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Radon Levels in Greene County, Ohio

EPA puts Greene County in Zone 1, its highest radon zone, and high results are common there: 58.6% of the 2,602 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    58.6%

    6.3 pts above OH

    Greene
    58.6%
    Ohio
    52.3%

    2,602 tests, 2008 to 2017

  • Median result

    4.9pCi/L

    Action level reached

    Greene
    4.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    2,602

    10th of 79 by tests

    Greene
    2,602
    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

    32 of 79

    Middle half

    Greene
    58.6%
    Pickaway
    81.4%

    By share, of 79 with 30+ tests

Read a result for Greene County

Starts at Greene County's median, 4.9 pCi/L

4.9pCi/L

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

EPA’s reading of 4.9 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. Greene County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Greene County, At a glance

Greene County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Greene 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 Greene County, 2008 to 2017, laboratory

Reported results by concentration band, Greene County, 2008 to 2017, laboratory
Under 2 pCi/L: 20%2 to 4 pCi/L: 21%4 pCi/L and above: 59%

Of 2,602 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Greene County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L52420.1%
2 to 4 pCi/L55221.2%
4 pCi/L and above1,52658.6%
What these figures count

These are the 2,602 tests reported to CDC for Greene 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

Greene County, Compared

Greene County radon figures, compared

Calculated by Radon411

More than half: 58.6% of the 2,602 radon tests reported to CDC for Greene County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 32nd of 79 Ohio counties with 30 or more tests for the same period. That is 6.3 points above the 52.3% pooled from 88 Ohio counties.

The median result, 4.9 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 240.5 pCi/L. The rest split 20.1% under 2 pCi/L and 21.2% from 2 to 4 (Ohio: 23.1% and 24.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 58.6% share point the same way here.

1 of its 5 bordering counties with figures ran higher, led by Madison County at 67.4%; Montgomery County reported 50.3%. 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 Greene County went from 3,790 tests (2005 to 2014) to 2,602 (2008 to 2017), the share going from 56.0% to 58.6%.

Nationally, every county with a figure for the same period pools to 35.7%; Greene County sits 22.9 points above it. CDC also counts 77 tests taken after mitigation in Greene County for the same period: tests in homes where a fix was already in.

Greene County against Ohio, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Greene County
Greene County2,60258.6%4.9 pCi/LThis county
Ohio, pooled88 counties, pooled98,84052.3%Not pooled−6.3 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−22.9 points
Pickaway Countyhighest in the state18381.4%9.5 pCi/L+22.8 points
Cuyahoga Countylowest in the state10,09221.7%2.0 pCi/L−36.9 points
Madison County, OHborders it54967.4%5.7 pCi/L+8.8 points
Fayette County, OHborders it1258.3%5.5 pCi/L−0.3 points
Clark County, OHborders it1,44757.5%4.9 pCi/L−1.1 points
Warren County, OHborders it2,51252.5%4.2 pCi/L−6.1 points
Clinton County, OHborders it10352.4%4.2 pCi/L−6.2 points
Montgomery County, OHborders it2,92250.3%4.0 pCi/L−8.3 points
Where Greene County's reported results fell, 2008 to 2017, laboratory, beside Ohio and the United States
ResultGreene County testsGreene County shareOhio shareU.S. shareAgainst Ohio
Under 2 pCi/L52420.1%23.1%39.6%−3.0 points
2 to 4 pCi/L55221.2%24.6%24.7%−3.4 points
4 pCi/L and above1,52658.6%52.3%35.7%+6.3 points
Greene 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
Crawford County27 of 7921059.5%4.7 pCi/L
Huron County28 of 7979659.4%4.9 pCi/L
Sandusky County29 of 7964959.2%5.0 pCi/L
Coshocton County30 of 7911258.9%5.1 pCi/L
Seneca County31 of 7954058.9%4.9 pCi/L
Greene County32 of 792,60258.6%4.9 pCi/L
Monroe County33 of 794858.3%5.0 pCi/L
Mercer County34 of 7914957.7%5.1 pCi/L
Clark County35 of 791,44757.5%4.9 pCi/L
Carroll County36 of 7948657.4%4.8 pCi/L
Allen County37 of 7923856.7%5.0 pCi/L
Greene County ten-year laboratory totals, against Ohio's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestOhio, pooledChange from the row before
2008 to 20172,60258.6%4.9 pCi/L240.5 pCi/L52.3%+1.0 points
2007 to 20162,98357.6%4.7 pCi/L240.5 pCi/L52.8%+0.6 points
2006 to 20153,51157.0%4.7 pCi/L240.5 pCi/L52.9%+1.0 points
2005 to 20143,79056.0%4.6 pCi/L240.5 pCi/L52.4%First on file

