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Radon Levels in Whitman County, Washington

EPA puts Whitman County in Zone 2, its middle radon zone, and only 17 radon tests from it are on file with CDC (2020). 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

    12.8%

    2.2 pts below WA

    Whitman
    12.8%
    Washington
    15.0%

    78 tests, 2014

  • Median result

    0.7pCi/L

    Below action level

    Whitman
    0.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2014

  • Tests reported

    78

    11th of 14 by tests

    Whitman
    78
    King
    689

    Reported to CDC before any fix, 2014

  • 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 Washington

    6 of 14

    Middle half

    Whitman
    12.8%
    Klickitat
    48.5%

    By share, of 14 with 30+ tests

Read a result for Whitman County

Starts at Whitman County's median, 0.7 pCi/L

0.7pCi/L

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

EPA’s reading of 0.7 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Whitman County's median reported result, 2014.

Interpret this reading

The data

Whitman County, At a glance

Whitman County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Whitman 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 99% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Whitman County, 2020

Share of reported tests at or above 4 pCi/L, by year, Whitman County
Share of reported tests at or above 4 pCi/L, by year, Whitman County
YearShare of reported tests at or above 4 pCi/L
201412.8%
201542.9%
201618.8%
201718.4%
201836.0%
201938.5%
202029.4%

2020: 29.4%. Across these years the share ran from 12.8% to 42.9%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 17 tests were reported to CDC for Whitman County over 2020, 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: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).

How to read these figures

Whitman County, Compared

Whitman County radon figures, compared

Calculated by Radon411

Whitman County reports fewer high tests than Washington overall. 12.8% of its 78 tests in 2014 were at or above 4 pCi/L. That is 2.2 points below the 15.0% pooled from 36 Washington counties.

The newest figure, in 2020, counts only 17 tests (29.4% at or above 4 pCi/L), too few to compare, so this reading uses the 78-test figure.

Ordered from highest share down, it comes 6th of 14 Washington counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 34.9%; Whitman County sits 22.1 points below it.

Spokane County, the one bordering county with a figure for the same period, reported 34.7%. Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 12.8% share point the same way here.

Half the tests came in under 0.7 pCi/L and half over it; the single highest reached 9.2 pCi/L. The rest split 75.6% under 2 pCi/L and 11.5% from 2 to 4 (Washington: 72.8% and 12.2%). Year by year, 2014 opened at 12.8% and 2017 closed at 18.4% (up 5.6 points), with 2015 the high at 42.9%.

The busiest year on file was 2014, with 78 tests reported; the quietest, 2020, had 17.

Share of reported tests at or above 4 pCi/L by year, Whitman County against Washington2014 to 2017, years with 30 or more tests: Whitman County 12.8% to 18.4%, the state's pooled share 19.1% in 2017.
Whitman CountyWashington, pooled
Share of reported tests at or above 4 pCi/L by year, Whitman County against Washington: data table
YearTestsWhitman County, at or above 4 pCi/LWashington, pooled
20147812.8%15.0%
20154942.9%17.4%
20163218.8%16.6%
20174918.4%19.1%
Whitman County against Washington, the United States and nearby counties, 2014
AreaTestsAt or above 4 pCi/LMedianDifference from Whitman County
Whitman County7812.8%0.7 pCi/LThis county
Washington, pooled36 counties, pooled3,15315.0%Not pooled+2.2 points
United States, pooled925 counties, pooled517,29334.9%Not pooled+22.1 points
Klickitat Countyhighest in the state3348.5%3.4 pCi/L+35.7 points
Skagit Countylowest in the state300.0%0.5 pCi/L−12.8 points
Lincoln County, WAborders it366.7%5.0 pCi/L+53.9 points
Spokane County, WAborders it60034.7%2.2 pCi/L+21.9 points
Franklin County, WAborders it812.5%1.1 pCi/L−0.3 points
Adams County, WAborders it20.0%2.2 pCi/L−12.8 points
Where Whitman County's reported results fell, 2014, beside Washington and the United States
ResultWhitman County testsWhitman County shareWashington shareU.S. shareAgainst Washington
Under 2 pCi/L5975.6%72.8%40.0%+2.8 points
2 to 4 pCi/L911.5%12.2%25.1%−0.7 points
4 pCi/L and above1012.8%15.0%34.9%−2.2 points
Whitman County ranked among the 14 Washington counties with 30 or more tests, by share at or above 4 pCi/L, 2014
CountyRankTestsAt or above 4 pCi/LMedian
Klickitat County1 of 143348.5%3.4 pCi/L
Spokane County2 of 1460034.7%2.2 pCi/L
Cowlitz County3 of 1413222.7%1.0 pCi/L
Clark County4 of 1457118.6%1.1 pCi/L
Pierce County5 of 1421515.3%0.9 pCi/L
Whitman County6 of 147812.8%0.7 pCi/L
Thurston County7 of 141126.3%0.6 pCi/L
Benton County8 of 141135.3%0.7 pCi/L
Snohomish County9 of 141303.8%0.5 pCi/L
Lewis County10 of 14712.8%0.4 pCi/L
King County11 of 146892.2%0.4 pCi/L
Whitman County radon tests by year, against Washington's pooled share
YearTestsAt or above 4 pCi/LMedianHighestWashington, pooledChange from the row before
20201729.4%1.4 pCi/L11.6 pCi/L19.0%−9.1 points
20192638.5%2.3 pCi/L15.3 pCi/L20.9%+2.5 points
20182536.0%2.7 pCi/L9.9 pCi/L16.1%+17.6 points
20174918.4%1.6 pCi/L12.1 pCi/L19.1%−0.4 points
20163218.8%2.5 pCi/L15.7 pCi/L16.6%−24.1 points
20154942.9%3.0 pCi/L19.0 pCi/L17.4%+30.1 points
20147812.8%0.7 pCi/L9.2 pCi/L15.0%First on file

