Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Nobles County, Minnesota
EPA puts Nobles County in Zone 1, its highest radon zone, and high results are common there: 58.5% of the 41 radon tests reported to CDC (2023) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
58.5%
23.9 pts above MN
- Nobles
- 58.5%
- Minnesota
- 34.6%
41 tests, 2023
Median result
4.7pCi/L
Action level reached
- Nobles
- 4.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
41
55th of 62 by tests
- Nobles
- 41
- Hennepin
- 6,545
Reported to CDC before any fix, 2023
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
15 of 62
Top quarter
- Nobles
- 58.5%
- Renville
- 75.7%
By share, of 62 with 30+ tests
Read a result for Nobles County
Starts at Nobles County's median, 4.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.7 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. Nobles County's median reported result, 2023.
The data
Nobles County, At a glance
Nobles County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Nobles County in
USGS geologic potential: High across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Nobles County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 70.8% |
| 2015 | 39.8% |
| 2016 | 65.8% |
| 2017 | 71.0% |
| 2018 | 67.5% |
| 2019 | 55.6% |
| 2020 | 63.3% |
| 2021 | 53.8% |
| 2022 | 57.9% |
| 2023 | 58.5% |
2023: 58.5%. Across these years the share ran from 39.8% to 71.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 41 tests reported to CDC for Nobles County over 2023, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Nobles County, Compared
Nobles County radon figures, compared
Calculated by Radon411More than half: 58.5% of the 41 radon tests reported to CDC for Nobles County in 2023 read at least 4 pCi/L. That places it 15th of 62 Minnesota counties with 30 or more tests for the same period. That is 23.9 points above the 34.6% pooled from 86 Minnesota counties.
The median result, 4.7 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 32.2 pCi/L. The rest split 22.0% under 2 pCi/L and 19.5% from 2 to 4 (Minnesota: 36.6% and 28.9%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 58.5% share point the same way here.
No bordering county with a figure for the same period reported a higher share; the closest is Jackson County at 52.3%, the lowest Rock County at 42.4%. Statewide for the same period, Renville County reported the highest share (75.7%) and Lake County the lowest (3.8%).
The busiest year on file was 2015, with 83 tests reported; the quietest, 2017, had 31.
Over 10 years of annual figures the share fell 12.3 points, from 70.8% in 2014 to 58.5% in 2023; its peak was 71.0% in 2017. Nationally, every county with a figure for the same period pools to 33.4%; Nobles County sits 25.1 points above it.
Nobles CountyMinnesota, pooled
58.5% % of tests34.6% % of tests
| Year | Tests | Nobles County, at or above 4 pCi/L | Minnesota, pooled |
|---|---|---|---|
| 2014 | 65 | 70.8% | 42.9% |
| 2015 | 83 | 39.8% | 43.6% |
| 2016 | 38 | 65.8% | 37.0% |
| 2017 | 31 | 71.0% | 38.2% |
| 2018 | 40 | 67.5% | 38.3% |
| 2019 | 36 | 55.6% | 36.1% |
| 2020 | 49 | 63.3% | 31.8% |
| 2021 | 39 | 53.8% | 33.1% |
| 2022 | 38 | 57.9% | 31.6% |
| 2023 | 41 | 58.5% | 34.6% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Nobles County, State data
Minnesota's own radon test data
MeasuredWhat Minnesota's own agencies publish about radon tests in Nobles 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 Nobles 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
71.8%
224 properties tested with one or more tests at or above 4 pCi/L
Median result
6.2 pCi/L
Average result
8.3 pCi/L
Tests behind these figures
31 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.
Nobles County, Geology
The ground under Nobles County
PredictedUSGS's geologic map puts all of Nobles County's mapped land in one class: high radon potential. The map puts 91.5% of Nobles County in the area it calls Central Lowland-Till Prairie and 7.5% in Prairie Coteau, with one smaller area beside them. USGS gives the first a radon index of 14 and the second 12, both in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Central Lowland-Till Prairie | Silty and clayey till derived from shale and sandstone. | High | 14 | 91.5% |
| Prairie Coteau | Pre-Wisconsinan glacial deposits (includes Wisconsinan loess and older bedrock). | High | 12 | 7.5% |
| Des Moines Lobe | Calcareous loamy till derived from shale, limestone, dolomite, sandstone. | High | 12 | 0.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Nobles County beside the ground around it
Nobles County has more high-potential ground than Minnesota as a whole: 100% of its land against 61.1%. Of the 6 counties that border it, none has as large a share of high-potential ground; Cottonwood County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Nobles County, Local resources
Radon testing and mitigation in Nobles 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
Nobles County, Questions
Questions about radon in Nobles County
Are radon levels high in Nobles County?
