Radon is a radioactive gas that naturally forms when radioactive metals such as uranium, thorium, or radium break down in rocks, soil, and groundwater. People can be exposed to radon primarily from breathing radon in air that comes through cracks and gaps in buildings and homes. Because radon comes naturally from the earth, people are always exposed to it. There is no ‘safe’ level of radon exposure. Look for weekly Radon Action month emails and our posts on social media to learn more about radon and how to test for it.