Learn about radon in your air and water. Radon is a colorless, tasteless and odorless gas that can cause lung cancer. It occurs naturally when uranium breaks down to radium which in turn breaks down to form radon. Radon is released into the soil and easily enters your home through the foundation and well water. It can build up to dangerous levels inside houses, schools, and other buildings. The only way to know if you have radon is to test. Why is radon a problem? Radon is the second leading cause of lung cancer in the United States, after tobacco smoke. Radon kills nearly 21,000 people each year, more than 800 of them in Georgia. Smokers are at an even higher risk of radon-induced lung cancer than nonsmokers by 7%.