The EPA county radon maps were developed based on limited "radon test data" that is now 20+ years old. Greenville County is the ONLY "Zone 1 county" in our state (homes "average" 4 picocuries or above). The rest of the counties in the upstate are designated ZONE 2 counties (Meaning the homes "average" between 2 and 4 picocuries). However, you can see from the map below a listing of ciities in these same counties that we have installed radon systems in (over the past 10 years) because houses with "double digit levels" were found in each for these counties. We even had someone from CHARLESTON call us about potential work!
OUR belief is that you can't make "assumptions" about the radon levels in ANY house regardless whether its in a county Like Greenville) that is "Zone 1" or other counties that are "Zone 2" or "Zone 3". One of the worst homes were asked to fix was a "new house" the builder called us to in Spartanburg County. The prospective buyer ordered a home inspection as well as a "radon test" The results came back at "50 picocuries". What if that family had not opted to test and simply believed the EPA maps that homes in "Zone 2" shouldn't have a problem? The same is true on any real estate transaction
The ONLY way to KNOW if a given house has a problem is to get your home tested! Our mantra is... "Test before you invest!"