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Ohio Radon Map and Levels by County

Ohio's counties span EPA Zones 1 and 2. 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

    52.3%

    16.6 pts above U.S.

    Ohio
    52.3%
    U.S.
    35.7%

    98,840 tests across 88 counties, 2008 to 2017

  • Rank among states

    5 of 47

    Ten highest states

    Ohio
    52.3%
    North Dakota
    59.3%

    By share, every state pooled the same way, 2008 to 2017

  • Counties in EPA Zone 1

    53 of 88

    Most at highest potential

    Zone 1
    53
    Zone 2
    35

    Most counties sit in Zone 1; Zone 1 is the highest potential

  • Highest county

    81.4%

    Pickaway County

    Pickaway
    81.4%
    Cuyahoga
    21.7%

    Counties with 30+ tests, 2008 to 2017

Read a result for Ohio

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 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. 52.3% of Ohio's reported tests reached 4 pCi/L, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Ohio, At a glance

Ohio at a glance

Predicted: EPA radon zone

88 of 88 counties classified

EPA classifies counties, not states. Of the 88 counties in Ohio with a zone, 53 are in Zone 1 and 35 in Zone 2.

  • Zone 1: Highest predicted potentialgreater than 4 pCi/L53 of 88 counties · 60.2%
  • Zone 2: Moderate predicted potential2 to 4 pCi/L35 of 88 counties · 39.8%

An EPA radon zone predicts a whole county. It is not intended to determine whether any individual home should be tested: homes with elevated levels occur in all three zones, and EPA recommends testing every home regardless of zone.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes Ohio's radon test figures by county: 88 of its 88 counties have one. Each one's share is in the county list.

How to read these figures

Ohio, Compared

Ohio radon figures, compared

Calculated by Radon411
Ohio, 2008 to 2017, laboratory
52.3%
of 98,840 tests at or above 4 pCi/L, pooled
Against the U.S.
+16.6points
35.7% pooled
Rank among the states
5 of 47
1 is the highest share
Counties with 30 or more tests
79
Highest
81.4%
Pickaway County
Lowest
21.7%
Cuyahoga County

Pooled across 88 counties, 52.3% of the 98,840 radon tests reported to CDC for Ohio over the 2008 to 2017 laboratory totals were at or above 4 pCi/L: close to half or more. That is 5th of 47 states with county figures for the period; Iowa (58.5%) above it and Colorado (47.0%) below.

Its 79 counties with 30 or more tests run from 21.7% in Cuyahoga County to 81.4% in Pickaway County; in 48 of them half or more of the reported tests reached 4 pCi/L. By band, 48 counties at 50% or more, 27 counties at 30% to 50%, 4 counties at 15% to 30%.

The national pool for the same period is 35.7%, so Ohio runs 16.6 points above the country. EPA's 1993 map puts 53 of its 88 classified counties in Zone 1; the tests reported since bear that out at 52.3%.

Across its 4 overlapping ten-year totals, the share went from 52.4% (2005 to 2014) to 52.3% (2008 to 2017), within 2 points, with 2006 to 2015 the highest at 52.9%.

