Radon Levels Guide

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Radon in South Carolina: Levels by County and EPA Zones

Updated November 2026 · Data: EPA Map of Radon Zones · Sources

South Carolina has a mix of radon risk: 1 county is in EPA Zone 1 (highest potential), 8 in Zone 2 and 37 in Zone 3. Find your county below, then learn how to test your home and what to do if the result is high.

1 of 46counties in EPA Zone 1 (highest potential)
8 of 46counties in Zone 2 (moderate)
37 of 46counties in Zone 3 (low)

Your county’s zone is not your home’s radon level. Homes with high radon are found in every zone. The EPA recommends testing every home, whatever its zone.

Map of EPA radon zones by county

Greenville: EPA radon Zone 1Bamberg: EPA radon Zone 3Chester: EPA radon Zone 3Union: EPA radon Zone 3Florence: EPA radon Zone 3Saluda: EPA radon Zone 3Anderson: EPA radon Zone 2Greenwood: EPA radon Zone 3Charleston: EPA radon Zone 3York: EPA radon Zone 2Jasper: EPA radon Zone 3Beaufort: EPA radon Zone 3Chesterfield: EPA radon Zone 3Dorchester: EPA radon Zone 3Clarendon: EPA radon Zone 3Darlington: EPA radon Zone 3Dillon: EPA radon Zone 3Georgetown: EPA radon Zone 3Hampton: EPA radon Zone 3Lancaster: EPA radon Zone 3Lee: EPA radon Zone 3McCormick: EPA radon Zone 3Pickens: EPA radon Zone 2Sumter: EPA radon Zone 3Allendale: EPA radon Zone 3Abbeville: EPA radon Zone 2Williamsburg: EPA radon Zone 3Aiken: EPA radon Zone 3Horry: EPA radon Zone 3Colleton: EPA radon Zone 3Laurens: EPA radon Zone 2Fairfield: EPA radon Zone 3Kershaw: EPA radon Zone 3Oconee: EPA radon Zone 2Spartanburg: EPA radon Zone 2Berkeley: EPA radon Zone 3Edgefield: EPA radon Zone 3Orangeburg: EPA radon Zone 3Newberry: EPA radon Zone 3Lexington: EPA radon Zone 3Marlboro: EPA radon Zone 3Barnwell: EPA radon Zone 3Cherokee: EPA radon Zone 2Marion: EPA radon Zone 3Richland: EPA radon Zone 3Calhoun: EPA radon Zone 3
Zone 1 (highest potential)Zone 2Zone 3Source: U.S. EPA Map of Radon Zones (June 2024 data file). County boundaries: U.S. Census Bureau via us-atlas.

Radon zones by county in South Carolina

The table lists the EPA radon zone for each of the 46 counties in South Carolina. The zone shows the predicted average indoor radon screening level for homes in that county.

CountyEPA zonePredicted average indoor level
AbbevilleZone 22 to 4 pCi/L
AikenZone 3Below 2 pCi/L
AllendaleZone 3Below 2 pCi/L
AndersonZone 22 to 4 pCi/L
BambergZone 3Below 2 pCi/L
BarnwellZone 3Below 2 pCi/L
BeaufortZone 3Below 2 pCi/L
BerkeleyZone 3Below 2 pCi/L
CalhounZone 3Below 2 pCi/L
CharlestonZone 3Below 2 pCi/L
CherokeeZone 22 to 4 pCi/L
ChesterZone 3Below 2 pCi/L
ChesterfieldZone 3Below 2 pCi/L
ClarendonZone 3Below 2 pCi/L
ColletonZone 3Below 2 pCi/L
DarlingtonZone 3Below 2 pCi/L
DillonZone 3Below 2 pCi/L
DorchesterZone 3Below 2 pCi/L
EdgefieldZone 3Below 2 pCi/L
FairfieldZone 3Below 2 pCi/L
FlorenceZone 3Below 2 pCi/L
GeorgetownZone 3Below 2 pCi/L
GreenvilleZone 1Above 4 pCi/L
GreenwoodZone 3Below 2 pCi/L
HamptonZone 3Below 2 pCi/L
HorryZone 3Below 2 pCi/L
JasperZone 3Below 2 pCi/L
KershawZone 3Below 2 pCi/L
LancasterZone 3Below 2 pCi/L
LaurensZone 22 to 4 pCi/L
LeeZone 3Below 2 pCi/L
LexingtonZone 3Below 2 pCi/L
McCormickZone 3Below 2 pCi/L
MarionZone 3Below 2 pCi/L
MarlboroZone 3Below 2 pCi/L
NewberryZone 3Below 2 pCi/L
OconeeZone 22 to 4 pCi/L
OrangeburgZone 3Below 2 pCi/L
PickensZone 22 to 4 pCi/L
RichlandZone 3Below 2 pCi/L
SaludaZone 3Below 2 pCi/L
SpartanburgZone 22 to 4 pCi/L
SumterZone 3Below 2 pCi/L
UnionZone 3Below 2 pCi/L
WilliamsburgZone 3Below 2 pCi/L
YorkZone 22 to 4 pCi/L
Source: U.S. EPA Map of Radon Zones (data file published June 2024).

