Skip to content
RADON411

Locations and reports

Radon Levels in Yakima County, Washington

EPA puts Yakima County in Zone 2, its middle radon zone, and most reported tests there come back low, though 5.3% of 57 (2020) reached 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

    5.3%

    13.7 pts below WA

    Yakima
    5.3%
    Washington
    19.0%

    57 tests, 2020

  • Median result

    0.7pCi/L

    Below action level

    Yakima
    0.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2020

  • Tests reported

    57

    6th of 10 by tests

    Yakima
    57
    Spokane
    721

    Reported to CDC before any fix, 2020

  • 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 10

    Middle half

    Yakima
    5.3%
    Spokane
    40.6%

    By share, of 10 with 30+ tests

Read a result for Yakima County

Starts at Yakima 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. Yakima County's median reported result, 2020.

Interpret this reading

The data

Yakima County, At a glance

Yakima County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Yakima 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 80% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Yakima County, 2020

Share of reported tests at or above 4 pCi/L, by year, Yakima County
Share of reported tests at or above 4 pCi/L, by year, Yakima County
YearShare of reported tests at or above 4 pCi/L
20140.0%
20150.0%
20163.4%
201710.5%
20180.0%
20195.0%
20205.3%

2020: 5.3%. Across these years the share ran from 0.0% to 10.5%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 57 tests reported to CDC for Yakima County over 2020, 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: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).

How to read these figures

Yakima County, Compared

Yakima County radon figures, compared

Calculated by Radon411

Yakima County reports fewer high tests than Washington overall. 5.3% of its 57 tests in 2020 were at or above 4 pCi/L. That is 13.7 points below the 19.0% pooled from 37 Washington counties.

Ordered from highest share down, it comes 6th of 10 Washington counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 25.5%; Yakima County sits 20.2 points below it.

Next door, the shares run from 4.3% in Pierce County to 5.0% in King County, with King County and Pierce County below Yakima County. The reported tests do not follow EPA's Zone 2 label for Yakima County (predicted average between 2 and 4 pCi/L): 5.3% of them reached 4 pCi/L, fewer than that label suggests.

Half the tests came in under 0.7 pCi/L and half over it; the single highest reached 4.9 pCi/L. The rest split 71.9% under 2 pCi/L and 22.8% from 2 to 4 (Washington: 67.6% and 13.3%).

The busiest year on file was 2015, with 60 tests reported; the quietest, 2018, had 12.

Yakima County against Washington, the United States and nearby counties, 2020
AreaTestsAt or above 4 pCi/LMedianDifference from Yakima County
Yakima County575.3%0.7 pCi/LThis county
Washington, pooled37 counties, pooled2,78119.0%Not pooled+13.7 points
United States, pooled915 counties, pooled405,35525.5%Not pooled+20.2 points
Spokane Countyhighest in the state72140.6%2.7 pCi/L+35.3 points
Kitsap Countylowest in the state500.0%0.4 pCi/L−5.3 points
Lewis County, WAborders it1070.0%15.6 pCi/L+64.7 points
Skamania County, WAborders it1752.9%4.9 pCi/L+47.6 points
Grant County, WAborders it450.0%16.4 pCi/L+44.7 points
Klickitat County, WAborders it2030.0%2.2 pCi/L+24.7 points
Kittitas County, WAborders it520.0%1.0 pCi/L+14.7 points
King County, WAborders it5035.0%0.3 pCi/L−0.3 points
Benton County, WAborders it214.8%1.4 pCi/L−0.5 points
Pierce County, WAborders it4204.3%0.7 pCi/L−1.0 points
Where Yakima County's reported results fell, 2020, beside Washington and the United States
ResultYakima County testsYakima County shareWashington shareU.S. shareAgainst Washington
Under 2 pCi/L4171.9%67.6%51.6%+4.3 points
2 to 4 pCi/L1322.8%13.3%22.9%+9.5 points
4 pCi/L and above35.3%19.0%25.5%−13.7 points
Yakima County ranked among the 10 Washington counties with 30 or more tests, by share at or above 4 pCi/L, 2020
CountyRankTestsAt or above 4 pCi/LMedian
Spokane County1 of 1072140.6%2.7 pCi/L
Stevens County2 of 104537.8%1.9 pCi/L
Walla Walla County3 of 103420.6%1.5 pCi/L
Clark County4 of 1049017.6%1.2 pCi/L
Thurston County5 of 10466.5%0.4 pCi/L
Yakima County6 of 10575.3%0.7 pCi/L
King County7 of 105035.0%0.3 pCi/L
Pierce County8 of 104204.3%0.7 pCi/L
Snohomish County9 of 101021.0%0.2 pCi/L
Kitsap County10 of 10500.0%0.4 pCi/L
Yakima County radon tests by year, against Washington's pooled share
YearTestsAt or above 4 pCi/LMedianHighestWashington, pooledChange from the row before
2020575.3%0.7 pCi/L4.9 pCi/L19.0%+0.3 points
2019205.0%1.1 pCi/L4.5 pCi/L20.9%+5.0 points
2018120.0%1.2 pCi/L2.2 pCi/L16.1%−10.5 points
20171910.5%1.3 pCi/L5.2 pCi/L19.1%+7.1 points
2016293.4%1.0 pCi/L4.0 pCi/L16.6%+3.4 points
2015600.0%0.1 pCi/L3.8 pCi/L17.4%Level
2014210.0%0.8 pCi/L1.8 pCi/L15.0%First on file

