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Radon Levels in Winona County, Minnesota

EPA puts Winona County in Zone 1, its highest radon zone, and 38.8% of its 139 reported radon tests (2023) were 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    38.8%

    4.2 pts above MN

    Winona
    38.8%
    Minnesota
    34.6%

    139 tests, 2023

  • Median result

    3.0pCi/L

    Below action level

    Winona
    3.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    139

    22nd of 62 by tests

    Winona
    139
    Hennepin
    6,545

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Minnesota

    42 of 62

    Middle half

    Winona
    38.8%
    Renville
    75.7%

    By share, of 62 with 30+ tests

Read a result for Winona County

Starts at Winona County's median, 3.0 pCi/L

3.0pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 3.0 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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. Winona County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Winona County, At a glance

Winona County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Winona County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

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 Winona County, 2023

Share of reported tests at or above 4 pCi/L, by year, Winona County
Share of reported tests at or above 4 pCi/L, by year, Winona County
YearShare of reported tests at or above 4 pCi/L
201449.0%
201546.0%
201641.6%
201748.7%
201842.0%
201942.7%
202021.2%
202138.5%
202243.8%
202338.8%

2023: 38.8%. Across these years the share ran from 21.2% to 49.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 139 tests reported to CDC for Winona 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).

How to read these figures

Winona County, Compared

Winona County radon figures, compared

Calculated by Radon411

In Winona County, about 4 in 10 reported tests in 2023 (54 of 139) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 5.4 points higher. Across 86 Minnesota counties pooled together, 34.6% of tests reached that level, so Winona County runs 4.2 points above its state.

Of 7 neighbours with a figure, 6 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 31.4% (La Crosse County, WI) to 53.6% (Buffalo County, WI). By share, Winona County is 42nd of 62 Minnesota counties with 30 or more tests for the same period.

Year by year, 2014 opened at 49.0% and 2023 closed at 38.8% (down 10.2 points), with 2014 the high at 49.0%. Half the tests came in under 3.0 pCi/L and half over it; the single highest reached 22.8 pCi/L. Below the action level, 43 tests (30.9%) came in under 2 pCi/L, against 36.6% statewide, and 42 tests (30.2%) fell between 2 and 4, against 28.9% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 38.8% share point the same way here. USGS geology rates 100% of the county's land high radon potential.

The busiest year on file was 2014, with 675 tests reported; the quietest, 2019, had 124.

Share of reported tests at or above 4 pCi/L by year, Winona County against Minnesota2014 to 2023, years with 30 or more tests: Winona County 49.0% to 38.8%, the state's pooled share 34.6% in 2023.
Winona CountyMinnesota, pooled
Share of reported tests at or above 4 pCi/L by year, Winona County against Minnesota: data table
YearTestsWinona County, at or above 4 pCi/LMinnesota, pooled
201467549.0%42.9%
201550746.0%43.6%
201645041.6%37.0%
201715848.7%38.2%
201817442.0%38.3%
201912442.7%36.1%
202029221.2%31.8%
202117438.5%33.1%
202222443.8%31.6%
202313938.8%34.6%
Winona County against Minnesota, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Winona County
Winona County13938.8%3.0 pCi/LThis county
Minnesota, pooled86 counties, pooled22,44934.6%Not pooled−4.2 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−5.4 points
Renville Countyhighest in the state3775.7%6.3 pCi/L+36.9 points
Lake Countylowest in the state783.8%1.3 pCi/L−35.0 points
Buffalo County, WIborders it5653.6%4.4 pCi/L+14.8 points
Fillmore County, MNborders it11853.4%4.2 pCi/L+14.6 points
Houston County, MNborders it11347.8%3.5 pCi/L+9.0 points
Olmsted County, MNborders it85446.1%3.7 pCi/L+7.3 points
Wabasha County, MNborders it11142.3%3.3 pCi/L+3.5 points
Trempealeau County, WIborders it11242.0%3.3 pCi/L+3.2 points
La Crosse County, WIborders it77131.4%2.7 pCi/L−7.4 points
Where Winona County's reported results fell, 2023, beside Minnesota and the United States
ResultWinona County testsWinona County shareMinnesota shareU.S. shareAgainst Minnesota
Under 2 pCi/L4330.9%36.6%41.4%−5.7 points
2 to 4 pCi/L4230.2%28.9%25.2%+1.3 points
4 pCi/L and above5438.8%34.6%33.4%+4.2 points
Winona County ranked among the 62 Minnesota counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Swift County37 of 623641.7%3.8 pCi/L
Scott County38 of 6266941.4%3.4 pCi/L
Beltrami County39 of 625440.7%3.0 pCi/L
Rice County40 of 6229740.4%3.2 pCi/L
Pine County41 of 624839.6%2.5 pCi/L
Winona County42 of 6213938.8%3.0 pCi/L
Aitkin County43 of 623138.7%3.1 pCi/L
Morrison County44 of 626235.5%3.0 pCi/L
Chisago County45 of 6216634.9%2.9 pCi/L
Dakota County46 of 622,18334.6%2.9 pCi/L
Carver County47 of 6248934.6%2.8 pCi/L
Winona County radon tests by year, against Minnesota's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMinnesota, pooledChange from the row before
202313938.8%3.0 pCi/L22.8 pCi/L34.6%−5.0 points
202222443.8%3.3 pCi/L26.4 pCi/L31.6%+5.3 points
202117438.5%2.8 pCi/L22.8 pCi/L33.1%+17.3 points
202029221.2%1.6 pCi/L14.7 pCi/L31.8%−21.5 points
201912442.7%3.5 pCi/L36.3 pCi/L36.1%+0.7 points
201817442.0%3.2 pCi/L49.4 pCi/L38.3%−6.7 points
201715848.7%3.8 pCi/L39.1 pCi/L38.2%+7.1 points
201645041.6%3.3 pCi/L85.7 pCi/L37.0%−4.4 points
201550746.0%3.7 pCi/L35.3 pCi/L43.6%−3.0 points
201467549.0%3.9 pCi/L52.7 pCi/L42.9%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Winona County, State data

