Radon levels in Tennessee: Moderate
The model predicts a population-weighted basement average of 2.3 pCi/L (model estimate) across Tennessee's 95 counties - about 1.3× the US average of 1.8 pCi/L. Above-ground floors average 1.4 pCi/L.
Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.
39 / 95
EPA Zone 1 counties (41%)
32 / 24
Zone 2 / Zone 3 counties
0
counties predicted ≥ 4 pCi/L
0.2%
of ZIP codes predicted ≥ 4 pCi/L
Test Tennessee - the EPA says "consider fixing" in this range
The predicted basement average here is 2.3 pCi/L, in the 2-4 pCi/L band where the EPA recommends considering mitigation. Plenty of individual homes in a moderate area test above 4. Start with a short-term test; if it comes back at 2 or higher, follow up with a long-term test or a continuous monitor.
Monitor link goes to the Airthings store - use code RADONGRADE-10OFF at checkout for 10% off any Airthings monitor.
Already tested at 4 pCi/L or higher? Find a certified mitigation professional (EPA). A mitigation system typically runs $800-$2,500 installed.
Affiliate links: we may earn a commission from Airthings or Amazon at no extra cost to you.
What the data says about radon in Tennessee
39 of Tennessee's 95 counties are EPA Zone 1 (41%), 32 are Zone 2 and 24 are Zone 3 on the EPA's county-level map. Zone 1 - the highest-potential class, predicted screening average above 4 pCi/L - is the most common designation in Tennessee. The zones were drawn once, from geology and the tests available in 1993, and the EPA itself notes that homes with elevated radon exist in all three zones.
Weighted by where people live, Tennessee's predicted basement average is 2.3 pCi/L - 1.3× the US population-weighted average of 1.8 - which puts the state in the moderate range. Of the 95 counties with predictions, 0 are predicted at or above 4 pCi/L, 75 in the 2-4 band and 20 below 2. The highest predicted county is Sullivan County at 3.2 pCi/L; the lowest is Shelby County at 1.4 - a 1.8 pCi/L spread that means a statewide average tells you little about any one county.
Nationally 4.2% of ZIPs are predicted at 4+ pCi/L and 48.7% at 2+; in Tennessee it is 0.2% and 70.9% - below the US share at the action level but above it at 2 pCi/L. With more than half of ZIPs above 2, a test is worth doing before any purchase or renovation here.
Tennessee counties by predicted radon
Sorted highest to lowest predicted basement average (model estimate). 95 counties.
| County | Predicted basement | Upstairs | Grade | EPA zone | ZIPs |
|---|---|---|---|---|---|
| Sullivan County | 3.2 pCi/L | 2.2 | Moderate | EPA Zone 1 | 8 |
| Washington County | 3.2 pCi/L | 2.0 | Moderate | EPA Zone 1 | 7 |
| Johnson County | 3.1 pCi/L | 1.9 | Moderate | EPA Zone 2 | 5 |
| Carter County | 3.1 pCi/L | 1.9 | Moderate | EPA Zone 2 | 4 |
| Loudon County | 3.0 pCi/L | 1.7 | Moderate | EPA Zone 1 | 5 |
| Cocke County | 3.0 pCi/L | 1.8 | Moderate | EPA Zone 2 | 6 |
| Blount County | 3.0 pCi/L | 1.9 | Moderate | EPA Zone 1 | 10 |
