(WJET/WFXP/YourErie.com) — The Pennsylvania Department of Environmental Protection (DEP) and the Department of Health (DOH) are encouraging Pennsylvania residents to test their homes for radon.

Radon is an invisible, odorless, radioactive gas. It enters homes from the ground as uranium and radium breakdown in the rocks and soil. Pennsylvania’s geology has led to some of the highest levels of radon in the United States, according to a joint statement from both departments.

Long-term exposure to radon is the second leading cause of lung cancer (smoking is the first).

According to the DEP and DOH, 40% of homes in Pennsylvania have a higher level of radon gas than federal guidelines.

A radon test can be bought at hardware stores for about $20. In general, the test will be placed in the home’s basement or on the lowest level closest to the ground. Winter is the best time to test for radon because windows are typically closed and that will provide more accurate results. The test is then mailed to a laboratory.

If radon levels are higher than the U.S. Environmental Protection Agency recommended guideline, a radon reduction system can be installed to vent the gas. The cost ranges from $800-$1,200, the joint statement said.

“We should take radon awareness seriously, as it could pose potential health risks,” said acting Secretary of Health and Pennsylvania Physician General Dr. Denise Johnson. “The danger in radon exposure is that you can’t see it, taste it, or smell it. And you won’t have any symptoms to alert you, but over time if you are breathing in high levels of radon, it can cause lung cancer. I encourage you to get your home tested and fixed to improve your and your family’s health and safety.”

The DEP website provides radon information and resources.