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 Grant County, Oregon
EPA puts Grant County in Zone 2, its middle radon zone, and only 3 radon tests from it are on file with CDC (2021). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
39.1%
Union County
- Union
- 39.1%
1 of 8 neighbours have 30+ tests, 2016
Nearest county
39.1%
Union County, 75 miles
- Union
- 39.1%
- Oregon
- 21.5%
Share at 4+ pCi/L, 64 tests, 2016
Ground above low
99.5%
37.2 pts above Oregon
- Grant
- 99.5%
- Oregon
- 62.3%
Share of land USGS rates moderate or high potential
Tests reported
15
Too few for a share
- Grant
- 15
- Needed
- 30
2020
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 99% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Grant County, 2021
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 60.0% |
| 2015 | 0.0% |
| 2016 | 0.0% |
| 2017 | 0.0% |
| 2018 | 0.0% |
| 2019 | 0.0% |
| 2020 | 0.0% |
| 2021 | 33.3% |
2021: 33.3%. Across these years the share ran from 0.0% to 60.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 3 tests were reported to CDC for Grant County over 2021, 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: 2021. Measured data period: 2005 to 2021 (every CDC figure on file).
Grant County, Compared
Grant County radon figures, compared
Calculated by Radon411CDC's largest figure for Grant County rests on 15 tests in 2020, 0 of them at or above 4 pCi/L, so each test moves its share by 6.7 points and no rank or comparison is drawn from it. Results reached as high as 2.6 pCi/L, with a middle value of 0.9 pCi/L.
Union County, the one bordering county with a figure in 2016, reported 39.1% of its tests at or above 4 pCi/L. Farther out, Wasco County (116 miles away) at 10.0%, Deschutes County (117 miles away) at 6.7% and Hood River County (148 miles away) at 20.8% have figures too. Pooled across 35 Oregon counties, 21.5% of reported tests reached that level; across every county in the country with a figure, 31.2%.
Statewide for the same period, Union County reported the highest share (39.1%) and Deschutes County the lowest (6.7%). 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 99% 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% low. 99.1% of it lies in the area the map calls Blue Mountains, to which USGS gives a radon index of 9, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Blue Mountains | Tertiary basalt and andesite, tuffaceous sedimentary rocks, and tuff. | Moderate | 9 | 99.1% |
| High Lava Plains | Tertiary and Quaternary basalt flows and Tertiary silicic ash-flow tuff. | Low | 7 | 0.5% |
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
Grant County has more moderate-potential ground than Oregon as a whole: 99.5% of its land against 62.3%. Of the 8 counties that border it, 1 has more high-potential ground, Malheur County the most at 0.2%.
The map rates the ground, not the air in any home.
Local help
Grant County, Local resources
Radon testing and mitigation in Grant County
- Oregon Radon Awareness ProgramOregon Radon Awareness Program, run by Oregon Health Authority, offers free or discounted test kits, and answers questions about testing and mitigation in Oregon.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Oregon Radon Awareness Program provides a FREE short-term radon test kit to those living in areas of Oregon where little radon testing has been done.
- Compare kits
- Professionals in Oregon38 professionals are listed in Oregon.
What Oregon's program says
- Radon.program@dhsoha.state.or.us
What it means
Grant County, Questions
Questions about radon in Grant County
Are radon levels high in Grant County?
In 2021, 33.3% of the radon tests reported to CDC for Grant County, Oregon were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.3 pCi/L. Union County, the one bordering county with a figure in 2016, reported 39.1% of its tests at or above 4 pCi/L.
Which counties border Grant County?
Grant County borders 8 counties: Wheeler County, Baker County, Morrow County, Umatilla County, Crook County, Union County, Harney County and Malheur County.
Products
Grant County, Products
Testing a home in Grant County
No CDC figure names Grant County; the nearest county with one, Union County (75 miles away), reported 39.1% of its tests at or above 4 pCi/L in 2016, 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
Corentium Home battery digital radon detector
- C-NRPP 2024/25: Approved
- Battery
- Screen
Method: Alpha spectrometry
- 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 Union CountyEPA zone 2
39.1%at or above 4 pCi/L
Median 3.3 pCi/L · 64 tests
- Radon levels in Baker CountyEPA zone 2
33.3%at or above 4 pCi/L
Median 2.0 pCi/L · 3 tests
- Radon levels in Umatilla CountyEPA zone 2
20.0%at or above 4 pCi/L
Median 1.8 pCi/L · 10 tests
- Radon levels in Morrow CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 1.9 pCi/L · 1 test
- Radon levels in Crook CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 0.8 pCi/L · 6 tests
- Radon levels in Harney CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 1.4 pCi/L · 4 tests
- Radon levels in Malheur CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 0.8 pCi/L · 3 tests
- Radon levels in Wheeler CountyEPA zone 2
No CDC figure for 2016; its page reads it against its own neighbours.
Grant County, Cities and towns
Cities and towns in Grant County
About 7,075 people live in Grant County by the Census Bureau's estimate for July 1, 2025, 165 fewer than in 2020 (−2.3%). Spread over its land, that is 1.6 people to the square mile. Its largest town, John Day, has 1,634 residents, 23.1% of the total. Together its 9 incorporated places hold 59.9% of those residents; the other 40.1% live outside any of them. Testing is reported here more often than across the state: CDC's 15 reported tests for 2020 come to 2.1 for every 1,000 residents (2025 estimate), against 1.3 for Oregon.
From John Day to Granite, CDC publishes no figure by town: each reads Grant County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| John Day | 1,634 | −2.4% | 23.1% |
| Prairie City | 819 | −2.7% | 11.6% |
| Canyon City | 644 | −2.9% | 9.1% |
| Mount Vernon | 545 | −0.7% | 7.7% |
| Long Creek | 166 | −2.4% | 2.3% |
| Seneca | 160 | −3.6% | 2.3% |
| Dayville | 130 | −2.3% | 1.8% |
| Monument | 112 | −1.8% | 1.6% |
| Granite | 29 | Level | 0.4% |
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).
Grant County, Homes
Homes in Grant County
Grant County is a place of houses on their own lots: 76% of its 4,147 homes are detached single-family houses, against 63% across Oregon. The homes are older than Oregon's as a whole: half were built before 1972 (1980 for Oregon), and 40% date from before 1960. Owners live in 81% of the occupied homes (Oregon: 63%), so for most households a test and a fix are their own to order.
| Homes | Grant County | Oregon |
|---|---|---|
| Housing units | 4,147 | 1,838,631 |
| Detached houses | 76% | 63% |
| In buildings of 5 or more | 4% | 17% |
| Mobile homes | 19% | 8% |
| Built before 1960 | 40% | 23% |
| Built since 2000 | 13% | 24% |
| Middle year built | 1972 | 1980 |
| Owner-occupied | 81% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.