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Radon Levels in Jefferson County, Ohio

EPA puts Jefferson County in Zone 1, its highest radon zone, and high results are common there: 49.8% of the 271 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

    49.8%

    2.5 pts below OH

    Jefferson
    49.8%
    Ohio
    52.3%

    271 tests, 2008 to 2017

  • Median result

    3.9pCi/L

    Below action level

    Jefferson
    3.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    271

    49th of 79 by tests

    Jefferson
    271
    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

    49 of 79

    Middle half

    Jefferson
    49.8%
    Pickaway
    81.4%

    By share, of 79 with 30+ tests

Read a result for Jefferson County

Starts at Jefferson County's median, 3.9 pCi/L

3.9pCi/L

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

EPA’s reading of 3.9 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. Jefferson County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Jefferson County, At a glance

Jefferson County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Jefferson County, 2008 to 2017, laboratory
Under 2 pCi/L: 19%2 to 4 pCi/L: 31%4 pCi/L and above: 50%

Of 271 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Jefferson County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L5219.2%
2 to 4 pCi/L8431.0%
4 pCi/L and above13549.8%
What these figures count

These are the 271 tests reported to CDC for Jefferson 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

Jefferson County, Compared

Jefferson County radon figures, compared

Calculated by Radon411

In Jefferson County, about 5 in 10 reported tests over the 2008 to 2017 laboratory totals (135 of 271) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 14.1 points higher. Across 88 Ohio counties pooled together, 52.3% of tests reached that level, so Jefferson County runs 2.5 points below its state.

Of 7 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 5 a smaller one; the spread is 40.3% (Ohio County, WV) to 57.4% (Carroll County). By share, Jefferson County is 49th of 79 Ohio counties with 30 or more tests for the same period.

Half the tests came in under 3.9 pCi/L and half over it; the single highest reached 583.7 pCi/L. Below the action level, 52 tests (19.2%) came in under 2 pCi/L, against 23.1% statewide, and 84 tests (31.0%) fell between 2 and 4, against 24.6% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 49.8% share point the same way here. USGS geology rates 100% of the county's land high radon potential. CDC also counts 40 tests taken after mitigation in Jefferson County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Jefferson County went from 232 tests (2005 to 2014) to 271 (2008 to 2017), the share going from 50.4% to 49.8%.

Jefferson County against Ohio, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Jefferson County
Jefferson County27149.8%3.9 pCi/LThis county
Ohio, pooled88 counties, pooled98,84052.3%Not pooled+2.5 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−14.1 points
Pickaway Countyhighest in the state18381.4%9.5 pCi/L+31.6 points
Cuyahoga Countylowest in the state10,09221.7%2.0 pCi/L−28.1 points
Carroll County, OHborders it48657.4%4.8 pCi/L+7.6 points
Harrison County, OHborders it4450.0%4.1 pCi/L+0.2 points
Columbiana County, OHborders it66249.1%3.8 pCi/L−0.7 points
Hancock County, WVborders it32649.1%3.9 pCi/L−0.7 points
Belmont County, OHborders it69745.2%3.6 pCi/L−4.6 points
Brooke County, WVborders it15743.9%3.4 pCi/L−5.9 points
Ohio County, WVborders it85340.3%3.2 pCi/L−9.5 points
Where Jefferson County's reported results fell, 2008 to 2017, laboratory, beside Ohio and the United States
ResultJefferson County testsJefferson County shareOhio shareU.S. shareAgainst Ohio
Under 2 pCi/L5219.2%23.1%39.6%−3.9 points
2 to 4 pCi/L8431.0%24.6%24.7%+6.4 points
4 pCi/L and above13549.8%52.3%35.7%−2.5 points
Jefferson 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
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
Harrison County48 of 794450.0%4.1 pCi/L
Jefferson County49 of 7927149.8%3.9 pCi/L
Columbiana County50 of 7966249.1%3.8 pCi/L
Perry County51 of 799048.9%3.8 pCi/L
Defiance County52 of 797048.6%3.8 pCi/L
Brown County53 of 797047.1%3.3 pCi/L
Wyandot County54 of 7932046.3%3.6 pCi/L
Jefferson County ten-year laboratory totals, against Ohio's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestOhio, pooledChange from the row before
2008 to 201727149.8%3.9 pCi/L583.7 pCi/L52.3%+0.2 points
2007 to 201627049.6%3.9 pCi/L583.7 pCi/L52.8%−2.3 points
2006 to 201524351.9%4.0 pCi/L583.7 pCi/L52.9%+1.5 points
2005 to 201423250.4%4.0 pCi/L583.7 pCi/L52.4%First on file