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

Whitman County, Geology

The ground under Whitman County

Predicted

Most of the ground under Whitman County is one class on USGS's geologic map: 99.1% of its land is moderate radon potential, with 0.9% high. 99.0% of it lies in the area the map calls Columbia Basin, to which USGS gives a radon index of 10, in the moderate band (9 to 11).

USGS's geologic areas under Whitman County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Columbia BasinBasaltic rocks low in uranium content. Uranium content of soils is moderately elevated.Moderate1099.0%
Northern Rocky Mountain ProvinceDiorite and granite of the Idaho batholith.High120.9%

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

Whitman County beside the ground around it

Washington as a whole has more high-potential ground than Whitman County: 13.7% of its land, against 0.9% here. Of the 10 counties that border it, 4 have more high-potential ground, Benewah County, ID the most at 90.4%.

Share of land by USGS radon potential: Whitman County, the 10 counties bordering it and Washington
AreaEPA zoneLow potentialModerate potentialHigh potential
Whitman CountyZone 2None99.1%0.9%
Garfield CountyZone 2None100%None
Columbia CountyZone 2None100%None
Latah County, IDZone 131.0%12.1%56.9%
Asotin CountyZone 2None100%None
Benewah County, IDZone 1None9.6%90.4%
Adams CountyZone 2None100%None
Nez Perce County, IDZone 399.5%0.5%None
Spokane CountyZone 1None56.7%43.3%
Lincoln CountyZone 2None95.3%4.7%
Franklin CountyZone 2None100%None
Washington38 counties, pooled by land areaVaries46.4%39.0%13.7%

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

Local help

Whitman County, Local resources

Radon testing and mitigation in Whitman County

What Washington's program says
Phone
360-236-3200
Email
doh.radon@doh.wa.gov

What it means

Whitman County, Questions

Questions about radon in Whitman County

Are radon levels high in Whitman County?

In 2020, 29.4% of the radon tests reported to CDC for Whitman County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.4 pCi/L. Of 14 Washington counties with 30 or more tests for the same period, 5 reported a higher share; pooled, the state comes to 15.0%.

Which counties border Whitman County?

Whitman County borders 10 counties: Garfield County, WA, Columbia County, WA, Latah County, ID, Asotin County, WA, Benewah County, ID, Adams County, WA, Nez Perce County, ID, Spokane County, WA, Lincoln County, WA and Franklin County, WA.

Products

Whitman County, Products

Testing a home in Whitman County

In Whitman County, 12.8% of 78 tests reported to CDC in 2014 reached 4 pCi/L, against 15.0% pooled across Washington. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Whitman County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Whitman County homes, compared

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Whitman County, Bordering counties

Counties bordering Whitman County

Calculated by Radon411

Whitman County, Cities and towns

Cities and towns in Whitman County

The Census Bureau estimates 48,512 residents in Whitman County for July 1, 2025, 696 more than in 2020 (+1.5%). That works out to 22 people per square mile of land. Pullman alone is home to 33,756 of them, 69.6% of the total. Together its 16 incorporated places hold 88.1% of those residents; the other 11.9% live outside any of them. Testing is reported here more often than across the state: CDC's 78 reported tests for 2014 come to 1.6 for every 1,000 residents (2025 estimate), against 0.4 for Washington.

From Pullman to Lamont, CDC publishes no figure by town: each reads Whitman County's.

The 12 largest cities and towns in Whitman County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Pullman33,756+2.7%69.6%
Colfax2,667−3.7%5.5%
Palouse1,019+1.3%2.1%
Tekoa812−0.2%1.7%
St. John586−1.7%1.2%
Rosalia573−3.0%1.2%
Garfield542−3.0%1.1%
Albion540−0.7%1.1%
Colton402+0.8%0.8%
Uniontown398+2.3%0.8%
Oakesdale392−2.2%0.8%
Endicott298−4.5%0.6%
  • LaCrosse
  • Malden
  • Farmington
  • Lamont

16 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).

Whitman County, Homes

Homes in Whitman County

Whitman County has 21,232 homes, and many share a building: 35% are in buildings of five or more, 44% are detached houses, against 62% across Washington. Half of its homes were built before 1978, close to Washington's 1984: 28% date from before 1960 and 22% from 2000 or later. Most occupied homes here are rented: owners live in 47% (Washington: 64%). A tenant can run a test; a fix is the landlord's to make.

Homes in Whitman County, Washington, 2019 to 2023
HomesWhitman CountyWashington
Housing units21,2323,262,667
Detached houses44%62%
In buildings of 5 or more35%22%
Mobile homes6%6%
Built before 196028%21%
Built since 200022%28%
Middle year built19781984
Owner-occupied47%64%

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