Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Spokane County, Washington
EPA puts Spokane County in Zone 1, its highest radon zone, and high results are common there: 40.6% of the 721 radon tests reported to CDC (2020) came back 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
40.6%
21.6 pts above WA
- Spokane
- 40.6%
- Washington
- 19.0%
721 tests, 2020
Median result
2.7pCi/L
Below action level
- Spokane
- 2.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2020
Tests reported
721
Most tested in Washington
- Spokane
- 721
Reported to CDC before any fix, 2020
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Washington
1 of 10
Top quarter
- Spokane
- 40.6%
- Spokane
- 40.6%
By share, of 10 with 30+ tests
Read a result for Spokane County
Starts at Spokane County's median, 2.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.7 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. Spokane County's median reported result, 2020.
The data
Spokane County, At a glance
Spokane County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Spokane County in
USGS geologic potential: Moderate across 57% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Spokane County, 2020
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 34.7% |
| 2015 | 31.8% |
| 2016 | 38.9% |
| 2017 | 39.8% |
| 2018 | 30.9% |
| 2019 | 41.7% |
| 2020 | 40.6% |
2020: 40.6%. Across these years the share ran from 30.9% to 41.7%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 721 tests reported to CDC for Spokane County over 2020, 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: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).
Spokane County, Compared
Spokane County radon figures, compared
Calculated by Radon411In Spokane County, about 4 in 10 reported tests in 2020 (293 of 721) were at or above EPA's action level. Against the national pool of 25.5%, the gap is 15.1 points higher. Across 37 Washington counties pooled together, 19.0% of tests reached that level, so Spokane County runs 21.6 points above its state.
Stevens County, the one bordering county with a figure for the same period, reported 37.8%. By share, Spokane County is 1st of 10 Washington counties with 30 or more tests for the same period.
Year by year, 2014 opened at 34.7% and 2020 closed at 40.6% (up 5.9 points), with 2019 the high at 41.7%. Half the tests came in under 2.7 pCi/L and half over it; the single highest reached 110.0 pCi/L. Below the action level, 310 tests (43.0%) came in under 2 pCi/L, against 67.6% statewide, and 118 tests (16.4%) fell between 2 and 4, against 13.3% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 40.6% share point the same way here. USGS geology rates 57% of the county's land moderate radon potential.
The busiest year on file was 2017, with 957 tests reported; the quietest, 2014, had 600.
Spokane CountyWashington, pooled
40.6% % of tests19.0% % of tests
| Year | Tests | Spokane County, at or above 4 pCi/L | Washington, pooled |
|---|---|---|---|
| 2014 | 600 | 34.7% | 15.0% |
| 2015 | 711 | 31.8% | 17.4% |
| 2016 | 750 | 38.9% | 16.6% |
| 2017 | 957 | 39.8% | 19.1% |
| 2018 | 842 | 30.9% | 16.1% |
| 2019 | 952 | 41.7% | 20.9% |
| 2020 | 721 | 40.6% | 19.0% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Spokane County, Geology
The ground under Spokane County
PredictedUSGS's geologic map splits Spokane County: 56.7% of its land is moderate radon potential and 43.3% high. The map puts 56.6% of Spokane County in the area it calls Columbia Basin and 43.3% in Okanogan Highland. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 16, in the high band (12 to 17).
| 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 | 56.6% |
| Okanogan Highland | Glaciofluvial outwash and granitic material. Outwash is generally uranium-bearing. | High | 16 | 43.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Spokane County beside the ground around it
Spokane County has more high-potential ground than Washington as a whole: 43.3% of its land against 13.7%. Of the 7 counties that border it, 5 have more high-potential ground, Bonner County, ID the most at 100%.
The map rates the ground, not the air in any home.
Local help
Spokane County, Local resources
Radon testing and mitigation in Spokane 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
Spokane County, Questions
Questions about radon in Spokane County
Are radon levels high in Spokane County?
In 2020, 40.6% of the radon tests reported to CDC for Spokane County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.7 pCi/L. Of 10 Washington counties with 30 or more tests for the same period, none reported a higher share; pooled, the state comes to 19.0%.
