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Radon Levels in Dewey County, Oklahoma

EPA puts Dewey County in Zone 3, its lowest radon zone, and only 6 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). 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

  • Nearest county

    8.9%

    Oklahoma County, 95 miles

    Oklahoma
    8.9%
    Oklahoma
    12.6%

    Share at 4+ pCi/L, 135 tests, 2006 to 2015

  • Ground above low

    2.2%

    12.9 pts below Oklahoma

    Dewey
    2.2%
    Oklahoma
    15.2%

    Share of land USGS rates moderate or high potential

  • Tests reported

    6

    Too few for a share

    Dewey
    6
    Needed
    30

    2008 to 2017, laboratory

  • EPA radon zone

    Zone 3

    Lower potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    EPA predicts under 2 pCi/L indoors

Read a result for Dewey County

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.

Interpret this readingWhat a fix costs

The data

Dewey County, At a glance

Dewey County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Dewey County as a whole is an average indoor of less than 2 pCi/L (less than 75 Bq/m³). A low zone clears no address in it: homes above EPA's turn up in all three zones.

USGS geologic potential: Low across 98% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

CDC holds 6 reported tests for Dewey County over the 2008 to 2017 laboratory totals, with a median of 3.3 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Dewey County beside the counties around it is how this page reads it.

What these figures count

Only 6 tests were reported to CDC for Dewey County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor 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

Dewey County, Compared

Dewey County radon figures, compared

Calculated by Radon411

CDC's largest figure for Dewey County rests on 6 tests over the 2008 to 2017 laboratory totals, 2 of them at or above 4 pCi/L, so each test moves its share by 16.7 points and no rank or comparison is drawn from it. Results reached as high as 18.2 pCi/L, with a middle value of 3.3 pCi/L.

The nearest counties with a figure are Oklahoma County (95 miles away) at 8.9%, Tulsa County (172 miles away) at 6.0% and Washington County (180 miles away) at 11.3%. Pooled across 53 Oklahoma counties, 12.6% of reported tests reached that level; across every county in the country with a figure, 36.3%.

Statewide for the same period, Delaware County reported the highest share (44.7%) and Tulsa County the lowest (6.0%). EPA's 1993 map puts Dewey County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 98% of the county's land low radon potential.

Oklahoma, the United States and the counties around Dewey County, 2006 to 2015, laboratory
AreaTestsAt or above 4 pCi/LMedian
Oklahoma, pooled53 counties, pooled86012.6%Not pooled
United States, pooled2,669 counties, pooled1,805,52836.3%Not pooled
Delaware Countyhighest in the state3844.7%2.5 pCi/L
Tulsa Countylowest in the state3006.0%0.9 pCi/L
Custer County, OKborders it20.0%2.3 pCi/L
Roger Mills County, OKborders it10.0%3.2 pCi/L
Major County, OKborders it20.0%2.7 pCi/L
The nearest Oklahoma counties to Dewey County with 30 or more tests, 2006 to 2015, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Oklahoma County95 mi1358.9%0.9 pCi/L
Tulsa County172 mi3006.0%0.9 pCi/L
Washington County180 mi5311.3%1.9 pCi/L
Cherokee County225 mi5032.0%1.9 pCi/L
Delaware County237 mi3844.7%2.5 pCi/L
Dewey County ten-year laboratory totals, against Oklahoma's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestOklahoma, pooledChange from the row before
2008 to 2017633.3%3.3 pCi/L18.2 pCi/L12.7%Level
2007 to 2016633.3%3.3 pCi/L18.2 pCi/L12.1%Level
2006 to 2015633.3%3.3 pCi/L18.2 pCi/L12.6%Level
2005 to 2014633.3%3.3 pCi/L18.2 pCi/L12.0%First on file

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

Dewey County, Geology

The ground under Dewey County

Predicted

Most of the ground under Dewey County is one class on USGS's geologic map: 97.8% of its land is low radon potential, with 2.2% moderate. 97.8% of it lies in the area the map calls Central Oklahoma Plains and Hills, to which USGS gives a radon index of 7, in the low band (5 to 8).