What the EPA radon zones mean

  • Zone 1 (highest potential): predicted average indoor screening level greater than 4 pCi/L. In South Carolina: 1 county (2%).
  • Zone 2 (moderate potential): predicted average between 2 and 4 pCi/L. In South Carolina: 8 counties (17%).
  • Zone 3 (low potential): predicted average below 2 pCi/L. In South Carolina: 37 counties (80%).

The EPA built the map from indoor radon measurements, geology, soil permeability and type of house foundation. It was made to help governments and builders target resources, not to decide whether a single home needs testing.

South Carolina counties with the highest radon potential

1 county in South Carolina is in Zone 1: Greenville.

How to test for radon in South Carolina

Testing is the only way to know your home’s radon level. Short-term test kits (2 to 90 days) are sold at hardware stores and online, and some state programs offer kits at low cost; check with the South Carolina Radon Program. Test in the lowest lived-in level of the home, with windows and doors closed, and follow the kit instructions.

  • Do-it-yourself kits: a simple, low-cost first step for your own home.
  • Long-term tests (more than 90 days): give a better picture of your home’s year-round average.
  • Certified professionals: look for certification from the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB), and ask the state program whether South Carolina requires a state license.
  • Buying or selling a home: ask for a radon test as part of the home inspection.

If your radon level is high

The EPA recommends fixing your home if the radon level is 4 pCi/L or higher, and considering a fix between 2 and 4 pCi/L. The most common fix is a radon mitigation system (sub-slab depressurization), which pulls radon from under the foundation and vents it outside, above the roof line.

  • The EPA says most homes can be fixed for about the same cost as other common home repairs; the price depends on the size and design of the home.
  • Get estimates from more than one qualified, certified mitigation contractor. See our radon mitigation cost guide for typical prices.
  • Test again after the system is installed, and retest every few years.

Learn more: safe radon levels · how to test · test kits compared · radon and home sales · radon in well water

South Carolina radon program

Radon rules and programs in South Carolina

  • Test kits: the South Carolina Radon Program uses free radon test kits as part of its outreach; contact the program for availability.

Contact

The South Carolina Radon Program answers questions from residents about radon testing, results and certified professionals.

Contact details as listed by the state radon program directory. Please confirm on the program’s website before calling.

Frequently asked questions

Is radon a problem in South Carolina?

1 of South Carolina’s 46 counties are in EPA Zone 1, where the predicted average indoor radon level is above 4 pCi/L, and 8 are in Zone 2 (2 to 4 pCi/L). High levels can be found in any home, so testing is the only way to know.

Which South Carolina counties have the highest radon potential?

The 1 county in EPA Zone 1 have the highest predicted average levels. You can find them in the table above and in the Zone 1 list.

What radon level is safe?

There is no known safe level of radon. The EPA recommends fixing your home at 4 pCi/L or higher and considering a fix between 2 and 4 pCi/L.

Who can I contact about radon in South Carolina?

The South Carolina Radon Program answers questions about testing, results and certified professionals. Phone: 1-800-768-0362.

Sources