radon gas risk 6

https://wiki-wire.win/index.php/Why_Radon_O%27Fallon_IL_Homeowners_Should_Test_Their_Basements

Radon gas is a naturally occurring radioactive substance that can seep into homes from the ground, often through cracks in foundations. It's the leading cause of lung cancer among non-smokers, and you can't see or smell it. Testing your home is the only way to know if levels are high, and mitigation systems can reduce risk.