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 Carter County, Tennessee
EPA puts Carter County in Zone 2, its middle radon zone, and only 9 radon tests from it are on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
47.2%
13.9 pts above TN
- Carter
- 47.2%
- Tennessee
- 33.3%
345 tests, 2008 to 2017
Median result
3.7pCi/L
Below action level
- Carter
- 3.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
345
17th of 80 by tests
- Carter
- 345
- Davidson
- 5,592
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Tennessee
10 of 80
Top quarter
- Carter
- 47.2%
- Jefferson
- 56.8%
By share, of 80 with 30+ tests
Read a result for Carter County
Starts at Carter County's median, 3.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.7 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Carter County's median reported result, 2008 to 2017.
The data
Carter County, At a glance
Carter County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Carter County is a
USGS geologic potential: High across 61% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Carter County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2022 | 33.3% |
| 2023 | 0.0% |
2023: 0.0%. Across these years the share ran from 0.0% to 33.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 9 tests were reported to CDC for Carter County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Carter County, Compared
Carter County radon figures, compared
Calculated by Radon411In Carter County, about 5 in 10 reported tests over the 2008 to 2017 laboratory totals (163 of 345) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 11.5 points higher. Across 95 Tennessee counties pooled together, 33.3% of tests reached that level, so Carter County runs 13.9 points above its state.
The newest figure, in 2023, counts only 9 tests (0.0% at or above 4 pCi/L), too few to compare, so this reading uses the 345-test figure.
Of 6 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 4 a smaller one; the spread is 28.6% (Mitchell County, NC) to 51.5% (Sullivan County). By share, Carter County is 10th of 80 Tennessee counties with 30 or more tests for the same period.
Half the tests came in under 3.7 pCi/L and half over it; the single highest reached 117.4 pCi/L. Below the action level, 97 tests (28.1%) came in under 2 pCi/L, against 42.4% statewide, and 85 tests (24.6%) fell between 2 and 4, against 24.3% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 47.2% share point the same way here. USGS geology rates 61% of the county's land high radon potential. CDC also counts 15 tests taken after mitigation in Carter County for the same period: tests in homes where a fix was already in.
The busiest year on file was 2022, with 36 tests reported; the quietest, 2023, had 9.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Carter County, Geology
The ground under Carter County
PredictedUSGS's geologic map splits Carter County: 60.5% of its land is high radon potential and 39.5% moderate. The map puts 60.5% of Carter County in the area it calls Ridge and Valley and 39.3% in Unaka Mountains. USGS gives the first a radon index of 14, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Ridge and Valley | Paleozoic sandstone and cherty dolostone. | High | 14 | 60.5% |
| Unaka Mountains | Precambrian and Paleozoic siltstone, sandstone, conglomerate, quartzite, phyllite, gneiss, granite, and metamorphosed volcanic rock. | Moderate | 11 | 39.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Carter County beside the ground around it
Carter County has more high-potential ground than Tennessee as a whole: 60.5% of its land against 47.2%. Of the 6 counties that border it, 4 have more high-potential ground, Washington County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Carter County, Local resources
Radon testing and mitigation in Carter County
- Tennessee Radon ProgramTennessee Radon Program, run by Department of Environment & Conservation, offers free or discounted test kits, and answers questions about testing and mitigation in Tennessee.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The Tennessee Radon Program provides free radon test kits and information assistance to residents, while also providing training opportunities to radon professionals across the state.
- Compare kits
- Professionals in Tennessee1 professional is listed in Tennessee.
What Tennessee's program says
- Phone
- 1-800-232-1139
- TDEC.Radon@tn.gov
What it means
Carter County, Questions
Questions about radon in Carter County
Are radon levels high in Carter County?
In 2023, 0.0% of the radon tests reported to CDC for Carter County, Tennessee were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L. Of 80 Tennessee counties with 30 or more tests for the same period, 9 reported a higher share; pooled, the state comes to 33.3%.
Which counties border Carter County?
Carter County borders 6 counties: Sullivan County, TN, Washington County, TN, Johnson County, TN, Avery County, NC, Mitchell County, NC and Unicoi County, TN.
Products
Carter County, Products
Testing a home in Carter County
In Carter County, 47.2% of 345 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 33.3% pooled across Tennessee. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Carter County; a long-term test tells the year-round average.
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
MonitorAEGTEST
HOUND-1085 palm-sized rechargeable radon detector
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Carter County, Bordering counties
Counties bordering Carter County
Calculated by Radon411- Radon levels in Sullivan County, TNEPA zone 1
51.5%at or above 4 pCi/L
Median 4.2 pCi/L · 1,799 tests · 4.3 points above Carter County
- Radon levels in Washington County, TNEPA zone 1
49.6%at or above 4 pCi/L
Median 3.9 pCi/L · 1,590 tests · 2.4 points above Carter County
- Radon levels in Avery County, NCEPA zone 2
38.8%at or above 4 pCi/L
Median 2.8 pCi/L · 160 tests · 8.4 points below Carter County
- Radon levels in Unicoi County, TNEPA zone 2
37.1%at or above 4 pCi/L
Median 2.8 pCi/L · 132 tests · 10.1 points below Carter County
- Radon levels in Johnson County, TNEPA zone 2
34.4%at or above 4 pCi/L
Median 2.3 pCi/L · 157 tests · 12.8 points below Carter County
- Radon levels in Mitchell County, NCEPA zone 1
28.6%at or above 4 pCi/L
Median 2.1 pCi/L · 433 tests · 18.6 points below Carter County
Carter County, Cities and towns
Cities and towns in Carter County
The Census Bureau estimates 57,361 residents in Carter County for July 1, 2025, 970 more than in 2020 (+1.7%). That works out to 168 people per square mile of land. Johnson City, the largest place on its list (74,943 residents in all), extends beyond Carter County, so no share of the total is worked out for it. CDC's 345 reported tests for 2008 to 2017 work out to 6.0 per 1,000 residents (2025 estimate), close to Tennessee's 4.2.
From Johnson City to Watauga, CDC publishes no figure by town: each reads Carter County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Johnson Cityextends beyond Carter County | 74,943 | +5.4% | Counted whole |
| Elizabethton | 14,350 | −1.2% | 25.0% |
| Wataugaextends beyond Carter County | 364 | +3.4% | Counted whole |
Places in Carter County with a city page: 1 of 1
3 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 Carter County is counted whole, so it has no share.
Carter County, Homes
Homes in Carter County
Of Carter County's 27,982 homes, 68% are detached houses, against 68% across Tennessee; 18% are mobile homes. The homes are older than Tennessee's as a whole: half were built before 1977 (1986 for Tennessee), and 29% date from before 1960. 74% of occupied homes are lived in by their owner (Tennessee: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Carter County | Tennessee |
|---|---|---|
| Housing units | 27,982 | 3,095,472 |
| Detached houses | 68% | 68% |
| In buildings of 5 or more | 7% | 14% |
| Mobile homes | 18% | 8% |
| Built before 1960 | 29% | 18% |
| Built since 2000 | 17% | 29% |
| Middle year built | 1977 | 1986 |
| Owner-occupied | 74% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.