Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
Locations and reports
Washington Radon Map and Levels by County
Washington's counties span all three EPA radon zones. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
25.5%
10.2 pts below U.S.
- Washington
- 25.5%
- U.S.
- 35.7%
8,201 tests across 39 counties, 2008 to 2017
Rank among states
26 of 47
Middle of the states
- Washington
- 25.5%
- North Dakota
- 59.3%
By share, every state pooled the same way, 2008 to 2017
Counties in EPA Zone 1
7 of 39
Some at highest potential
- Zone 1
- 7
- Zone 2
- 14
Most counties sit in Zone 3; Zone 1 is the highest potential
Highest county
63.2%
Pend Oreille County
- Pend Oreille
- 63.2%
- Snohomish
- 2.3%
Counties with 30+ tests, 2008 to 2017
Read a result for Washington
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. 25.5% of Washington's reported tests reached 4 pCi/L, 2008 to 2017.
The data
Washington, At a glance
Washington at a glance
Predicted: EPA radon zone
39 of 39 counties classified
EPA classifies counties, not states. Of the 39 counties in Washington with a zone, 7 are in Zone 1, 14 in Zone 2 and 18 in Zone 3.
- Zone 1: Highest predicted potentialgreater than 4 pCi/L7 of 39 counties · 17.9%
- Zone 2: Moderate predicted potential2 to 4 pCi/L14 of 39 counties · 35.9%
- Zone 3: Lower predicted potentialless than 2 pCi/L18 of 39 counties · 46.2%
An EPA radon zone predicts a whole county. It is not intended to determine whether any individual home should be tested: homes with elevated levels occur in all three zones, and EPA recommends testing every home regardless of zone.
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
CDC test figures, county by county
CDC publishes Washington's radon test figures by county: 39 of its 39 counties have one. Each one's share is in the county list.
Washington, Compared
Washington radon figures, compared
Calculated by Radon411- Washington, 2008 to 2017, laboratory
- 25.5%
- of 8,201 tests at or above 4 pCi/L, pooled
- Against the U.S.
- −10.2points
- 35.7% pooled
- Rank among the states
- 26 of 47
- 1 is the highest share
- Counties with 30 or more tests
- 19
- Highest
- 63.2%
- Pend Oreille County
- Lowest
- 2.3%
- Snohomish County
About 3 in 10 of the 8,201 tests reported for Washington over the 2008 to 2017 laboratory totals came back at or above 4 pCi/L (25.5%, 39 counties pooled). That is 26th of 47 states with county figures for the period; Connecticut (26.5%) above it and Oregon (25.4%) below.
By band, 1 county at 50% or more, 4 counties at 30% to 50%, 4 counties at 15% to 30%, 5 counties at 5% to 15%, 5 counties at under 5%. Its 19 counties with 30 or more tests run from 2.3% in Snohomish County to 63.2% in Pend Oreille County; in 1 of them half or more of the reported tests reached 4 pCi/L.
EPA's 1993 map puts 7 of its 39 classified counties in Zone 1; the tests reported since bear that out at 25.5%. The national pool for the same period is 35.7%, so Washington runs 10.2 points below the country.
Across its 4 overlapping ten-year totals, the share went from 27.2% (2005 to 2014) to 25.5% (2008 to 2017), within 2 points, with 2005 to 2014 the highest at 27.2%.
| County | Rank | Tests | At or above 4 pCi/L |
|---|---|---|---|
| Pend Oreille County | 1 of 19 | 38 | 63.2% |
| Spokane County | 2 of 19 | 3,125 | 41.4% |
| Skamania County | 3 of 19 | 68 | 39.7% |
| Stevens County | 4 of 19 | 196 | 36.2% |
| Okanogan County | 5 of 19 | 40 | 35.0% |
| Clark County | 6 of 19 | 1,814 | 25.1% |
| Whitman County | 7 of 19 | 58 | 22.4% |
| Benton County | 8 of 19 | 113 | 19.5% |
| Walla Walla County | 9 of 19 | 122 | 16.4% |
| Chelan County | 10 of 19 | 48 | 14.6% |
| Snohomish County | 19 of 19 | 265 | 2.3% |
| King County | 18 of 19 | 1,267 | 2.6% |
| Skagit County | 17 of 19 | 36 | 2.8% |
| Pierce County | 16 of 19 | 226 | 4.9% |
| Kitsap County | 15 of 19 | 82 | 4.9% |
| Share | Counties | Their tests | For example |
|---|---|---|---|
| 50% or more | 1 | 38 | Pend Oreille County |
| 30% to 50% | 4 | 3,429 | Spokane County, Skamania County, Stevens County |
| 15% to 30% | 4 | 2,107 | Clark County, Whitman County, Benton County |
| 5% to 15% | 5 | 499 | Chelan County, Cowlitz County, Thurston County |
| Under 5% | 5 | 1,876 | Kitsap County, Pierce County, Skagit County |
Pooled shares: Radon411's sum of CDC's county counts for one period. CDC publishes no state or national figure.