| Hawkins County | 3.0 pCi/L | 1.6 | Moderate | EPA Zone 1 | 7 |
| McMinn County | 3.0 pCi/L | 1.7 | Moderate | EPA Zone 1 | 6 |
| Monroe County | 3.0 pCi/L | 1.6 | Moderate | EPA Zone 1 | 4 |
| White County | 3.0 pCi/L | 1.5 | Moderate | EPA Zone 2 | 3 |
| Hamblen County | 2.9 pCi/L | 1.8 | Moderate | EPA Zone 1 | 4 |
| Lawrence County | 2.9 pCi/L | 1.6 | Moderate | EPA Zone 1 | 8 |
| Cannon County | 2.9 pCi/L | 1.6 | Moderate | EPA Zone 2 | 2 |
| Claiborne County | 2.9 pCi/L | 1.6 | Moderate | EPA Zone 1 | 6 |
| Hancock County | 2.9 pCi/L | 1.6 | Moderate | EPA Zone 1 | 2 |
| Jefferson County | 2.8 pCi/L | 1.8 | Moderate | EPA Zone 1 | 5 |
| Roane County | 2.8 pCi/L | 1.8 | Moderate | EPA Zone 1 | 3 |
| Sevier County | 2.8 pCi/L | 1.9 | Moderate | EPA Zone 2 | 6 |
| Polk County | 2.8 pCi/L | 1.5 | Moderate | EPA Zone 2 | 8 |
| Grainger County | 2.8 pCi/L | 1.6 | Moderate | EPA Zone 1 | 6 |
| Unicoi County | 2.8 pCi/L | 1.7 | Moderate | EPA Zone 2 | 3 |
| Lewis County | 2.8 pCi/L | 1.3 | Moderate | EPA Zone 1 | 2 |
| Moore County | 2.8 pCi/L | 1.6 | Moderate | EPA Zone 1 | 1 |
| Union County | 2.7 pCi/L | 1.5 | Moderate | EPA Zone 1 | 3 |
| Anderson County | 2.7 pCi/L | 1.7 | Moderate | EPA Zone 1 | 6 |
| Smith County | 2.7 pCi/L | 1.6 | Moderate | EPA Zone 1 | 9 |
| Rhea County | 2.7 pCi/L | 1.6 | Moderate | EPA Zone 3 | 4 |
| Campbell County | 2.7 pCi/L | 1.5 | Moderate | EPA Zone 3 | 7 |
| Greene County | 2.6 pCi/L | 1.8 | Moderate | EPA Zone 1 | 7 |
| Maury County | 2.6 pCi/L | 1.7 | Moderate | EPA Zone 3 | 6 |
| Giles County | 2.6 pCi/L | 1.8 | Moderate | EPA Zone 1 | 5 |
| Jackson County | 2.6 pCi/L | 1.5 | Moderate | EPA Zone 1 | 4 |
| Marshall County | 2.6 pCi/L | 1.4 | Moderate | EPA Zone 1 | 4 |
| Bedford County | 2.6 pCi/L | 1.6 | Moderate | EPA Zone 1 | 5 |
| Clay County | 2.6 pCi/L | 1.4 | Moderate | EPA Zone 2 | 2 |
| Davidson County | 2.6 pCi/L | 1.9 | Moderate | EPA Zone 1 | 28 |
| Macon County | 2.6 pCi/L | 1.4 | Moderate | EPA Zone 1 | 2 |
| Trousdale County | 2.6 pCi/L | 1.7 | Moderate | EPA Zone 1 | 2 |
| DeKalb County | 2.6 pCi/L | 1.4 | Moderate | EPA Zone 2 | 4 |
| Meigs County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 1 | 2 |
| Overton County | 2.5 pCi/L | 1.6 | Moderate | EPA Zone 2 | 8 |
| Warren County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 2 | 3 |
| Hickman County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 1 | 6 |
| Lincoln County | 2.5 pCi/L | 1.5 | Moderate | EPA Zone 1 | 10 |
| Pickett County | 2.5 pCi/L | 1.3 | Moderate | EPA Zone 2 | 2 |
| Franklin County | 2.5 pCi/L | 1.5 | Moderate | EPA Zone 3 | 8 |
| Sumner County | 2.5 pCi/L | 1.6 | Moderate | EPA Zone 2 | 7 |
| Knox County | 2.4 pCi/L | 1.7 | Moderate | EPA Zone 1 | 22 |
| Cheatham County | 2.4 pCi/L | 1.6 | Moderate | EPA Zone 2 | 4 |
| Coffee County | 2.4 pCi/L | 1.1 | Moderate | EPA Zone 2 | 4 |
| Bradley County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 1 | 5 |
| Dickson County | 2.4 pCi/L | 1.6 | Moderate | EPA Zone 2 | 6 |
| Humphreys County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 1 | 4 |
