Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
Locations and reports
Radon Levels in Calhoun County, South Carolina
EPA puts Calhoun County in Zone 3, its lowest radon zone, and only 11 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
12.5%
Lexington County
- Lexington
- 12.5%
- Richland
- 4.9%
4 of 5 neighbours have 30+ tests, 2008 to 2017
Nearest county
5.7%
Orangeburg County, 16 miles
- Orangeburg
- 5.7%
- SC
- 19.4%
Share at 4+ pCi/L, 53 tests, 2008 to 2017
Ground above low
None
18.5 pts below SC
- Calhoun
- 0.0%
- SC
- 18.5%
Share of land USGS rates moderate or high potential
Tests reported
22
Too few for a share
- Calhoun
- 22
- 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 Calhoun 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
Calhoun County, At a glance
Calhoun 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 Calhoun County, 2008 to 2017, laboratory
CDC holds 11 reported tests for Calhoun 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). Calhoun County beside the counties around it is how this page reads it.
What these figures count
Only 11 tests were reported to CDC for Calhoun 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).
Calhoun County, Compared
Calhoun County radon figures, compared
Calculated by Radon411CDC's largest figure for Calhoun County rests on 22 tests over the 2005 to 2014 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 4.5 points and no rank or comparison is drawn from it. Results reached as high as 3.2 pCi/L, with a middle value of 0.8 pCi/L.
Of the counties bordering it, 4 have a figure over the 2008 to 2017 laboratory totals: Lexington County reported the largest share at or above 4 pCi/L, 12.5%, and Richland County the smallest, 4.9%, with Sumter County at 11.9% and Orangeburg County at 5.7% between. Farther out, Dorchester County (46 miles away) at 4.8%, Kershaw County (47 miles away) at 5.0% and Aiken County (50 miles away) at 13.3% 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 Calhoun 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.
Calhoun County, Geology
The ground under Calhoun County
PredictedUSGS's geologic map puts all of Calhoun County's mapped land in one class: low radon potential. All of it lies in the area the map calls Upper and Middle Coastal Plain, to which USGS gives a radon index of 8, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Upper and Middle Coastal Plain | Tertiary coastal plain sandy and silty sediments and marsh deposits. | Low | 8 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Calhoun County beside the ground around it
Across South Carolina 0.2% of the land is rated high; none of Calhoun County's is. Of the 5 counties that border it, 1 has more moderate-potential ground, Richland County the most at 0.5%.
The map rates the ground, not the air in any home.
Local help
Calhoun County, Local resources
Radon testing and mitigation in Calhoun 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
Calhoun County, Questions
Questions about radon in Calhoun County
Are radon levels high in Calhoun County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Calhoun 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, 4 have a figure over the 2008 to 2017 laboratory totals: Lexington County reported the largest share at or above 4 pCi/L, 12.5%, and Richland County the smallest, 4.9%, with Sumter County at 11.9% and Orangeburg County at 5.7% between.
Which counties border Calhoun County?
Calhoun County borders 5 counties: Orangeburg County, Richland County, Sumter County, Clarendon County and Lexington County.
Products
Calhoun County, Products
Testing a home in Calhoun County
No CDC figure names Calhoun County; the nearest county with one, Orangeburg County (16 miles away), reported 5.7% 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 Calhoun 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
MonitorAranet
Radon One battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Alarm
- Screen, app
Method: Ion chamber
First reading: Within 10 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Calhoun County, Bordering counties
Counties bordering Calhoun County
Calculated by Radon411- Radon levels in Lexington CountyEPA zone 3
12.5%at or above 4 pCi/L
Median 0.9 pCi/L · 591 tests
- Radon levels in Sumter CountyEPA zone 3
11.9%at or above 4 pCi/L
Median 1.3 pCi/L · 42 tests
- Radon levels in Orangeburg CountyEPA zone 3
5.7%at or above 4 pCi/L
Median 0.9 pCi/L · 53 tests
- Radon levels in Richland CountyEPA zone 3
4.9%at or above 4 pCi/L
Median 0.7 pCi/L · 671 tests
- Radon levels in Clarendon CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.8 pCi/L · 3 tests
Calhoun County, Cities and towns
Cities and towns in Calhoun County
The Census Bureau estimates 14,188 residents in Calhoun County for July 1, 2025, 77 more than in 2020 (+0.5%). That works out to 37 people per square mile of land. No town dominates: St. Matthews, the largest, has 1,827 residents, 12.9% of the total. Together its 2 incorporated places hold 15.5% of those residents; the other 84.5% live outside any of them. Reported testing is thin here: 22 tests over 2005 to 2014, or 1.6 for every 1,000 residents (2025 estimate), where South Carolina as a whole comes to 3.9.
From St. Matthews to Cameron, CDC publishes no figure by town: each reads Calhoun County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| St. Matthews | 1,827 | −1.2% | 12.9% |
| Cameron | 367 | −1.6% | 2.6% |
2 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).
Calhoun County, Homes
Homes in Calhoun County
Of Calhoun County's 7,061 homes, 64% are detached houses, against 64% across South Carolina; 32% are mobile homes. Half of its homes were built before 1989, close to South Carolina's 1991: 16% date from before 1960 and 26% from 2000 or later. Owners live in 84% of the occupied homes (South Carolina: 71%), so for most households a test and a fix are their own to order.
| Homes | Calhoun County | South Carolina |
|---|---|---|
| Housing units | 7,061 | 2,401,638 |
| Detached houses | 64% | 64% |
| In buildings of 5 or more | 1% | 13% |
| Mobile homes | 32% | 15% |
| Built before 1960 | 16% | 13% |
| Built since 2000 | 26% | 35% |
| Middle year built | 1989 | 1991 |
| Owner-occupied | 84% | 71% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.