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 Grant County, Washington
EPA puts Grant County in Zone 2, its middle radon zone, and only 4 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
35.0%
Okanogan County
- Okanogan
- 35.0%
- Yakima
- 7.5%
3 of 8 neighbours have 30+ tests, 2008 to 2017
Nearest county
19.5%
Benton County, 67 miles
- Benton
- 19.5%
- Washington
- 25.5%
Share at 4+ pCi/L, 113 tests, 2008 to 2017
Ground above low
100.0%
47.3 pts above Washington
- Grant
- 100.0%
- Washington
- 52.7%
Share of land USGS rates moderate or high potential
Tests reported
21
Too few for a share
- Grant
- 21
- Needed
- 30
2005 to 2014, laboratory
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 Grant 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
Grant County, At a glance
Grant County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Grant 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 Grant County, 2020
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 37.5% |
| 2016 | 15.8% |
| 2017 | 30.0% |
| 2018 | 33.3% |
| 2019 | 33.3% |
| 2020 | 50.0% |
2020: 50.0%. Across these years the share ran from 15.8% to 50.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 4 tests were reported to CDC for Grant 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).
Grant County, Compared
Grant County radon figures, compared
Calculated by Radon411CDC's largest figure for Grant County rests on 21 tests over the 2005 to 2014 laboratory totals, 7 of them at or above 4 pCi/L, so each test moves its share by 4.8 points and no rank or comparison is drawn from it. Results reached as high as 22.8 pCi/L, with a middle value of 2.9 pCi/L.
Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Okanogan County reported the largest share at or above 4 pCi/L, 35.0%, and Yakima County the smallest, 7.5%, with Benton County at 19.5% between. Farther out, Chelan County (71 miles away) at 14.6%, Walla Walla County (82 miles away) at 16.4% and Whitman County (93 miles away) at 22.4% 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 Grant 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.
Grant County, Geology
The ground under Grant County
PredictedMost of the ground under Grant County is one class on USGS's geologic map: 99.5% of its land is moderate radon potential, with 0.5% high. 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 | 99.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Grant County beside the ground around it
Washington as a whole has more high-potential ground than Grant County: 13.7% of its land, against 0.5% here. Of the 8 counties that border it, 3 have more high-potential ground, Okanogan County the most at 38.7%.
The map rates the ground, not the air in any home.
Local help
Grant County, Local resources
Radon testing and mitigation in Grant 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
Grant County, Questions
Questions about radon in Grant County
Are radon levels high in Grant County?
In 2020, 50.0% of the radon tests reported to CDC for Grant County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 16.4 pCi/L. Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Okanogan County reported the largest share at or above 4 pCi/L, 35.0%, and Yakima County the smallest, 7.5%, with Benton County at 19.5% between.
Which counties border Grant County?
Grant County borders 8 counties: Douglas County, Adams County, Lincoln County, Kittitas County, Franklin County, Benton County, Yakima County and Okanogan County.
Products
Grant County, Products
Testing a home in Grant County
No CDC figure names Grant County; the nearest county with one, Benton County (67 miles away), reported 19.5% 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 Grant 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
Grant County, Bordering counties
Counties bordering Grant County
Calculated by Radon411- Radon levels in Lincoln CountyEPA zone 2
40.0%at or above 4 pCi/L
Median 3.1 pCi/L · 15 tests
- Radon levels in Douglas CountyEPA zone 2
35.7%at or above 4 pCi/L
Median 2.3 pCi/L · 14 tests
- Radon levels in Okanogan CountyEPA zone 1
35.0%at or above 4 pCi/L
Median 2.3 pCi/L · 40 tests
- Radon levels in Kittitas CountyEPA zone 2
25.0%at or above 4 pCi/L
Median 1.4 pCi/L · 8 tests
- Radon levels in Benton CountyEPA zone 2
19.5%at or above 4 pCi/L
Median 2.0 pCi/L · 113 tests
- Radon levels in Adams CountyEPA zone 2
14.3%at or above 4 pCi/L
Median 1.5 pCi/L · 7 tests
- Radon levels in Franklin CountyEPA zone 2
10.5%at or above 4 pCi/L
Median 1.8 pCi/L · 19 tests
- Radon levels in Yakima CountyEPA zone 2
7.5%at or above 4 pCi/L
Median 0.7 pCi/L · 80 tests
Grant County, Cities and towns
Cities and towns in Grant County
Grant County is growing: the Census Bureau puts it at 105,727 residents on July 1, 2025, up 6.3% from 99,446 in 2020. That works out to 39 people per square mile of land. Its largest town, Moses Lake, has 27,469 residents, 26.0% of the total. Reported testing is thin here: 21 tests over 2005 to 2014, or 0.2 for every 1,000 residents (2025 estimate), where Washington as a whole comes to 0.8.
From Moses Lake to Krupp (Marlin), CDC publishes no figure by town: each reads Grant County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Moses Lake | 27,469 | +8.0% | 26.0% |
| Ephrata | 8,834 | +4.1% | 8.4% |
| Quincy | 8,510 | +11.5% | 8.0% |
| Mattawa | 3,874 | +15.5% | 3.7% |
| Warden | 2,830 | +14.9% | 2.7% |
| Royal City | 1,896 | +5.9% | 1.8% |
| Soap Lake | 1,817 | +6.6% | 1.7% |
| Coulee Damextends beyond Grant County | 1,241 | +2.3% | Counted whole |
| George | 1,024 | +26.9% | 1.0% |
| Electric City | 954 | −0.4% | 0.9% |
| Grand Coulee | 947 | −2.9% | 0.9% |
| Coulee City | 550 | Level | 0.5% |
- Wilson Creek
- Hartline
- Krupp (Marlin)
15 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Grant County is counted whole, so it has no share.
Grant County, Homes
Homes in Grant County
Of Grant County's 39,496 homes, 59% are detached houses, against 62% across Washington; 24% are mobile homes. Half of its homes were built before 1987, close to Washington's 1984: 23% date from before 1960 and 31% from 2000 or later. 66% 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 | Grant County | Washington |
|---|---|---|
| Housing units | 39,496 | 3,262,667 |
| Detached houses | 59% | 62% |
| In buildings of 5 or more | 9% | 22% |
| Mobile homes | 24% | 6% |
| Built before 1960 | 23% | 21% |
| Built since 2000 | 31% | 28% |
| Middle year built | 1987 | 1984 |
| Owner-occupied | 66% | 64% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.