer care team that takes questions. The page was last updated on October 1, 2026.