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 Warren County, Ohio
EPA puts Warren County in Zone 1, its highest radon zone, and high results are common there: 52.5% of the 2,512 radon tests reported to CDC (2008 to 2017, laboratory totals) came back 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
52.5%
0.2 pts above OH
- Warren
- 52.5%
- Ohio
- 52.3%
2,512 tests, 2008 to 2017
Median result
4.2pCi/L
Action level reached
- Warren
- 4.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
2,512
11th of 79 by tests
- Warren
- 2,512
- Franklin
- 16,142
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 Ohio
44 of 79
Middle half
- Warren
- 52.5%
- Pickaway
- 81.4%
By share, of 79 with 30+ tests
Read a result for Warren County
Starts at Warren County's median, 4.2 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.2 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. Warren County's median reported result, 2008 to 2017.
The data
Warren County, At a glance
Warren County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Warren County in
USGS geologic potential: High across 60% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Warren County, 2008 to 2017, laboratory
Under 2 pCi/L: 20%2 to 4 pCi/L: 27%4 pCi/L and above: 53%
Of 2,512 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 516 | 20.5% |
| 2 to 4 pCi/L | 676 | 26.9% |
| 4 pCi/L and above | 1,320 | 52.5% |
What these figures count
These are the 2,512 tests reported to CDC for Warren 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).
Warren County, Compared
Warren County radon figures, compared
Calculated by Radon411More than half: 52.5% of the 2,512 radon tests reported to CDC for Warren County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 44th of 79 Ohio counties with 30 or more tests for the same period. That is 0.2 points above the 52.3% pooled from 88 Ohio counties.
The median result, 4.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 70.2 pCi/L. The rest split 20.5% under 2 pCi/L and 26.9% from 2 to 4 (Ohio: 23.1% and 24.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 52.5% share point the same way here.
2 of its 6 bordering counties with figures ran higher, led by Greene County at 58.6%; Hamilton County reported 34.7%. Statewide for the same period, Pickaway County reported the highest share (81.4%) and Cuyahoga County the lowest (21.7%).
CDC's ten-year totals for Warren County went from 2,822 tests (2005 to 2014) to 2,512 (2008 to 2017), the share going from 48.9% to 52.5%.
Nationally, every county with a figure for the same period pools to 35.7%; Warren County sits 16.8 points above it. CDC also counts 90 tests taken after mitigation in Warren County for the same period: tests in homes where a fix was already in.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Warren County, Geology
The ground under Warren County
PredictedUSGS's geologic map splits Warren County: 59.6% of its land is high radon potential and 40.4% moderate. The map puts 59.6% of Warren County in the area it calls Till Plains and 40.4% in Till Plains. USGS gives the first a radon index of 14, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Till Plains | Glacial deposits underlain by Ordovician through Devonian limestone and shale. | High | 14 | 59.6% |
| Till Plains | Ordovician shale and limestone; glacial till. | Moderate | 11 | 40.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Warren County beside the ground around it
On high-potential ground Warren County is close to Ohio as a whole: 59.6% of its land against 62.8%. Of the 6 counties that border it, 4 have more high-potential ground, Greene County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Warren County, Local resources
Radon testing and mitigation in Warren County
Listed radon businesses with an address in Warren County:
- Radon Education and Licensing ProgramRadon Education and Licensing Program, run by Ohio Department of Health, licenses or certifies radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Ohio.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Free radon test kits are available for Ohio homeowners.
- Compare kits
- Professionals in Ohio479 professionals are listed in Ohio.
Listed radon professionals by town: Middletown, Springboro, Monroe, Loveland, South Lebanon, Waynesville, Maineville
What Ohio's program says
- Phone
- 614-728-0272
- indoor.radon@odh.ohio.gov
- Licensing of radon professionals
This program licenses companies and persons directly involved with the radon testing and mitigation industry.
What it means
Warren County, Questions
Questions about radon in Warren County
Are radon levels high in Warren County?
Over the 2008 to 2017 laboratory totals, 52.5% of the radon tests reported to CDC for Warren County, Ohio were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.2 pCi/L. Of 79 Ohio counties with 30 or more tests for the same period, 43 reported a higher share; pooled, the state comes to 52.3%.
