Radon levels in South Carolina: Low
The model predicts a population-weighted basement average of 1.6 pCi/L (model estimate) across South Carolina's 46 counties - close to the US average of 1.8 pCi/L. Above-ground floors average 0.9 pCi/L.
Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.
1 / 46
EPA Zone 1 counties (2%)
8 / 37
Zone 2 / Zone 3 counties
0
counties predicted ≥ 4 pCi/L
0%
of ZIP codes predicted ≥ 4 pCi/L
Test South Carolina once anyway - radon varies house to house
The predicted basement average here is 1.6 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
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What the data says about radon in South Carolina
On the EPA's 1993 radon zone map, 1 of South Carolina's 46 counties is EPA Zone 1 (2%), 8 are Zone 2 and 37 are Zone 3. Most counties fall in Zone 3, the EPA's lowest-potential class (predicted screening average under 2 pCi/L), but 1 county is still Zone 1. That classification has not been revised since 1993; it describes counties, not homes, and elevated readings turn up in Zone 3 counties every year.
South Carolina models out at 1.6 pCi/L predicted basement average (low; close to the US average of 1.8). Of the 46 counties with predictions, 0 are predicted at or above 4 pCi/L, 5 in the 2-4 band and 41 below 2. The highest predicted county is Oconee County at 2.5 pCi/L; the lowest is Charleston County at 1.3 - a 1.2 pCi/L spread that means a statewide average tells you little about any one county.
At ZIP-code resolution, 0% of South Carolina ZIPs are predicted at 4 pCi/L or higher in the basement and 13.9% at 2 or higher - below the national shares of 4.2% and 48.7%. No ZIP in the state is predicted above 4 on average - but averages hide individual homes, which is why the EPA still asks everyone to test.
South Carolina counties by predicted radon
Sorted highest to lowest predicted basement average (model estimate). 46 counties.
| County | Predicted basement | Upstairs | Grade | EPA zone | ZIPs |
|---|---|---|---|---|---|
| Oconee County | 2.5 pCi/L | 1.2 | Moderate | EPA Zone 2 | 10 |
| Greenville County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 1 | 20 |
| Pickens County | 2.2 pCi/L | 1.1 | Moderate | EPA Zone 2 | 8 |
| Cherokee County | 2.2 pCi/L | 1.0 | Moderate | EPA Zone 2 | 5 |
| Spartanburg County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 2 | 17 |
| Anderson County | 2.0 pCi/L | 0.9 | Low | EPA Zone 2 | 11 |
| Union County | 1.9 pCi/L | 1.1 | Low | EPA Zone 3 | 3 |
| Abbeville County | 1.9 pCi/L | 0.9 | Low | EPA Zone 2 | 6 |
| Laurens County | 1.9 pCi/L | 1.0 | Low | EPA Zone 2 | 8 |
| Greenwood County | 1.8 pCi/L | 0.9 | Low | EPA Zone 3 | 5 |
| Fairfield County | 1.7 pCi/L | 0.9 | Low | EPA Zone 3 | 5 |
| Newberry County | 1.7 pCi/L | 0.9 | Low | EPA Zone 3 | 8 |
| Saluda County | 1.7 pCi/L | 0.8 | Low | EPA Zone 3 | 3 |
| McCormick County | 1.6 pCi/L | 0.8 | Low | EPA Zone 3 | 4 |
| York County | 1.6 pCi/L | 0.8 | Low | EPA Zone 2 | 11 |
| Chester County | 1.6 pCi/L | 0.8 | Low | EPA Zone 3 | 6 |
| Edgefield County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 6 |
| Lancaster County | 1.6 pCi/L | 0.7 | Low | EPA Zone 3 | 4 |
| Calhoun County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 2 |
| Chesterfield County | 1.5 pCi/L | 0.7 | Low | EPA Zone 3 | 8 |
| Lexington County | 1.5 pCi/L | 0.7 | Low | EPA Zone 3 | 13 |
| Clarendon County | 1.5 pCi/L | 0.8 | Low | EPA Zone 3 | 6 |
| Kershaw County | 1.5 pCi/L | 0.6 | Low | EPA Zone 3 | 6 |
| Florence County | 1.5 pCi/L | 0.8 | Low | EPA Zone 3 | 11 |
| Bamberg County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 4 |
| Darlington County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 5 |
| Orangeburg County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 16 |
| Sumter County | 1.4 pCi/L | 0.9 | Low | EPA Zone 3 | 8 |
| Berkeley County | 1.4 pCi/L | 0.7 | Low | EPA Zone 3 | 12 |
| Dillon County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 6 |
| Allendale County | 1.4 pCi/L | 0.9 | Low | EPA Zone 3 | 5 |
| Barnwell County | 1.4 pCi/L | 0.9 | Low | EPA Zone 3 | 3 |
| Dorchester County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 8 |
| Lee County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 4 |
| Marlboro County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 5 |
| Aiken County | 1.4 pCi/L | 0.9 | Low | EPA Zone 3 | 15 |
| Marion County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 4 |
| Hampton County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 6 |
| Beaufort County | 1.4 pCi/L | 0.7 | Low | EPA Zone 3 | 12 |
| Georgetown County | 1.4 pCi/L | 0.7 | Low | EPA Zone 3 | 3 |
| Williamsburg County | 1.4 pCi/L | 0.7 | Low | EPA Zone 3 | 7 |
| Colleton County | 1.3 pCi/L | 0.7 | Low | EPA Zone 3 | 9 |
| Jasper County | 1.3 pCi/L | 0.7 | Low | EPA Zone 3 | 4 |
| Richland County | 1.3 pCi/L | 0.6 | Low | EPA Zone 3 | 14 |
| Horry County | 1.3 pCi/L | 0.6 | Low | EPA Zone 3 | 16 |
| Charleston County | 1.3 pCi/L | 0.7 | Low | EPA Zone 3 | 22 |
Radon levels in South Carolina cities
The 9 most-populous South Carolina places among the 1,000 largest US cities (Census incorporated places and CDPs), by population. City figures are ZIP-land-weighted means of the model's ZIP predictions (model estimate).
