Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Hamilton County, Tennessee
EPA puts Hamilton County in Zone 2, its middle radon zone, and most reported tests there come back low, though 2.4% of 169 (2023) reached 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
2.4%
22.5 pts below TN
- Hamilton
- 2.4%
- Tennessee
- 24.9%
169 tests, 2023
Median result
0.7pCi/L
Below action level
- Hamilton
- 0.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
169
4th of 15 by tests
- Hamilton
- 169
- Hamblen
- 594
Reported to CDC before any fix, 2023
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
15 of 15
Lowest quarter
- Hamilton
- 2.4%
- Blount
- 50.0%
By share, of 15 with 30+ tests
Read a result for Hamilton County
Starts at Hamilton County's median, 0.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 0.7 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. Hamilton County's median reported result, 2023.
The data
Hamilton County, At a glance
Hamilton County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Hamilton County is a
USGS geologic potential: High across 80% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Hamilton County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2022 | 7.0% |
| 2023 | 2.4% |
2023: 2.4%. Across these years the share ran from 2.4% to 7.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 169 tests reported to CDC for Hamilton 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).
Hamilton County, Compared
Hamilton County radon figures, compared
Calculated by Radon411Only 4 of 169 radon tests reported for Hamilton County in 2023 reached 4 pCi/L (2.4%). The median result, 0.7 pCi/L, sits below 2, well under EPA's 4 pCi/L action level, and the top reported result was 50.7 pCi/L.
Across 70 Tennessee counties pooled together, 24.9% of tests reached that level, so Hamilton County runs 22.5 points below its state. Against the national pool of 33.4%, the gap is 31.0 points lower. Its place in the state: 15th of 15 Tennessee counties with 30 or more tests for the same period.
The reported tests do not follow EPA's Zone 2 label for Hamilton County (predicted average between 2 and 4 pCi/L): 2.4% of them reached 4 pCi/L, fewer than that label suggests. Bradley County, the one bordering county with a figure for the same period, reported 25.7%.
Below the action level, 146 tests (86.4%) came in under 2 pCi/L, against 49.4% statewide, and 19 tests (11.2%) fell between 2 and 4, against 25.7% statewide. USGS geology rates 80% of the county's land high radon potential.
The busiest year on file was 2022, with 603 tests reported; the quietest, 2023, had 169.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Hamilton County, Geology
The ground under Hamilton County
PredictedMost of the ground under Hamilton County is one class on USGS's geologic map: 79.6% of its land is high radon potential, with 20.4% low. The map puts 78.3% of Hamilton County in the area it calls Ridge and Valley and 20.1% in Appalachian Plateau, with one smaller area beside them. USGS gives the first a radon index of 14, in the high band (12 to 17), and the second 8, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Ridge and Valley | Paleozoic sandstone and cherty dolostone. | High | 14 | 78.3% |
| Appalachian Plateau | Sandstone and shale. | Low | 8 | 20.1% |
| Interior Low Plateaus | Mississippian carbonate rocks and shales. | High | 12 | 1.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Hamilton County beside the ground around it
Hamilton County has more high-potential ground than Tennessee as a whole: 79.6% of its land against 47.2%. Of the 10 counties that border it, 2 have more high-potential ground, Meigs County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Hamilton County, Local resources
Radon testing and mitigation in Hamilton 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
Hamilton County, Questions
Questions about radon in Hamilton County
Are radon levels high in Hamilton County?
In 2023, 2.4% of the radon tests reported to CDC for Hamilton County, Tennessee were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.7 pCi/L. Of 15 Tennessee counties with 30 or more tests for the same period, 14 reported a higher share; pooled, the state comes to 24.9%.
Which counties border Hamilton County?
Hamilton County borders 10 counties: Sequatchie County, TN, Bradley County, TN, Catoosa County, GA, Bledsoe County, TN, Meigs County, TN, Marion County, TN, Rhea County, TN, Walker County, GA, Whitfield County, GA and Dade County, GA.
