EPA Zone Data 2026
Washington Radon Map, Levels & Testing Guide
View EPA radon zone classifications for every county in Washington. Open your county to compare basement test meaning, EPA action thresholds, and when mitigation pricing becomes worth checking.
7
Zone 1
High Risk
High Risk
14
Zone 2
Moderate
Moderate
18
Zone 3
Low Risk
Low Risk
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Browse Counties
Jump to the Directory
Open your county to see its EPA zone, testing meaning, and the point where mitigation becomes worth pricing.
Adams County
Zone 2
Asotin County
Zone 2
Benton County
Zone 2
Clark County
Zone 1
Columbia County
Zone 2
Douglas County
Zone 2
Ferry County
Zone 1
Franklin County
Zone 2
Garfield County
Zone 2
Grant County
Zone 2
Kittitas County
Zone 2
Klickitat County
Zone 2
Lincoln County
Zone 2
Okanogan County
Zone 1
Pend Oreille County
Zone 1
Skamania County
Zone 1
Spokane County
Zone 1
Stevens County
Zone 1
Walla Walla County
Zone 2
Whitman County
Zone 2
Yakima County
Zone 2
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