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 Columbia County, Oregon
EPA puts Columbia County in Zone 2, its middle radon zone, and only 23 radon tests from it are on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
36.8%
11.4 pts above OR
- Columbia
- 36.8%
- Oregon
- 25.4%
212 tests, 2008 to 2017
Median result
1.9pCi/L
Below action level
- Columbia
- 1.9 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
212
9th of 23 by tests
- Columbia
- 212
- Multnomah
- 12,330
Reported to CDC before any fix, 2008 to 2017
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
4 of 23
Top quarter
- Columbia
- 36.8%
- Union
- 42.0%
By share, of 23 with 30+ tests
Read a result for Columbia County
Starts at Columbia County's median, 1.9 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.9 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. Columbia County's median reported result, 2008 to 2017.
The data
Columbia County, At a glance
Columbia County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Columbia County is a
USGS geologic potential: Moderate across 92% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Columbia County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 33.3% |
| 2015 | 34.0% |
| 2016 | 23.5% |
| 2017 | 35.3% |
| 2018 | 29.4% |
| 2019 | 25.0% |
| 2020 | 28.4% |
| 2021 | 15.2% |
| 2022 | 16.7% |
| 2023 | 4.3% |
2023: 4.3%. Across these years the share ran from 4.3% to 35.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 23 tests were reported to CDC for Columbia County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Columbia County, Compared
Columbia County radon figures, compared
Calculated by Radon411In Columbia County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (78 of 212) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.1 points higher. Across 34 Oregon counties pooled together, 25.4% of tests reached that level, so Columbia County runs 11.4 points above its state.
The newest figure, in 2023, counts only 23 tests (4.3% at or above 4 pCi/L), too few to compare, so this reading uses the 212-test figure.
Of 5 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 4 a smaller one; the spread is 10.1% (Washington County) to 40.0% (Clatsop County). By share, Columbia County is 4th of 23 Oregon counties with 30 or more tests for the same period.
Year by year, 2014 opened at 33.3% and 2022 closed at 16.7% (down 16.6 points), with 2017 the high at 35.3%. Half the tests came in under 1.9 pCi/L and half over it; the single highest reached 58.9 pCi/L. Below the action level, 106 tests (50.0%) came in under 2 pCi/L, against 51.9% statewide, and 28 tests (13.2%) fell between 2 and 4, against 22.7% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 36.8% share point the same way here. USGS geology rates 92% of the county's land moderate radon potential. CDC also counts 20 tests taken after mitigation in Columbia County for the same period: tests in homes where a fix was already in.
The busiest year on file was 2015, with 150 tests reported; the quietest, 2023, had 23.
Columbia CountyOregon, pooled
| Year | Tests | Columbia County, at or above 4 pCi/L | Oregon, pooled |
|---|---|---|---|
| 2014 | 39 | 33.3% | 25.1% |
| 2015 | 150 | 34.0% | 27.4% |
| 2016 | 115 | 23.5% | 21.5% |
| 2017 | 68 | 35.3% | 19.2% |
| 2018 | 51 | 29.4% | 19.6% |
| 2020 | 116 | 28.4% | 16.8% |
| 2021 | 33 | 15.2% | 16.3% |
| 2022 | 54 | 16.7% | 20.2% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Columbia County, Geology
The ground under Columbia County
PredictedMost of the ground under Columbia County is one class on USGS's geologic map: 91.6% of its land is moderate radon potential, with 4.2% low. The map puts 91.6% of Columbia County in the area it calls Columbia River Gorge and 4.2% in Coast Range. 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 | 91.6% |
| Coast Range | Northern Coast Range is marine sedimentary rocks and Tertiary mafic volcanic rocks. Southern Coast Range is Tertiary estuarine and marine sedimentary rocks, feldspathic and micaceous. | Low | 7 | 4.2% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Columbia County beside the ground around it
Columbia County has more moderate-potential ground than Oregon as a whole: 91.6% of its land against 62.3%. Of the 7 counties that border it, none has as large a share of moderate-potential ground; Multnomah County comes nearest at 88.3%.
The map rates the ground, not the air in any home.