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

Yakima County, Geology

The ground under Yakima County

Predicted

Most of the ground under Yakima County is one class on USGS's geologic map: 80.3% of its land is moderate radon potential, with 19.7% low. The map puts 80.3% of Yakima County in the area it calls Columbia Basin and 19.7% in Cascade Mountains. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 6, in the low band (5 to 8).

USGS's geologic areas under Yakima County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Columbia BasinBasaltic rocks low in uranium content. Uranium content of soils is moderately elevated.Moderate1080.3%
Cascade MountainsNorthern Cascade Mountains are Mesozoic metamorphic rocks intruded by Mesozoic and Tertiary granitic rocks. Southern Cascade Mountains are composed primarily of Tertiary and Holocene volcanic rocks.Low619.7%

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

Yakima County beside the ground around it

Across Washington 13.7% of the land is rated high; none of Yakima County's is. Of the 8 counties that border it, 1 has more high-potential ground, Grant County the most at 0.5%.

Share of land by USGS radon potential: Yakima County, the 8 counties bordering it and Washington
AreaEPA zoneLow potentialModerate potentialHigh potential
Yakima CountyZone 219.7%80.3%None
Kittitas CountyZone 222.5%77.5%None
Klickitat CountyZone 29.8%90.2%None
Benton CountyZone 2None100%None
Grant CountyZone 2None99.5%0.5%
Pierce CountyZone 398.4%NoneNone
Skamania CountyZone 175.5%24.0%None
King CountyZone 398.1%NoneNone
Lewis CountyZone 3100%NoneNone
Washington38 counties, pooled by land areaVaries46.4%39.0%13.7%

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

Local help

Yakima County, Local resources

Radon testing and mitigation in Yakima County

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

What it means

Yakima County, Questions

Questions about radon in Yakima County

Are radon levels high in Yakima County?

In 2020, 5.3% of the radon tests reported to CDC for Yakima County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.7 pCi/L. Of 10 Washington counties with 30 or more tests for the same period, 5 reported a higher share; pooled, the state comes to 19.0%.

Which counties border Yakima County?

Yakima County borders 8 counties: Kittitas County, Klickitat County, Benton County, Grant County, Pierce County, Skamania County, King County and Lewis County.

Products

Yakima County, Products

Testing a home in Yakima County

In Yakima County, 5.3% of 57 tests reported to CDC in 2020 reached 4 pCi/L, against 19.0% pooled across Washington. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Yakima County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Yakima County homes, compared

Explore

Yakima County, Bordering counties

Counties bordering Yakima County

Calculated by Radon411

Yakima County, Cities and towns

Cities and towns in Yakima County

The Census Bureau estimates 259,185 residents in Yakima County for July 1, 2025, 2,469 more than in 2020 (+1.0%). That works out to 60 people per square mile of land. Its largest town, Yakima, has 97,458 residents, 37.6% of the total. Together its 14 incorporated places hold 66.1% of those residents; the other 33.9% live outside any of them. Reported testing is thin here: 57 tests over 2020, or 0.2 for every 1,000 residents (2025 estimate), where Washington as a whole comes to 0.3.

From Yakima to Harrah, CDC publishes no figure by town: each reads Yakima County's.

The 12 largest cities and towns in Yakima County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Yakima97,458+0.4%37.6%
Sunnyside16,430+0.2%6.3%
Grandview12,062+10.0%4.7%
Selah8,678+5.3%3.3%
Toppenish8,635−2.2%3.3%
Union Gap6,617+0.4%2.6%
Moxee4,765+8.5%1.8%
Wapato4,469−2.7%1.7%
Granger3,831+5.2%1.5%
Zillah3,111−1.8%1.2%
Mabton1,967+0.5%0.8%
Tieton1,657+19.8%0.6%
  • Naches
  • Harrah

14 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).

Yakima County, Homes

Homes in Yakima County

Of Yakima County's 91,647 homes, 66% are detached houses, against 62% across Washington; 12% are mobile homes. The homes are older than Washington's as a whole: half were built before 1976 (1984 for Washington), and 30% date from before 1960. 62% of occupied homes are lived in by their owner (Washington: 64%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Yakima County, Washington, 2019 to 2023
HomesYakima CountyWashington
Housing units91,6473,262,667
Detached houses66%62%
In buildings of 5 or more11%22%
Mobile homes12%6%
Built before 196030%21%
Built since 200019%28%
Middle year built19761984
Owner-occupied62%64%

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