Radon Levels in Washington

39 counties — 7 high risk, 14 moderate, 18 low risk

7
14
18
Zone 1 High (17.9%) Zone 2 Moderate (35.9%) Zone 3 Low (46.2%)

Washington Radon Zone Map

Counties colored by EPA radon zone. Red = Zone 1, Orange = Zone 2, Green = Zone 3.

Highest-Risk Counties

Clark39.2% above action level
FerryZone 1 — High
Okanogan50% above action level
Pend OreilleZone 1 — High
SkamaniaZone 1 — High
Spokane38.4% above action level
Stevens55.6% above action level

Check Your Washington ZIP Code

All 39 Counties — By Radon Risk

CountyEPA ZoneTests% Above 4 pCi/L
Clark High 74 39.2%
Ferry High — —
Okanogan High 8 50%
Pend Oreille High — —
Skamania High — —
Spokane High 86 38.4%
Stevens High 9 55.6%
Adams Moderate — —
Asotin Moderate 5 —
Benton Moderate 31 32.3%
Columbia Moderate — —
Douglas Moderate 4 —
Franklin Moderate 9 44.4%
Garfield Moderate — —
Grant Moderate 14 42.9%
Kittitas Moderate 9 —
Klickitat Moderate 4 —
Lincoln Moderate 4 —
Walla Walla Moderate 11 45.5%
Whitman Moderate 5 —
Yakima Moderate 32 46.9%
Chelan Low 13 30.8%
Clallam Low 20 55%
Cowlitz Low 19 47.4%
Grays Harbor Low 18 38.9%
Island Low 19 36.8%
Jefferson Low 11 —
King Low 298 32.2%
Kitsap Low 45 31.1%
Lewis Low 17 41.2%
Mason Low 16 43.8%
Pacific Low 7 —
Pierce Low 133 36.1%
San Juan Low — —
Skagit Low 23 47.8%
Snohomish Low 114 41.2%
Thurston Low 47 36.2%
Wahkiakum Low — —
Whatcom Low 41 36.6%

Sources: EPA Map of Radon Zones, CDC Environmental Health Tracking Network

Frequently Asked Questions

How many counties in Washington have high radon risk?

Washington has 7 counties classified as EPA Zone 1 (high radon risk), 14 as Zone 2 (moderate), and 18 as Zone 3 (low risk).

Is radon a problem in Washington?

Washington has 7 high-risk counties where elevated radon is likely. The EPA recommends all homes in Washington be tested for radon, regardless of which zone they're in.

How do I check radon levels for my Washington address?

Enter your ZIP code in the search box above to see your county's EPA radon zone and available testing data. For your specific home's radon level, you'll need a radon test kit.