"Radon is a radioactive gas that cannot be seen, smelled, or tasted. Radon gas is a natural substance that can be found in the dirt and rocks beneath houses, in well water, and in some building materials. It can enter homes through soil, crawlspaces, foundation cracks, floors, and walls. Once inside, it can sometimes become trapped in your home. All homes have some radon gas. Breathing high levels of radon can put you at risk for lung cancer. To see if your house has dangerous radon levels, you should test it.

Radon is measured in picoCuries per liter of air (pCi/L). Radon levels inside houses below 4 pCi/L are considered acceptable. If your home has radon levels above 4 pCi/L, you should take action." 

                           U.S. Department of Housing and Urban Development

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