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Radon in Cincinnati, Ohio

EPA puts Hamilton County, where Cincinnati is, 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

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  • Share at 4+ pCi/L

    34.7%

    17.6 pts below OH

    Hamilton
    34.7%
    Ohio
    52.3%

    Hamilton, 71st of 79 in OH, 2008 to 2017

  • Median result

    2.8pCi/L

    Below action level

    Hamilton
    2.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of Hamilton's tests, 2008 to 2017

  • Nearest county

    50.0%

    Clermont, 20 miles

    Clermont
    50.0%
    Hamilton
    34.7%

    1,363 tests, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    Hamilton, where Cincinnati is

  • Tests reported

    3,754

    In Hamilton

    Hamilton
    3,754
    Clermont
    1,363

    Reported to CDC before any fix, 2008 to 2017

Read a result for Cincinnati

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

Cincinnati, What is published

What is published for Cincinnati

Information:

Every figure for Cincinnati is a county's

Radon data is published by county, not by city, so for Cincinnati it is Hamilton County's: its EPA zone (Zone 1) and the 3,754 tests reported to CDC for 2008 to 2017, laboratory. Only a test tells you about one home.

Cincinnati covers 77.8 square miles of land, all of it in Hamilton County. About 314,367 people live there, 4,039 to the square mile.

Cincinnati, Counties

The county Cincinnati lies in

Measured

Hamilton County's EPA zone and the figures CDC publishes for it, 2008 to 2017, laboratory.

Hamilton CountyZone 1Highest predicted potential

34.7%
Reported tests at or above 4 pCi/L
2.8 pCi/L
Median reported result
3,754 tests
Tests reported to CDC
None
Yearly figures on file

Hamilton County ranks 71st of 79 Ohio counties with 30 or more tests for that period, 17.6 points below the 52.3% pooled across Ohio's counties, 1.0 points below the national pool of 35.7%.

The counties nearest Cincinnati with a CDC figure for 2008 to 2017, laboratory, measured from the middle of the city: Clermont County (20 miles, 50.0% of 1,363 tests), Butler County (21 miles, 54.3% of 1,953 tests) and Warren County (27 miles, 52.5% of 2,512 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 47.1% to 62.7%; the farthest of them, Highland County, is 49 miles away at 56.7%.

The directory lists 24 businesses with an address in Cincinnati, 17 for testing and 7 for mitigation. Ohio's other cities with a page of their own: Columbus, Dayton, Toledo and Cleveland.

The counties around Cincinnati

By distance from the middle of Cincinnati; counties with 30 or more tests.

Nearest counties to Cincinnati with 30 or more tests
CountyDistanceTestsAt or above 4 pCi/LMedian
Clermont County20 mi1,36350.0%4.0 pCi/L
Butler County21 mi1,95354.3%4.4 pCi/L
Warren County27 mi2,51252.5%4.2 pCi/L
Brown County37 mi7047.1%3.3 pCi/L
Clinton County42 mi10352.4%4.2 pCi/L
Preble County42 mi21262.7%5.5 pCi/L
Montgomery County44 mi2,92250.3%4.0 pCi/L
Highland County49 mi6756.7%4.8 pCi/L

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2008 to 2017, laboratory.

Cincinnati, Geology

The ground under Cincinnati

Predicted

USGS's geologic map puts all of Cincinnati's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Till Plains, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Cincinnati
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Till PlainsOrdovician shale and limestone; glacial till.Moderate1199.7%

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

Cincinnati beside its county and Ohio

Hamilton County as a whole has 11.5% of its land rated high; none of that ground lies under Cincinnati. Across Ohio 62.8% of the land is rated high; none of Cincinnati's is.

Share of land by USGS radon potential: Cincinnati, the county it lies in and Ohio
AreaEPA zoneLow potentialModerate potentialHigh potential
CincinnatiBy countyNone99.7%None
Hamilton CountyZone 1None88.5%11.5%
Ohio88 counties, pooled by land areaVariesNone37.2%62.8%

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

Cincinnati, Homes

Homes in Cincinnati

Cincinnati has 159,731 homes, and many share a building: 36% are in buildings of five or more, 38% are detached houses, against 58% across Hamilton County. The homes are older than Hamilton County's as a whole: half were built before 1951 (1963 for Hamilton County), and 59% date from before 1960. Most occupied homes here are rented: owners live in 39% (Hamilton County: 59%). A tenant can run a test; a fix is the landlord's to make.

Homes in Cincinnati, Hamilton County, Ohio, 2019 to 2023
HomesCincinnatiHamilton CountyOhio
Housing units159,731380,4145,271,573
Detached houses38%58%69%
In buildings of 5 or more36%24%15%
Mobile homesunder 1%1%4%
Built before 196059%46%38%
Built since 20009%10%16%
Middle year built195119631970
Owner-occupied39%59%67%

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

Local help

Cincinnati, Professionals

Radon professionals listed in Cincinnati

Businesses whose listed city is Cincinnati, from the state registries and listings in the Radon411 directory, with the same business and certification status the directory shows.

24 listings with Cincinnati as the city. See radon mitigation and testing in Cincinnati, or all radon professionals in Ohio.

Cincinnati, Local resources

Local resources for Cincinnati

Who to ask in Ohio: its radon program, test kits and professionals.

The program's own words on licensing are on the Ohio page.

What it means

Cincinnati, Questions

Questions about radon in Cincinnati

What radon zone is Cincinnati in?

EPA's map puts Hamilton County, and with it Cincinnati, in Zone 1, the map's highest class: a predicted county average above 4 pCi/L.

What are radon levels in Cincinnati?

A high result is no surprise around Cincinnati: 34.7% of 3,754 tests reported from Hamilton County for 2008 to 2017 (laboratory totals) reached 4 pCi/L or more. The median reported result was 2.8 pCi/L.

Should I test my home in Cincinnati?

Yes. About 1,303 of the 3,754 tests reported from Hamilton County were at or above 4 pCi/L. That is below Ohio's pooled 52.3%, and still not a reason to skip it, and ranks Hamilton County 71st of the 79 Ohio counties with 30 or more tests. No map says which homes those are. How to test a home.

What ground is Cincinnati built on, as far as radon goes?

USGS's geologic map puts all of Cincinnati on one named area, "Till Plains", rated moderate for radon potential, radon index 11.

Is radon higher in the counties around Cincinnati?

Yes, in every direction measured. Each of the 8 nearest counties with a figure reports a larger share of high tests than Hamilton County's 34.7%; the highest is Preble County (62.7%, 42 miles off).

Who tests for or fixes radon in Cincinnati?

Radon411's directory has 24 businesses with an address in Cincinnati, 17 listed for testing and 7 for mitigation. Every entry names the public list it was taken from. Radon professionals in Cincinnati.

The answers use the published figures of Hamilton County, the county Cincinnati lies in.

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