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Radon Levels in Hamilton County, Ohio

EPA puts Hamilton County in Zone 1, its highest radon zone, and 34.7% of its 3,754 reported radon tests (2008 to 2017, laboratory totals) were 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

    34.7%

    17.6 pts below OH

    Hamilton
    34.7%
    Ohio
    52.3%

    3,754 tests, 2008 to 2017

  • Median result

    2.8pCi/L

    Below action level

    Hamilton
    2.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    3,754

    5th of 79 by tests

    Hamilton
    3,754
    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

    71 of 79

    Lowest quarter

    Hamilton
    34.7%
    Pickaway
    81.4%

    By share, of 79 with 30+ tests

Read a result for Hamilton County

Starts at Hamilton County's median, 2.8 pCi/L

2.8pCi/L

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

EPA’s reading of 2.8 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Hamilton County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Hamilton County, At a glance

Hamilton County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Hamilton 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: Moderate across 89% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Hamilton County, 2008 to 2017, laboratory

Reported results by concentration band, Hamilton County, 2008 to 2017, laboratory
Under 2 pCi/L: 33%2 to 4 pCi/L: 32%4 pCi/L and above: 35%

Of 3,754 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Hamilton County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1,24633.2%
2 to 4 pCi/L1,20532.1%
4 pCi/L and above1,30334.7%
What these figures count

These are the 3,754 tests reported to CDC for Hamilton 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

Hamilton County, Compared

Hamilton County radon figures, compared

Calculated by Radon411

In Hamilton County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (1,303 of 3,754) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.0 points lower. Across 88 Ohio counties pooled together, 52.3% of tests reached that level, so Hamilton County runs 17.6 points below its state.

Of 8 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 4 a smaller one; the spread is 26.0% (Kenton County, KY) to 54.3% (Butler County). By share, Hamilton County is 71st of 79 Ohio counties with 30 or more tests for the same period.

Half the tests came in under 2.8 pCi/L and half over it; the single highest reached 81.4 pCi/L. Below the action level, 1,246 tests (33.2%) came in under 2 pCi/L, against 23.1% statewide, and 1,205 tests (32.1%) fell between 2 and 4, against 24.6% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 34.7% share point the same way here. USGS geology rates 89% of the county's land moderate radon potential. CDC also counts 58 tests taken after mitigation in Hamilton County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Hamilton County went from 3,510 tests (2005 to 2014) to 3,754 (2008 to 2017), the share going from 33.2% to 34.7%.

Hamilton County against Ohio, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Hamilton County
Hamilton County3,75434.7%2.8 pCi/LThis county
Ohio, pooled88 counties, pooled98,84052.3%Not pooled+17.6 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+1.0 points
Pickaway Countyhighest in the state18381.4%9.5 pCi/L+46.7 points
Cuyahoga Countylowest in the state10,09221.7%2.0 pCi/L−13.0 points
Butler County, OHborders it1,95354.3%4.4 pCi/L+19.6 points
Warren County, OHborders it2,51252.5%4.2 pCi/L+17.8 points
Clermont County, OHborders it1,36350.0%4.0 pCi/L+15.3 points
Boone County, KYborders it1,43442.9%3.5 pCi/L+8.2 points
Dearborn County, INborders it13630.1%2.6 pCi/L−4.6 points
Franklin County, INborders it5028.0%2.1 pCi/L−6.7 points
Campbell County, KYborders it54326.2%2.3 pCi/L−8.5 points
Kenton County, KYborders it1,16726.0%2.3 pCi/L−8.7 points
Where Hamilton County's reported results fell, 2008 to 2017, laboratory, beside Ohio and the United States
ResultHamilton County testsHamilton County shareOhio shareU.S. shareAgainst Ohio
Under 2 pCi/L1,24633.2%23.1%39.6%+10.1 points
2 to 4 pCi/L1,20532.1%24.6%24.7%+7.5 points
4 pCi/L and above1,30334.7%52.3%35.7%−17.6 points
Hamilton 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
Portage County66 of 791,66139.3%3.2 pCi/L
Summit County67 of 796,48638.7%3.1 pCi/L
Washington County68 of 7934938.1%3.1 pCi/L
Athens County69 of 7931838.1%3.1 pCi/L
Scioto County70 of 797337.0%2.7 pCi/L
Hamilton County71 of 793,75434.7%2.8 pCi/L
Trumbull County72 of 7942534.6%2.9 pCi/L
Ashtabula County73 of 7931434.4%2.5 pCi/L
Noble County74 of 794231.0%2.2 pCi/L
Lawrence County75 of 796630.3%2.5 pCi/L
Lake County76 of 792,34927.2%2.4 pCi/L
Hamilton County ten-year laboratory totals, against Ohio's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestOhio, pooledChange from the row before
2008 to 20173,75434.7%2.8 pCi/L81.4 pCi/L52.3%−0.4 points
2007 to 20163,78735.1%2.8 pCi/L81.4 pCi/L52.8%+0.5 points
2006 to 20153,73234.6%2.8 pCi/L81.4 pCi/L52.9%+1.4 points
2005 to 20143,51033.2%2.7 pCi/L81.4 pCi/L52.4%First on file

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

Hamilton County, Geology

The ground under Hamilton County

Predicted

Most of the ground under Hamilton County is one class on USGS's geologic map: 88.5% of its land is moderate radon potential, with 11.5% high. The map puts 88.4% of Hamilton County in the area it calls Till Plains and 11.5% in Till Plains. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 14, in the high band (12 to 17).

