This radon booklet is available in English and is developed by the U.S. Environmental Protection Agency in consultation with the American Medical Association (AMA). It is intended for physicians in the national effort to provide awareness of radon to the American public and the serious health risks posed by indoor radon gas. Physicians are in a unique position to play a vital role in informing the public about the common and serious risks of radon, and in educating their patients in testing procedures and remediation methods for correcting elevated indoor radon levels, thereby helping to reduce the number of lung cancer deaths. This booklet contains information regarding what radon is, its characteristics and sources, the health risk, the solution, as well as other indoor air pollutants.