Short-term kit
Radon Short Term Test Kit short-term charcoal radon test kit, lab fee included
- Lab fee included
Method: Charcoal
In home: 2 to 7 days
Locations and reports
Radon Levels in Clackamas County, Oregon
EPA puts Clackamas County in Zone 3, its lowest radon zone, and 15.9% of its 321 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
15.9%
3.0 pts below OR
- Clackamas
- 15.9%
- Oregon
- 18.9%
321 tests, 2023
Median result
1.6pCi/L
Below action level
- Clackamas
- 1.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
321
3rd of 14 by tests
- Clackamas
- 321
- Multnomah
- 792
Reported to CDC before any fix, 2023
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Rank in Oregon
7 of 14
Middle half
- Clackamas
- 15.9%
- Hood River
- 39.0%
By share, of 14 with 30+ tests
Read a result for Clackamas County
Starts at Clackamas County's median, 1.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.6 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Clackamas County's median reported result, 2023.
The data
Clackamas County, At a glance
Clackamas County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 87% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Clackamas County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 20.4% |
| 2015 | 20.3% |
| 2016 | 17.9% |
| 2017 | 17.3% |
| 2018 | 16.7% |
| 2019 | 20.2% |
| 2020 | 16.8% |
| 2021 | 14.7% |
| 2022 | 15.2% |
| 2023 | 15.9% |
2023: 15.9%. Across these years the share ran from 14.7% to 20.4%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 321 tests reported to CDC for Clackamas 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).
Clackamas County, Compared
Clackamas County radon figures, compared
Calculated by Radon411Clackamas County's 321 reported tests in 2023 had a middle value of 1.6 pCi/L and a maximum of 17.7 pCi/L, and 15.9% reached 4 pCi/L. Oregon as a whole (28 Oregon counties, pooled) comes to 18.9%: 3.0 points higher than here.
Among its state's counties it ranks 7th 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, 185 tests (57.6%) came in under 2 pCi/L, against 59.5% statewide, and 85 tests (26.5%) fell between 2 and 4, against 21.6% statewide. The busiest year on file was 2022, with 1,125 tests reported; the quietest, 2023, had 321.
EPA's 1993 zone map puts Clackamas County in Zone 3, a predicted county average under 2 pCi/L. USGS geology rates 87% of the county's land low radon potential.
Next door, the shares run from 11.4% in Washington County to 39.0% in Hood River County, with Washington County below Clackamas County. Over 10 years of annual figures the share fell 4.5 points, from 20.4% in 2014 to 15.9% in 2023; its peak was 20.4% in 2014.
Clackamas CountyOregon, pooled
| Year | Tests | Clackamas County, at or above 4 pCi/L | Oregon, pooled |
|---|---|---|---|
| 2014 | 938 | 20.4% | 25.1% |
| 2015 | 918 | 20.3% | 27.4% |
| 2016 | 843 | 17.9% | 21.5% |
| 2017 | 770 | 17.3% | 19.2% |
| 2018 | 550 | 16.7% | 19.6% |
| 2019 | 401 | 20.2% | 20.2% |
| 2020 | 555 | 16.8% | 16.8% |
| 2021 | 422 | 14.7% | 16.3% |
| 2022 | 1,125 | 15.2% | 20.2% |
| 2023 | 321 | 15.9% | 18.9% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Clackamas County, Geology
The ground under Clackamas County
PredictedMost of the ground under Clackamas County is one class on USGS's geologic map: 86.6% of its land is low radon potential, with 13.4% moderate. The map puts 86.6% of Clackamas County in the area it calls Cascade Range and 11.5% in Wilamette Valley, with one smaller area beside them. USGS gives the first a radon index of 7, in the low band (5 to 8), and the second 9, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| 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 | 86.6% |
| Wilamette Valley | Gravelly to clayey alluvium with moderately elevated uranium content. | Moderate | 9 | 11.5% |
| Columbia River Gorge | River and lacustrine delta deposits and volcanic debris flows. | Moderate | 9 | 1.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Clackamas County beside the ground around it
Oregon as a whole has more moderate-potential ground than Clackamas County: 62.3% of its land, against 13.4% here. Every one of the 6 counties that border it has more moderate-potential ground, Wasco County the most at 95.0%.
The map rates the ground, not the air in any home.
Local help
Clackamas County, Local resources
Radon testing and mitigation in Clackamas County
Listed radon businesses with an address in Clackamas 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, Lake Oswego, Wilsonville, Milwaukie, Molalla
What Oregon's program says
- Radon.program@dhsoha.state.or.us
What it means
Clackamas County, Questions
Questions about radon in Clackamas County
Are radon levels high in Clackamas County?