USGS's geologic areas under Hamilton County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Till PlainsOrdovician shale and limestone; glacial till.Moderate1188.4%
Till PlainsGlacial deposits underlain by Ordovician through Devonian limestone and shale.High1411.5%

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

Hamilton County beside the ground around it

Ohio as a whole has more high-potential ground than Hamilton County: 62.8% of its land, against 11.5% here. Of the 8 counties that border it, 5 have more high-potential ground, Butler County the most at 99.8%.

Share of land by USGS radon potential: Hamilton County, the 8 counties bordering it and Ohio
AreaEPA zoneLow potentialModerate potentialHigh potential
Hamilton CountyZone 1None88.5%11.5%
Kenton County, KYZone 2None81.3%18.7%
Campbell County, KYZone 2None86.3%13.7%
Boone County, KYZone 2None100%None
Butler CountyZone 1None0.2%99.8%
Dearborn County, INZone 2None100%None
Clermont CountyZone 2None100%None
Warren CountyZone 1None40.4%59.6%
Franklin County, INZone 2None63.0%37.0%
Ohio88 counties, pooled by land areaVariesNone37.2%62.8%

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

Local help

Hamilton County, Local resources

Radon testing and mitigation in Hamilton County

Listed radon businesses with an address in Hamilton County:

Listed radon professionals by town: Cincinnati, Fairfield, Harrison, Blue Ash, Loveland, Milford, Cleves, North Bend

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

Hamilton County, Questions

Questions about radon in Hamilton County

Are radon levels high in Hamilton County?

Over the 2008 to 2017 laboratory totals, 34.7% of the radon tests reported to CDC for Hamilton County, Ohio were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.8 pCi/L. Of 79 Ohio counties with 30 or more tests for the same period, 70 reported a higher share; pooled, the state comes to 52.3%.

Which counties border Hamilton County?

Hamilton County borders 8 counties: Kenton County, KY, Campbell County, KY, Boone County, KY, Butler County, OH, Dearborn County, IN, Clermont County, OH, Warren County, OH and Franklin County, IN.

Products

Hamilton County, Products

Testing a home in Hamilton County

In Hamilton County, 34.7% of 3,754 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 Hamilton 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

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

Explore

Hamilton County, Bordering counties

Counties bordering Hamilton County

Calculated by Radon411

Hamilton County, Cities and towns

Cities and towns in Hamilton County

The Census Bureau estimates 838,418 residents in Hamilton County for July 1, 2025, 8,006 more than in 2020 (+1.0%). Packed into its land, that is 2,068 people per square mile. Its largest town, Cincinnati, has 314,367 residents, 37.5% of the total. Reported testing is thin here: 3,754 tests over 2008 to 2017, or 4.5 for every 1,000 residents (2025 estimate), where Ohio as a whole comes to 8.3.

From Cincinnati to Arlington Heights, CDC publishes no figure by town: each reads Hamilton County's.

The 12 largest cities and towns in Hamilton County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Cincinnati314,367+1.5%37.5%
Fairfieldextends beyond Hamilton County44,682−0.5%Counted whole
Forest Park20,041−0.6%2.4%
Norwood19,658+3.5%2.3%
Sharonvilleextends beyond Hamilton County13,997−0.7%Counted whole
Harrison13,795+9.2%1.6%
Blue Ash13,707+2.3%1.6%
Lovelandextends beyond Hamilton County13,288LevelCounted whole
Springdale11,134+1.2%1.3%
Montgomery10,922+0.7%1.3%
Reading10,491−1.0%1.3%
Madeira9,637+1.5%1.1%
  • North College Hill
  • Wyoming
  • Cheviot
  • Mount Healthy
  • Milford (part)
  • The Village of Indian Hill
  • Deer Park
  • Silverton
  • St. Bernard
  • Woodlawn
  • Amberley
  • Golf Manor
  • Greenhills
  • Lockland
  • Mariemont
  • Cleves
  • Lincoln Heights
  • Newtown
  • Evendale
  • Terrace Park
  • Glendale
  • Elmwood Place
  • Fairfax
  • Addyston
The other 2 places in Hamilton County
  • North Bend
  • Arlington Heights

38 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 Hamilton County is counted whole, so it has no share.

Hamilton County, Homes

Homes in Hamilton County

Of Hamilton County's 380,414 homes, 58% are detached houses, against 69% across Ohio; 24% are in buildings of five or more homes. Half of its homes were built before 1963, close to Ohio's 1970: 46% date from before 1960 and 10% from 2000 or later. 59% 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 Hamilton County, Ohio, 2019 to 2023
HomesHamilton CountyOhio
Housing units380,4145,271,573
Detached houses58%69%
In buildings of 5 or more24%15%
Mobile homes1%4%
Built before 196046%38%
Built since 200010%16%
Middle year built19631970
Owner-occupied59%67%

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