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Radon Levels in Butler County, Ohio

EPA puts Butler County in Zone 1, its highest radon zone, and high results are common there: 54.3% of the 1,953 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

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  • Share at 4+ pCi/L

    54.3%

    2.0 pts above OH

    Butler
    54.3%
    Ohio
    52.3%

    1,953 tests, 2008 to 2017

  • Median result

    4.4pCi/L

    Action level reached

    Butler
    4.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,953

    14th of 79 by tests

    Butler
    1,953
    Franklin
    16,142

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Ohio

    42 of 79

    Middle half

    Butler
    54.3%
    Pickaway
    81.4%

    By share, of 79 with 30+ tests

Read a result for Butler County

Starts at Butler County's median, 4.4 pCi/L

4.4pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 4.4 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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. Butler County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Butler County, At a glance

Butler County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Butler County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

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 Butler County, 2008 to 2017, laboratory

Reported results by concentration band, Butler County, 2008 to 2017, laboratory
Under 2 pCi/L: 22%2 to 4 pCi/L: 23%4 pCi/L and above: 55%

Of 1,953 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Butler County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L43622.3%
2 to 4 pCi/L45623.3%
4 pCi/L and above1,06154.3%
What these figures count

These are the 1,953 tests reported to CDC for Butler 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).

How to read these figures

Butler County, Compared

Butler County radon figures, compared

Calculated by Radon411

More than half: 54.3% of the 1,953 radon tests reported to CDC for Butler County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 42nd of 79 Ohio counties with 30 or more tests for the same period. That is 2.0 points above the 52.3% pooled from 88 Ohio counties.

The median result, 4.4 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 143.8 pCi/L. The rest split 22.3% under 2 pCi/L and 23.3% from 2 to 4 (Ohio: 23.1% and 24.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 54.3% share point the same way here.

1 of its 6 bordering counties with figures ran higher, led by Preble County at 62.7%; Franklin County, IN reported 28.0%. 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 Butler County went from 2,104 tests (2005 to 2014) to 1,953 (2008 to 2017), the share going from 49.6% to 54.3%.

Nationally, every county with a figure for the same period pools to 35.7%; Butler County sits 18.6 points above it. CDC also counts 49 tests taken after mitigation in Butler County for the same period: tests in homes where a fix was already in.

Butler County against Ohio, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Butler County
Butler County1,95354.3%4.4 pCi/LThis county
Ohio, pooled88 counties, pooled98,84052.3%Not pooled−2.0 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−18.6 points
Pickaway Countyhighest in the state18381.4%9.5 pCi/L+27.1 points
Cuyahoga Countylowest in the state10,09221.7%2.0 pCi/L−32.6 points
Preble County, OHborders it21262.7%5.5 pCi/L+8.4 points
Warren County, OHborders it2,51252.5%4.2 pCi/L−1.8 points
Montgomery County, OHborders it2,92250.3%4.0 pCi/L−4.0 points
Union County, INborders it850.0%3.8 pCi/L−4.3 points
Hamilton County, OHborders it3,75434.7%2.8 pCi/L−19.6 points
Dearborn County, INborders it13630.1%2.6 pCi/L−24.2 points
Franklin County, INborders it5028.0%2.1 pCi/L−26.3 points
Where Butler County's reported results fell, 2008 to 2017, laboratory, beside Ohio and the United States
ResultButler County testsButler County shareOhio shareU.S. shareAgainst Ohio
Under 2 pCi/L43622.3%23.1%39.6%−0.8 points
2 to 4 pCi/L45623.3%24.6%24.7%−1.3 points
4 pCi/L and above1,06154.3%52.3%35.7%+2.0 points
Butler County ranked among the 79 Ohio counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Allen County37 of 7923856.7%5.0 pCi/L
Highland County38 of 796756.7%4.8 pCi/L
Muskingum County39 of 7939156.3%4.9 pCi/L
Pike County40 of 795756.1%4.5 pCi/L
Erie County41 of 791,65154.5%4.4 pCi/L
Butler County42 of 791,95354.3%4.4 pCi/L
Hocking County43 of 796053.3%4.0 pCi/L
Warren County44 of 792,51252.5%4.2 pCi/L
Clinton County45 of 7910352.4%4.2 pCi/L
Montgomery County46 of 792,92250.3%4.0 pCi/L
Clermont County47 of 791,36350.0%4.0 pCi/L
Butler County ten-year laboratory totals, against Ohio's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestOhio, pooledChange from the row before
2008 to 20171,95354.3%4.4 pCi/L143.8 pCi/L52.3%+0.9 points
2007 to 20162,04553.4%4.3 pCi/L143.8 pCi/L52.8%+2.9 points
2006 to 20152,19550.5%4.0 pCi/L143.8 pCi/L52.9%+0.9 points
2005 to 20142,10449.6%3.9 pCi/L143.8 pCi/L52.4%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Butler County, Geology

The ground under Butler County

Predicted

Most of the ground under Butler County is one class on USGS's geologic map: 99.8% of its land is high radon potential, with 0.2% moderate. All of it lies in the area the map calls Till Plains, to which USGS gives a radon index of 14, in the high band (12 to 17).