Products
Hamilton County, Products
Testing a home in Hamilton County
In Hamilton County, 2.4% of 169 tests reported to CDC in 2023 reached 4 pCi/L, against 24.9% pooled across Tennessee. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Hamilton County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorForensics Detectors
FD-65-RADON rechargeable radon detector with a color screen
- 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
Hamilton County, Bordering counties
Counties bordering Hamilton County
Calculated by Radon411- Radon levels in Marion County, TNEPA zone 2
60.0%at or above 4 pCi/L
Median 4.6 pCi/L · 5 tests · 57.6 points above Hamilton County
- Radon levels in Rhea County, TNEPA zone 3
50.0%at or above 4 pCi/L
Median 4.2 pCi/L · 2 tests · 47.6 points above Hamilton County
- Radon levels in Bradley County, TNEPA zone 1
25.7%at or above 4 pCi/L
Median 2.2 pCi/L · 105 tests · 23.3 points above Hamilton County
- Radon levels in Sequatchie County, TNEPA zone 3
0.0%at or above 4 pCi/L
Median 0.8 pCi/L · 1 test · 2.4 points below Hamilton County
- Radon levels in Bledsoe County, TNEPA zone 3
0.0%at or above 4 pCi/L
Median 0.2 pCi/L · 1 test · 2.4 points below Hamilton County
- Radon levels in Meigs County, TNEPA zone 1
0.0%at or above 4 pCi/L
Median 1.3 pCi/L · 2 tests · 2.4 points below Hamilton County
- Radon levels in Catoosa County, GAEPA zone 2
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Walker County, GAEPA zone 2
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Whitfield County, GAEPA zone 2
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Dade County, GAEPA zone 3
No CDC figure for 2023; its page reads it against its own neighbours.
Hamilton County, Cities and towns
Cities and towns in Hamilton County
Hamilton County is growing: the Census Bureau puts it at 390,833 residents on July 1, 2025, up 6.2% from 367,886 in 2020. That works out to 721 people per square mile of land. Its largest town, Chattanooga, has 194,144 residents, 49.7% of the total. Together its 10 incorporated places hold 68.7% of those residents; the other 31.3% live outside any of them. CDC's 169 reported tests for 2023 work out to 0.4 per 1,000 residents (2025 estimate), close to Tennessee's 0.3.
From Chattanooga to Ridgeside, CDC publishes no figure by town: each reads Hamilton County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Chattanooga | 194,144 | +6.5% | 49.7% |
| East Ridge | 21,921 | −1.3% | 5.6% |
| Soddy-Daisy | 13,474 | +3.2% | 3.4% |
| Red Bank | 12,405 | +4.0% | 3.2% |
| Collegedale | 11,499 | +3.4% | 2.9% |
| Signal Mountain | 8,824 | −0.3% | 2.3% |
| Lookout Mountain | 2,044 | −1.2% | 0.5% |
| Lakesite | 1,980 | +4.2% | 0.5% |
| Walden | 1,965 | −1.0% | 0.5% |
| Ridgeside | 441 | −1.3% | 0.1% |
Places in Hamilton County with a city page: 1 of 1
10 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).
Hamilton County, Homes
Homes in Hamilton County
Of Hamilton County's 165,605 homes, 68% are detached houses, against 68% across Tennessee; 17% are in buildings of five or more homes. Half of its homes were built before 1980, close to Tennessee's 1986: 24% date from before 1960 and 27% from 2000 or later. 64% 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 | Hamilton County | Tennessee |
|---|---|---|
| Housing units | 165,605 | 3,095,472 |
| Detached houses | 68% | 68% |
| In buildings of 5 or more | 17% | 14% |
| Mobile homes | 3% | 8% |
| Built before 1960 | 24% | 18% |
| Built since 2000 | 27% | 29% |
| Middle year built | 1980 | 1986 |
| Owner-occupied | 64% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.