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Washington Radon Map and Levels by County

Washington's counties span all three EPA radon zones. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

Predicted
7 of 39counties in Zone 1, EPA's highest radon zone
Measured
By countyCDC publishes Washington's test figures by county: 39 of 39 counties have one.
Your home
Test to knowNo area figure here is a reading of your home.
How to test this homeFind a certified tester

The data

Washington, At a glance

Washington at a glance

Predicted: EPA radon zone

39 of 39 counties classified

EPA classifies counties, not states. Of the 39 counties in Washington with a zone, 7 are in Zone 1, 14 in Zone 2 and 18 in Zone 3.

  • Zone 1: Highest predicted potentialgreater than 4 pCi/L7 of 39 counties · 17.9%
  • Zone 2: Moderate predicted potential2 to 4 pCi/L14 of 39 counties · 35.9%
  • Zone 3: Lower predicted potentialless than 2 pCi/L18 of 39 counties · 46.2%

An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes Washington's radon test figures by county: 39 of its 39 counties have one. Each one's share is in the county list.

Washington, Counties

Washington counties by EPA zone

Predicted

Washington's radon map, then all 39 counties by the zone EPA predicts for each, highest reported share of tests at or above 4 pCi/L first. Each has its own report.

Washington radon map by county: EPA radon zones. Map of Washington's 39 counties shaded by EPA radon zone: Zone 1 in red-orange, Zone 2 in amber, Zone 3 in pale sand. 7 in Zone 1, 14 in Zone 2, 18 in Zone 3.
Washington radon map by countyEPA radon zones for Washington's counties: 7 counties in Zone 1, 14 counties in Zone 2, 18 counties in Zone 3.Predicted potential for each county, not a reading of any home. Homes with elevated levels of radon have been found in all three zones.

Zone 1: highest predicted potential7

Local help

Washington, Local resources

Local resources in Washington

Who to ask in Washington: its radon program, test kits and professionals.

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

Radon Action Brief

National Radon Action MonthPre-sale

The radon brief for your Washington county, in one dated file.

  • Your area's radon record, explained.
  • Your plan to test this week.
  • Fix costs and pros near you.

Save 64%Sale price: $8.99Price after the sale: $25Ends Jan 31Then $25

Get your Washington county's BriefSee a free sample

Area data, not a test of the building.

What it means

Washington, Questions

Questions about radon in Washington

Common questions

9 questions, answered from the figures above

Is radon a problem in Washington?

EPA's Map of Radon Zones places 7 of the 39 Washington counties it classifies in Zone 1, the highest predicted potential, 14 in Zone 2 and 18 in Zone 3. An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.

Washington on the radon mapRadon levels by state

Who does radon mitigation in Washington?

Radon411 has no radon business listed for Washington yet. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional.

How radon mitigation worksWhat mitigation costsRadon professionals in Washington

Which Washington counties are in EPA radon Zone 1?

7 counties are in Zone 1: Clark County, Ferry County, Okanogan County, Pend Oreille County, Skamania County, Spokane County, Stevens County. Zone 1 is EPA's class for highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. A zone is a prediction for a county, not a measurement of any home.

Radon in Clark CountyRadon in Ferry CountyRadon in Okanogan County

How do I get a radon test in Washington?

EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. The Washington radon program is the place to ask about certified testers and any test kit offer it runs.

How to test a homeFree and low-cost kits by stateWashington radon program

Which Washington counties have the highest radon?

39 of Washington's 39 counties have an EPA radon zone published here. Radon411 will not rank counties on data it does not hold, and a zone is a prediction for an area rather than a measurement of any building.

What share of radon tests in Washington are high?

CDC has published no statewide radon testing statistics for Washington, so we cannot give a figure. Where CDC does publish one, the percentage describes radon tests reported to CDC, not homes.

Which EPA region is Washington in?

Washington is in EPA Region 10: Pacific Northwest.

Do I need to test my home in Washington?

Yes, wherever you live in the state. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L.

Why does this page show coverage rather than one radon level for Washington?

A statewide figure averages counties with very different geology and very different numbers of reported tests, so it hides more than it shows. The county report is the level at which the EPA zone, the geologic potential and the reported testing statistics are actually published, which is why the county table above links to every one of them.

If you own, buy, sell or rent

What these figures mean for each reader, with the guide that covers it

The zone counts on this page describe counties across Washington. They are predictions for areas, and none of them measures your building.

Washington in figures

The figures above, said in words

What the published data says about Washington, in words. A zone and a share of tests describe an area, never the level in any one home.

    • Predicted

      Predicted

      EPA places 7 of Washington's 39 counties in Zone 1, 14 in Zone 2 and 18 in Zone 3.

      Zone 1 counties, A to Z, begin with Clark County, Ferry County and Okanogan County; the county section below lists all 7.

    • Compared

      Calculated by Radon411

      18% of Washington's counties with a zone on file are in Zone 1, a smaller share than across all U.S. counties (34%). It is a share of counties, not of land, people or homes.

  • Reported tests

    Measured

    CDC has no statewide testing figure for Washington on file here.

    39 of the 39 counties have a published county figure; the most tests in each one's latest year were reported for Spokane County (721 tests in 2020), King County (503 tests in 2020) and Clark County (490 tests in 2020).

Washington's radon program is the Radon Program, run by Washington State Department of Health; its contacts are under Local resources.

Products

Washington, Products

Testing and mitigation products

Whatever the figures for Washington show, only a test tells you about one home.

Test kits and monitors42

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Best radon monitors for Washington homes, compared

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5

Mitigation

3

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Washington, Next steps

What to do next

  1. LearnKnow what radon isWhat radon is, how it gets indoors, and why a county zone is not a reading for your home.Learn about radon
  2. TestTest the building you live inShort-term or long-term, where the device goes, and closed-house conditions.How to test
  3. FixBring a high level downHow a mitigation system works, and the retest that confirms it.How mitigation works
  4. Find a proHire a certified professionalMeasurement and mitigation professionals by state, with their certifications.Find a professional

Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.