Ohio ranked among 47 states by pooled share of tests at or above 4 pCi/L, 2008 to 2017, laboratory
StateRankCountiesTestsAt or above 4 pCi/L
North Dakota1 of 47536,60759.3%
Nebraska2 of 479342,78258.5%
South Dakota3 of 47626,27558.5%
Iowa4 of 479995,24558.5%
Ohio5 of 478898,84052.3%
Colorado6 of 476396,36747.0%
Wisconsin7 of 477268,10446.9%
Montana8 of 47519,89345.5%
Wyoming9 of 47237,63844.3%
Kentucky10 of 4712028,79343.7%
Minnesota11 of 4787130,91243.4%
Ohio's highest and lowest counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/L
Pickaway County1 of 7918381.4%
Fairfield County2 of 791,17576.8%
Logan County3 of 7975573.6%
Delaware County4 of 793,73072.2%
Knox County5 of 791,53072.0%
Franklin County6 of 7916,14271.9%
Licking County7 of 794,69471.2%
Auglaize County8 of 7913971.2%
Champaign County9 of 7959671.1%
Madison County10 of 7954967.4%
Cuyahoga County79 of 7910,09221.7%
Geauga County78 of 791,46923.4%
Mahoning County77 of 7966623.4%
Lake County76 of 792,34927.2%
Lawrence County75 of 796630.3%
Ohio's counties with 30 or more tests, by their own share at or above 4 pCi/L, 2008 to 2017, laboratory
ShareCountiesTheir testsFor example
50% or more4858,208Pickaway County, Fairfield County, Logan County
30% to 50%2725,904Jefferson County, Columbiana County, Perry County
15% to 30%414,576Lake County, Mahoning County, Geauga County
5% to 15%00None
Under 5%00None
Ohio ten-year laboratory totals, pooled, against the United States
PeriodCountiesTestsAt or above 4 pCi/LUnited StatesChange from the row before
2008 to 20178898,84052.3%35.7%−0.5 points
2007 to 20168895,44452.8%35.8%−0.2 points
2006 to 20158890,76952.9%36.3%+0.6 points
2005 to 20148883,67452.4%36.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period. CDC publishes no state or national figure.

Ohio, Counties

Ohio counties by EPA zone

Predicted

All 88 counties, grouped by the zone EPA predicts and ordered by their reported share at or above 4 pCi/L, under Ohio's map. Each county has a page of its own.

Ohio radon map by county: EPA radon zones. Map of Ohio's 88 counties shaded by EPA radon zone: Zone 1 in red-orange, Zone 2 in amber. 53 in Zone 1, 35 in Zone 2, 0 in Zone 3.
Ohio radon map by countyEPA radon zones for Ohio's counties: 53 counties in Zone 1, 35 counties in Zone 2, 0 counties in Zone 3.A prediction for each county, not a reading of any home; elevated homes occur in all three zones.

The 12 highest in Ohio, 2008 to 2017

Zone 1: highest predicted potential53

Local help

Ohio, Local resources

Local resources in Ohio

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

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

Ohio, Questions

Questions about radon in Ohio

Is radon a problem in Ohio?

Of the 88 counties in Ohio that EPA's Map of Radon Zones classifies, 53 carry Zone 1 (the highest predicted potential), 35 Zone 2 and 0 Zone 3. Pooled from 88 counties, 52.3% of the 98,840 radon tests reported to CDC over the 2008 to 2017 laboratory totals were at or above 4 pCi/L, 5th of 47 states.

Who does radon mitigation in Ohio?

Radon411's Ohio directory lists 479 radon businesses for testing, mitigation or both, each with the licensing list it was read from.

Which Ohio counties are in EPA radon Zone 1?

53 counties are in Zone 1: Adams County, Allen County, Ashland County, Auglaize County, Belmont County, Butler County, Carroll County, Champaign County, and 45 more in the county table on this page.

Which Ohio counties have the highest radon?

By the share of reported tests at or above 4 pCi/L, 2008 to 2017, laboratory: Pickaway County 81.4% (183 tests), Fairfield County 76.8% (1,175 tests), Logan County 73.6% (755 tests), Delaware County 72.2% (3,730 tests), Knox County 72.0% (1,530 tests).

Which EPA region is Ohio in?

Ohio is in EPA Region 5: Great Lakes.

Products

Ohio, Products

Testing a home in Ohio

52.3% of the 98,840 tests reported to CDC for Ohio over the 2008 to 2017 laboratory totals reached 4 pCi/L: a short-term kit (2 to 90 days) gives a first answer in days, a long-term test the year-round average. A short-term kit (2 to 90 days) is the quick first check for a home in Ohio; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Ohio homes, compared

Explore

Cities in Ohio with their own page

Radon data is published by county, not by city. Each city page sets the figures of the counties the city lies in side by side.