Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Union County, Oregon
EPA puts Union County in Zone 2, its middle radon zone, and only 24 radon tests from it are on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
40.7%
13.3 pts above OR
- Union
- 40.7%
- Oregon
- 27.4%
113 tests, 2015
Median result
3.3pCi/L
Below action level
- Union
- 3.3 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2015
Tests reported
113
8th of 14 by tests
- Union
- 113
- Multnomah
- 2,728
Reported to CDC before any fix, 2015
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Oregon
1 of 14
Top quarter
- Union
- 40.7%
- Union
- 40.7%
By share, of 14 with 30+ tests
Read a result for Union County
Starts at Union County's median, 3.3 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.3 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. Union County's median reported result, 2015.
The data
Union County, At a glance
Union County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Union 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 Union County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 33.3% |
| 2015 | 40.7% |
| 2016 | 39.1% |
| 2017 | 25.0% |
| 2018 | 40.6% |
| 2019 | 46.7% |
| 2020 | 35.3% |
| 2021 | 34.6% |
| 2022 | 27.8% |
| 2023 | 20.8% |
2023: 20.8%. Across these years the share ran from 20.8% to 46.7%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 24 tests were reported to CDC for Union County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Union County, Compared
Union County radon figures, compared
Calculated by Radon411In Union County, about 4 in 10 reported tests in 2015 (46 of 113) were at or above EPA's action level. Against the national pool of 35.5%, the gap is 5.2 points higher. Across 34 Oregon counties pooled together, 27.4% of tests reached that level, so Union County runs 13.3 points above its state.
The newest figure, in 2023, counts only 24 tests (20.8% at or above 4 pCi/L), too few to compare, so this reading uses the 113-test figure.
By share, Union County is 1st of 14 Oregon counties with 30 or more tests for the same period.
Year by year, 2015 opened at 40.7% and 2022 closed at 27.8% (down 12.9 points), with 2019 the high at 46.7%. Half the tests came in under 3.3 pCi/L and half over it; the single highest reached 32.8 pCi/L. Below the action level, 37 tests (32.7%) came in under 2 pCi/L, against 46.3% statewide, and 30 tests (26.5%) fell between 2 and 4, against 26.3% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 40.7% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential.
The busiest year on file was 2015, with 113 tests reported; the quietest, 2014, had 12.
Union CountyOregon, pooled
27.8% % of tests20.2% % of tests
| Year | Tests | Union County, at or above 4 pCi/L | Oregon, pooled |
|---|---|---|---|
| 2015 | 113 | 40.7% | 27.4% |
| 2016 | 64 | 39.1% | 21.5% |
| 2018 | 32 | 40.6% | 19.6% |
| 2019 | 30 | 46.7% | 20.2% |
| 2020 | 34 | 35.3% | 16.8% |
| 2021 | 52 | 34.6% | 16.3% |
| 2022 | 54 | 27.8% | 20.2% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Union County, Geology
The ground under Union County
PredictedUSGS's geologic map puts all of Union County's mapped land in one class: moderate radon potential. All 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 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Union County beside the ground around it
Union County has more moderate-potential ground than Oregon as a whole: 100% of its land against 62.3%. Of the 4 counties that border it, none has as large a share of moderate-potential ground; Umatilla County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Union County, Local resources
Radon testing and mitigation in Union 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
Union County, Questions
Questions about radon in Union County
Are radon levels high in Union County?
In 2023, 20.8% of the radon tests reported to CDC for Union County, Oregon were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.1 pCi/L. Of 14 Oregon counties with 30 or more tests for the same period, none reported a higher share; pooled, the state comes to 27.4%.
Which counties border Union County?
Union County borders 4 counties: Umatilla County, Wallowa County, Baker County and Grant County.
Products
Union County, Products
Testing a home in Union County
In Union County, 40.7% of 113 tests reported to CDC in 2015 reached 4 pCi/L, against 27.4% pooled across Oregon. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Union County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
MonitorAEGTEST
HOUND-3786 rechargeable radon monitor with a 3.5-inch color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Ion chamber
First reading: Within 10 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Union County, Bordering counties
Counties bordering Union County
Calculated by Radon411- Radon levels in Baker CountyEPA zone 2
37.9%at or above 4 pCi/L
Median 3.1 pCi/L · 29 tests · 2.8 points below Union County
- Radon levels in Wallowa CountyEPA zone 3
14.3%at or above 4 pCi/L
Median 2.4 pCi/L · 7 tests · 26.4 points below Union County
- Radon levels in Umatilla CountyEPA zone 2
10.0%at or above 4 pCi/L
Median 1.7 pCi/L · 10 tests · 30.7 points below Union County
- Radon levels in Grant CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 3 tests · 40.7 points below Union County
Union County, Cities and towns
Cities and towns in Union County
About 25,900 people live in Union County by the Census Bureau's estimate for July 1, 2025, 271 fewer than in 2020 (−1.0%). That works out to 13 people per square mile of land. La Grande alone is home to 12,985 of them, 50.1% of the total. Together its 8 incorporated places hold 74.9% of those residents; the other 25.1% live outside any of them. Testing is reported here more often than across the state: CDC's 113 reported tests for 2015 come to 4.4 for every 1,000 residents (2025 estimate), against 1.4 for Oregon.
From La Grande to Summerville, CDC publishes no figure by town: each reads Union County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| La Grande | 12,985 | −0.7% | 50.1% |
| Union | 2,118 | −1.6% | 8.2% |
| Elgin | 1,689 | −1.5% | 6.5% |
| Island City | 1,142 | −1.5% | 4.4% |
| Cove | 610 | −1.3% | 2.4% |
| North Powder | 500 | −0.8% | 1.9% |
| Imbler | 242 | −1.6% | 0.9% |
| Summerville | 119 | Level | 0.5% |
8 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).
Union County, Homes
Homes in Union County
Of Union County's 11,786 homes, 69% are detached houses, against 63% across Oregon; 12% are mobile homes. The homes are older than Oregon's as a whole: half were built before 1972 (1980 for Oregon), and 39% date from before 1960. 65% of occupied homes are lived in by their owner (Oregon: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Union County | Oregon |
|---|---|---|
| Housing units | 11,786 | 1,838,631 |
| Detached houses | 69% | 63% |
| In buildings of 5 or more | 10% | 17% |
| Mobile homes | 12% | 8% |
| Built before 1960 | 39% | 23% |
| Built since 2000 | 14% | 24% |
| Middle year built | 1972 | 1980 |
| Owner-occupied | 65% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.