Which counties border Warren County?
Warren County borders 6 counties: Montgomery County, Greene County, Clinton County, Butler County, Hamilton County and Clermont County.
Products
Warren County, Products
Testing a home in Warren County
In Warren County, 52.5% of 2,512 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 52.3% pooled across Ohio. In Zone 1 the year-round level in Warren 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
MonitorX-Sense
XR0A-SR battery digital radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
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
Warren County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Warren County
Explore
Warren County, Bordering counties
Counties bordering Warren County
Calculated by Radon411- Radon levels in Greene CountyEPA zone 1
58.6%at or above 4 pCi/L
Median 4.9 pCi/L · 2,602 tests · 6.1 points above Warren County
- Radon levels in Butler CountyEPA zone 1
54.3%at or above 4 pCi/L
Median 4.4 pCi/L · 1,953 tests · 1.8 points above Warren County
- Radon levels in Clinton CountyEPA zone 1
52.4%at or above 4 pCi/L
Median 4.2 pCi/L · 103 tests · 0.1 points below Warren County
- Radon levels in Montgomery CountyEPA zone 1
50.3%at or above 4 pCi/L
Median 4.0 pCi/L · 2,922 tests · 2.2 points below Warren County
- Radon levels in Clermont CountyEPA zone 2
50.0%at or above 4 pCi/L
Median 4.0 pCi/L · 1,363 tests · 2.5 points below Warren County
- Radon levels in Hamilton CountyEPA zone 1
34.7%at or above 4 pCi/L
Median 2.8 pCi/L · 3,754 tests · 17.8 points below Warren County
Warren County, Cities and towns
Cities and towns in Warren County
Warren County is growing: the Census Bureau puts it at 257,181 residents on July 1, 2025, up 5.7% from 243,211 in 2020. That works out to 641 people per square mile of land. Middletown, the largest place on its list (52,146 residents in all), extends beyond Warren County, so no share of the total is worked out for it. CDC's 2,512 reported tests for 2008 to 2017 work out to 9.8 per 1,000 residents (2025 estimate), close to Ohio's 8.3.
From Middletown to Pleasant Plain, CDC publishes no figure by town: each reads Warren County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Middletownextends beyond Warren County | 52,146 | +2.2% | Counted whole |
| Mason | 35,834 | +2.7% | 13.9% |
| Lebanon | 22,110 | +6.0% | 8.6% |
| Springboroextends beyond Warren County | 19,606 | +2.5% | Counted whole |
| Monroeextends beyond Warren County | 15,880 | +2.8% | Counted whole |
| Lovelandextends beyond Warren County | 13,288 | Level | Counted whole |
| Franklin | 11,647 | −0.2% | 4.5% |
| South Lebanon | 6,965 | +7.9% | 2.7% |
| Carlisleextends beyond Warren County | 5,885 | +6.7% | Counted whole |
| Blanchesterextends beyond Warren County | 4,250 | +0.6% | Counted whole |
| Waynesville | 2,890 | +7.6% | 1.1% |
| Morrow | 2,223 | +7.9% | 0.9% |
- Maineville
- Harveysburg
- Corwin
- Butlerville
- Pleasant Plain
17 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Warren County is counted whole, so it has no share.
Warren County, Homes
Homes in Warren County
Warren County is a place of houses on their own lots: 77% of its 94,910 homes are detached single-family houses, against 69% across Ohio. Much of Warren County is recent building: 37% of its homes have gone up since 2000 and the middle year built is 1994, against 1970 for Ohio. Owners live in 80% of the occupied homes (Ohio: 67%), so for most households a test and a fix are their own to order.
| Homes | Warren County | Ohio |
|---|---|---|
| Housing units | 94,910 | 5,271,573 |
| Detached houses | 77% | 69% |
| In buildings of 5 or more | 11% | 15% |
| Mobile homes | 1% | 4% |
| Built before 1960 | 14% | 38% |
| Built since 2000 | 37% | 16% |
| Middle year built | 1994 | 1970 |
| Owner-occupied | 80% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.