USGS's geologic areas under Butler County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Till PlainsGlacial deposits underlain by Ordovician through Devonian limestone and shale.High1499.7%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Butler County beside the ground around it

Butler County has more high-potential ground than Ohio as a whole: 99.8% of its land against 62.8%. Of the 7 counties that border it, 3 have more high-potential ground, Montgomery County the most at 100%.

Share of land by USGS radon potential: Butler County, the 7 counties bordering it and Ohio
AreaEPA zoneLow potentialModerate potentialHigh potential
Butler CountyZone 1None0.2%99.8%
Hamilton CountyZone 1None88.5%11.5%
Union County, INZone 1NoneNone100%
Warren CountyZone 1None40.4%59.6%
Montgomery CountyZone 1NoneNone100%
Preble CountyZone 1NoneNone100%
Franklin County, INZone 2None63.0%37.0%
Dearborn County, INZone 2None100%None
Ohio88 counties, pooled by land areaVariesNone37.2%62.8%

The map rates the ground, not the air in any home.

Local help

Butler County, Local resources

Radon testing and mitigation in Butler County

Listed radon businesses with an address in Butler County:

Listed radon professionals by town: Hamilton, Middletown, Fairfield, Monroe

What Ohio's program says
Phone
614-728-0272
Email
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

Butler County, Questions

Questions about radon in Butler County

Are radon levels high in Butler County?

Over the 2008 to 2017 laboratory totals, 54.3% of the radon tests reported to CDC for Butler County, Ohio were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.4 pCi/L. Of 79 Ohio counties with 30 or more tests for the same period, 41 reported a higher share; pooled, the state comes to 52.3%.

Which counties border Butler County?

Butler County borders 7 counties: Hamilton County, OH, Union County, IN, Warren County, OH, Montgomery County, OH, Preble County, OH, Franklin County, IN and Dearborn County, IN.

Products

Butler County, Products

Testing a home in Butler County

In Butler County, 54.3% of 1,953 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 Butler 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

Butler County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Butler County

Explore

Butler County, Bordering counties

Counties bordering Butler County

Calculated by Radon411

Butler County, Cities and towns

Cities and towns in Butler County

The Census Bureau estimates 400,128 residents in Butler County for July 1, 2025, 9,283 more than in 2020 (+2.4%). That works out to 858 people per square mile of land. No town dominates: Hamilton, the largest, has 64,644 residents, 16.2% of the total. Reported testing is thin here: 1,953 tests over 2008 to 2017, or 4.9 for every 1,000 residents (2025 estimate), where Ohio as a whole comes to 8.3.

From Hamilton to Jacksonburg, CDC publishes no figure by town: each reads Butler County's.

The cities and towns in Butler County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Hamilton64,644+1.9%16.2%
Middletownextends beyond Butler County52,146+2.2%Counted whole
Fairfieldextends beyond Butler County44,682−0.5%Counted whole
Oxford22,387−2.8%5.6%
Monroeextends beyond Butler County15,880+2.8%Counted whole
Trenton14,241+9.1%3.6%
Sharonvilleextends beyond Butler County13,997−0.7%Counted whole
New Miami2,287+3.2%0.6%
Seven Mile737+2.9%0.2%
Millville642+2.2%0.2%
College Cornerextends beyond Butler County398+1.8%Counted whole
Jacksonburg53LevelUnder 0.1%

12 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 Butler County is counted whole, so it has no share.

Butler County, Homes

Homes in Butler County

Of Butler County's 154,777 homes, 73% are detached houses, against 69% across Ohio; 13% are in buildings of five or more homes. Much of Butler County is recent building: 22% of its homes have gone up since 2000 and the middle year built is 1979, against 1970 for Ohio. 70% of occupied homes are lived in by their owner (Ohio: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Butler County, Ohio, 2019 to 2023
HomesButler CountyOhio
Housing units154,7775,271,573
Detached houses73%69%
In buildings of 5 or more13%15%
Mobile homes2%4%
Built before 196026%38%
Built since 200022%16%
Middle year built19791970
Owner-occupied70%67%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.