Which counties border Spokane County?
Spokane County borders 7 counties: Kootenai County, ID, Benewah County, ID, Lincoln County, WA, Whitman County, WA, Stevens County, WA, Bonner County, ID and Pend Oreille County, WA.
Products
Spokane County, Products
Testing a home in Spokane County
In Spokane County, 40.6% of 721 tests reported to CDC in 2020 reached 4 pCi/L, against 19.0% pooled across Washington. In Zone 1 the year-round level in Spokane County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
Monitor
RadonScan USB-powered radon monitor with a color screen
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
First reading: Within 5 minutes
Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Spokane County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Spokane County
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Spokane County, Bordering counties
Counties bordering Spokane County
Calculated by Radon411- Radon levels in Lincoln County, WAEPA zone 2
45.5%at or above 4 pCi/L
Median 2.4 pCi/L · 11 tests · 4.9 points above Spokane County
- Radon levels in Stevens County, WAEPA zone 1
37.8%at or above 4 pCi/L
Median 1.9 pCi/L · 45 tests · 2.8 points below Spokane County
- Radon levels in Whitman County, WAEPA zone 2
29.4%at or above 4 pCi/L
Median 1.4 pCi/L · 17 tests · 11.2 points below Spokane County
- Radon levels in Pend Oreille County, WAEPA zone 1
20.0%at or above 4 pCi/L
Median 2.3 pCi/L · 20 tests · 20.6 points below Spokane County
- Radon levels in Kootenai County, IDEPA zone 1
No CDC figure for 2020; its page reads it against its own neighbours.
- Radon levels in Benewah County, IDEPA zone 1
No CDC figure for 2020; its page reads it against its own neighbours.
- Radon levels in Bonner County, IDEPA zone 1
No CDC figure for 2020; its page reads it against its own neighbours.
Spokane County, Cities and towns
Cities and towns in Spokane County
The Census Bureau estimates 558,344 residents in Spokane County for July 1, 2025, 17,200 more than in 2020 (+3.2%). That works out to 316 people per square mile of land. Its largest town, Spokane, has 230,783 residents, 41.3% of the total. Together its 13 incorporated places hold 70.1% of those residents; the other 29.9% live outside any of them. Testing is reported here more often than across the state: CDC's 721 reported tests for 2020 come to 1.3 for every 1,000 residents (2025 estimate), against 0.3 for Washington.
From Spokane to Waverly, CDC publishes no figure by town: each reads Spokane County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Spokane | 230,783 | +0.7% | 41.3% |
| Spokane Valley | 108,405 | +4.6% | 19.4% |
| Liberty Lake | 14,029 | +15.6% | 2.5% |
| Cheney | 12,650 | −5.5% | 2.3% |
| Airway Heights | 11,811 | +9.5% | 2.1% |
| Deer Park | 5,370 | +21.8% | 1.0% |
| Medical Lake | 4,964 | +1.8% | 0.9% |
| Millwood | 1,825 | −2.9% | 0.3% |
| Rockford | 632 | +20.2% | 0.1% |
| Fairfield | 590 | −0.2% | 0.1% |
| Spangle | 276 | −2.1% | Under 0.1% |
| Latah | 175 | −1.7% | Under 0.1% |
- Waverly
13 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).
Spokane County, Homes
Homes in Spokane County
Of Spokane County's 228,156 homes, 66% are detached houses, against 62% across Washington; 20% are in buildings of five or more homes. Half of its homes were built before 1978, close to Washington's 1984: 31% date from before 1960 and 24% from 2000 or later. 64% 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 | Spokane County | Washington |
|---|---|---|
| Housing units | 228,156 | 3,262,667 |
| Detached houses | 66% | 62% |
| In buildings of 5 or more | 20% | 22% |
| Mobile homes | 5% | 6% |
| Built before 1960 | 31% | 21% |
| Built since 2000 | 24% | 28% |
| Middle year built | 1978 | 1984 |
| Owner-occupied | 64% | 64% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.