ROCKFORD, Ill. (WTVO) — Doctors are using January to bring awareness to a unseen killer which could be lurking in your home.

Radon is a radioactive gas that forms from the decay of certain elements in the ground. The gas can enter the home through the basement, and is common in counties along the Stateline.

Nationwide, radon is responsible for more than 20,000 lung cancer deaths each year and is the second-leading cause of lung cancer aside from smoking.

Dr. Iftekhar Amad, a radiation oncologist at OSF HealthCare, said, “If you are in an environment and you find out down the line that there was high levels of radon here, or you’re not sure, but you suspect…you just want to be more vigilant about your breathing and lung health.”

The best way to find out if your home contains high levels of radon is to have it tested. You can hire a professional or do it yourself with a radon test kit.