Skip to content
RADON411

Locations and reports

Radon Levels in Washington County, Ohio

EPA puts Washington County in Zone 2, its middle radon zone, and 38.1% of its 349 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

    38.1%

    14.2 pts below OH

    Washington
    38.1%
    Ohio
    52.3%

    349 tests, 2008 to 2017

  • Median result

    3.1pCi/L

    Below action level

    Washington
    3.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    349

    44th of 79 by tests

    Washington
    349
    Franklin
    16,142

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Ohio

    68 of 79

    Lowest quarter

    Washington
    38.1%
    Pickaway
    81.4%

    By share, of 79 with 30+ tests

Read a result for Washington County

Starts at Washington County's median, 3.1 pCi/L

3.1pCi/L

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

EPA’s reading of 3.1 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. Washington County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Washington County, At a glance

Washington County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Washington County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Washington County, 2008 to 2017, laboratory
Under 2 pCi/L: 29%2 to 4 pCi/L: 33%4 pCi/L and above: 38%

Of 349 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Washington County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L10229.2%
2 to 4 pCi/L11432.7%
4 pCi/L and above13338.1%
What these figures count

These are the 349 tests reported to CDC for Washington 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

Washington County, Compared

Washington County radon figures, compared

Calculated by Radon411

In Washington County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (133 of 349) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 2.4 points higher. Across 88 Ohio counties pooled together, 52.3% of tests reached that level, so Washington County runs 14.2 points below its state.

Of 5 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 15.9% (Wood County, WV) to 58.3% (Monroe County). By share, Washington County is 68th of 79 Ohio counties with 30 or more tests for the same period.

Half the tests came in under 3.1 pCi/L and half over it; the single highest reached 41.8 pCi/L. Below the action level, 102 tests (29.2%) came in under 2 pCi/L, against 23.1% statewide, and 114 tests (32.7%) fell between 2 and 4, against 24.6% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 38.1% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential. CDC also counts 32 tests taken after mitigation in Washington County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Washington County went from 348 tests (2005 to 2014) to 349 (2008 to 2017), the share going from 36.5% to 38.1%.

Washington County against Ohio, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Washington County
Washington County34938.1%3.1 pCi/LThis county
Ohio, pooled88 counties, pooled98,84052.3%Not pooled+14.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−2.4 points
Pickaway Countyhighest in the state18381.4%9.5 pCi/L+43.3 points
Cuyahoga Countylowest in the state10,09221.7%2.0 pCi/L−16.4 points
Monroe County, OHborders it4858.3%5.0 pCi/L+20.2 points
Pleasants County, WVborders it2450.0%4.0 pCi/L+11.9 points
Athens County, OHborders it31838.1%3.1 pCi/LLevel
Noble County, OHborders it4231.0%2.2 pCi/L−7.1 points
Morgan County, OHborders it1030.0%3.3 pCi/L−8.1 points
Tyler County, WVborders it3522.9%1.8 pCi/L−15.2 points
Wood County, WVborders it90515.9%1.8 pCi/L−22.2 points
Where Washington County's reported results fell, 2008 to 2017, laboratory, beside Ohio and the United States
ResultWashington County testsWashington County shareOhio shareU.S. shareAgainst Ohio
Under 2 pCi/L10229.2%23.1%39.6%+6.1 points
2 to 4 pCi/L11432.7%24.6%24.7%+8.1 points
4 pCi/L and above13338.1%52.3%35.7%−14.2 points
Washington 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
Jackson County63 of 794841.7%3.3 pCi/L
Ottawa County64 of 7954140.3%2.9 pCi/L
Lucas County65 of 791,38140.2%3.0 pCi/L
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
Washington County ten-year laboratory totals, against Ohio's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestOhio, pooledChange from the row before
2008 to 201734938.1%3.1 pCi/L41.8 pCi/L52.3%−0.1 points
2007 to 201635638.2%3.2 pCi/L39.7 pCi/L52.8%+2.0 points
2006 to 201535936.2%3.1 pCi/L39.7 pCi/L52.9%−0.3 points
2005 to 201434836.5%3.1 pCi/L39.7 pCi/L52.4%First on file

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

Washington County, Geology

The ground under Washington County

Predicted

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

USGS's geologic areas under Washington County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Unglaciated PlateauMississippian through Permian limestone, dolomite, and shale.Moderate1199.9%

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

Washington County beside the ground around it

Across Ohio 62.8% of the land is rated high; none of Washington County's is. Of the 7 counties that border it, none has as large a share of moderate-potential ground; Athens County comes nearest at 100%.

Share of land by USGS radon potential: Washington County, the 7 counties bordering it and Ohio
AreaEPA zoneLow potentialModerate potentialHigh potential
Washington CountyZone 2None100%None
Wood County, WVZone 2None100%None
Pleasants County, WVZone 2None100%None
Morgan CountyZone 2None100%None
Noble CountyZone 2None100%None
Athens CountyZone 2None100%None
Monroe CountyZone 2None100%None
Tyler County, WVZone 2None100%None
Ohio88 counties, pooled by land areaVariesNone37.2%62.8%

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

Local help

Washington County, Local resources

Radon testing and mitigation in Washington County

Listed radon businesses with an address in Washington County:

Listed radon professionals by town: Marietta

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

Washington County, Questions

Questions about radon in Washington County

Are radon levels high in Washington County?

Over the 2008 to 2017 laboratory totals, 38.1% of the radon tests reported to CDC for Washington County, Ohio were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.1 pCi/L. Of 79 Ohio counties with 30 or more tests for the same period, 67 reported a higher share; pooled, the state comes to 52.3%.

Which counties border Washington County?

Washington County borders 7 counties: Wood County, WV, Pleasants County, WV, Morgan County, OH, Noble County, OH, Athens County, OH, Monroe County, OH and Tyler County, WV.

Products

Washington County, Products

Testing a home in Washington County

In Washington County, 38.1% of 349 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 52.3% pooled across Ohio. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Washington County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Washington County homes, compared

Explore

Washington County, Bordering counties

Counties bordering Washington County

Calculated by Radon411

Washington County, Cities and towns

Cities and towns in Washington County

About 58,389 people live in Washington County by the Census Bureau's estimate for July 1, 2025, 1,268 fewer than in 2020 (−2.1%). That works out to 92 people per square mile of land. Its largest town, Marietta, has 13,053 residents, 22.4% of the total. Together its 7 incorporated places hold 38.3% of those residents; the other 61.7% live outside any of them. CDC's 349 reported tests for 2008 to 2017 work out to 6.0 per 1,000 residents (2025 estimate), close to Ohio's 8.3.

From Marietta to Lower Salem, CDC publishes no figure by town: each reads Washington County's.

The cities and towns in Washington County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Marietta13,053−2.3%22.4%
Belpre6,657−0.9%11.4%
Beverly1,200−2.8%2.1%
Matamoras690−2.5%1.2%
Lowell552−2.1%0.9%
Macksburg114−2.6%0.2%
Lower Salem72−2.7%0.1%

7 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).

Washington County, Homes

Homes in Washington County

Washington County is a place of houses on their own lots: 78% of its 27,979 homes are detached single-family houses, against 69% across Ohio. Half of its homes were built before 1973, close to Ohio's 1970: 35% date from before 1960 and 14% from 2000 or later. 75% 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 Washington County, Ohio, 2019 to 2023
HomesWashington CountyOhio
Housing units27,9795,271,573
Detached houses78%69%
In buildings of 5 or more5%15%
Mobile homes10%4%
Built before 196035%38%
Built since 200014%16%
Middle year built19731970
Owner-occupied75%67%

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