Local help
Columbia County, Local resources
Radon testing and mitigation in Columbia County
Listed radon businesses with an address in Columbia 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: Rainier
What Oregon's program says
- Radon.program@dhsoha.state.or.us
What it means
Columbia County, Questions
Questions about radon in Columbia County
Are radon levels high in Columbia County?
In 2023, 4.3% of the radon tests reported to CDC for Columbia County, Oregon were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.6 pCi/L. Of 23 Oregon counties with 30 or more tests for the same period, 3 reported a higher share; pooled, the state comes to 25.4%.
Which counties border Columbia County?
Columbia County borders 7 counties: Wahkiakum County, WA, Cowlitz County, WA, Clatsop County, OR, Washington County, OR, Clark County, WA, Multnomah County, OR and Tillamook County, OR.
Products
Columbia County, Products
Testing a home in Columbia County
In Columbia County, 36.8% of 212 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 25.4% pooled across Oregon. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Columbia County; a long-term test tells the year-round average.
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
Monitor
Corentium Home battery digital radon detector
- C-NRPP 2024/25: Approved
- Battery
- Screen
Method: Alpha spectrometry
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Columbia County, Bordering counties
Counties bordering Columbia County
Calculated by Radon411- Radon levels in Clatsop County, OREPA zone 2
40.0%at or above 4 pCi/L
Median 3.0 pCi/L · 55 tests · 3.2 points above Columbia County
- Radon levels in Multnomah County, OREPA zone 2
33.1%at or above 4 pCi/L
Median 2.5 pCi/L · 12,330 tests · 3.7 points below Columbia County
- Radon levels in Tillamook County, OREPA zone 3
30.8%at or above 4 pCi/L
Median 1.0 pCi/L · 13 tests · 6.0 points below Columbia County
- Radon levels in Clark County, WAEPA zone 1
25.1%at or above 4 pCi/L
Median 1.8 pCi/L · 1,814 tests · 11.7 points below Columbia County
- Radon levels in Cowlitz County, WAEPA zone 3
11.3%at or above 4 pCi/L
Median 1.1 pCi/L · 62 tests · 25.5 points below Columbia County
- Radon levels in Washington County, OREPA zone 2
10.1%at or above 4 pCi/L
Median 1.0 pCi/L · 3,338 tests · 26.7 points below Columbia County
- Radon levels in Wahkiakum County, WAEPA zone 3
0.0%at or above 4 pCi/L
Median 2.9 pCi/L · 1 test · 36.8 points below Columbia County
Columbia County, Cities and towns
Cities and towns in Columbia County
The Census Bureau estimates 54,091 residents in Columbia County for July 1, 2025, 1,376 more than in 2020 (+2.6%). That works out to 82 people per square mile of land. Its largest town, St. Helens, has 14,450 residents, 26.7% of the total. Together its 7 incorporated places hold 57.0% of those residents; the other 43.0% live outside any of them. CDC's 212 reported tests for 2008 to 2017 work out to 3.9 per 1,000 residents (2025 estimate), close to Oregon's 5.6.
From St. Helens to Prescott, CDC publishes no figure by town: each reads Columbia County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| St. Helens | 14,450 | +4.0% | 26.7% |
| Scappoose | 8,257 | +3.1% | 15.3% |
| Vernonia | 2,412 | +1.9% | 4.5% |
| Columbia City | 1,946 | −0.5% | 3.6% |
| Rainier | 1,924 | +1.2% | 3.6% |
| Clatskanie | 1,779 | +3.3% | 3.3% |
| Prescott | 81 | +1.3% | 0.1% |
7 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).
Columbia County, Homes
Homes in Columbia County
Of Columbia County's 21,980 homes, 74% are detached houses, against 63% across Oregon; 14% are mobile homes. Half of its homes were built before 1981, close to Oregon's 1980: 26% date from before 1960 and 21% from 2000 or later. Owners live in 76% of the occupied homes (Oregon: 63%), so for most households a test and a fix are their own to order.
| Homes | Columbia County | Oregon |
|---|---|---|
| Housing units | 21,980 | 1,838,631 |
| Detached houses | 74% | 63% |
| In buildings of 5 or more | 3% | 17% |
| Mobile homes | 14% | 8% |
| Built before 1960 | 26% | 23% |
| Built since 2000 | 21% | 24% |
| Middle year built | 1981 | 1980 |
| Owner-occupied | 76% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.