Radon in Oregon: radon map by county
EPA's Map of Radon Zones puts 0 of Oregon's 36 counties in Zone 1 (predicted average indoor radon above 4 pCi/L), 21 in Zone 2 and 15 in Zone 3. Of 17,034 building tests that radon laboratories reported for 2008 to 2017, 25.2% were at or above EPA's 4 pCi/L action level, against 36.5% nationally (number 26 of 42 states with 1,000+ tests). The highest county share is Union County (42% of 81 tests).
Radon by county in Oregon
| County | EPA zone | Lab tests | Median | 4+ pCi/L |
|---|---|---|---|---|
| Baker County | Zone 2 | 28 | 2.4 | 37.5% |
| Benton County | Zone 3 | 244 | 1.2 | 13.1% |
| Clackamas County | Zone 3 | 2,695 | 1.4 | 18% |
| Clatsop County | Zone 2 | 34 | 3.0 | 40% |
| Columbia County | Zone 2 | 162 | 1.9 | 36.8% |
| Coos County | Zone 3 | 14 | 0.6 | 11.1% |
| Crook County | Zone 2 | 19 | 0.9 | 5.4% |
| Curry County | Zone 3 | 7 | 0.9 | 16.7% |
| Deschutes County | Zone 3 | 122 | 0.7 | 3.8% |
| Douglas County | Zone 3 | 32 | 0.6 | 8.8% |
| Gilliam County | Zone 2 | n/a | n/a | n/a |
| Grant County | Zone 2 | 3 | 1.2 | 0% |
| Harney County | Zone 2 | 5 | 0.7 | 20% |
| Hood River County | Zone 2 | 85 | 2.3 | 30.8% |
| Jackson County | Zone 3 | 93 | 1.0 | 5.3% |
| Jefferson County | Zone 2 | 7 | 0.6 | 0% |
| Josephine County | Zone 3 | 23 | 0.7 | 10% |
| Klamath County | Zone 2 | 24 | 0.4 | 5.3% |
| Lake County | Zone 2 | 3 | 0.3 | 0% |
| Lane County | Zone 3 | 280 | 0.9 | 9.1% |
| Lincoln County | Zone 3 | 26 | 1.1 | 13.2% |
| Linn County | Zone 3 | 90 | 1.0 | 9.5% |
| Malheur County | Zone 2 | 12 | 2.0 | 8.3% |
| Marion County | Zone 3 | 1,098 | 2.0 | 26% |
| Morrow County | Zone 2 | 2 | 0.8 | 0% |
| Multnomah County | Zone 2 | 8,538 | 2.5 | 33.1% |
| Polk County | Zone 3 | 445 | 2.0 | 25.2% |
| Sherman County | Zone 2 | n/a | n/a | n/a |
| Tillamook County | Zone 3 | 12 | 1.0 | 30.8% |
| Umatilla County | Zone 2 | 29 | 1.9 | 11.8% |
| Union County | Zone 2 | 81 | 3.0 | 42% |
| Wallowa County | Zone 3 | 8 | 1.1 | 26.7% |
| Wasco County | Zone 2 | 29 | 1.0 | 5.6% |
| Washington County | Zone 2 | 2,427 | 1.0 | 10.1% |
| Wheeler County | Zone 2 | 1 | 0.1 | 0% |
| Yamhill County | Zone 2 | 356 | 1.5 | 26.2% |
Lab tests: buildings tested by radon laboratories, 2008 to 2017; median in pCi/L; “4+ pCi/L” is the share of tests at or above EPA's action level. n/a: no value on file (no tests, or too few to report).
What the zones mean
Zone 1 counties have a predicted average indoor radon screening level above 4 pCi/L, Zone 2 from 2 to 4 pCi/L and Zone 3 below 2 pCi/L. The prediction is from 1993 indoor measurements, geology, aerial radioactivity, soils and foundation types. EPA: “This map should not be used to determine if individual homes need to be tested.” EPA recommends fixing a home at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of exposure.
Radon in Oregon: questions
What radon zone is Oregon?
EPA's 1993 map does not give states one zone; it zones each county. In Oregon, 0 counties are Zone 1, 21 Zone 2 and 15 Zone 3. EPA says the map "should not be used to determine if individual homes need to be tested".
Which Oregon counties have the highest radon levels?
By the share of laboratory tests at or above 4 pCi/L for 2008 to 2017 (counties with 20 or more tests): Union County 42% (median 3.0 pCi/L, 81 tests); Clatsop County 40% (median 3.0 pCi/L, 34 tests); Baker County 37.5% (median 2.4 pCi/L, 28 tests); Columbia County 36.8% (median 1.9 pCi/L, 162 tests); Multnomah County 33.1% (median 2.5 pCi/L, 8,538 tests).
How common is high radon in Oregon?
25.2% of the 17,034 tests in the laboratory data for Oregon (2008 to 2017) were at or above 4 pCi/L; the national share was 36.5%. Buildings are tested by choice, often because of a sale or a concern, so the share describes the tests on file, not every home.
Does Oregon publish its own radon test data?
Oregon's radon program reports county test results; the latest year with county results is 2023, shown on each county page.
Should I test for radon in Oregon?
Yes. EPA recommends testing every home no matter where it is, fixing it at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of radon exposure.
States bordering Oregon
Other free hazard lookups
- Radon by county and ZIP codeEPA radon zone and the radon test results on file for any county, ZIP code or address.
- Fault lines near an addressUSGS-mapped earthquake faults within 5 miles, their age and slip rate, and the USGS seismic hazard value.
- Power lines near an addressHigh-voltage transmission lines within 1 mile from federal maps, with voltage and distance.
- Flood zone lookupThe FEMA flood zone mapped at any US address. Not an official flood zone determination.
- Superfund sites near an addressThe nearest EPA Superfund (NPL) sites and their status.
All of these, plus wetlands, FEMA hazard ratings and the federal contamination lists, are in the Environmental Records Report for any US address ($29).
Superfund sites in Oregon · Radon map of every state
Data compiled 2026-10-20. County-level screening information, not a radon measurement of any building.