| City | Population | Predicted basement | Upstairs | Grade | ZIPs ≥ 4 |
|---|---|---|---|---|---|
| Charleston | 155,369 | 1.4 pCi/L | 0.7 | Low | 0% |
| Columbia | 142,416 | 1.3 pCi/L | 0.7 | Low | 0% |
| North Charleston | 121,469 | 1.3 pCi/L | 0.7 | Low | 0% |
| Mount Pleasant | 95,232 | 1.4 pCi/L | 0.6 | Low | 0% |
| Rock Hill | 75,654 | 1.5 pCi/L | 0.6 | Low | 0% |
| Greenville | 72,824 | 2.0 pCi/L | 1.3 | Low | 0% |
| Summerville | 51,884 | 1.4 pCi/L | 0.8 | Low | 0% |
| Goose Creek | 49,249 | 1.4 pCi/L | 0.7 | Low | 0% |
| Greer | 44,387 | 2.5 pCi/L | 1.4 | Moderate | 0% |
Highest-radon ZIP codes in South Carolina
The 10 South Carolina ZIP codes with the highest predicted basement average (model estimate), out of 374 modeled. A ZIP average is still an area figure - neighboring homes routinely test several pCi/L apart.
| ZIP | County | Predicted basement | Upstairs | Grade |
|---|---|---|---|---|
| 29685 | Pickens County | 3.6 pCi/L | 1.7 | Moderate |
| 29676 | Oconee County | 3.5 pCi/L | 1.8 | Moderate |
| 29672 | Oconee County | 2.9 pCi/L | 1.4 | Moderate |
| 29650 | Greenville County | 2.8 pCi/L | 2.0 | Moderate |
| 29615 | Greenville County | 2.7 pCi/L | 1.9 | Moderate |
| 29664 | Oconee County | 2.7 pCi/L | 1.4 | Moderate |
| 29686 | Oconee County | 2.7 pCi/L | 1.2 | Moderate |
| 29687 | Greenville County | 2.6 pCi/L | 1.7 | Moderate |
| 29682 | Pickens County | 2.6 pCi/L | 1.2 | Moderate |
| 29635 | Greenville County | 2.6 pCi/L | 1.4 | Moderate |
South Carolina radon questions
- Is radon high in South Carolina?
- South Carolina's population-weighted predicted basement average is 1.6 pCi/L, close to the US average of 1.8. 0 of its 46 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 5 are in the 2-4 "consider fixing" range and 41 are below 2. 0% of South Carolina ZIP codes are predicted at 4 or higher.
- Which South Carolina county has the highest radon?
- Oconee County has the highest predicted basement average in South Carolina at 2.5 pCi/L (EPA Zone 2). The lowest is Charleston County at 1.3 pCi/L. These are area figures; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in South Carolina?
- 1 of South Carolina's 46 counties (2%) are EPA Zone 1 (highest potential), 8 are Zone 2 and 37 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in South Carolina?
- Yes. Even though South Carolina's predicted average is below 2 pCi/L, the EPA recommends every home be tested - radon varies house to house, and 13.9% of South Carolina ZIP codes are still predicted at 2 pCi/L or higher.
South Carolina radon program
State programs keep lists of certified testers and mitigators and sometimes run kit programs. We link only pages we could verify, and South Carolina's program page did not respond when we checked, so start from the EPA state radon contacts page. Then read how to test and what mitigation costs.