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

Jefferson County, Geology

The ground under Jefferson County

Predicted

USGS's geologic map puts all of Jefferson County's mapped land in one class: high radon potential. All of it lies in the area the map calls Area of Elevated Radioactivity, to which USGS gives a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under Jefferson County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Area of Elevated RadioactivityPennsylvanian shale, sandstone, coal, and limestone.High1299.8%

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

Jefferson County beside the ground around it

Jefferson County has more high-potential ground than Ohio as a whole: 100% of its land against 62.8%. Of the 7 counties that border it, none has as large a share of high-potential ground; Harrison County comes nearest at 100%.

Share of land by USGS radon potential: Jefferson County, the 7 counties bordering it and Ohio
AreaEPA zoneLow potentialModerate potentialHigh potential
Jefferson CountyZone 1NoneNone100%
Brooke County, WVZone 1None10.2%89.8%
Hancock County, WVZone 1NoneNone100%
Harrison CountyZone 1NoneNone100%
Ohio County, WVZone 1None69.7%30.3%
Carroll CountyZone 1None11.8%88.2%
Columbiana CountyZone 1None39.2%60.8%
Belmont CountyZone 1None30.9%69.1%
Ohio88 counties, pooled by land areaVariesNone37.2%62.8%

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

Local help

Jefferson County, Local resources

Radon testing and mitigation in Jefferson County

Listed radon businesses with an address in Jefferson County:

Listed radon professionals by town: Steubenville, Toronto, Mingo Junction, Empire

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

Jefferson County, Questions

Questions about radon in Jefferson County

Are radon levels high in Jefferson County?

Over the 2008 to 2017 laboratory totals, 49.8% of the radon tests reported to CDC for Jefferson County, Ohio were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.9 pCi/L. Of 79 Ohio counties with 30 or more tests for the same period, 48 reported a higher share; pooled, the state comes to 52.3%.

Which counties border Jefferson County?

Jefferson County borders 7 counties: Brooke County, WV, Hancock County, WV, Harrison County, OH, Ohio County, WV, Carroll County, OH, Columbiana County, OH and Belmont County, OH.

Products

Jefferson County, Products

Testing a home in Jefferson County

In Jefferson County, 49.8% of 271 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 Jefferson 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

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

Explore

Jefferson County, Bordering counties

Counties bordering Jefferson County

Calculated by Radon411

Jefferson County, Cities and towns

Cities and towns in Jefferson County

About 63,597 people live in Jefferson County by the Census Bureau's estimate for July 1, 2025, 1,562 fewer than in 2020 (−2.4%). That works out to 156 people per square mile of land. Its largest town, Steubenville, has 17,922 residents, 28.2% of the total. Reported testing is thin here: 271 tests over 2008 to 2017, or 4.3 for every 1,000 residents (2025 estimate), where Ohio as a whole comes to 8.3.

From Steubenville to Bloomingdale, CDC publishes no figure by town: each reads Jefferson County's.

The 12 largest cities and towns in Jefferson County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Steubenville17,922−1.2%28.2%
Toronto5,149−2.5%8.1%
Wintersville3,660−2.7%5.8%
Mingo Junction3,233−3.1%5.1%
Tiltonsville1,215−3.0%1.9%
Yorkvilleextends beyond Jefferson County933−3.4%Counted whole
Adenaextends beyond Jefferson County651−3.0%Counted whole
Dillonvale591−3.7%0.9%
Bergholz524−3.5%0.8%
Amsterdam425−3.6%0.7%
Richmond397−2.5%0.6%
Rayland384−3.0%0.6%
  • Mount Pleasant
  • Irondale
  • Stratton
  • Empire
  • New Alexandria
  • Bloomingdale

18 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 Jefferson County is counted whole, so it has no share.

Jefferson County, Homes

Homes in Jefferson County

Jefferson County is a place of houses on their own lots: 78% of its 31,118 homes are detached single-family houses, against 69% across Ohio. The homes are older than Ohio's as a whole: half were built before 1958 (1970 for Ohio), and 54% date from before 1960. 72% 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 Jefferson County, Ohio, 2019 to 2023
HomesJefferson CountyOhio
Housing units31,1185,271,573
Detached houses78%69%
In buildings of 5 or more9%15%
Mobile homes5%4%
Built before 196054%38%
Built since 20007%16%
Middle year built19581970
Owner-occupied72%67%

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