Short-term kit
PicoCan short-term charcoal canister radon test
- Lab fee included
Method: Charcoal
In home: 48 to 96 hours
Locations and reports
Radon Levels in Charleston County, South Carolina
EPA puts Charleston County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 1.5% of 272 (2008 to 2017, laboratory totals) reached 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
1.5%
17.9 pts below SC
- Charleston
- 1.5%
- SC
- 19.4%
272 tests, 2008 to 2017
Median result
0.6pCi/L
Below action level
- Charleston
- 0.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
272
10th of 24 by tests
- Charleston
- 272
- Greenville
- 12,004
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Rank in SC
22 of 24
Lowest quarter
- Charleston
- 1.5%
- Oconee
- 42.6%
By share, of 24 with 30+ tests
Read a result for Charleston County
Starts at Charleston County's median, 0.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 0.6 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Charleston County's median reported result, 2008 to 2017.
The data
Charleston County, At a glance
Charleston County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 94% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Charleston County, 2008 to 2017, laboratory
Under 2 pCi/L: 90%2 to 4 pCi/L: 8%4 pCi/L and above: 2%
Of 272 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 245 | 90.1% |
| 2 to 4 pCi/L | 23 | 8.5% |
| 4 pCi/L and above | 4 | 1.5% |
What these figures count
These are the 272 tests reported to CDC for Charleston County over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Charleston County, Compared
Charleston County radon figures, compared
Calculated by Radon411Only 4 of 272 radon tests reported for Charleston County over the 2008 to 2017 laboratory totals reached 4 pCi/L (1.5%). The median result, 0.6 pCi/L, sits below 2, well under EPA's 4 pCi/L action level, and the top reported result was 15.6 pCi/L.
Across 46 South Carolina counties pooled together, 19.4% of tests reached that level, so Charleston County runs 17.9 points below its state. Against the national pool of 35.7%, the gap is 34.2 points lower. Its place in the state: 22nd of 24 South Carolina counties with 30 or more tests for the same period.
Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 1.5% share point the same way here. Of 2 neighbours with a figure, all 2 reported a larger share at or above 4 pCi/L; the spread is 4.0% (Berkeley County) to 4.8% (Dorchester County).
Below the action level, 245 tests (90.1%) came in under 2 pCi/L, against 57.4% statewide, and 23 tests (8.5%) fell between 2 and 4, against 23.1% statewide. USGS geology rates 94% of the county's land low radon potential.
CDC's ten-year totals for Charleston County went from 253 tests (2005 to 2014) to 272 (2008 to 2017), the share going from 2.0% to 1.5%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Charleston County, Geology
The ground under Charleston County
PredictedUSGS's geologic map puts all of Charleston County's mapped land in one class: low radon potential. 93.5% of it lies in the area the map calls Lower Coastal Plain, to which USGS gives a radon index of 7, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Lower Coastal Plain | Dune, beach, and marine sediments. | Low | 7 | 93.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Charleston County beside the ground around it
Across South Carolina 0.2% of the land is rated high; none of Charleston County's is. None of the 4 counties that border it has any moderate-potential ground either.
The map rates the ground, not the air in any home.
Local help
Charleston County, Local resources
Radon testing and mitigation in Charleston County
- South Carolina Radon ProgramSouth Carolina Radon Program, run by South Carolina Department of Environmental Services, offers free or discounted test kits, and answers questions about testing and mitigation in South Carolina.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The South Carolina Radon Program offers free short-term radon test kits to South Carolina homeowners, subject to availability.
- Compare kits
- Professionals in South Carolina2 professionals are listed in South Carolina.
What South Carolina's program says
- Phone
- 1-800-768-0362
- radon@des.sc.gov
What it means
Charleston County, Questions
Questions about radon in Charleston County
Are radon levels high in Charleston County?
Over the 2008 to 2017 laboratory totals, 1.5% of the radon tests reported to CDC for Charleston County, South Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.6 pCi/L. Of 24 South Carolina counties with 30 or more tests for the same period, 21 reported a higher share; pooled, the state comes to 19.4%.
Which counties border Charleston County?
Charleston County borders 4 counties: Berkeley County, Dorchester County, Colleton County and Georgetown County.
Products
Charleston County, Products
Testing a home in Charleston County
In Charleston County, 1.5% of 272 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 19.4% pooled across South Carolina. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Charleston County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
MonitorX-Sense
XR0A-SR battery digital radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Charleston County, Bordering counties
Counties bordering Charleston County
Calculated by Radon411- Radon levels in Colleton CountyEPA zone 3
9.1%at or above 4 pCi/L
Median 0.1 pCi/L · 11 tests · 7.6 points above Charleston County
- Radon levels in Dorchester CountyEPA zone 3
4.8%at or above 4 pCi/L
Median 1.0 pCi/L · 104 tests · 3.3 points above Charleston County
- Radon levels in Berkeley CountyEPA zone 3
4.0%at or above 4 pCi/L
Median 0.7 pCi/L · 99 tests · 2.5 points above Charleston County
- Radon levels in Georgetown CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 29 tests · 1.5 points below Charleston County
Charleston County, Cities and towns
Cities and towns in Charleston County
Charleston County is growing: the Census Bureau puts it at 436,200 residents on July 1, 2025, up 6.4% from 409,934 in 2020. That works out to 475 people per square mile of land. Charleston, the largest place on its list (159,423 residents in all), extends beyond Charleston County, so no share of the total is worked out for it. Reported testing is thin here: 272 tests over 2008 to 2017, or 0.6 for every 1,000 residents (2025 estimate), where South Carolina as a whole comes to 4.8.
From Charleston to Rockville, CDC publishes no figure by town: each reads Charleston County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Charlestonextends beyond Charleston County | 159,423 | +5.4% | Counted whole |
| North Charlestonextends beyond Charleston County | 129,245 | +11.8% | Counted whole |
| Mount Pleasant | 95,469 | +4.6% | 21.9% |
| Summervilleextends beyond Charleston County | 53,177 | +4.4% | Counted whole |
| James Island | 12,660 | +5.4% | 2.9% |
| Hollywood | 5,652 | +6.6% | 1.3% |
| Isle of Palms | 4,377 | +0.7% | 1.0% |
| Ravenel | 2,728 | +6.9% | 0.6% |
| Seabrook Island | 2,171 | +5.6% | 0.5% |
| Folly Beach | 2,081 | +0.3% | 0.5% |
| Kiawah Island | 2,014 | Level | 0.5% |
| Sullivan's Island | 1,961 | +3.3% | 0.4% |
- Awendaw
- Meggett
- Lincolnville (part)
- McClellanville
- Rockville
17 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Charleston County is counted whole, so it has no share.
Charleston County, Homes
Homes in Charleston County
Of Charleston County's 206,299 homes, 58% are detached houses, against 64% across South Carolina; 23% are in buildings of five or more homes. Half of its homes were built before 1991, close to South Carolina's 1991: 15% date from before 1960 and 37% from 2000 or later. 63% of occupied homes are lived in by their owner (South Carolina: 71%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Charleston County | South Carolina |
|---|---|---|
| Housing units | 206,299 | 2,401,638 |
| Detached houses | 58% | 64% |
| In buildings of 5 or more | 23% | 13% |
| Mobile homes | 5% | 15% |
| Built before 1960 | 15% | 13% |
| Built since 2000 | 37% | 35% |
| Middle year built | 1991 | 1991 |
| Owner-occupied | 63% | 71% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.