You can鈥檛 see radon, and you can鈥檛 smell it or taste it. But, radon, also known as 鈥渢he silent killer,鈥 could be present in your home at dangerous levels. Radon is a radioactive gas that occurs naturally in soil. Outdoors, radon levels are low because they are diluted. Inside, radon enters homes and buildings from the soil through cracks in concrete floors and walls, floor drains, sump pits, etc. Indoor radon levels can build up over time, increasing the risk of developing lung cancer from prolonged exposure to breathing air with elevated radon levels. EPA has designated January as . Read on for five facts about radon and how you can take radon action this year.