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      Seattle, WA Radon Levels

      Check local Seattle radon levels and find certified testing and mitigation professionals to keep your home safe

      Seattle, WA Radon Facts

      EPA Radon Zone Zone 3 — Low Risk < 2.0 pCi/L (Zone 3)
      County King County, WA
      Zip Code 98101
      Avg. User Level 5.30 pCi/L
      User Tests 4

      Washington's largest city, Seattle spans multiple zip codes throughout King County in the Puget Sound region, where recent testing shows an average radon level of 5.25 pCi/L that exceeds the EPA action threshold. This Pacific Northwest metropolis sits on glacial deposits and marine sediments that can trap radon gas, particularly in the area's many basement-equipped homes. With readings ranging from 2.0 to 11.0 pCi/L, Seattle residents should prioritize radon testing regardless of neighborhood or home age.

      5.30
      pCi/L average
      Above EPA Action Level

      Based on 4 user-submitted radon tests for homes in Seattle, WA. The EPA recommends taking action at or above 4.0 pCi/L.

      0
      4.0 EPA
      10+

      Seattle, WA Radon Mitigation

      Professional radon mitigation is the most effective way to permanently lower radon levels and protect your household.

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      Seattle, WA Radon Levels

      User-submitted radon test readings from homes in the Seattle area.

      Radon LevelCityHome AgeFoundation
      4 pCi/L Seattle, WA 21-50 Years No Basement/All Slab
      11 pCi/L Seattle, WA 21-50 Years Full Basement
      2 pCi/L Seattle, WA — Full Basement
      4 pCi/L Seattle, WA 21-50 Years Partial Basement

      Have a radon test result for Seattle? Submit your reading to help other homeowners.

      Radon FAQ for Seattle, WA

      What is the average radon level in Seattle, WA?
      Based on 4 user-submitted tests, the average radon level in Seattle is 5.30 pCi/L. This exceeds the EPA's recommended action level of 4.0 pCi/L, and radon testing is recommended for all homes in the area.
      What EPA Radon Zone is Seattle in?
      Seattle and the 98101 zip code are in King County, which has an EPA assigned Radon Zone of 3. A zone of 3 predicts an average indoor radon screening level less than 2 pCi/L.
      How much does radon mitigation cost in Seattle?
      Radon mitigation in Seattle typically costs between $800 and $2,000. Most homes with standard basements can be mitigated with a sub-slab depressurization system in the $1,000–$1,500 range. Factors that can increase cost include complex foundations, crawl spaces, or very high radon levels.
      Should I test for radon if I'm buying a home in Seattle?
      Yes. Radon testing should be part of every home purchase. A short-term radon test is typically included as part of the home inspection process and costs $150–$250. If elevated levels are found, you can negotiate mitigation as part of the sale.

      Most Active Radon Markets in Washington

      Cities in Washington with the most user-submitted radon test data, ranked by number of submissions.

      CityAvg User Radon LevelSubmissions
      Vancouver 6.56 pCi/L 9
      Kent 3.50 pCi/L 6
      Olympia 7.00 pCi/L 5
      Seattle 5.25 pCi/L 4
      Bellevue 3.75 pCi/L 4
      Spokane 11.67 pCi/L 3
      Camas 8.00 pCi/L 3
      Centralia 7.00 pCi/L 3
      Bellingham 4.50 pCi/L 2
      Kirkland 4.50 pCi/L 2

      Free Radon Mitigation Quote

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      Free Radon Mitigation Quote

      Or call for a free quote: 1-800-299-3578 Local: 206-973-0096

      A licensed contractor will contact you immediately.

      * Required