| Perry County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 1 | 2 |
| Rutherford County | 2.3 pCi/L | 1.5 | Moderate | EPA Zone 1 | 12 |
| Marion County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 2 | 9 |
| Montgomery County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Putnam County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 6 |
| Wayne County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 1 | 6 |
| Robertson County | 2.3 pCi/L | 1.5 | Moderate | EPA Zone 2 | 8 |
| Houston County | 2.3 pCi/L | 1.5 | Moderate | EPA Zone 2 | 3 |
| Fentress County | 2.2 pCi/L | 1.0 | Moderate | EPA Zone 2 | 5 |
| Williamson County | 2.2 pCi/L | 1.7 | Moderate | EPA Zone 1 | 10 |
| Morgan County | 2.2 pCi/L | 1.0 | Moderate | EPA Zone 3 | 6 |
| Hardin County | 2.1 pCi/L | 1.4 | Moderate | EPA Zone 2 | 8 |
| Stewart County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 5 |
| Scott County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 3 | 5 |
| Van Buren County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 2 | 2 |
| Hamilton County | 2.1 pCi/L | 1.4 | Moderate | EPA Zone 2 | 24 |
| Sequatchie County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 3 | 1 |
| Bledsoe County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 3 | 2 |
| Grundy County | 2.1 pCi/L | 1.0 | Moderate | EPA Zone 3 | 7 |
| Cumberland County | 2.1 pCi/L | 0.9 | Moderate | EPA Zone 3 | 6 |
| Wilson County | 2.0 pCi/L | 1.2 | Moderate | EPA Zone 1 | 5 |
| Decatur County | 1.9 pCi/L | 1.3 | Low | EPA Zone 2 | 5 |
| Benton County | 1.9 pCi/L | 1.2 | Low | EPA Zone 2 | 4 |
| Chester County | 1.8 pCi/L | 1.0 | Low | EPA Zone 2 | 4 |
| Dyer County | 1.8 pCi/L | 0.9 | Low | EPA Zone 3 | 4 |
| Henry County | 1.7 pCi/L | 1.0 | Low | EPA Zone 3 | 7 |
| Fayette County | 1.7 pCi/L | 0.9 | Low | EPA Zone 3 | 7 |
| McNairy County | 1.7 pCi/L | 1.0 | Low | EPA Zone 2 | 9 |
| Henderson County | 1.7 pCi/L | 1.0 | Low | EPA Zone 2 | 6 |
| Obion County | 1.7 pCi/L | 0.9 | Low | EPA Zone 3 | 7 |
| Haywood County | 1.7 pCi/L | 0.9 | Low | EPA Zone 3 | 4 |
| Lauderdale County | 1.7 pCi/L | 0.9 | Low | EPA Zone 3 | 3 |
| Carroll County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 11 |
| Tipton County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 7 |
| Weakley County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 7 |
| Crockett County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 3 |
| Gibson County | 1.6 pCi/L | 0.9 | Low | EPA Zone 3 | 7 |
| Madison County | 1.6 pCi/L | 0.9 | Low | EPA Zone 1 | 9 |
| Hardeman County | 1.5 pCi/L | 0.9 | Low | EPA Zone 3 | 8 |
| Lake County | 1.5 pCi/L | 0.7 | Low | EPA Zone 3 | 2 |
| Shelby County | 1.4 pCi/L | 0.8 | Low | EPA Zone 3 | 32 |
Radon levels in Tennessee cities
The 20 most-populous Tennessee places among the 1,000 largest US cities (Census incorporated places and CDPs), by population. City figures are ZIP-land-weighted means of the model's ZIP predictions (model estimate).
