31%tests ≥ 4 pCi/L
588tests on record
—median pCi/L
Zone 1EPA zone (1993 prediction)

Test results in Okanogan County

ResultShareEPA guidance
Below 2 pCi/L54%Below EPA's levels
2 to 4 pCi/L15%Consider fixing
4 pCi/L or more31%EPA recommends fixing

What the data shows

Where Okanogan County sits among Washington's 39 counties with dataEach dot is a county's share of tests at or above 4 pCi/L · Radon test results by county (Washington Tracking Network), 2000–2025
0%20%40%60%

How Okanogan County compares

Okanogan County ranks 2 of 8 among its neighboursShare of tests at or above 4 pCi/L · Radon test results by county (Washington Tracking Network), 2000–2025 · whisker: 95% range
Lincoln County36%Okanogan County31%Ferry County29%Douglas County23%Chelan County16%Grant County14%Whatcom County6%Skagit County6%Washington 19%
Data table
AreaTests ≥ 4 pCi/LTests
Lincoln County36%152
Okanogan County31%588
Ferry County29%201
Douglas County23%101
Chelan County16%372
Grant County14%464
Whatcom County6%991
Skagit County6%394
Washington (39 counties)19%64,932

Same source as Okanogan County.

What it means for your home

About 1 in 3 results in Okanogan County were at or above 4 pCi/L, where the EPA recommends a fix. Only a test shows your own home's level.

Levels in pCi/L from the EPA. The WHO reference level is 100 Bq/m³, about 2.7 pCi/L.

Test your home

Start with a short-term test (2–90 days) and confirm a result of 4 pCi/L or more with a second test. EPA guide

Sponsored: we earn a commission on purchases through these links. We haven't tested Airthings monitors yet.

Prefer a digital monitor? See Airthings radon monitors, or enter code radonbycounty-10OFF at their discount store for 10% off.

Fixing high radon

No local job records yet. National range: $800–$2,500, average $1,200 (EPA, 2003). Cost guide →

Washington doesn't license radon mitigators; look for NRPP or NRSB certification. Source

Buying or selling here

Washington's seller disclosure statement asks whether the seller knows of substances that may be environmental concerns, including radon gas (RCW 64.06.020). Source

Checked against the official text on 2026-11-03. Not legal advice.

About this data

Source: Radon test results by county (Washington Tracking Network) (Washington State Department of Health). Period: 2000–2025. Tests: 588. Read the methodology →

These are voluntary and real-estate tests, not a random sample of homes, so they describe tested homes rather than every home.

About this page

Published by Ray Roman, editor of Radon by County. Figures are loaded from the cited source and spot-checked against it. Editorial policy · About us