Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Union County, Indiana
EPA puts Union County in Zone 1, its highest radon zone, and only 8 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
62.7%
Preble County
- Preble
- 62.7%
- Franklin
- 28.0%
4 of 5 neighbours have 30+ tests, 2008 to 2017
Nearest county
28.0%
Franklin County, 16 miles
- Franklin
- 28.0%
- Indiana
- 38.9%
Share at 4+ pCi/L, 50 tests, 2008 to 2017
Ground above low
100.0%
Level with Indiana
- Union
- 100.0%
- Indiana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
8
Too few for a share
- Union
- 8
- Needed
- 30
2008 to 2017, laboratory
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Read a result for Union 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
Union County, At a glance
Union County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Union 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 Union County, 2008 to 2017, laboratory
CDC holds 8 reported tests for Union County over the 2008 to 2017 laboratory totals, with a median of 3.8 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Union County beside the counties around it is how this page reads it.
What these figures count
Only 8 tests were reported to CDC for Union 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).
Union County, Compared
Union County radon figures, compared
Calculated by Radon411CDC's largest figure for Union County rests on 8 tests over the 2008 to 2017 laboratory totals, 4 of them at or above 4 pCi/L, so each test moves its share by 12.5 points and no rank or comparison is drawn from it. Results reached as high as 14.2 pCi/L, with a middle value of 3.8 pCi/L.
Of the counties bordering it, 4 have a figure over the 2008 to 2017 laboratory totals: Preble County, OH reported the largest share at or above 4 pCi/L, 62.7%, and Franklin County the smallest, 28.0%, with Wayne County at 56.4% and Butler County, OH at 54.3% between. Farther out, Henry County (33 miles away) at 50.5%, Dearborn County (33 miles away) at 30.1% and Decatur County (38 miles away) at 33.3% 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 Union County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Union County, Geology
The ground under Union County
PredictedUSGS's geologic map puts all of Union 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 | 99.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Union County beside the ground around it
Union County has more high-potential ground than Indiana as a whole: 100% of its land against 56.6%. Of the 5 counties that border it, none has as large a share of high-potential ground; Wayne County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Union County, Local resources
Radon testing and mitigation in Union 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
Union County, Questions
Questions about radon in Union County
Are radon levels high in Union County?
Over the 2008 to 2017 laboratory totals, 50.0% of the radon tests reported to CDC for Union County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.8 pCi/L. Of the counties bordering it, 4 have a figure over the 2008 to 2017 laboratory totals: Preble County, OH reported the largest share at or above 4 pCi/L, 62.7%, and Franklin County the smallest, 28.0%, with Wayne County at 56.4% and Butler County, OH at 54.3% between.
Which counties border Union County?
Union County borders 5 counties: Fayette County, IN, Wayne County, IN, Preble County, OH, Franklin County, IN and Butler County, OH.
Products
Union County, Products
Testing a home in Union County
No CDC figure names Union County; the nearest county with one, Franklin County (16 miles away), reported 28.0% 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 1 the year-round level in Union 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
Corentium Home battery digital radon detector
- C-NRPP 2024/25: Approved
- Battery
- Screen
Method: Alpha spectrometry
Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Union County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Union County
Explore
Union County, Bordering counties
Counties bordering Union County
Calculated by Radon411- Radon levels in Fayette County, INEPA zone 1
76.9%at or above 4 pCi/L
Median 7.9 pCi/L · 13 tests
- Radon levels in Preble County, OHEPA zone 1
62.7%at or above 4 pCi/L
Median 5.5 pCi/L · 212 tests
- Radon levels in Wayne County, INEPA zone 1
56.4%at or above 4 pCi/L
Median 4.5 pCi/L · 140 tests
- Radon levels in Butler County, OHEPA zone 1
54.3%at or above 4 pCi/L
Median 4.4 pCi/L · 1,953 tests
- Radon levels in Franklin County, INEPA zone 2
28.0%at or above 4 pCi/L
Median 2.1 pCi/L · 50 tests
Union County, Cities and towns
Cities and towns in Union County
About 6,863 people live in Union County by the Census Bureau's estimate for July 1, 2025, 222 fewer than in 2020 (−3.1%). That works out to 43 people per square mile of land. Its largest town, Liberty, has 1,967 residents, 28.7% of the total. Together its 2 incorporated places hold 36.1% of those residents; the other 63.9% live outside any of them. Reported testing is thin here: 8 tests over 2008 to 2017, or 1.2 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 6.2.
From Liberty to West College Corner, CDC publishes no figure by town: each reads Union County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Liberty | 1,967 | −3.7% | 28.7% |
| West College Corner | 511 | −3.0% | 7.4% |
2 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).
Union County, Homes
Homes in Union County
Union County is a place of houses on their own lots: 84% of its 3,250 homes are detached single-family houses, against 73% across Indiana. The homes are older than Indiana's as a whole: half were built before 1968 (1976 for Indiana), and 43% date from before 1960. Owners live in 83% of the occupied homes (Indiana: 70%), so for most households a test and a fix are their own to order.
| Homes | Union County | Indiana |
|---|---|---|
| Housing units | 3,250 | 2,953,344 |
| Detached houses | 84% | 73% |
| In buildings of 5 or more | 4% | 13% |
| Mobile homes | 7% | 4% |
| Built before 1960 | 43% | 32% |
| Built since 2000 | 12% | 21% |
| Middle year built | 1968 | 1976 |
| Owner-occupied | 83% | 70% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.