Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
Locations and reports
Radon Levels in Columbia County, Washington
EPA puts Columbia County in Zone 2, its middle radon zone, and only 4 radon tests from it are on file with CDC (2019). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
22.4%
Whitman County
- Whitman
- 22.4%
- Umatilla
- 11.8%
3 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
16.4%
Walla Walla County, 28 miles
- Walla Walla
- 16.4%
- Washington
- 25.5%
Share at 4+ pCi/L, 122 tests, 2008 to 2017
Ground above low
100.0%
47.3 pts above Washington
- Columbia
- 100.0%
- Washington
- 52.7%
Share of land USGS rates moderate or high potential
Tests reported
4
Too few for a share
- Columbia
- 4
- Needed
- 30
2019
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Columbia County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
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 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Columbia County, 2019
CDC holds 4 reported tests for Columbia County in 2019, with a median of 3.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Columbia County beside the counties around it is how this page reads it.
What these figures count
Only 4 tests were reported to CDC for Columbia County over 2019, 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: 2019. Measured data period: 2005 to 2019 (every CDC figure on file).
Columbia County, Compared
Columbia County radon figures, compared
Calculated by Radon411CDC's largest figure for Columbia County rests on 4 tests in 2019, 0 of them at or above 4 pCi/L, so each test moves its share by 25.0 points and no rank or comparison is drawn from it. Results reached as high as 3.5 pCi/L, with a middle value of 3.2 pCi/L.
Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Whitman County reported the largest share at or above 4 pCi/L, 22.4%, and Umatilla County, OR the smallest, 11.8%, with Walla Walla County at 16.4% between. Farther out, Benton County (77 miles away) at 19.5%, Spokane County (94 miles away) at 41.4% and Yakima County (136 miles away) at 7.5% have figures too. Pooled across 39 Washington counties, 25.5% of reported tests reached that level; across every county in the country with a figure, 35.7%.
Statewide for the same period, Pend Oreille County reported the highest share (63.2%) and Snohomish County the lowest (2.3%). EPA's 1993 map puts Columbia County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Columbia County, Geology
The ground under Columbia County
PredictedUSGS's geologic map puts all of Columbia County's mapped land in one class: moderate radon potential. The map puts 57.9% of Columbia County in the area it calls Columbia Basin and 41.9% in Blue Mountains. USGS gives the first a radon index of 10 and the second 9, both in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Columbia Basin | Basaltic rocks low in uranium content. Uranium content of soils is moderately elevated. | Moderate | 10 | 57.9% |
| Blue Mountains | Tertiary basalt, andesite, tuffaceous sedimentary rocks, and tuff. | Moderate | 9 | 41.9% |
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
Across Washington 13.7% of the land is rated high; none of Columbia County's is. Of the 6 counties that border it, 1 has more high-potential ground, Whitman County the most at 0.9%.
The map rates the ground, not the air in any home.
Local help
Columbia County, Local resources
Radon testing and mitigation in Columbia County
- Radon ProgramRadon Program, run by Washington State Department of Health, offers free or discounted test kits, and answers questions about testing and mitigation in Washington.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
We have a limited supply of free radon test kits.
- Compare kits
- See the Washington directoryNo professionals are listed in Washington yet. The state program can point you to registered testers and mitigators.
What Washington's program says
- Phone
- 360-236-3200
- doh.radon@doh.wa.gov
What it means
Columbia County, Questions
Questions about radon in Columbia County
Are radon levels high in Columbia County?
In 2019, 0.0% of the radon tests reported to CDC for Columbia County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.2 pCi/L. Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Whitman County reported the largest share at or above 4 pCi/L, 22.4%, and Umatilla County, OR the smallest, 11.8%, with Walla Walla County at 16.4% between.
Which counties border Columbia County?
Columbia County borders 6 counties: Garfield County, WA, Walla Walla County, WA, Whitman County, WA, Franklin County, WA, Wallowa County, OR and Umatilla County, OR.
Products
Columbia County, Products
Testing a home in Columbia County
No CDC figure names Columbia County; the nearest county with one, Walla Walla County (28 miles away), reported 16.4% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. 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
RM-63Pro rechargeable radon monitor with a touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
- 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 Garfield County, WAEPA zone 2
50.0%at or above 4 pCi/L
Median 3.8 pCi/L · 2 tests
- Radon levels in Wallowa County, OREPA zone 3
26.7%at or above 4 pCi/L
Median 1.1 pCi/L · 15 tests
- Radon levels in Whitman County, WAEPA zone 2
22.4%at or above 4 pCi/L
Median 1.5 pCi/L · 58 tests
- Radon levels in Walla Walla County, WAEPA zone 2
16.4%at or above 4 pCi/L
Median 1.4 pCi/L · 122 tests
- Radon levels in Umatilla County, OREPA zone 2
11.8%at or above 4 pCi/L
Median 1.9 pCi/L · 34 tests
- Radon levels in Franklin County, WAEPA zone 2
10.5%at or above 4 pCi/L
Median 1.8 pCi/L · 19 tests
Columbia County, Cities and towns
Cities and towns in Columbia County
The Census Bureau estimates 4,141 residents in Columbia County for July 1, 2025, 187 more than in 2020 (+4.7%). Spread over its land, that is 4.8 people to the square mile. Dayton alone is home to 2,538 of them, 61.3% of the total. Together its 2 incorporated places hold 64.7% of those residents; the other 35.3% live outside any of them. Testing is reported here more often than across the state: CDC's 4 reported tests for 2019 come to 1.0 for every 1,000 residents (2025 estimate), against 0.5 for Washington.
From Dayton to Starbuck, CDC publishes no figure by town: each reads Columbia County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Dayton | 2,538 | +3.6% | 61.3% |
| Starbuck | 143 | +20.2% | 3.5% |
2 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
Columbia County is a place of houses on their own lots: 86% of its 2,218 homes are detached single-family houses, against 62% across Washington. The homes are older than Washington's as a whole: half were built before 1948 (1984 for Washington), and 62% date from before 1960. Owners live in 78% of the occupied homes (Washington: 64%), so for most households a test and a fix are their own to order.
| Homes | Columbia County | Washington |
|---|---|---|
| Housing units | 2,218 | 3,262,667 |
| Detached houses | 86% | 62% |
| In buildings of 5 or more | 1% | 22% |
| Mobile homes | 7% | 6% |
| Built before 1960 | 62% | 21% |
| Built since 2000 | 15% | 28% |
| Middle year built | 1948 | 1984 |
| Owner-occupied | 78% | 64% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.