Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Benton County, Washington
EPA puts Benton County in Zone 2, its middle radon zone, and only 21 radon tests from it are on file with CDC (2020). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
2.5%
18.4 pts below WA
- Benton
- 2.5%
- Washington
- 20.9%
162 tests, 2019
Median result
0.9pCi/L
Below action level
- Benton
- 0.9 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2019
Tests reported
162
5th of 14 by tests
- Benton
- 162
- Spokane
- 952
Reported to CDC before any fix, 2019
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 Washington
11 of 14
Middle half
- Benton
- 2.5%
- Pend Oreille
- 51.4%
By share, of 14 with 30+ tests
Read a result for Benton County
Starts at Benton County's median, 0.9 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 0.9 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. Benton County's median reported result, 2019.
The data
Benton County, At a glance
Benton County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Benton 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 Benton County, 2020
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 5.3% |
| 2015 | 8.2% |
| 2016 | 24.3% |
| 2017 | 28.9% |
| 2018 | 5.0% |
| 2019 | 2.5% |
| 2020 | 4.8% |
2020: 4.8%. Across these years the share ran from 2.5% to 28.9%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 21 tests were reported to CDC for Benton County over 2020, 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: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).
Benton County, Compared
Benton County radon figures, compared
Calculated by Radon411Only 4 of 162 radon tests reported for Benton County in 2019 reached 4 pCi/L (2.5%). The median result, 0.9 pCi/L, sits below 2, well under EPA's 4 pCi/L action level, and the top reported result was 28.2 pCi/L.
The newest figure, in 2020, counts only 21 tests (4.8% at or above 4 pCi/L), too few to compare, so this reading uses the 162-test figure.
Across 38 Washington counties pooled together, 20.9% of tests reached that level, so Benton County runs 18.4 points below its state. Against the national pool of 29.0%, the gap is 26.5 points lower. Its place in the state: 11th of 14 Washington counties with 30 or more tests for the same period.
The reported tests do not follow EPA's Zone 2 label for Benton County (predicted average between 2 and 4 pCi/L): 2.5% of them reached 4 pCi/L, fewer than that label suggests. Walla Walla County, the one bordering county with a figure for the same period, reported 27.3%.
Below the action level, 138 tests (85.2%) came in under 2 pCi/L, against 66.1% statewide, and 20 tests (12.3%) fell between 2 and 4, against 13.1% statewide. Over 6 years of annual figures the share fell 2.8 points, from 5.3% in 2014 to 2.5% in 2019; its peak was 28.9% in 2017. USGS geology rates 100% of the county's land moderate radon potential.
The busiest year on file was 2019, with 162 tests reported; the quietest, 2020, had 21.
Benton CountyWashington, pooled
2.5% % of tests20.9% % of tests
| Year | Tests | Benton County, at or above 4 pCi/L | Washington, pooled |
|---|---|---|---|
| 2014 | 113 | 5.3% | 15.0% |
| 2015 | 61 | 8.2% | 17.4% |
| 2016 | 111 | 24.3% | 16.6% |
| 2017 | 76 | 28.9% | 19.1% |
| 2018 | 121 | 5.0% | 16.1% |
| 2019 | 162 | 2.5% | 20.9% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Benton County, Geology
The ground under Benton County
PredictedUSGS's geologic map puts all of Benton County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Columbia Basin, to which USGS gives a radon index of 10, 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 | 99.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Benton County beside the ground around it
Across Washington 13.7% of the land is rated high; none of Benton County's is. Of the 7 counties that border it, 1 has more high-potential ground, Grant County the most at 0.5%.
The map rates the ground, not the air in any home.
Local help
Benton County, Local resources
Radon testing and mitigation in Benton 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
Benton County, Questions
Questions about radon in Benton County
Are radon levels high in Benton County?
In 2020, 4.8% of the radon tests reported to CDC for Benton County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.4 pCi/L. Of 14 Washington counties with 30 or more tests for the same period, 10 reported a higher share; pooled, the state comes to 20.9%.
Which counties border Benton County?
Benton County borders 7 counties: Franklin County, WA, Walla Walla County, WA, Yakima County, WA, Morrow County, OR, Klickitat County, WA, Umatilla County, OR and Grant County, WA.
Products
Benton County, Products
Testing a home in Benton County
In Benton County, 2.5% of 162 tests reported to CDC in 2019 reached 4 pCi/L, against 20.9% pooled across Washington. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Benton 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
lüft plug-in radon and indoor air quality monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Wi-Fi, Bluetooth
- App only
First reading: Within 90 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Benton County, Bordering counties
Counties bordering Benton County
Calculated by Radon411- Radon levels in Umatilla County, OREPA zone 2
42.9%at or above 4 pCi/L
Median 2.7 pCi/L · 14 tests · 40.4 points above Benton County
- Radon levels in Grant County, WAEPA zone 2
33.3%at or above 4 pCi/L
Median 1.8 pCi/L · 9 tests · 30.8 points above Benton County
- Radon levels in Klickitat County, WAEPA zone 2
30.4%at or above 4 pCi/L
Median 3.2 pCi/L · 23 tests · 27.9 points above Benton County
- Radon levels in Walla Walla County, WAEPA zone 2
27.3%at or above 4 pCi/L
Median 2.0 pCi/L · 33 tests · 24.8 points above Benton County
- Radon levels in Yakima County, WAEPA zone 2
5.0%at or above 4 pCi/L
Median 1.1 pCi/L · 20 tests · 2.5 points above Benton County
- Radon levels in Franklin County, WAEPA zone 2
0.0%at or above 4 pCi/L
Median 0.9 pCi/L · 11 tests · 2.5 points below Benton County
- Radon levels in Morrow County, OREPA zone 2
0.0%at or above 4 pCi/L
Median 1.6 pCi/L · 6 tests · 2.5 points below Benton County
Benton County, Cities and towns
Cities and towns in Benton County
Benton County is growing: the Census Bureau puts it at 221,722 residents on July 1, 2025, up 6.9% from 207,408 in 2020. That works out to 130 people per square mile of land. Its largest town, Kennewick, has 88,366 residents, 39.9% of the total. Together its 5 incorporated places hold 82.8% of those residents; the other 17.2% live outside any of them. CDC's 162 reported tests for 2019 work out to 0.7 per 1,000 residents (2025 estimate), close to Washington's 0.5.
From Kennewick to Benton City, CDC publishes no figure by town: each reads Benton County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Kennewick | 88,366 | +5.2% | 39.9% |
| Richland | 65,258 | +7.2% | 29.4% |
| West Richland | 19,257 | +17.7% | 8.7% |
| Prosser | 6,654 | +8.4% | 3.0% |
| Benton City | 4,019 | +15.3% | 1.8% |
5 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).
Benton County, Homes
Homes in Benton County
Of Benton County's 81,792 homes, 63% are detached houses, against 62% across Washington; 17% are in buildings of five or more homes. Half of its homes were built before 1987, close to Washington's 1984: 19% date from before 1960 and 32% from 2000 or later. 68% of occupied homes are lived in by their owner (Washington: 64%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Benton County | Washington |
|---|---|---|
| Housing units | 81,792 | 3,262,667 |
| Detached houses | 63% | 62% |
| In buildings of 5 or more | 17% | 22% |
| Mobile homes | 9% | 6% |
| Built before 1960 | 19% | 21% |
| Built since 2000 | 32% | 28% |
| Middle year built | 1987 | 1984 |
| Owner-occupied | 68% | 64% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.