Radon is a cancer-causing, radioactive gas. You can’t see, smell, or taste radon, but if you’re breathing in air containing high levels of radon, you can get lung cancer. The Surgeon General has warned that radon is the second leading cause of lung cancer. If you smoke and your home has high levels of radon gas, your risk of lung cancer is especially high. –EPA, A Citizen’s Guide to Radon, January 2009.