HARRISBURG, Pa. (WHTM) — Pennsylvania leaders and advocates are encouraging residents to test for radon in their homes as part of National Radon Action Month.

Radon is an invisible, odorless radioactive gas that can cause lung cancer with long-term exposure, the Pennsylvania departments of Environmental Protection (DEP) and Health (DOH) said. The gas enters homes from the ground due to the breakdown of uranium and radium in rocks and soil, the departments explained.

“Forty percent of homes in Pennsylvania have a higher level of radon gas than federal guidelines,” said DEP Acting Secretary Ramez Ziadeh. “Because radon levels vary from home to home based on local geology and house foundation type, all Pennsylvanians should test their home to protect themselves and their families.”

“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,” Acting Secretary of Health and Pennsylvania Physician General Dr. Denise Johnson said.

Allegheny County resident Jackie Nixon knows this first-hand. She didn’t smoke and was a lifelong fitness practitioner, but she was diagnosed with lung cancer. Then she discovered that there were high levels of radon in her condominium building, the DOH and DEP explained.

“There was no other explanation that made sense for my lung cancer,” said Nixon. “I’m happy to share my experience if I can help other Pennsylvanians learn about the risk of radon gas in their home.”

Radon tests can be purchased from hardware stores for about $20, or residents can hire a professional radon tester, the DEP and DOH said.

They noted that winter is the ideal time to test for radon because doors and windows are typically kept closed, facilitating more accurate results.