Short-term kit
PicoCan short-term charcoal canister radon test
- Lab fee included
Method: Charcoal
In home: 48 to 96 hours
Locations and reports
Radon Levels in Multnomah County, Oregon
EPA puts Multnomah County in Zone 2, its middle radon zone, and 27.8% of its 792 reported radon tests (2023) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
27.8%
8.9 pts above OR
- Multnomah
- 27.8%
- Oregon
- 18.9%
792 tests, 2023
Median result
2.0pCi/L
Below action level
- Multnomah
- 2.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
792
Most tested in Oregon
- Multnomah
- 792
Reported to CDC before any fix, 2023
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Oregon
3 of 14
Top quarter
- Multnomah
- 27.8%
- Hood River
- 39.0%
By share, of 14 with 30+ tests
Read a result for Multnomah County
Starts at Multnomah County's median, 2.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.0 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Multnomah County's median reported result, 2023.
The data
Multnomah County, At a glance
Multnomah County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Multnomah County is a
USGS geologic potential: Moderate across 88% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Multnomah County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 31.3% |
| 2015 | 33.6% |
| 2016 | 28.6% |
| 2017 | 24.6% |
| 2018 | 24.0% |
| 2019 | 25.7% |
| 2020 | 19.9% |
| 2021 | 21.3% |
| 2022 | 23.0% |
| 2023 | 27.8% |
2023: 27.8%. Across these years the share ran from 19.9% to 33.6%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 792 tests reported to CDC for Multnomah County over 2023, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Multnomah County, Compared
Multnomah County radon figures, compared
Calculated by Radon411Multnomah County's 792 reported tests in 2023 had a middle value of 2.0 pCi/L and a maximum of 85.0 pCi/L, and 27.8% reached 4 pCi/L. Oregon as a whole (28 Oregon counties, pooled) comes to 18.9%: 8.9 points lower than here.
Among its state's counties it ranks 3rd of 14 Oregon counties with 30 or more tests for the same period. Statewide for the same period, Hood River County reported the highest share (39.0%) and Deschutes County the lowest (1.7%).
Below the action level, 383 tests (48.4%) came in under 2 pCi/L, against 59.5% statewide, and 189 tests (23.9%) fell between 2 and 4, against 21.6% statewide. The busiest year on file was 2014, with 2,749 tests reported; the quietest, 2023, had 792.
EPA's 1993 zone map puts Multnomah County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 88% of the county's land moderate radon potential.
Next door, the shares run from 11.4% in Washington County to 39.0% in Hood River County, with Clackamas County and Washington County below Multnomah County. Over 10 years of annual figures the share fell 3.5 points, from 31.3% in 2014 to 27.8% in 2023; its peak was 33.6% in 2015.
Multnomah CountyOregon, pooled
27.8% % of tests18.9% % of tests
| Year | Tests | Multnomah County, at or above 4 pCi/L | Oregon, pooled |
|---|---|---|---|
| 2014 | 2,749 | 31.3% | 25.1% |
| 2015 | 2,728 | 33.6% | 27.4% |
| 2016 | 2,512 | 28.6% | 21.5% |
| 2017 | 1,936 | 24.6% | 19.2% |
| 2018 | 1,442 | 24.0% | 19.6% |
| 2019 | 863 | 25.7% | 20.2% |
| 2020 | 1,753 | 19.9% | 16.8% |
| 2021 | 1,623 | 21.3% | 16.3% |
| 2022 | 2,679 | 23.0% | 20.2% |
| 2023 | 792 | 27.8% | 18.9% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Multnomah County, Geology
The ground under Multnomah County
PredictedMost of the ground under Multnomah County is one class on USGS's geologic map: 88.3% of its land is moderate radon potential, with 5.3% low. The map puts 84.1% of Multnomah County in the area it calls Columbia River Gorge and 5.3% in Cascade Range, with one smaller area beside them. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 7, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Columbia River Gorge | River and lacustrine delta deposits and volcanic debris flows. | Moderate | 9 | 84.1% |
| Cascade Range | Western Cascade Range is Tertiary andesite, basalt flows, and pyroclastic rocks. Eastern Cascades are late Tertiary to Quaternary basaltic and andesitic volcanic rocks. | Low | 7 | 5.3% |
| Wilamette Valley | Gravelly to clayey alluvium with moderately elevated uranium content. | Moderate | 9 | 4.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Multnomah County beside the ground around it
Multnomah County has more moderate-potential ground than Oregon as a whole: 88.3% of its land against 62.3%. Of the 6 counties that border it, 1 has more moderate-potential ground, Columbia County the most at 91.6%.