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

Greene County, Geology

The ground under Greene County

Predicted

USGS's geologic map puts all of Greene County's mapped land in one class: high radon potential. 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 Greene County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Till PlainsGlacial deposits underlain by Ordovician through Devonian limestone and shale.High14100%

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

Greene County beside the ground around it

Greene County has more high-potential ground than Ohio as a whole: 100% of its land against 62.8%. Of the 6 counties that border it, none has as large a share of high-potential ground; Clark County comes nearest at 100%.

Share of land by USGS radon potential: Greene County, the 6 counties bordering it and Ohio
AreaEPA zoneLow potentialModerate potentialHigh potential
Greene CountyZone 1NoneNone100%
Clinton CountyZone 1None26.0%74.0%
Clark CountyZone 1NoneNone100%
Warren CountyZone 1None40.4%59.6%
Montgomery CountyZone 1NoneNone100%
Fayette CountyZone 1NoneNone100%
Madison CountyZone 1NoneNone100%
Ohio88 counties, pooled by land areaVariesNone37.2%62.8%

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

Local help

Greene County, Local resources

Radon testing and mitigation in Greene County

Listed radon businesses with an address in Greene County:

Listed radon professionals by town: Dayton, Beavercreek, Fairborn, Cedarville

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

Greene County, Questions

Questions about radon in Greene County

Are radon levels high in Greene County?

Over the 2008 to 2017 laboratory totals, 58.6% of the radon tests reported to CDC for Greene County, Ohio were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.9 pCi/L. Of 79 Ohio counties with 30 or more tests for the same period, 31 reported a higher share; pooled, the state comes to 52.3%.

Which counties border Greene County?

Greene County borders 6 counties: Clinton County, Clark County, Warren County, Montgomery County, Fayette County and Madison County.

Products

Greene County, Products

Testing a home in Greene County

In Greene County, 58.6% of 2,602 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 Greene 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

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

Explore

Greene County, Bordering counties

Counties bordering Greene County

Calculated by Radon411

Greene County, Cities and towns

Cities and towns in Greene County

The Census Bureau estimates 174,322 residents in Greene County for July 1, 2025, 6,181 more than in 2020 (+3.7%). That works out to 422 people per square mile of land. Dayton, the largest place on its list (136,688 residents in all), extends beyond Greene County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 2,602 reported tests for 2008 to 2017 come to 14.9 for every 1,000 residents (2025 estimate), against 8.3 for Ohio.

From Dayton to Clifton, CDC publishes no figure by town: each reads Greene County's.

The 12 largest cities and towns in Greene County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Daytonextends beyond Greene County136,688−0.5%Counted whole
Ketteringextends beyond Greene County57,396−0.7%Counted whole
Beavercreek48,134+3.3%27.6%
Fairborn35,754+3.5%20.5%
Xenia26,425+3.7%15.2%
Centervilleextends beyond Greene County25,194+2.9%Counted whole
Bellbrook7,563+3.3%4.3%
Cedarville4,667+8.8%2.7%
Yellow Springs3,730+0.7%2.1%
Jamestown2,121+2.7%1.2%
Spring Valley427+2.9%0.2%
Bowersville273−1.1%0.2%
  • Clifton (part)

13 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 Greene County is counted whole, so it has no share.

Greene County, Homes

Homes in Greene County

Of Greene County's 71,925 homes, 72% are detached houses, against 69% across Ohio; 15% are in buildings of five or more homes. Half of its homes were built before 1976, close to Ohio's 1970: 28% date from before 1960 and 22% from 2000 or later. 68% 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 Greene County, Ohio, 2019 to 2023
HomesGreene CountyOhio
Housing units71,9255,271,573
Detached houses72%69%
In buildings of 5 or more15%15%
Mobile homes1%4%
Built before 196028%38%
Built since 200022%16%
Middle year built19761970
Owner-occupied68%67%

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