In recognizing January as National Radon Action Month, The U.S. Environmental Protection Agency (EPA) encourages Americans around the country to test their homes for this naturally occurring radioactive gas and make 2015 a healthier, safer new year.

“Many people don’t realize that radon is the second cause of lung cancer after smoking,” said EPA Administrator Gina McCarthy. “The good news is radon exposure is preventable. Testing and fixing for radon will save thousands of lives, prevent burdensome health care costs, and make America’s homes and schools safer for future generations.”

Each year about 21,000 Americans die from lung cancer caused by exposure to radon. Testing is the only way to know if a home has elevated levels of radon. The U.S. Surgeon General and EPA recommend taking action to reduce the radon level if it’s at or above 4 picocuries per Liter (pCi/L) of air.

Affordable do-it-yourself radon test kits are available online, at many home improvement and hardware stores, or you can hire a qualified radon professional.

If your test result is 4 pCi/L or more, you should contact a qualified radon-reduction or mitigation contractor.

A professionally installed radon reduction system removes the radon from beneath your home and discharges it harmlessly outside. That’s done by using a vent pipe and exhaust fan.

Taking action to reduce your exposure to radon is also a long-term health investment. A working mitigation system is a positive selling point for homes on the market; in many areas a radon test is a standard part of real estate transactions. If you’re building a new home, work with your builder to include radon-resistant construction techniques.