Radon is a colorless, odorless, chemically inert, naturally occurring, radioactive gas that could be present in unhealthy concentrations in your home. Radon comes from the decay of heavy elements that may be present in the soil beneath your house. In the US, 1:15 homes have radon concentrations exceeding the EPA's 4.0 pCi/L recommended action level. Long term radon test kits are inexpensive and available at local hardware stores, online, or provided by some local community resources. The only way to know if radon is in your home is to perform a radon test.