Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
Locations and reports
Radon Levels in Union County, South Carolina
EPA puts Union County in Zone 3, its lowest radon zone, and only 27 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
19.1%
Spartanburg County
- Spartanburg
- 19.1%
- York
- 13.6%
5 of 7 neighbours have 30+ tests, 2008 to 2017
Nearest county
13.7%
Cherokee County, 25 miles
- Cherokee
- 13.7%
- SC
- 19.4%
Share at 4+ pCi/L, 153 tests, 2008 to 2017
Ground above low
53.6%
35.2 pts above SC
- Union
- 53.6%
- SC
- 18.5%
Share of land USGS rates moderate or high potential
Tests reported
28
Too few for a share
- Union
- 28
- Needed
- 30
2006 to 2015, 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 Union 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
Union County, At a glance
Union County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Moderate across 54% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Union County, 2008 to 2017, laboratory
CDC holds 27 reported tests for Union County over the 2008 to 2017 laboratory totals, with a median of 1.0 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Union County beside the counties around it is how this page reads it.
What these figures count
Only 27 tests were reported to CDC for Union 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).
Union County, Compared
Union County radon figures, compared
Calculated by Radon411CDC's largest figure for Union County rests on 28 tests over the 2006 to 2015 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 3.6 points and no rank or comparison is drawn from it. Results reached as high as 3.0 pCi/L, with a middle value of 1.0 pCi/L.
Of the counties bordering it, 5 have a figure over the 2008 to 2017 laboratory totals: Spartanburg County reported the largest share at or above 4 pCi/L, 19.1%, and York County the smallest, 13.6%, with Newberry County at 16.0%, Laurens County at 13.9% and Cherokee County at 13.7% between. Farther out, Greenville County (45 miles away) at 19.6%, Greenwood County (47 miles away) at 7.1% and Lancaster County (52 miles away) at 13.6% 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 Union County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 54% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Union County, Geology
The ground under Union County
PredictedUSGS's geologic map splits Union County: 53.6% of its land is moderate radon potential and 46.4% low. The map puts 46.4% of Union County in the area it calls Charlotte Belt and 30.9% in Carolina and Charlotte Belt Granites, with 2 smaller areas beside them. USGS gives the first a radon index of 8, in the low band (5 to 8), and the second 11, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Charlotte Belt | Biotite gneiss and schist, metavolcanic rocks, mica gneiss. | Low | 8 | 46.4% |
| Carolina and Charlotte Belt Granites | Granite and granite gneiss | Moderate | 11 | 30.9% |
| Kings Mountain Belt | Proterozoic-Cambrain metasedimentary and metavolcanic rocks. | Moderate | 11 | 20.1% |
| Inner Piedmont Belt | Proterozoic through Cambrian biotite gneiss and schist, and mica schist. | Moderate | 11 | 2.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Union County beside the ground around it
Across South Carolina 0.2% of the land is rated high; none of Union County's is. Of the 7 counties that border it, 3 have more moderate-potential ground, Spartanburg County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Union County, Local resources
Radon testing and mitigation in Union 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
Union County, Questions
Questions about radon in Union County
Are radon levels high in Union County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Union County, South Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.0 pCi/L. Of the counties bordering it, 5 have a figure over the 2008 to 2017 laboratory totals: Spartanburg County reported the largest share at or above 4 pCi/L, 19.1%, and York County the smallest, 13.6%, with Newberry County at 16.0%, Laurens County at 13.9% and Cherokee County at 13.7% between.
Which counties border Union County?
Union County borders 7 counties: Laurens County, Cherokee County, Spartanburg County, Newberry County, Chester County, York County and Fairfield County.
Products
Union County, Products
Testing a home in Union County
No CDC figure names Union County; the nearest county with one, Cherokee County (25 miles away), reported 13.7% 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 Union 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
Monitor
RadonEye RD200 plug-in continuous radon monitor
- C-NRPP 2024/25: Approved
- Plug-in
- 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
Union County, Bordering counties
Counties bordering Union County
Calculated by Radon411- Radon levels in Chester CountyEPA zone 3
22.2%at or above 4 pCi/L
Median 1.1 pCi/L · 18 tests
- Radon levels in Spartanburg CountyEPA zone 2
19.1%at or above 4 pCi/L
Median 1.7 pCi/L · 3,280 tests
- Radon levels in Newberry CountyEPA zone 3
16.0%at or above 4 pCi/L
Median 1.1 pCi/L · 75 tests
- Radon levels in Laurens CountyEPA zone 2
13.9%at or above 4 pCi/L
Median 1.3 pCi/L · 244 tests
- Radon levels in Cherokee CountyEPA zone 2
13.7%at or above 4 pCi/L
Median 1.6 pCi/L · 153 tests
- Radon levels in York CountyEPA zone 2
13.6%at or above 4 pCi/L
Median 1.2 pCi/L · 1,412 tests
- Radon levels in Fairfield CountyEPA zone 3
7.4%at or above 4 pCi/L
Median 0.9 pCi/L · 27 tests
Union County, Cities and towns
Cities and towns in Union County
About 26,799 people live in Union County by the Census Bureau's estimate for July 1, 2025, 374 fewer than in 2020 (−1.4%). That works out to 52 people per square mile of land. Its largest town, Union, has 8,077 residents, 30.1% of the total. Together its 4 incorporated places hold 35.8% of those residents; the other 64.2% live outside any of them. Reported testing is thin here: 28 tests over 2006 to 2015, or 1.0 for every 1,000 residents (2025 estimate), where South Carolina as a whole comes to 4.3.
From Union to Carlisle, CDC publishes no figure by town: each reads Union County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Union | 8,077 | −1.6% | 30.1% |
| Jonesville | 817 | −4.0% | 3.0% |
| Lockhart | 369 | −2.9% | 1.4% |
| Carlisle | 320 | −0.3% | 1.2% |
4 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).
Union County, Homes
Homes in Union County
Of Union County's 13,508 homes, 68% are detached houses, against 64% across South Carolina; 22% are mobile homes. The homes are older than South Carolina's as a whole: half were built before 1973 (1991 for South Carolina), and 28% date from before 1960. 69% 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 | Union County | South Carolina |
|---|---|---|
| Housing units | 13,508 | 2,401,638 |
| Detached houses | 68% | 64% |
| In buildings of 5 or more | 6% | 13% |
| Mobile homes | 22% | 15% |
| Built before 1960 | 28% | 13% |
| Built since 2000 | 13% | 35% |
| Middle year built | 1973 | 1991 |
| Owner-occupied | 69% | 71% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.