Radon is a naturally occurring gas produced by the breakdown of uranium in soil, rock and water. Air pressure inside your home is usually lower than the pressure in the soil around your homes foundation. Because of this difference in pressure, your home acts as a vacuum, drawing radon in through foundation cracks and other openings. Radon may also be present in well water and can be released into the air in your home when water is used for showering and or other household uses. In most cases, radon entering the home through water is a small risk compared to radon entering your home through soil. In a small number of homes, the building materials can give off radon, although building materials rarely cause radon problems by themselves.

Radon is estimated to cause many thousands of lung cancer deaths each year. In fact, the surgeon general has warned that radon is the second leading cause of lung cancer in the United States. If you smoke and your home has high radon levels, your risk of lung cancer is especially high.