USGS's geologic areas under Dewey County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Central Oklahoma Plains and HillsNonmarine Permian and Tertiary rocks, including shale, sandstone, and conglomerate in the western part, and Mississippian and Pennsylvanian rocks in the eastern part.Low797.8%
High PlainsTertiary sandstone, siltstone, shale.Moderate92.2%

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

Dewey County beside the ground around it

Across Oklahoma 0.6% of the land is rated high; none of Dewey County's is. Of the 6 counties that border it, 3 have more moderate-potential ground, Ellis County the most at 79.4%.

Share of land by USGS radon potential: Dewey County, the 6 counties bordering it and Oklahoma
AreaEPA zoneLow potentialModerate potentialHigh potential
Dewey CountyZone 397.8%2.2%None
Custer CountyZone 3100%NoneNone
Woodward CountyZone 380.1%19.9%None
Blaine CountyZone 3100%NoneNone
Major CountyZone 3100%NoneNone
Roger Mills CountyZone 365.8%34.2%None
Ellis CountyZone 220.6%79.4%None
Oklahoma77 counties, pooled by land areaVaries84.8%14.6%0.6%

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

Local help

Dewey County, Local resources

Radon testing and mitigation in Dewey County

What it means

Dewey County, Questions

Questions about radon in Dewey County

Are radon levels high in Dewey County?

Over the 2008 to 2017 laboratory totals, 33.3% of the radon tests reported to CDC for Dewey County, Oklahoma were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.3 pCi/L. Of the 5 nearest counties with a figure, within 237 miles, the share of tests at or above 4 pCi/L runs from 6.0% to 44.7%.

Which counties border Dewey County?

Dewey County borders 6 counties: Custer County, Woodward County, Blaine County, Major County, Roger Mills County and Ellis County.

Products

Dewey County, Products

Testing a home in Dewey County

No CDC figure names Dewey County; the nearest county with one, Oklahoma County (95 miles away), reported 8.9% of its tests at or above 4 pCi/L over the 2006 to 2015 laboratory totals, the only reading nearby until a test of this home. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Dewey County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Dewey County homes, compared

Explore

Dewey County, Bordering counties

Counties bordering Dewey County

Calculated by Radon411

Dewey County, Cities and towns

Cities and towns in Dewey County

Dewey County has been losing residents: from 4,476 in 2020 to 4,207 on July 1, 2025, a fall of 6.0% by the Census Bureau's estimates. Spread over its land, that is 4.2 people to the square mile. Seiling, the largest place on its list (800 residents in all), extends beyond Dewey County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 6 reported tests for 2008 to 2017 come to 1.4 for every 1,000 residents (2025 estimate), against 0.2 for Oklahoma.

From Seiling to Putnam, CDC publishes no figure by town: each reads Dewey County's.

The cities and towns in Dewey County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Seilingextends beyond Dewey County800−5.7%Counted whole
Vici576−5.9%13.7%
Leedey384−6.8%9.1%
Taloga270−6.3%6.4%
Camargo182−5.7%4.3%
Oakwood69−8.0%1.6%
Putnam26−3.7%0.6%

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). A place that extends beyond Dewey County is counted whole, so it has no share.

Dewey County, Homes

Homes in Dewey County

Dewey County is a place of houses on their own lots: 77% of its 2,195 homes are detached single-family houses, against 73% across Oklahoma. Half of its homes were built before 1973, close to Oklahoma's 1980: 33% date from before 1960 and 18% from 2000 or later. 75% of occupied homes are lived in by their owner (Oklahoma: 66%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Dewey County, Oklahoma, 2019 to 2023
HomesDewey CountyOklahoma
Housing units2,1951,763,036
Detached houses77%73%
In buildings of 5 or moreunder 1%12%
Mobile homes21%9%
Built before 196033%21%
Built since 200018%25%
Middle year built19731980
Owner-occupied75%66%

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