Radon demonstrates that what you don’t see can hurt you. Radon is a radioactive gas that can seep undetected into our homes, mixing into the air we breathe and boosting our risk of lung cancer. Nearly one in 15 U.S. homes is believed to have an elevated radon level, the U.S. Environmental Protection Agency says, and the risk is especially high in most of Ohio. It’s a serious problem, experts say. Radon kills an estimated 21,000 people each year, according to the EPA. That’s m