Radon levels by zip code in East Tennessee
Actual indoor radon test results from Tennessee Department of Health data: 606 Tennessee zip codes, every county in the state. Type your zip and you'll see what your neighbors' homes actually tested at, in about five seconds. Readings are in pCi/L; the EPA action level is 4.0.
Data: TDH compiled state test data through Oct 2020 (zip-level) + CDC EPHT county data through 2023 · EPA Map of Radon Zones (1993) · zip-county assignment via US Census. County-level context refreshed from CDC tracking data through 2023. Tests are homes that chose to test, not a random sample. No dataset replaces testing your own home.
Your neighborhood, on the radon map.
Fifty-eight metro zips, colored by what tests found. Hover for the numbers, or click a zip to run the full lookup.
White lines are county borders. Zips marked no-data have no tests on file, not no radon. Source: TDH state test data (zip-level, through Oct 2020).
Five counties. Every zip with tests on file.
Sorted by average reading, highest first. Rows marked † have fewer than five tests. Treat those as anecdotes, not averages.
Knox County
| Zip | Area | Avg | Median | Max | Tests | % ≥ 4.0 |
|---|---|---|---|---|---|---|
| 37914 | Knoxville | 4.87 | 3.1 | 20.2 | 17 | 35.3% |
| 37922 | Knoxville | 4.74 | 2.6 | 48.7 | 131 | 38.2% |
| 37923 | Knoxville | 4.71 | 2.4 | 103.9 | 58 | 22.4% |
| 37932 | Knoxville | 4.31 | 1.6 | 41.3 | 57 | 22.8% |
| 37918 | Knoxville | 4.08 | 2.2 | 24 | 37 | 27% |
| 37931 | Knoxville | 4.06 | 1.6 | 22.9 | 59 | 27.1% |
| 37919 | Knoxville | 4.01 | 2.9 | 21.4 | 63 | 39.7% |
| 37915 | Knoxville | 3.8 | 3.8 | 3.8 | 1 † | n/a |
| 37924 | Knoxville | 3.75 | 1.8 | 13.1 | 13 | 38.5% |
| 37849 | Powell | 3.74 | 2.05 | 28.1 | 40 | 20% |
| 37921 | Knoxville | 3.67 | 2.2 | 12.3 | 29 | 27.6% |
| 37920 | Knoxville | 3.49 | 2.4 | 20.2 | 57 | 33.3% |
| 37938 | Knoxville | 3.38 | 2.8 | 10.1 | 25 | 28% |
| 37871 | Strawberry Plains | 3.22 | 1.45 | 8.8 | 4 † | n/a |
| 37917 | Knoxville | 2.9 | 1.6 | 11.8 | 37 | 27% |
| 37909 | Knoxville | 2.89 | 1.9 | 8.9 | 33 | 24.2% |
| 37912 | Knoxville | 2.67 | 2 | 11.1 | 22 | 18.2% |
| 37902 | Knoxville | 2.57 | 1.5 | 5.9 | 3 † | n/a |
| 37721 | Corryton | 2.26 | 2.7 | 4.3 | 9 | 11.1% |
| 37806 | Mascot | 1.45 | 1.45 | 1.8 | 2 † | n/a |
| 37916 | Knoxville | 1.3 | 1.3 | 1.3 | 1 † | n/a |
| 37934 | Knoxville | n/a | n/a | n/a | 0 | n/a |
Blount County
| Zip | Area | Avg | Median | Max | Tests | % ≥ 4.0 |
|---|---|---|---|---|---|---|
| 37777 | Louisville | 8.98 | 2.2 | 90.3 | 16 | 25% |
| 37803 | Maryville | 5.33 | 3.3 | 23.2 | 51 | 43.1% |
| 37853 | Rockford | 4.53 | 2.9 | 9.6 | 3 † | n/a |
| 37804 | Maryville | 4.34 | 3.4 | 17.2 | 27 | 44.4% |
| 37801 | Maryville | 3.7 | 2.4 | 15.7 | 33 | 24.2% |
| 37886 | Walland | 3.63 | 2.75 | 9.9 | 10 | 40% |
| 37737 | Friendsville | 3.45 | 2.4 | 11 | 11 | 27.3% |
| 37882 | Townsend | 3.1 | 2.75 | 5.5 | 6 | 33.3% |
| 37701 | Alcoa | 1.1 | 1.4 | 1.6 | 3 † | n/a |
| 37878 | Tallassee | n/a | n/a | n/a | 0 | n/a |
Anderson County
| Zip | Area | Avg | Median | Max | Tests | % ≥ 4.0 |
|---|---|---|---|---|---|---|
| 37769 | Lake City | 21.5 | 21.5 | 40.3 | 2 † | n/a |
| 37705 | Andersonville | 6.48 | 3 | 29.3 | 9 | 33.3% |
| 37830 | Oak Ridge | 3.96 | 2.8 | 22.3 | 81 | 25.9% |
| 37754 | Heiskell | 3.04 | 1.9 | 6.9 | 7 | 28.6% |
| 37716 | Clinton | 2.85 | 1.9 | 8.5 | 31 | 19.4% |
| 37710 | Briceville | n/a | n/a | n/a | 0 | n/a |
Loudon County
| Zip | Area | Avg | Median | Max | Tests | % ≥ 4.0 |
|---|---|---|---|---|---|---|
| 37774 | Loudon | 6.32 | 4.6 | 78.1 | 169 | 52.7% |
