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 Hamilton County, Indiana
EPA puts Hamilton County in Zone 1, its highest radon zone, and 37.6% of its 3,479 reported radon tests (2008 to 2017, laboratory totals) 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
37.6%
1.3 pts below IN
- Hamilton
- 37.6%
- Indiana
- 38.9%
3,479 tests, 2008 to 2017
Median result
2.7pCi/L
Below action level
- Hamilton
- 2.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
3,479
4th of 69 by tests
- Hamilton
- 3,479
- St. Joseph
- 7,346
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Indiana
47 of 69
Middle half
- Hamilton
- 37.6%
- Miami
- 63.3%
By share, of 69 with 30+ tests
Read a result for Hamilton County
Starts at Hamilton County's median, 2.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.7 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. Hamilton County's median reported result, 2008 to 2017.
The data
Hamilton County, At a glance
Hamilton County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Hamilton 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 Hamilton County, 2008 to 2017, laboratory
Under 2 pCi/L: 40%2 to 4 pCi/L: 22%4 pCi/L and above: 38%
Of 3,479 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 1,407 | 40.4% |
| 2 to 4 pCi/L | 765 | 22.0% |
| 4 pCi/L and above | 1,307 | 37.6% |
What these figures count
These are the 3,479 tests reported to CDC for Hamilton County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Hamilton County, Compared
Hamilton County radon figures, compared
Calculated by Radon411In Hamilton County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (1,307 of 3,479) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.9 points higher. Across 92 Indiana counties pooled together, 38.9% of tests reached that level, so Hamilton County runs 1.3 points below its state.
Of 6 neighbours with a figure, 5 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 33.9% (Hancock County) to 49.3% (Tipton County). By share, Hamilton County is 47th of 69 Indiana counties with 30 or more tests for the same period.
Half the tests came in under 2.7 pCi/L and half over it; the single highest reached 129.9 pCi/L. Below the action level, 1,407 tests (40.4%) came in under 2 pCi/L, against 32.8% statewide, and 765 tests (22.0%) fell between 2 and 4, against 28.3% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 37.6% share point the same way here. USGS geology rates 100% of the county's land high radon potential. CDC also counts 378 tests taken after mitigation in Hamilton County for the same period: tests in homes where a fix was already in.
CDC's ten-year totals for Hamilton County went from 3,555 tests (2005 to 2014) to 3,479 (2008 to 2017), the share going from 34.8% to 37.6%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Hamilton County, Geology
The ground under Hamilton County
PredictedUSGS's geologic map puts all of Hamilton County's mapped land in one class: high radon potential. All of it lies in the area the map calls Huron-Erie Lobe, to which USGS gives a radon index of 13, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Huron-Erie Lobe | Calcareous clayey and loamy glacial deposits derived from marine carbonate and clastic sedimentary rocks. | High | 13 | 100% |
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 Indiana as a whole: 100% of its land against 56.6%. Of the 6 counties that border it, none has as large a share of high-potential ground; Boone County comes nearest 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
Listed radon businesses with an address in Hamilton County:
- Indiana's radon programIndiana Department of HealthIndiana's radon program licenses or certifies radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Indiana.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
To purchase a low-cost radon short term or long term test kit, please visit the American Lung Association
- Compare kits
- Professionals in Indiana17 professionals are listed in Indiana.
Listed radon professionals by town: Carmel, Fishers
What Indiana's program says
- Phone
- 1-800-272-9723
- Licensing of radon professionals
According to the Indiana Radon Rule, 410 IAC 5.1, everyone who is serving Indiana by doing radon testing, analysis and mitigation (radon reduction) in residential structures must be certified by the Indiana State Department of Health.
What it means
Hamilton County, Questions
Questions about radon in Hamilton County
Are radon levels high in Hamilton County?
Over the 2008 to 2017 laboratory totals, 37.6% of the radon tests reported to CDC for Hamilton County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.7 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 46 reported a higher share; pooled, the state comes to 38.9%.
Which counties border Hamilton County?
Hamilton County borders 6 counties: Tipton County, Madison County, Marion County, Boone County, Hancock County and Clinton County.
Products
Hamilton County, Products
Testing a home in Hamilton County
In Hamilton County, 37.6% of 3,479 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 38.9% pooled across Indiana. In Zone 1 the year-round level in Hamilton 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
MonitorAEGTEST
HOUND-1011 rechargeable radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
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
Hamilton County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Hamilton County
Explore
Hamilton County, Bordering counties
Counties bordering Hamilton County
Calculated by Radon411- Radon levels in Tipton CountyEPA zone 1
49.3%at or above 4 pCi/L
Median 3.9 pCi/L · 69 tests · 11.7 points above Hamilton County
- Radon levels in Madison CountyEPA zone 1
49.0%at or above 4 pCi/L
Median 3.8 pCi/L · 239 tests · 11.4 points above Hamilton County
- Radon levels in Clinton CountyEPA zone 1
45.9%at or above 4 pCi/L
Median 3.5 pCi/L · 85 tests · 8.3 points above Hamilton County
- Radon levels in Marion CountyEPA zone 1
40.1%at or above 4 pCi/L
Median 3.1 pCi/L · 3,668 tests · 2.5 points above Hamilton County
- Radon levels in Boone CountyEPA zone 1
39.7%at or above 4 pCi/L
Median 3.0 pCi/L · 614 tests · 2.1 points above Hamilton County
- Radon levels in Hancock CountyEPA zone 1
33.9%at or above 4 pCi/L
Median 2.6 pCi/L · 271 tests · 3.7 points below Hamilton County
Hamilton County, Cities and towns
Cities and towns in Hamilton County
Hamilton County is growing: the Census Bureau puts it at 387,036 residents on July 1, 2025, up 10.9% from 349,011 in 2020. That works out to 981 people per square mile of land. Its largest town, Carmel, has 105,634 residents, 27.3% of the total. Together its 8 incorporated places hold 94.7% of those residents; the other 5.3% live outside any of them. CDC's 3,479 reported tests for 2008 to 2017 work out to 9.0 per 1,000 residents (2025 estimate), close to Indiana's 6.2.
From Carmel to Atlanta, CDC publishes no figure by town: each reads Hamilton County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Carmel | 105,634 | +5.7% | 27.3% |
| Fishers | 104,812 | +5.3% | 27.1% |
| Noblesville | 76,111 | +8.4% | 19.7% |
| Westfield | 66,258 | +40.9% | 17.1% |
| Sheridan | 5,746 | +10.2% | 1.5% |
| Cicero | 5,581 | +5.0% | 1.4% |
| Arcadia | 1,458 | −3.8% | 0.4% |
| Atlanta | 731 | +1.7% | 0.2% |
8 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
Hamilton County is a place of houses on their own lots: 75% of its 140,389 homes are detached single-family houses, against 73% across Indiana. Much of Hamilton County is recent building: 50% of its homes have gone up since 2000 and the middle year built is 2000, against 1976 for Indiana. Owners live in 76% of the occupied homes (Indiana: 70%), so for most households a test and a fix are their own to order.
| Homes | Hamilton County | Indiana |
|---|---|---|
| Housing units | 140,389 | 2,953,344 |
| Detached houses | 75% | 73% |
| In buildings of 5 or more | 15% | 13% |
| Mobile homes | 2% | 4% |
| Built before 1960 | 7% | 32% |
| Built since 2000 | 50% | 21% |
| Middle year built | 2000 | 1976 |
| Owner-occupied | 76% | 70% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.