In 2023, 15.9% of the radon tests reported to CDC for Clackamas County, Oregon were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.6 pCi/L. Of 14 Oregon counties with 30 or more tests for the same period, 6 reported a higher share; pooled, the state comes to 18.9%.
Which counties border Clackamas County?
Clackamas County borders 6 counties: Marion County, Multnomah County, Hood River County, Washington County, Yamhill County and Wasco County.
Products
Clackamas County, Products
Testing a home in Clackamas County
In Clackamas County, 15.9% of 321 tests reported to CDC in 2023 reached 4 pCi/L, against 18.9% pooled across Oregon. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Clackamas County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorX-Sense
XR0B-SR battery digital radon monitor with an alarm
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- 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
Clackamas County, Bordering counties
Counties bordering Clackamas County
Calculated by Radon411- Radon levels in Hood River CountyEPA zone 2
39.0%at or above 4 pCi/L
Median 2.2 pCi/L · 41 tests · 23.1 points above Clackamas County
- Radon levels in Wasco CountyEPA zone 2
37.5%at or above 4 pCi/L
Median 1.4 pCi/L · 16 tests · 21.6 points above Clackamas County
- Radon levels in Multnomah CountyEPA zone 2
27.8%at or above 4 pCi/L
Median 2.0 pCi/L · 792 tests · 11.9 points above Clackamas County
- Radon levels in Yamhill CountyEPA zone 2
21.2%at or above 4 pCi/L
Median 1.6 pCi/L · 33 tests · 5.3 points above Clackamas County
- Radon levels in Marion CountyEPA zone 3
16.0%at or above 4 pCi/L
Median 1.4 pCi/L · 194 tests · 0.1 points above Clackamas County
- Radon levels in Washington CountyEPA zone 2
11.4%at or above 4 pCi/L
Median 1.3 pCi/L · 396 tests · 4.5 points below Clackamas County
Clackamas County, Cities and towns
Cities and towns in Clackamas County
The Census Bureau estimates 426,280 residents in Clackamas County for July 1, 2025, 3,797 more than in 2020 (+0.9%). That works out to 228 people per square mile of land. Portland, the largest place on its list (635,109 residents in all), extends beyond Clackamas County, so no share of the total is worked out for it. CDC's 321 reported tests for 2023 work out to 0.8 per 1,000 residents (2025 estimate), close to Oregon's 0.5.
From Portland to Barlow, CDC publishes no figure by town: each reads Clackamas County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Portlandextends beyond Clackamas County | 635,109 | −2.7% | Counted whole |
| Lake Oswegoextends beyond Clackamas County | 39,722 | −2.8% | Counted whole |
| Oregon City | 38,175 | +1.0% | 9.0% |
| Happy Valley | 28,916 | +22.0% | 6.8% |
| Tualatinextends beyond Clackamas County | 28,139 | +0.9% | Counted whole |
| Wilsonvilleextends beyond Clackamas County | 27,833 | +4.2% | Counted whole |
| West Linn | 26,567 | −2.9% | 6.2% |
| Milwaukieextends beyond Clackamas County | 22,114 | +4.4% | Counted whole |
| Canby | 18,004 | −1.1% | 4.2% |
| Sandy | 13,323 | +5.1% | 3.1% |
| Gladstone | 11,865 | −1.5% | 2.8% |
| Molalla | 10,104 | −1.2% | 2.4% |
Places in Clackamas County with a city page: 1 of 1
- Estacada
- Johnson City
- Rivergrove (part)
- Barlow
16 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Clackamas County is counted whole, so it has no share.
Clackamas County, Homes
Homes in Clackamas County
Of Clackamas County's 172,599 homes, 68% are detached houses, against 63% across Oregon; 17% are in buildings of five or more homes. Half of its homes were built before 1985, close to Oregon's 1980: 16% date from before 1960 and 25% from 2000 or later. 71% 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 | Clackamas County | Oregon |
|---|---|---|
| Housing units | 172,599 | 1,838,631 |
| Detached houses | 68% | 63% |
| In buildings of 5 or more | 17% | 17% |
| Mobile homes | 6% | 8% |
| Built before 1960 | 16% | 23% |
| Built since 2000 | 25% | 24% |
| Middle year built | 1985 | 1980 |
| Owner-occupied | 71% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.