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
Locations and reports
Radon Levels in Jefferson County, Tennessee
EPA puts Jefferson County in Zone 1, its highest radon zone, and 17.1% of its 35 reported radon tests (2023) were at or above 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
17.1%
7.8 pts below TN
- Jefferson
- 17.1%
- Tennessee
- 24.9%
35 tests, 2023
Median result
2.6pCi/L
Below action level
- Jefferson
- 2.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
35
14th of 15 by tests
- Jefferson
- 35
- Hamblen
- 594
Reported to CDC before any fix, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Tennessee
11 of 15
Middle half
- Jefferson
- 17.1%
- Blount
- 50.0%
By share, of 15 with 30+ tests
Read a result for Jefferson County
Starts at Jefferson County's median, 2.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.6 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. Jefferson County's median reported result, 2023.
The data
Jefferson County, At a glance
Jefferson County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Jefferson County in
USGS geologic potential: High across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Jefferson County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2022 | 33.3% |
| 2023 | 17.1% |
2023: 17.1%. Across these years the share ran from 17.1% to 33.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 35 tests reported to CDC for Jefferson County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Jefferson County, Compared
Jefferson County radon figures, compared
Calculated by Radon411Jefferson County's 35 reported tests in 2023 had a middle value of 2.6 pCi/L and a maximum of 9.2 pCi/L, and 17.1% reached 4 pCi/L. Tennessee as a whole (70 Tennessee counties, pooled) comes to 24.9%: 7.8 points higher than here.
Among its state's counties it ranks 11th of 15 Tennessee counties with 30 or more tests for the same period. Statewide for the same period, Blount County reported the highest share (50.0%) and Hamilton County the lowest (2.4%).
Below the action level, 14 tests (40.0%) came in under 2 pCi/L, against 49.4% statewide, and 15 tests (42.9%) fell between 2 and 4, against 25.7% statewide. The busiest year on file was 2022, with 144 tests reported; the quietest, 2023, had 35.
EPA's 1993 zone map puts Jefferson County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.
Next door, the shares run from 17.7% in Knox County to 37.0% in Hamblen County.
CDC also counts 8 tests taken after mitigation in Jefferson County for the same period: tests in homes where a fix was already in.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Jefferson County, Geology
The ground under Jefferson County
PredictedUSGS's geologic map puts all of Jefferson County's mapped land in one class: high radon potential. All of it lies in the area the map calls Ridge and Valley, to which USGS gives a radon index of 14, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Ridge and Valley | Paleozoic sandstone and cherty dolostone. | High | 14 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Jefferson County beside the ground around it
Jefferson County has more high-potential ground than Tennessee as a whole: 100% of its land against 47.2%. Of the 5 counties that border it, none has as large a share of high-potential ground; Grainger County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Jefferson County, Local resources
Radon testing and mitigation in Jefferson 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
Jefferson County, Questions
Questions about radon in Jefferson County
Are radon levels high in Jefferson County?
In 2023, 17.1% of the radon tests reported to CDC for Jefferson County, Tennessee were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.6 pCi/L. Of 15 Tennessee counties with 30 or more tests for the same period, 10 reported a higher share; pooled, the state comes to 24.9%.
Which counties border Jefferson County?
Jefferson County borders 5 counties: Hamblen County, Grainger County, Sevier County, Cocke County and Knox County.
Products
Jefferson County, Products
Testing a home in Jefferson County
In Jefferson County, 17.1% of 35 tests reported to CDC in 2023 reached 4 pCi/L, against 24.9% pooled across Tennessee. In Zone 1 the year-round level in Jefferson County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
Monitor
EcoQube Wi-Fi continuous radon monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Wi-Fi
- App only
Method: Ion chamber
First reading: Within 10 minutes
Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Jefferson County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Jefferson County
Explore
Jefferson County, Bordering counties
Counties bordering Jefferson County
Calculated by Radon411- Radon levels in Grainger CountyEPA zone 1
100.0%at or above 4 pCi/L
Median 12.5 pCi/L · 4 tests · 82.9 points above Jefferson County
- Radon levels in Hamblen CountyEPA zone 1
37.0%at or above 4 pCi/L
Median 3.1 pCi/L · 594 tests · 19.9 points above Jefferson County
- Radon levels in Sevier CountyEPA zone 2
33.3%at or above 4 pCi/L
Median 2.3 pCi/L · 18 tests · 16.2 points above Jefferson County
- Radon levels in Cocke CountyEPA zone 2
18.4%at or above 4 pCi/L
Median 1.4 pCi/L · 347 tests · 1.3 points above Jefferson County
- Radon levels in Knox CountyEPA zone 1
17.7%at or above 4 pCi/L
Median 1.8 pCi/L · 203 tests · 0.6 points above Jefferson County
Jefferson County, Cities and towns
Cities and towns in Jefferson County
Jefferson County is growing: the Census Bureau puts it at 60,024 residents on July 1, 2025, up 9.3% from 54,897 in 2020. That works out to 218 people per square mile of land. Morristown, the largest place on its list (33,517 residents in all), extends beyond Jefferson County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 35 reported tests for 2023 come to 0.6 for every 1,000 residents (2025 estimate), against 0.3 for Tennessee.
From Morristown to Baneberry, CDC publishes no figure by town: each reads Jefferson County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Morristownextends beyond Jefferson County | 33,517 | +9.8% | Counted whole |
| Jefferson City | 9,103 | +8.1% | 15.2% |
| Dandridge | 3,947 | +17.6% | 6.6% |
| White Pineextends beyond Jefferson County | 2,619 | +2.8% | Counted whole |
| New Market | 1,431 | +4.2% | 2.4% |
| Baneberry | 585 | +11.4% | 1.0% |
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 Jefferson County is counted whole, so it has no share.
Jefferson County, Homes
Homes in Jefferson County
Of Jefferson County's 25,223 homes, 68% are detached houses, against 68% across Tennessee; 22% are mobile homes. Half of its homes were built before 1990, close to Tennessee's 1986: 15% date from before 1960 and 29% from 2000 or later. 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 | Jefferson County | Tennessee |
|---|---|---|
| Housing units | 25,223 | 3,095,472 |
| Detached houses | 68% | 68% |
| In buildings of 5 or more | 3% | 14% |
| Mobile homes | 22% | 8% |
| Built before 1960 | 15% | 18% |
| Built since 2000 | 29% | 29% |
| Middle year built | 1990 | 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.