Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
Locations and reports
Radon Levels in Clay County, Indiana
EPA puts Clay County in Zone 2, its middle radon zone, and only 23 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
44.0%
Vigo County
- Vigo
- 44.0%
- Greene
- 32.7%
4 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
44.0%
Vigo County, 15 miles
- Vigo
- 44.0%
- Indiana
- 38.9%
Share at 4+ pCi/L, 455 tests, 2008 to 2017
Ground above low
100.0%
Level with Indiana
- Clay
- 100.0%
- Indiana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
24
Too few for a share
- Clay
- 24
- Needed
- 30
2007 to 2016, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Clay County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
The data
Clay County, At a glance
Clay County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Clay County is a
USGS geologic potential: Moderate across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Clay County, 2008 to 2017, laboratory
CDC holds 23 reported tests for Clay County over the 2008 to 2017 laboratory totals, with a median of 2.9 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Clay County beside the counties around it is how this page reads it.
What these figures count
Only 23 tests were reported to CDC for Clay County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Clay County, Compared
Clay County radon figures, compared
Calculated by Radon411CDC's largest figure for Clay County rests on 24 tests over the 2007 to 2016 laboratory totals, 8 of them at or above 4 pCi/L, so each test moves its share by 4.2 points and no rank or comparison is drawn from it. Results reached as high as 19.9 pCi/L, with a middle value of 3.0 pCi/L.
Of the counties bordering it, 4 have a figure over the 2008 to 2017 laboratory totals: Vigo County reported the largest share at or above 4 pCi/L, 44.0%, and Greene County the smallest, 32.7%, with Owen County at 39.1% and Putnam County at 34.5% between. Farther out, Monroe County (36 miles away) at 34.2%, Morgan County (36 miles away) at 44.2% and Hendricks County (41 miles away) at 41.5% have figures too. Pooled across 92 Indiana counties, 38.9% of reported tests reached that level; across every county in the country with a figure, 35.7%.
Statewide for the same period, Miami County reported the highest share (63.3%) and Jasper County the lowest (14.1%). EPA's 1993 map puts Clay County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Clay County, Geology
The ground under Clay County
PredictedUSGS's geologic map puts all of Clay County's mapped land in one class: moderate radon potential. 98.1% of it lies in the area the map calls Wabash Lowland, to which USGS gives a radon index of 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Wabash Lowland | Loess, pre-Wisconsinan glacial deposits, Pennsylvanian shale, sandstone, and carbonate bedrock. | Moderate | 10 | 98.1% |
| Crawford Upland/Mitchell Plain/Norman Upland | Unglaciated, underlain by karsted Mississippian carbonate rocks. | Moderate | 11 | 1.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Clay County beside the ground around it
Across Indiana 56.6% of the land is rated high; none of Clay County's is. Of the 6 counties that border it, 3 have more high-potential ground, Putnam County the most at 70.0%.
The map rates the ground, not the air in any home.
Local help
Clay County, Local resources
Radon testing and mitigation in Clay 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
Clay County, Questions
Questions about radon in Clay County
Are radon levels high in Clay County?
Over the 2008 to 2017 laboratory totals, 26.1% of the radon tests reported to CDC for Clay County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.9 pCi/L. Of the counties bordering it, 4 have a figure over the 2008 to 2017 laboratory totals: Vigo County reported the largest share at or above 4 pCi/L, 44.0%, and Greene County the smallest, 32.7%, with Owen County at 39.1% and Putnam County at 34.5% between.
Which counties border Clay County?
Clay County borders 6 counties: Vigo County, Owen County, Greene County, Parke County, Putnam County and Sullivan County.
Products
Clay County, Products
Testing a home in Clay County
No CDC figure names Clay County; the nearest county with one, Vigo County (15 miles away), reported 44.0% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Clay County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
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
Monitor
RadonEye RD200 plug-in continuous radon monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Bluetooth
- Alarm
- Screen, app
Method: Ion chamber
First reading: Within 10 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Clay County, Bordering counties
Counties bordering Clay County
Calculated by Radon411- Radon levels in Parke CountyEPA zone 2
68.0%at or above 4 pCi/L
Median 4.8 pCi/L · 25 tests
- Radon levels in Sullivan CountyEPA zone 2
46.2%at or above 4 pCi/L
Median 3.1 pCi/L · 13 tests
- Radon levels in Vigo CountyEPA zone 2
44.0%at or above 4 pCi/L
Median 3.6 pCi/L · 455 tests
- Radon levels in Owen CountyEPA zone 2
39.1%at or above 4 pCi/L
Median 2.8 pCi/L · 110 tests
- Radon levels in Putnam CountyEPA zone 1
34.5%at or above 4 pCi/L
Median 2.7 pCi/L · 119 tests
- Radon levels in Greene CountyEPA zone 2
32.7%at or above 4 pCi/L
Median 3.0 pCi/L · 49 tests
Clay County, Cities and towns
Cities and towns in Clay County
Clay County's population has barely moved since 2020: 26,410 residents on July 1, 2025 against 26,426 then, by the Census Bureau's estimates. That works out to 74 people per square mile of land. Its largest town, Brazil, has 8,343 residents, 31.6% of the total. Together its 7 incorporated places hold 43.5% of those residents; the other 56.5% live outside any of them. Reported testing is thin here: 24 tests over 2007 to 2016, or 0.9 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 5.7.
From Brazil to Center Point, CDC publishes no figure by town: each reads Clay County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Brazil | 8,343 | +2.3% | 31.6% |
| Clay City | 884 | +0.2% | 3.3% |
| Knightsville | 673 | −3.2% | 2.5% |
| Harmony | 668 | −1.2% | 2.5% |
| Staunton | 467 | −0.6% | 1.8% |
| Carbon | 251 | −1.2% | 1.0% |
| Center Point | 206 | −2.4% | 0.8% |
7 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).
Clay County, Homes
Homes in Clay County
Clay County is a place of houses on their own lots: 81% of its 11,648 homes are detached single-family houses, against 73% across Indiana. Half of its homes were built before 1972, close to Indiana's 1976: 40% date from before 1960 and 19% from 2000 or later. Owners live in 77% of the occupied homes (Indiana: 70%), so for most households a test and a fix are their own to order.
| Homes | Clay County | Indiana |
|---|---|---|
| Housing units | 11,648 | 2,953,344 |
| Detached houses | 81% | 73% |
| In buildings of 5 or more | 4% | 13% |
| Mobile homes | 10% | 4% |
| Built before 1960 | 40% | 32% |
| Built since 2000 | 19% | 21% |
| Middle year built | 1972 | 1976 |
| Owner-occupied | 77% | 70% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.