The map rates the ground, not the air in any home.
Local help
Multnomah County, Local resources
Radon testing and mitigation in Multnomah County
Listed radon businesses with an address in Multnomah County:
- Oregon Radon Awareness ProgramOregon Radon Awareness Program, run by Oregon Health Authority, offers free or discounted test kits, and answers questions about testing and mitigation in Oregon.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Oregon Radon Awareness Program provides a FREE short-term radon test kit to those living in areas of Oregon where little radon testing has been done.
- Compare kits
- Professionals in Oregon38 professionals are listed in Oregon.
Listed radon professionals by town: Portland, Gresham, Lake Oswego, Milwaukie, Troutdale
What Oregon's program says
- Radon.program@dhsoha.state.or.us
What it means
Multnomah County, Questions
Questions about radon in Multnomah County
Are radon levels high in Multnomah County?
In 2023, 27.8% of the radon tests reported to CDC for Multnomah County, Oregon were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 14 Oregon counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 18.9%.
Which counties border Multnomah County?
Multnomah County borders 6 counties: Clark County, WA, Washington County, OR, Columbia County, OR, Clackamas County, OR, Skamania County, WA and Hood River County, OR.
Products
Multnomah County, Products
Testing a home in Multnomah County
In Multnomah County, 27.8% of 792 tests reported to CDC in 2023 reached 4 pCi/L, against 18.9% pooled across Oregon. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Multnomah County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
MonitorX-Sense
XR0A-SR battery digital radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Multnomah County, Bordering counties
Counties bordering Multnomah County
Calculated by Radon411- Radon levels in Hood River County, OREPA zone 2
39.0%at or above 4 pCi/L
Median 2.2 pCi/L · 41 tests · 11.2 points above Multnomah County
- Radon levels in Clackamas County, OREPA zone 3
15.9%at or above 4 pCi/L
Median 1.6 pCi/L · 321 tests · 11.9 points below Multnomah County
- Radon levels in Washington County, OREPA zone 2
11.4%at or above 4 pCi/L
Median 1.3 pCi/L · 396 tests · 16.4 points below Multnomah County
- Radon levels in Columbia County, OREPA zone 2
4.3%at or above 4 pCi/L
Median 0.6 pCi/L · 23 tests · 23.5 points below Multnomah County
- Radon levels in Clark County, WAEPA zone 1
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Skamania County, WAEPA zone 1
No CDC figure for 2023; its page reads it against its own neighbours.
Multnomah County, Cities and towns
Cities and towns in Multnomah County
About 795,391 people live in Multnomah County by the Census Bureau's estimate for July 1, 2025, 20,870 fewer than in 2020 (−2.6%). Packed into its land, that is 1,845 people per square mile. Portland, the largest place on its list (635,109 residents in all), extends beyond Multnomah County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 792 reported tests for 2023 come to 1.0 for every 1,000 residents (2025 estimate), against 0.5 for Oregon.
From Portland to Maywood Park, CDC publishes no figure by town: each reads Multnomah County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Portlandextends beyond Multnomah County | 635,109 | −2.7% | Counted whole |
| Gresham | 111,513 | −2.6% | 14.0% |
| Lake Oswegoextends beyond Multnomah County | 39,722 | −2.8% | Counted whole |
| Milwaukieextends beyond Multnomah County | 22,114 | +4.4% | Counted whole |
| Troutdale | 15,776 | −3.2% | 2.0% |
| Fairview | 10,762 | +3.6% | 1.4% |
| Wood Village | 4,706 | +7.1% | 0.6% |
| Maywood Park | 808 | −3.2% | 0.1% |
Places in Multnomah County with a city page: 1 of 1
8 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Multnomah County is counted whole, so it has no share.
Multnomah County, Homes
Homes in Multnomah County
Multnomah County has 367,704 homes, and many share a building: 31% are in buildings of five or more, 54% are detached houses, against 63% across Oregon. The homes are older than Oregon's as a whole: half were built before 1971 (1980 for Oregon), and 40% date from before 1960. 54% of occupied homes are lived in by their owner (Oregon: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Multnomah County | Oregon |
|---|---|---|
| Housing units | 367,704 | 1,838,631 |
| Detached houses | 54% | 63% |
| In buildings of 5 or more | 31% | 17% |
| Mobile homes | 2% | 8% |
| Built before 1960 | 40% | 23% |
| Built since 2000 | 21% | 24% |
| Middle year built | 1971 | 1980 |
| Owner-occupied | 54% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.