Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
Locations and reports
Radon Levels in Williamsburg County, South Carolina
EPA puts Williamsburg County in Zone 3, its lowest radon zone, and only 14 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
4.0%
Berkeley County
- Berkeley
- 4.0%
- Florence
- 0.0%
2 of 5 neighbours have 30+ tests, 2008 to 2017
Nearest county
0.0%
Florence County, 28 miles
- Florence
- 0.0%
- SC
- 19.4%
Share at 4+ pCi/L, 59 tests, 2008 to 2017
Ground above low
None
18.5 pts below SC
- Williamsburg
- 0.0%
- SC
- 18.5%
Share of land USGS rates moderate or high potential
Tests reported
16
Too few for a share
- Williamsburg
- 16
- Needed
- 30
2005 to 2014, laboratory
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Williamsburg County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
The data
Williamsburg County, At a glance
Williamsburg County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Williamsburg County, 2008 to 2017, laboratory
CDC holds 14 reported tests for Williamsburg County over the 2008 to 2017 laboratory totals, with a median of 0.6 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Williamsburg County beside the counties around it is how this page reads it.
What these figures count
Only 14 tests were reported to CDC for Williamsburg County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Williamsburg County, Compared
Williamsburg County radon figures, compared
Calculated by Radon411CDC's largest figure for Williamsburg County rests on 16 tests over the 2005 to 2014 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 6.3 points and no rank or comparison is drawn from it. Results reached as high as 1.3 pCi/L, with a middle value of 0.6 pCi/L.
Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Berkeley County reported the largest share at or above 4 pCi/L, 4.0%, and Florence County the smallest, 0.0%. Farther out, Sumter County (43 miles away) at 11.9%, Horry County (47 miles away) at 0.9% and Dorchester County (54 miles away) at 4.8% have figures too. Pooled across 46 South Carolina counties, 19.4% of reported tests reached that level; across every county in the country with a figure, 35.7%.
Statewide for the same period, Oconee County reported the highest share (42.6%) and Florence County the lowest (0.0%). EPA's 1993 map puts Williamsburg County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 100% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Williamsburg County, Geology
The ground under Williamsburg County
PredictedUSGS's geologic map puts all of Williamsburg County's mapped land in one class: low radon potential. The map puts 85.6% of Williamsburg County in the area it calls Lower Coastal Plain and 14.4% in Upper and Middle Coastal Plain. USGS gives the first a radon index of 7 and the second 8, both 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 | 85.6% |
| Upper and Middle Coastal Plain | Tertiary coastal plain sandy and silty sediments and marsh deposits. | Low | 8 | 14.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Williamsburg County beside the ground around it
Across South Carolina 0.2% of the land is rated high; none of Williamsburg County's is. None of the 5 counties that border it has any moderate-potential ground either.
The map rates the ground, not the air in any home.
Local help
Williamsburg County, Local resources
Radon testing and mitigation in Williamsburg 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
Williamsburg County, Questions
Questions about radon in Williamsburg County
Are radon levels high in Williamsburg County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Williamsburg County, South Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.6 pCi/L. Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Berkeley County reported the largest share at or above 4 pCi/L, 4.0%, and Florence County the smallest, 0.0%.
Which counties border Williamsburg County?
Williamsburg County borders 5 counties: Georgetown County, Clarendon County, Florence County, Berkeley County and Marion County.
Products
Williamsburg County, Products
Testing a home in Williamsburg County
No CDC figure names Williamsburg County; the nearest county with one, Florence County (28 miles away), reported 0.0% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. 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 Williamsburg County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Monitor
View Plus radon and air quality monitor
- C-NRPP 2024/25: Approved
- Battery
- Wi-Fi, Bluetooth
- Screen, app
Method: Alpha spectrometry
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Williamsburg County, Bordering counties
Counties bordering Williamsburg County
Calculated by Radon411- Radon levels in Berkeley CountyEPA zone 3
4.0%at or above 4 pCi/L
Median 0.7 pCi/L · 99 tests
- Radon levels in Georgetown CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 29 tests
- Radon levels in Clarendon CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.8 pCi/L · 3 tests
- Radon levels in Florence CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.7 pCi/L · 59 tests
- Radon levels in Marion CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.9 pCi/L · 9 tests
Williamsburg County, Cities and towns
Cities and towns in Williamsburg County
About 29,662 people live in Williamsburg County by the Census Bureau's estimate for July 1, 2025, 1,252 fewer than in 2020 (−4.0%). That works out to 32 people per square mile of land. No town dominates: Kingstree, the largest, has 3,022 residents, 10.2% of the total. Reported testing is thin here: 16 tests over 2005 to 2014, or 0.5 for every 1,000 residents (2025 estimate), where South Carolina as a whole comes to 3.9.
From Kingstree to Stuckey, CDC publishes no figure by town: each reads Williamsburg County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Kingstree | 3,022 | −6.4% | 10.2% |
| Andrewsextends beyond Williamsburg County | 2,522 | −2.6% | Counted whole |
| Hemingway | 464 | −7.4% | 1.6% |
| Lane | 449 | −4.9% | 1.5% |
| Greeleyville | 357 | −5.3% | 1.2% |
| Stuckey | 186 | −4.1% | 0.6% |
6 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Williamsburg County is counted whole, so it has no share.
Williamsburg County, Homes
Homes in Williamsburg County
Mobile homes are 42% of Williamsburg County's 14,837 homes and detached houses 51%, against 64% across South Carolina. Half of its homes were built before 1985, close to South Carolina's 1991: 14% date from before 1960 and 24% from 2000 or later. 75% 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 | Williamsburg County | South Carolina |
|---|---|---|
| Housing units | 14,837 | 2,401,638 |
| Detached houses | 51% | 64% |
| In buildings of 5 or more | 2% | 13% |
| Mobile homes | 42% | 15% |
| Built before 1960 | 14% | 13% |
| Built since 2000 | 24% | 35% |
| Middle year built | 1985 | 1991 |
| Owner-occupied | 75% | 71% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.