Radon is a naturally occurring, invisible, odorless gas. Radon is a radioactive decay product of radium which is a radioactive decay product of uranium. Both uranium and radium are common day elements found in soil, rock and water.

Common Locations

Radon is released harmlessly into the outdoor air, but when it becomes trapped in buildings it can be harmful, especially at high levels. Radon comes into houses through foundation cracks or other floor openings such as drains, ductwork or pipes. Radon can also become trapped in underground water sources such as wells and enters the home through showering, washing clothes or other household water use but this is usually a much smaller risk.


The U.S. Surgeon General has determined that radon gas is a substantial risk. It is the second leading cause of lung cancer in the U.S. (behind smoking which causes nearly 90% of all lung cancers). Radon can cause cancer when it is inhaled into the lungs. In the lungs, radon decays which releases alpha particles that can damage DNA. The damaged DNA can lead to lung cancer.

How to Reduce/Prevent Radon Exposure

Radon is measured in picocuries per liter of air (pCi/L). The US Environmental Protection Agency and the Centers for Disease Control and Prevention recommend that people in homes with 4pCi/L or higher in household air or 300 pCi/L in water make changes to reduce the amount of radon in their homes. (It takes much higher levels of radon in water for significant health risks.) The most commonly recommended steps people take to reduce radon in their homes is to caulk cracks along basement foundations, seal leaks around pipes or installing a pipe and fan system to vent radon out from under the house. If water is the problem, water aeration or carbon filters may help.

Test Kits

You can get information and order test kits from the National Safety Council's Radon Hotline, 800-767-7236, or visit the North Carolina Radon Program website.