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 Decatur County, Indiana
EPA puts Decatur County in Zone 1, its highest radon zone, and 33.3% of its 63 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
33.3%
5.6 pts below IN
- Decatur
- 33.3%
- Indiana
- 38.9%
63 tests, 2008 to 2017
Median result
2.8pCi/L
Below action level
- Decatur
- 2.8 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
63
58th of 69 by tests
- Decatur
- 63
- 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
59 of 69
Lowest quarter
- Decatur
- 33.3%
- Miami
- 63.3%
By share, of 69 with 30+ tests
Read a result for Decatur County
Starts at Decatur County's median, 2.8 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.8 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. Decatur County's median reported result, 2008 to 2017.
The data
Decatur County, At a glance
Decatur County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Decatur County in
USGS geologic potential: High across 67% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Decatur County, 2008 to 2017, laboratory
Under 2 pCi/L: 38%2 to 4 pCi/L: 29%4 pCi/L and above: 33%
Of 63 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 24 | 38.1% |
| 2 to 4 pCi/L | 18 | 28.6% |
| 4 pCi/L and above | 21 | 33.3% |
What these figures count
These are the 63 tests reported to CDC for Decatur 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).
Decatur County, Compared
Decatur County radon figures, compared
Calculated by Radon411In Decatur County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (21 of 63) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 2.4 points lower. Across 92 Indiana counties pooled together, 38.9% of tests reached that level, so Decatur County runs 5.6 points below its state.
Of 5 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 28.0% (Franklin County) to 50.0% (Shelby County). By share, Decatur County is 59th of 69 Indiana counties with 30 or more tests for the same period.
Half the tests came in under 2.8 pCi/L and half over it; the single highest reached 37.8 pCi/L. Below the action level, 24 tests (38.1%) came in under 2 pCi/L, against 32.8% statewide, and 18 tests (28.6%) fell between 2 and 4, against 28.3% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 33.3% share point the same way here. USGS geology rates 67% of the county's land high radon potential. CDC also counts 20 tests taken after mitigation in Decatur County for the same period: tests in homes where a fix was already in.
CDC's ten-year totals for Decatur County went from 50 tests (2005 to 2014) to 63 (2008 to 2017), the share going from 46.0% to 33.3%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Decatur County, Geology
The ground under Decatur County
PredictedUSGS's geologic map splits Decatur County: 66.5% of its land is high radon potential and 33.5% moderate. The map puts 66.5% of Decatur County in the area it calls Huron-Erie Lobe and 33.5% in Dearborn Upland. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).
| 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 | 66.5% |
| Dearborn Upland | Ordovician through Devonian limestone, dolostone, and gray shale, and pre-Wisconsinan glacial deposits. | Moderate | 10 | 33.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Decatur County beside the ground around it
On high-potential ground Decatur County is close to Indiana as a whole: 66.5% of its land against 56.6%. Of the 6 counties that border it, 3 have more high-potential ground, Shelby County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Decatur County, Local resources
Radon testing and mitigation in Decatur 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.
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
Decatur County, Questions
Questions about radon in Decatur County
Are radon levels high in Decatur County?
Over the 2008 to 2017 laboratory totals, 33.3% of the radon tests reported to CDC for Decatur County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.8 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 58 reported a higher share; pooled, the state comes to 38.9%.
Which counties border Decatur County?
Decatur County borders 6 counties: Ripley County, Rush County, Bartholomew County, Shelby County, Jennings County and Franklin County.
Products
Decatur County, Products
Testing a home in Decatur County
In Decatur County, 33.3% of 63 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 Decatur 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
Monitor
Wave Radon battery smart radon monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- App only
Method: Alpha spectrometry
Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Decatur County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Decatur County
Explore
Decatur County, Bordering counties
Counties bordering Decatur County
Calculated by Radon411- Radon levels in Shelby CountyEPA zone 1
50.0%at or above 4 pCi/L
Median 4.0 pCi/L · 84 tests · 16.7 points above Decatur County
- Radon levels in Bartholomew CountyEPA zone 1
48.7%at or above 4 pCi/L
Median 3.9 pCi/L · 1,707 tests · 15.4 points above Decatur County
- Radon levels in Rush CountyEPA zone 1
47.1%at or above 4 pCi/L
Median 3.9 pCi/L · 17 tests · 13.8 points above Decatur County
- Radon levels in Ripley CountyEPA zone 2
35.3%at or above 4 pCi/L
Median 2.9 pCi/L · 68 tests · 2.0 points above Decatur County
- Radon levels in Jennings CountyEPA zone 1
35.1%at or above 4 pCi/L
Median 2.8 pCi/L · 57 tests · 1.8 points above Decatur County
- Radon levels in Franklin CountyEPA zone 2
28.0%at or above 4 pCi/L
Median 2.1 pCi/L · 50 tests · 5.3 points below Decatur County
Decatur County, Cities and towns
Cities and towns in Decatur County
Decatur County's population has barely moved since 2020: 26,576 residents on July 1, 2025 against 26,467 then, by the Census Bureau's estimates. That works out to 71 people per square mile of land. Its largest town, Greensburg, has 12,315 residents, 46.3% of the total. Reported testing is thin here: 63 tests over 2008 to 2017, or 2.4 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 6.2.
From Greensburg to Millhousen, CDC publishes no figure by town: each reads Decatur County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Greensburg | 12,315 | −0.1% | 46.3% |
| Westport | 1,406 | +0.9% | 5.3% |
| St. Paulextends beyond Decatur County | 974 | +1.4% | Counted whole |
| New Point | 319 | +0.3% | 1.2% |
| Millhousen | 145 | Level | 0.5% |
5 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). A place that extends beyond Decatur County is counted whole, so it has no share.
Decatur County, Homes
Homes in Decatur County
Decatur County is a place of houses on their own lots: 83% of its 11,619 homes are detached single-family houses, against 73% across Indiana. Half of its homes were built before 1973, close to Indiana's 1976: 34% date from before 1960 and 18% from 2000 or later. Owners live in 75% of the occupied homes (Indiana: 70%), so for most households a test and a fix are their own to order.
| Homes | Decatur County | Indiana |
|---|---|---|
| Housing units | 11,619 | 2,953,344 |
| Detached houses | 83% | 73% |
| In buildings of 5 or more | 7% | 13% |
| Mobile homes | 4% | 4% |
| Built before 1960 | 34% | 32% |
| Built since 2000 | 18% | 21% |
| Middle year built | 1973 | 1976 |
| Owner-occupied | 75% | 70% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.