TUESDAY, Jan. 20, 2015 (HealthDay News) -- Americans should test their homes for a naturally occurring radioactive gas called radon, the U.S. Environmental Protection Agency says.

"Many people don't realize that radon is the second cause of lung cancer after smoking," EPA Administrator Gina McCarthy said in an agency news release.

"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," she added.

Each year, lung cancer caused by radon exposure kills about 21,000 Americans, the EPA says. Testing is the only way to know if your home has elevated levels of radon. You need to take action to reduce the radon level in your home if it is at or above 4 picocuries per liter (pCi/L) of air, according to the U.S. Surgeon General.

Do-it-yourself radon testing kits are available online and at many home improvement and hardware stores. Another option is to hire a qualified radon professional, the EPA said.

If your home has elevated radon levels, a radon-reduction system can be installed to remove radon from beneath your home and harmlessly discharge it outdoors. These systems have a vent pipe and exhaust fan.

If you're building a new home, ask your builder to use radon-resistant construction methods, the EPA said.

SOURCE: U.S. Environmental Protection Agency, news release, Jan. 15, 2015