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
Locations and reports
Radon Levels in Pennington County, Minnesota
EPA puts Pennington County in Zone 1, its highest radon zone, and only 15 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
52.3%
8.9 pts above MN
- Pennington
- 52.3%
- Minnesota
- 43.4%
151 tests, 2008 to 2017
Median result
4.1pCi/L
Action level reached
- Pennington
- 4.1 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
151
74th of 85 by tests
- Pennington
- 151
- Hennepin
- 35,213
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Minnesota
47 of 85
Middle half
- Pennington
- 52.3%
- Rock
- 83.8%
By share, of 85 with 30+ tests
Read a result for Pennington County
Starts at Pennington County's median, 4.1 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.1 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. Pennington County's median reported result, 2008 to 2017.
The data
Pennington County, At a glance
Pennington County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Pennington County in
USGS geologic potential: Moderate across 71% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Pennington County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 52.6% |
| 2015 | 50.0% |
| 2016 | 51.2% |
| 2017 | 56.0% |
| 2018 | 45.0% |
| 2019 | 57.7% |
| 2020 | 37.5% |
| 2021 | 61.1% |
| 2022 | 59.5% |
| 2023 | 53.3% |
2023: 53.3%. Across these years the share ran from 37.5% to 61.1%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 15 tests were reported to CDC for Pennington 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).
Pennington County, Compared
Pennington County radon figures, compared
Calculated by Radon411More than half: 52.3% of the 151 radon tests reported to CDC for Pennington County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 47th of 85 Minnesota counties with 30 or more tests for the same period. That is 8.9 points above the 43.4% pooled from 87 Minnesota counties.
The newest figure, in 2023, counts only 15 tests (53.3% at or above 4 pCi/L), too few to compare, so this reading uses the 151-test figure.
The median result, 4.1 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 56.3 pCi/L. The rest split 32.5% under 2 pCi/L and 15.2% from 2 to 4 (Minnesota: 27.4% and 29.2%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 52.3% share point the same way here.
2 of its 5 bordering counties with figures ran higher, led by Polk County at 70.8%; Red Lake County reported 33.3%. Statewide for the same period, Rock County reported the highest share (83.8%) and Anoka County the lowest (17.4%).
The busiest year on file was 2015, with 42 tests reported; the quietest, 2023, had 15.
Over 4 years of annual figures the share rose 6.9 points, from 52.6% in 2014 to 59.5% in 2022; its peak was 59.5% in 2022. Nationally, every county with a figure for the same period pools to 35.7%; Pennington County sits 16.6 points above it. CDC also counts 11 tests taken after mitigation in Pennington County for the same period: tests in homes where a fix was already in.
Pennington CountyMinnesota, pooled
59.5% % of tests31.6% % of tests
| Year | Tests | Pennington County, at or above 4 pCi/L | Minnesota, pooled |
|---|---|---|---|
| 2014 | 38 | 52.6% | 42.9% |
| 2015 | 42 | 50.0% | 43.6% |
| 2016 | 41 | 51.2% | 37.0% |
| 2022 | 37 | 59.5% | 31.6% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Pennington County, State data
Minnesota's own radon test data
MeasuredWhat Minnesota's own agencies publish about radon tests in Pennington County, with their period. These are not CDC's figures and are never added to them.
MeasuredState figures, not CDC's
What the Minnesota Department of Health reports for Pennington County
Radon Testing (MN Public Health Data Access Portal): home radon tests reported voluntarily by private laboratories and licensed radon measurement professionals, counted by property. Period: 2016-2025.
Share with one or more tests at or above 4 pCi/L
56.3%
103 properties tested with one or more tests at or above 4 pCi/L
Median result
4.3 pCi/L
Average result
5.8 pCi/L
Tests behind these figures
18 properties tested a year on average
- MDH says these data do not include all of the radon tests conducted in Minnesota.
- Post-mitigation tests are excluded from the averages and the median; the percentages use each property's highest test.
- Each home is unique and can have very different results than a neighbor's home; the only way to know is to test.
- These figures describe tests reported to the Minnesota Department of Health in this area. They count a different set of tests than CDC's figures and are not a reading of any one home.
Measured: Minnesota Department of Health data, 2016-2025.