In 2023, 58.5% of the radon tests reported to CDC for Nobles County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.7 pCi/L. Of 62 Minnesota counties with 30 or more tests for the same period, 14 reported a higher share; pooled, the state comes to 34.6%.
Which counties border Nobles County?
Nobles County borders 6 counties: Osceola County, IA, Murray County, MN, Rock County, MN, Jackson County, MN, Lyon County, IA and Cottonwood County, MN.
Products
Nobles County, Products
Testing a home in Nobles County
In Nobles County, 58.5% of 41 tests reported to CDC in 2023 reached 4 pCi/L, against 34.6% pooled across Minnesota. In Zone 1 the year-round level in Nobles 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
Monitor
RM-63Pro rechargeable radon monitor with a touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Nobles County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Nobles County
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Nobles County, Bordering counties
Counties bordering Nobles County
Calculated by Radon411- Radon levels in Murray County, MNEPA zone 1
72.0%at or above 4 pCi/L
Median 8.1 pCi/L · 25 tests · 13.5 points above Nobles County
- Radon levels in Jackson County, MNEPA zone 1
52.3%at or above 4 pCi/L
Median 4.1 pCi/L · 44 tests · 6.2 points below Nobles County
- Radon levels in Cottonwood County, MNEPA zone 1
50.0%at or above 4 pCi/L
Median 3.5 pCi/L · 12 tests · 8.5 points below Nobles County
- Radon levels in Rock County, MNEPA zone 1
42.4%at or above 4 pCi/L
Median 2.0 pCi/L · 59 tests · 16.1 points below Nobles County
- Radon levels in Osceola County, IAEPA zone 1
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Lyon County, IAEPA zone 1
No CDC figure for 2023; its page reads it against its own neighbours.
Nobles County, Cities and towns
Cities and towns in Nobles County
The Census Bureau estimates 22,338 residents in Nobles County for July 1, 2025, 137 more than in 2020 (+0.6%). That works out to 31 people per square mile of land. Worthington alone is home to 13,979 of them, 62.6% of the total. Together its 11 incorporated places hold 79.6% of those residents; the other 20.4% live outside any of them. Reported testing is thin here: 41 tests over 2023, or 1.8 for every 1,000 residents (2025 estimate), where Minnesota as a whole comes to 3.9.
From Worthington to Kinbrae, CDC publishes no figure by town: each reads Nobles County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Worthington | 13,979 | +0.7% | 62.6% |
| Adrian | 1,219 | +1.9% | 5.5% |
| Brewster | 508 | Level | 2.3% |
| Ellsworth | 493 | Level | 2.2% |
| Rushmore | 373 | +0.8% | 1.7% |
| Round Lake | 371 | −0.8% | 1.7% |
| Wilmont | 329 | −0.6% | 1.5% |
| Bigelow | 223 | −0.9% | 1.0% |
| Lismore | 207 | +1.5% | 0.9% |
| Dundee | 78 | +8.3% | 0.3% |
| Kinbrae | 12 | Level | Under 0.1% |
11 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).
Nobles County, Homes
Homes in Nobles County
Nobles County is a place of houses on their own lots: 79% of its 8,398 homes are detached single-family houses, against 66% across Minnesota. The homes are older than Minnesota's as a whole: half were built before 1968 (1978 for Minnesota), and 42% date from before 1960. 72% 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 | Nobles County | Minnesota |
|---|---|---|
| Housing units | 8,398 | 2,519,538 |
| Detached houses | 79% | 66% |
| In buildings of 5 or more | 13% | 19% |
| Mobile homes | 3% | 3% |
| Built before 1960 | 42% | 29% |
| Built since 2000 | 11% | 22% |
| Middle year built | 1968 | 1978 |
| Owner-occupied | 72% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.