Locations and reports
Radon in Knoxville, Tennessee
EPA puts Knox County, where Knoxville is, in Zone 1, its highest radon zone, and 17.7% of its 203 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
17.7%
7.2 pts below TN
- Knox
- 17.7%
- Tennessee
- 24.9%
Knox, 10th of 15 in TN, 2023
Median result
1.8pCi/L
Below action level
- Knox
- 1.8 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of Knox's tests, 2023
Nearest county
16.2%
Anderson, 17 miles
- Anderson
- 16.2%
- Knox
- 17.7%
37 tests, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
Knox, where Knoxville is
Tests reported
203
In Knox
- Knox
- 203
- Anderson
- 37
Reported to CDC before any fix, 2023
Read a result for Knoxville
Starts at Knox County's median, 1.8 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.8 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Knox County's median reported result, 2023.
The data
Knoxville, What is published
What is published for Knoxville
Every figure for Knoxville is a county's
Radon data is published by county, not by city, so for Knoxville it is Knox County's: its EPA zone (Zone 1) and the 203 tests reported to CDC for 2023. Only a test tells you about one home.
Knoxville covers 98.7 square miles of land, all of it in Knox County. About 202,021 people live there, 2,046 to the square mile.
Knoxville, Counties
The county Knoxville lies in
MeasuredKnox County's EPA zone and the figures CDC publishes for it, 2023.
Knox CountyZone 1Highest predicted potential
- 17.7%
- Reported tests at or above 4 pCi/L
- 1.8 pCi/L
- Median reported result
- 203 tests
- Tests reported to CDC
- 2
- Annual years on file
Knox County ranks 10th of 15 Tennessee counties with 30 or more tests for that period, 7.2 points below the 24.9% pooled across Tennessee's counties, 15.7 points below the national pool of 33.4%.
Measured from the middle of Knoxville, the nearest counties with a CDC figure for 2023 are Anderson County (17 miles, 16.2% of 37 tests), Blount County (19 miles, 50.0% of 46 tests) and Loudon County (26 miles, 40.2% of 82 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 16.2% to 50.0%; the farthest of them, Washington County, is 84 miles away at 26.1%.
No business in the directory gives Knoxville as its address; the Tennessee list covers it. Tennessee's other cities with a page of their own: Nashville, Chattanooga, Cleveland and Johnson City.
The counties around Knoxville
By distance from the middle of Knoxville; counties with 30 or more tests.
Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2023.
Knoxville, Geology
The ground under Knoxville
PredictedUSGS's geologic map puts all of Knoxville'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.
Knoxville beside its county and Tennessee
All of Knoxville, like all of Knox County, is rated high. Knoxville has more high-potential ground than Tennessee as a whole: 100% of its land against 47.2%.
The map rates the ground, not the air in any home.
Knoxville, Homes
Homes in Knoxville
Knoxville has 94,885 homes, and many share a building: 34% are in buildings of five or more, 53% are detached houses, against 66% across Knox County. The homes are older than Knox County's as a whole: half were built before 1974 (1985 for Knox County), and 34% date from before 1960. Most occupied homes here are rented: owners live in 47% (Knox County: 65%). A tenant can run a test; a fix is the landlord's to make.
| Homes | Knoxville | Knox County | Tennessee |
|---|---|---|---|
| Housing units | 94,885 | 214,606 | 3,095,472 |
| Detached houses | 53% | 66% | 68% |
| In buildings of 5 or more | 34% | 20% | 14% |
| Mobile homes | 1% | 4% | 8% |
| Built before 1960 | 34% | 20% | 18% |
| Built since 2000 | 19% | 27% | 29% |
| Middle year built | 1974 | 1985 | 1986 |
| Owner-occupied | 47% | 65% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.
Local help
Knoxville, Local resources
Local resources for Knoxville
Who to ask in Tennessee: its radon program, test kits and professionals.
- Tennessee Radon ProgramRun by Department of Environment & Conservation, phone 1-800-232-1139.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 TennesseeRadon testers and mitigators in Tennessee, each with how its listing was checked.
The program's own words on licensing are on the Tennessee page.
What it means
Knoxville, Questions
Questions about radon in Knoxville
What radon zone is Knoxville in?
Knoxville takes its zone from Knox County, which EPA puts in Zone 1, the map's highest class: a predicted county average above 4 pCi/L.
What are radon levels in Knoxville?
Most tests near Knoxville come back under EPA's action level, but not all: 17.7% of Knox County's 203 tests for 2023 were at or above 4 pCi/L. The median reported result was 1.8 pCi/L.
Should I test my home in Knoxville?
Yes. In Knox County, about one reported test in 6 reached 4 pCi/L. That is below Tennessee's pooled 24.9%, and still not a reason to skip it, and ranks Knox County 10th of the 15 Tennessee counties with 30 or more tests. The number for one house comes only from testing it. How to test a home.
What ground is Knoxville built on, as far as radon goes?
USGS's geologic map puts all of Knoxville on one named area, "Ridge and Valley", rated high for radon potential, radon index 14.
Is radon higher in the counties around Knoxville?
It depends which way you go. 6 of the 8 nearest counties with a figure report a larger share than Knox County's 17.7% and 2 a smaller one: from Anderson County (16.2%, 17 miles off) to Blount County (50.0%, 19 miles off).
The answers use the published figures of Knox County, the county Knoxville lies in.
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