| 37771 | Lenoir City | 5.06 | 4.7 | 10.2 | 19 | 52.6% |
| 37742 | Greenback | 4.7 | 2.95 | 23.7 | 16 | 43.8% |
| 37772 | Lenoir City | 3.37 | 2.5 | 17.8 | 44 | 22.7% |
| 37846 | Philadelphia | 2.78 | 1.4 | 7.7 | 4 † | n/a |
Sevier County
| Zip | Area | Avg | Median | Max | Tests | % ≥ 4.0 |
|---|---|---|---|---|---|---|
| 37862 | Sevierville | 10.41 | 3.9 | 113 | 34 | 47.1% |
| 37863 | Pigeon Forge | 7.9 | 7.9 | 15 | 2 † | n/a |
| 37764 | Kodak | 7.59 | 6.45 | 20.4 | 10 | 60% |
| 37738 | Gatlinburg | 7.3 | 4.3 | 31.6 | 21 | 52.4% |
| 37876 | Sevierville | 4.98 | 3.75 | 27.5 | 58 | 44.8% |
| 37865 | Seymour | 3.54 | 3.1 | 14.2 | 25 | 36% |
Outside these five counties? The lookup above covers all 606 Tennessee zips with tests on file. County-by-county context for the whole state lives in our East Tennessee radon guide.
Zip-level statistics come from the Tennessee Department of Health's Environmental Public Health Tracking program: the state's compiled indoor radon test results (through October 2020, the most recent zip-resolution dataset the state has published). County-level context is refreshed from the CDC's national tracking network, which carries annual county data through 2023. Those figures appear in teal on the county headers below. EPA zone designations come from the EPA Map of Radon Zones (1993), built on USGS geologic assessment. Zip-to-county assignment uses the US Census 2020 ZCTA relationship files. Averages are means of reported tests; zips with fewer than five tests are flagged because small samples swing hard. Radon varies house to house. Two identical homes next door can test a factor of ten apart, which is why every agency including the EPA says the same thing we do: test your own home.
Questions about these numbers
What does pCi/L actually mean?
Picocuries per liter, a measure of radioactive decay in the air. The EPA action level is 4.0: at or above it, fix the house. Between 2.0 and 4.0, the EPA says consider fixing. The average outdoor level is about 0.4, and there's no known fully safe level. Radon is the leading cause of lung cancer in nonsmokers.
My zip averages above 4.0. Does my house have a radon problem?
Not necessarily, and a low zip average doesn't clear you either. Radon depends on the rock under your foundation, the cracks in it, and how your house breathes. The zip data tells you how seriously to take testing, not whether your house passes. A test kit settles it in days; the state of Tennessee gives them away free, and we'll show you how on our radon testing page.
Why does East Tennessee test so high?
Geology. The Ridge-and-Valley karst that runs under Knoxville is carbonate rock laced with uranium-bearing shales: EPA Zone 1, the highest designation. The Cumberland Plateau's sandstone (Morgan, Scott counties) tests low; the Smokies foothills sit in between, though Sevier County's actual tests run higher than its Zone 2 label suggests.
The tests say I should act. What does mitigation cost here?
Most East Tennessee radon mitigation installs (active soil depressurization with a fan and vent stack) run $800 to $2,500, with the typical job landing around $1,500 to $2,000. Crawl space homes often pair mitigation with encapsulation since the same membrane does both jobs. One vetted local pro can quote yours: hit the button below.
High reading? Get it handled.
Radon risk accumulates with every year spent at an elevated level, and a mitigation system takes a day or two to install. Knowing the number is only useful if it changes something.
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