Radon is a colorless, odorless, radioactive gas that occurs in nature as uranium breaks down in the soil and rocks. It can get into homes and accumulate amounts that are known to cause lung cancer. 

Radon is the leading cause of cancer among non-smokers and the second leading cause of lung cancer in the U.S.

The only way to know if radon is present in dangerous amounts is by testing. 

I recommend having this test. The counties I serve are in EPA Zone 5. This Zone has the most likelihood of the test showing an elevated reading above the 4pCi/liter level and requiring mitigation. Mitigation involves having a system to lower levels of radon installed by a licensed Mitigation expert.