Washington, Counties
Washington counties by EPA zone
PredictedAll 39 counties, grouped by the zone EPA predicts and ordered by their reported share at or above 4 pCi/L, under Washington's map. Each county has a page of its own.
The 12 highest in Washington, 2008 to 2017
- Radon levels in Pend Oreille CountyEPA zone 1
63.2%at or above 4 pCi/L
Median 4.8 pCi/L · 38 tests · 37.6 points above Washington
- Radon levels in Spokane CountyEPA zone 1
41.4%at or above 4 pCi/L
Median 2.9 pCi/L · 3,125 tests · 15.9 points above Washington
- Radon levels in Skamania CountyEPA zone 1
39.7%at or above 4 pCi/L
Median 2.9 pCi/L · 68 tests · 14.2 points above Washington
- Radon levels in Stevens CountyEPA zone 1
36.2%at or above 4 pCi/L
Median 2.3 pCi/L · 196 tests · 10.7 points above Washington
- Radon levels in Okanogan CountyEPA zone 1
35.0%at or above 4 pCi/L
Median 2.3 pCi/L · 40 tests · 9.5 points above Washington
- Radon levels in Clark CountyEPA zone 1
25.1%at or above 4 pCi/L
Median 1.8 pCi/L · 1,814 tests · 0.5 points below Washington
- Radon levels in Whitman CountyEPA zone 2
22.4%at or above 4 pCi/L
Median 1.5 pCi/L · 58 tests · 3.1 points below Washington
- Radon levels in Benton CountyEPA zone 2
19.5%at or above 4 pCi/L
Median 2.0 pCi/L · 113 tests · 6.1 points below Washington
- Radon levels in Walla Walla CountyEPA zone 2
16.4%at or above 4 pCi/L
Median 1.4 pCi/L · 122 tests · 9.2 points below Washington
- Radon levels in Chelan CountyEPA zone 3
14.6%at or above 4 pCi/L
Median 1.8 pCi/L · 48 tests · 11.0 points below Washington
- Radon levels in Cowlitz CountyEPA zone 3
11.3%at or above 4 pCi/L
Median 1.1 pCi/L · 62 tests · 14.3 points below Washington
- Radon levels in Thurston CountyEPA zone 3
10.1%at or above 4 pCi/L
Median 0.7 pCi/L · 198 tests · 15.4 points below Washington
Zone 1: highest predicted potential7
- Okanogan County60.7% of reported tests at or above 4 pCi/L, 2020
- Skamania County52.9% of reported tests at or above 4 pCi/L, 2020
- Spokane County40.6% of reported tests at or above 4 pCi/L, 2020
- Stevens County37.8% of reported tests at or above 4 pCi/L, 2020
- Ferry County20.0% of reported tests at or above 4 pCi/L, 2020
- Pend Oreille County20.0% of reported tests at or above 4 pCi/L, 2020
- Clark County17.6% of reported tests at or above 4 pCi/L, 2020
Local help
Washington, Local resources
Local resources in Washington
Who to ask in Washington: its radon program, test kits and professionals.
- 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
Washington, Questions
Questions about radon in Washington
Is radon a problem in Washington?
Of the 39 counties in Washington that EPA's Map of Radon Zones classifies, 7 carry Zone 1 (the highest predicted potential), 14 Zone 2 and 18 Zone 3. Pooled from 39 counties, 25.5% of the 8,201 radon tests reported to CDC over the 2008 to 2017 laboratory totals were at or above 4 pCi/L, 26th of 47 states.
Which Washington counties are in EPA radon Zone 1?
7 counties are in Zone 1: Clark County, Ferry County, Okanogan County, Pend Oreille County, Skamania County, Spokane County, Stevens County.
Which Washington counties have the highest radon?
By the share of reported tests at or above 4 pCi/L, 2008 to 2017, laboratory: Pend Oreille County 63.2% (38 tests), Spokane County 41.4% (3,125 tests), Skamania County 39.7% (68 tests), Stevens County 36.2% (196 tests), Okanogan County 35.0% (40 tests).
Which EPA region is Washington in?
Washington is in EPA Region 10: Pacific Northwest.
Products
Washington, Products
Testing a home in Washington
25.5% of the 8,201 tests reported to CDC for Washington over the 2008 to 2017 laboratory totals reached 4 pCi/L: a short-term kit (2 to 90 days) gives a first answer in days, a long-term test the year-round average. A short-term kit (2 to 90 days) is the quick first check for a home in Washington; 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
View Plus radon and air quality monitor
- C-NRPP 2024/25: Approved
- Battery
- Wi-Fi, Bluetooth
- Screen, app
Method: Alpha spectrometry
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3