Pennington County, Geology
The ground under Pennington County
PredictedUSGS's geologic map splits Pennington County: 70.5% of its land is moderate radon potential and 29.5% high. The map puts 70.5% of Pennington County in the area it calls Lake Agassiz Plain/Central Lowland-Western Lake Section and 29.5% in Lake Agassiz Plain. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 15, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Lake Agassiz Plain/Central Lowland-Western Lake Section | Silty and clayey glacial deposits and lake deposits. | Moderate | 10 | 70.5% |
| Lake Agassiz Plain | Silt and clay deposits of Glacial Lake Agassiz derived from Cretaceous shales containing higher than average amounts of uranium. | High | 15 | 29.5% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Pennington County beside the ground around it
Minnesota as a whole has more high-potential ground than Pennington County: 61.1% of its land, against 29.5% here. Of the 5 counties that border it, 4 have more high-potential ground, Polk County the most at 96.5%.
The map rates the ground, not the air in any home.
Local help
Pennington County, Local resources
Radon testing and mitigation in Pennington County
- MDH Indoor Air UnitMDH Indoor Air Unit, run by MN Dept. of Health, licenses or certifies radon professionals and states the rule for disclosing radon when a home is sold, and answers questions about testing and mitigation in Minnesota.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Minnesota255 professionals are listed in Minnesota.
What Minnesota's program says
- Phone
- 651-201-4601
- health.indoorair@state.mn.us
- Licensing of radon professionals
The Radon Licensing Act requires anyone who performs a radon test or radon mitigation, in a building they do not own or lease, must be licensed by MDH.
- Disclosure when a home is sold or rented
The Minnesota Radon Awareness Act requires specific disclosure and education be provided to potential home buyers during residential real estate transactions in Minnesota.
What it means
Pennington County, Questions
Questions about radon in Pennington County
Are radon levels high in Pennington County?
In 2023, 53.3% of the radon tests reported to CDC for Pennington County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.5 pCi/L. Of 85 Minnesota counties with 30 or more tests for the same period, 46 reported a higher share; pooled, the state comes to 43.4%.
Which counties border Pennington County?
Pennington County borders 5 counties: Red Lake County, Marshall County, Polk County, Clearwater County and Beltrami County.
Products
Pennington County, Products
Testing a home in Pennington County
In Pennington County, 52.3% of 151 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 43.4% pooled across Minnesota. In Zone 1 the year-round level in Pennington County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
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
Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Pennington County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Pennington County
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Pennington County, Bordering counties
Counties bordering Pennington County
Calculated by Radon411- Radon levels in Polk CountyEPA zone 1
70.8%at or above 4 pCi/L
Median 6.7 pCi/L · 397 tests · 18.5 points above Pennington County
- Radon levels in Marshall CountyEPA zone 1
55.6%at or above 4 pCi/L
Median 5.4 pCi/L · 99 tests · 3.3 points above Pennington County
- Radon levels in Clearwater CountyEPA zone 2
50.5%at or above 4 pCi/L
Median 4.0 pCi/L · 91 tests · 1.8 points below Pennington County
- Radon levels in Beltrami CountyEPA zone 2
41.9%at or above 4 pCi/L
Median 3.4 pCi/L · 580 tests · 10.4 points below Pennington County
- Radon levels in Red Lake CountyEPA zone 1
33.3%at or above 4 pCi/L
Median 2.7 pCi/L · 51 tests · 19.0 points below Pennington County
Pennington County, Cities and towns
Cities and towns in Pennington County
About 13,686 people live in Pennington County by the Census Bureau's estimate for July 1, 2025, 256 fewer than in 2020 (−1.8%). That works out to 22 people per square mile of land. Thief River Falls alone is home to 8,799 of them, 64.3% of the total. Together its 3 incorporated places hold 67.0% of those residents; the other 33.0% live outside any of them. Reported testing is thin here: 151 tests over 2008 to 2017, or 11.0 for every 1,000 residents (2025 estimate), where Minnesota as a whole comes to 22.5.
From Thief River Falls to Goodridge, CDC publishes no figure by town: each reads Pennington County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Thief River Falls | 8,799 | −0.4% | 64.3% |
| St. Hilaire | 259 | −5.1% | 1.9% |
| Goodridge | 108 | −2.7% | 0.8% |
3 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).
Pennington County, Homes
Homes in Pennington County
Of Pennington County's 6,755 homes, 64% are detached houses, against 66% across Minnesota; 17% are in buildings of five or more homes. Half of its homes were built before 1975, close to Minnesota's 1978: 31% date from before 1960 and 20% from 2000 or later. 71% of occupied homes are lived in by their owner (Minnesota: 72%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Pennington County | Minnesota |
|---|---|---|
| Housing units | 6,755 | 2,519,538 |
| Detached houses | 64% | 66% |
| In buildings of 5 or more | 17% | 19% |
| Mobile homes | 12% | 3% |
| Built before 1960 | 31% | 29% |
| Built since 2000 | 20% | 22% |
| Middle year built | 1975 | 1978 |
| Owner-occupied | 71% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.