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 Grays Harbor County, Washington
EPA puts Grays Harbor County in Zone 3, its lowest radon zone, and only 9 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
Highest bordering
10.1%
Thurston County
- Thurston
- 10.1%
1 of 5 neighbours have 30+ tests, 2008 to 2017
Nearest county
10.1%
Thurston County, 47 miles
- Thurston
- 10.1%
- Washington
- 25.5%
Share at 4+ pCi/L, 198 tests, 2008 to 2017
Ground above low
None
52.7 pts below Washington
- Grays Harbor
- 0.0%
- Washington
- 52.7%
Share of land USGS rates moderate or high potential
Tests reported
14
Too few for a share
- Grays Harbor
- 14
- Needed
- 30
2019
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Grays Harbor 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
Grays Harbor County, At a glance
Grays Harbor County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 99% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Grays Harbor County, 2020
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 25.0% |
| 2016 | 0.0% |
| 2017 | 70.0% |
| 2019 | 21.4% |
| 2020 | 0.0% |
2020: 0.0%. Across these years the share ran from 0.0% to 70.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 9 tests were reported to CDC for Grays Harbor 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).
Grays Harbor County, Compared
Grays Harbor County radon figures, compared
Calculated by Radon411CDC's largest figure for Grays Harbor County rests on 14 tests in 2019, 3 of them at or above 4 pCi/L, so each test moves its share by 7.1 points and no rank or comparison is drawn from it. Results reached as high as 9.3 pCi/L, with a middle value of 0.5 pCi/L.
Thurston County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 10.1% of its tests at or above 4 pCi/L. Farther out, Kitsap County (61 miles away) at 4.9%, Pierce County (79 miles away) at 4.9% and Cowlitz County (84 miles away) at 11.3% 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 Grays Harbor County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 99% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Grays Harbor County, Geology
The ground under Grays Harbor County
PredictedUSGS's geologic map puts all of Grays Harbor County's mapped land in one class: low radon potential. The map puts 60.2% of Grays Harbor County in the area it calls Coastal Hills and 39.2% in Coastal Mountains. USGS gives both a radon index of 6, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Coastal Hills | Cretaceous and Tertiary continental and marine sedimentary rocks and pre-Miocene volcanic rocks. | Low | 6 | 60.2% |
| Coastal Mountains | Cretaceous and Tertiary continental and marine sedimentary rocks and pre-Miocene volcanic rocks. | Low | 6 | 39.2% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Grays Harbor County beside the ground around it
Across Washington 13.7% of the land is rated high; none of Grays Harbor County's is. None of the 5 counties that border it has any moderate-potential ground either.
The map rates the ground, not the air in any home.
Local help
Grays Harbor County, Local resources
Radon testing and mitigation in Grays Harbor 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
Grays Harbor County, Questions
Questions about radon in Grays Harbor County
Are radon levels high in Grays Harbor County?
In 2020, 0.0% of the radon tests reported to CDC for Grays Harbor County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.3 pCi/L. Thurston County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 10.1% of its tests at or above 4 pCi/L.
Which counties border Grays Harbor County?
Grays Harbor County borders 5 counties: Mason County, Jefferson County, Pacific County, Thurston County and Lewis County.
Products
Grays Harbor County, Products
Testing a home in Grays Harbor County
No CDC figure names Grays Harbor County; the nearest county with one, Thurston County (47 miles away), reported 10.1% 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. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Grays Harbor County.
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
MonitorINKBIRD
INK-RD3 battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Grays Harbor County, Bordering counties
Counties bordering Grays Harbor County
Calculated by Radon411- Radon levels in Thurston CountyEPA zone 3
10.1%at or above 4 pCi/L
Median 0.7 pCi/L · 198 tests
- Radon levels in Jefferson CountyEPA zone 3
9.1%at or above 4 pCi/L
Median 1.0 pCi/L · 22 tests
- Radon levels in Lewis CountyEPA zone 3
9.1%at or above 4 pCi/L
Median 0.1 pCi/L · 11 tests
- Radon levels in Mason CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.7 pCi/L · 14 tests
- Radon levels in Pacific CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.5 pCi/L · 2 tests
Grays Harbor County, Cities and towns
Cities and towns in Grays Harbor County
The Census Bureau estimates 78,144 residents in Grays Harbor County for July 1, 2025, 2,278 more than in 2020 (+3.0%). That works out to 41 people per square mile of land. Its largest town, Aberdeen, has 17,088 residents, 21.9% of the total. Together its 9 incorporated places hold 61.7% of those residents; the other 38.3% live outside any of them. Reported testing is thin here: 14 tests over 2019, or 0.2 for every 1,000 residents (2025 estimate), where Washington as a whole comes to 0.5.
From Aberdeen to Oakville, CDC publishes no figure by town: each reads Grays Harbor County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Aberdeen | 17,088 | +0.3% | 21.9% |
| Hoquiam | 8,710 | −0.8% | 11.1% |
| Ocean Shores | 7,892 | +16.5% | 10.1% |
| Montesano | 4,181 | +0.5% | 5.4% |
| Elma | 3,534 | +2.4% | 4.5% |
| Westport | 2,372 | +6.8% | 3.0% |
| McCleary | 2,053 | +1.9% | 2.6% |
| Cosmopolis | 1,656 | +1.5% | 2.1% |
| Oakville | 734 | +2.4% | 0.9% |
9 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).
Grays Harbor County, Homes
Homes in Grays Harbor County
Of Grays Harbor County's 36,568 homes, 74% are detached houses, against 62% across Washington; 12% are mobile homes. The homes are older than Washington's as a whole: half were built before 1974 (1984 for Washington), and 34% date from before 1960. 73% 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 | Grays Harbor County | Washington |
|---|---|---|
| Housing units | 36,568 | 3,262,667 |
| Detached houses | 74% | 62% |
| In buildings of 5 or more | 8% | 22% |
| Mobile homes | 12% | 6% |
| Built before 1960 | 34% | 21% |
| Built since 2000 | 18% | 28% |
| Middle year built | 1974 | 1984 |
| Owner-occupied | 73% | 64% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.