Oregon: 36 counties covered
Of 36 rated Oregon counties, 0 are in EPA's highest radon-potential zone (Zone 1) — but every county page links to testing guidance regardless of zone, because a county rating is a county-wide average, not a reading for any one house.
- Multnomah County
- Washington County
- Clackamas County
- Lane County
- Marion County
- Jackson County
- Deschutes County
- Linn County
- Douglas County
- Yamhill County
- Benton County
- Polk County
- Josephine County
- Umatilla County
- Klamath County
- Coos County
- Columbia County
- Lincoln County
- Clatsop County
- Malheur County
- Crook County
- Tillamook County
- Wasco County
- Union County
- Jefferson County
- Hood River County
- Curry County
- Baker County
- Morrow County
- Lake County
- Wallowa County
- Harney County
- Grant County
- Sherman County
- Gilliam County
- Wheeler County