Radon Risk in South Carolina

South Carolina's statewide average radon level is 1.5 pCi/L, which falls well below the EPA's action level of 4 pCi/L. That's a reasonable baseline, but statewide averages can mask significant county-to-county variation. Some parts of South Carolina run considerably higher than others.

Looking at the zone breakdown: 1 of South Carolina's 46 counties are EPA Zone 1 (high risk), 8 are Zone 2 (moderate), and 37 are Zone 3 (low). That means 2% of the state falls into the highest risk category, counties where the EPA predicts average indoor levels above 4 pCi/L. Use the county list below to find your area and see the most specific data available.

Within South Carolina, the spread is notable. Oconee County has the highest measured average in the state at 4.8 pCi/L. Allendale County sits at the other end with 0.1 pCi/L. 1 county has a measured average above 4 pCi/L. Remember: these are averages. Individual homes can test significantly higher or lower than their county average depending on construction, foundation type, and ventilation.

Tipper's recommendation for South Carolina residents: if you haven't tested your home, start there. A short-term test kit costs around $15 and gives you a result in 48 hours. If your home tests at or above 4 pCi/L, a professional mitigation system (typically $800–$2,000 depending on your foundation and home size) will reliably bring levels down.