| City | Population | Predicted basement | Upstairs | Grade | ZIPs ≥ 4 |
|---|---|---|---|---|---|
| Nashville | 687,788 | 2.6 pCi/L | 1.9 | Moderate | 0% |
| Memphis | 618,639 | 1.4 pCi/L | 0.8 | Low | 0% |
| Knoxville | 198,162 | 2.5 pCi/L | 1.8 | Moderate | 0% |
| Chattanooga | 187,030 | 2.2 pCi/L | 1.4 | Moderate | 0% |
| Clarksville | 180,716 | 2.3 pCi/L | 1.3 | Moderate | 0% |
| Murfreesboro | 165,430 | 2.3 pCi/L | 1.5 | Moderate | 0% |
| Franklin | 88,558 | 2.2 pCi/L | 1.8 | Moderate | 0% |
| Johnson City | 73,337 | 3.3 pCi/L | 2.0 | Moderate | 0% |
| Jackson | 68,264 | 1.6 pCi/L | 0.9 | Low | 0% |
| Hendersonville | 63,618 | 2.2 pCi/L | 1.6 | Moderate | 0% |
| Spring Hill | 57,637 | 1.9 pCi/L | 1.3 | Low | 0% |
| Smyrna | 57,418 | 2.1 pCi/L | 1.3 | Moderate | 0% |
| Kingsport | 56,704 | 2.8 pCi/L | 2.0 | Moderate | 0% |
| Bartlett | 56,030 | 1.6 pCi/L | 0.8 | Low | 0% |
| Collierville | 51,317 | 1.5 pCi/L | 0.7 | Low | 0% |
| Gallatin | 50,355 | 2.8 pCi/L | 1.9 | Moderate | 0% |
| Cleveland | 49,086 | 2.3 pCi/L | 1.3 | Moderate | 0% |
| Lebanon | 48,112 | 2.3 pCi/L | 1.1 | Moderate | 0% |
| Columbia | 47,445 | 3.0 pCi/L | 2.0 | Moderate | 0% |
| Brentwood | 45,265 | 2.1 pCi/L | 1.7 | Moderate | 0% |
Highest-radon ZIP codes in Tennessee
The 10 Tennessee ZIP codes with the highest predicted basement average (model estimate), out of 595 modeled. A ZIP average is still an area figure - neighboring homes routinely test several pCi/L apart.
| ZIP | County | Predicted basement | Upstairs | Grade |
|---|---|---|---|---|
| 37620 | Sullivan County | 4.1 pCi/L | 2.6 | High |
| 37774 | Loudon County | 3.8 pCi/L | 1.9 | Moderate |
| 37206 | Davidson County | 3.7 pCi/L | 3.1 | Moderate |
| 37617 | Sullivan County | 3.5 pCi/L | 2.0 | Moderate |
| 37601 | Washington County | 3.5 pCi/L | 1.9 | Moderate |
| 37686 | Sullivan County | 3.5 pCi/L | 1.8 | Moderate |
| 37205 | Davidson County | 3.4 pCi/L | 3.0 | Moderate |
| 37216 | Davidson County | 3.4 pCi/L | 2.9 | Moderate |
| 37843 | Cocke County | 3.3 pCi/L | 2.0 | Moderate |
| 37885 | Monroe County | 3.3 pCi/L | 1.7 | Moderate |
Tennessee radon questions
- Is radon high in Tennessee?
- Tennessee's population-weighted predicted basement average is 2.3 pCi/L, about 1.3× the US average of 1.8. 0 of its 95 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 75 are in the 2-4 "consider fixing" range and 20 are below 2. 0.2% of Tennessee ZIP codes are predicted at 4 or higher.
- Which Tennessee county has the highest radon?
- Sullivan County has the highest predicted basement average in Tennessee at 3.2 pCi/L (EPA Zone 1). The lowest is Shelby County at 1.4 pCi/L. These are area figures; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in Tennessee?
- 39 of Tennessee's 95 counties (41%) are EPA Zone 1 (highest potential), 32 are Zone 2 and 24 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in Tennessee?
- Yes - with some urgency. Tennessee's predicted average is in the moderate range, and 70.9% of its ZIP codes are predicted at 2 pCi/L or higher. A short-term charcoal kit or a continuous digital monitor will tell you your actual level within days.
Tennessee radon program
State programs keep lists of certified testers and mitigators and sometimes run kit programs. We link only pages we could verify, and Tennessee's program page did not respond when we checked, so start from the EPA state radon contacts page. Then read how to test and what mitigation costs.