Minnesota's own radon test data

Measured

What Minnesota's own agencies publish about radon tests in Winona 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 Winona 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

41.3%

806 properties tested with one or more tests at or above 4 pCi/L

Median result

3.1 pCi/L

Average result

4.3 pCi/L

Tests behind these figures

195 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.

Winona County, Geology

The ground under Winona County

Predicted

USGS's geologic map puts all of Winona County's mapped land in one class: high radon potential. All of it lies in the area the map calls Driftless Section, to which USGS gives a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under Winona County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Driftless SectionOrdivician carbonates and sandstones.High1299.8%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Winona County beside the ground around it

Winona County has more high-potential ground than Minnesota as a whole: 100% of its land against 61.1%. Of the 7 counties that border it, none has as large a share of high-potential ground; Olmsted County comes nearest at 100%.

Share of land by USGS radon potential: Winona County, the 7 counties bordering it and Minnesota
AreaEPA zoneLow potentialModerate potentialHigh potential
Winona CountyZone 1NoneNone100%
Buffalo County, WIZone 1None15.8%84.2%
Fillmore CountyZone 1NoneNone100%
Wabasha CountyZone 1NoneNone100%
Houston CountyZone 1NoneNone100%
Olmsted CountyZone 1NoneNone100%
La Crosse County, WIZone 2None66.4%33.6%
Trempealeau County, WIZone 2None65.7%34.3%
Minnesota87 counties, pooled by land areaVariesNone38.9%61.1%

The map rates the ground, not the air in any home.

Local help

Winona County, Local resources

Radon testing and mitigation in Winona County

Listed radon businesses with an address in Winona County:

Listed radon professionals by town: Winona, Altura

What Minnesota's program says
Phone
651-201-4601
Email
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

Winona County, Questions

Questions about radon in Winona County

Are radon levels high in Winona County?

In 2023, 38.8% of the radon tests reported to CDC for Winona County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.0 pCi/L. Of 62 Minnesota counties with 30 or more tests for the same period, 41 reported a higher share; pooled, the state comes to 34.6%.

Which counties border Winona County?

Winona County borders 7 counties: Buffalo County, WI, Fillmore County, MN, Wabasha County, MN, Houston County, MN, Olmsted County, MN, La Crosse County, WI and Trempealeau County, WI.

Products

Winona County, Products

Testing a home in Winona County

In Winona County, 38.8% of 139 tests reported to CDC in 2023 reached 4 pCi/L, against 34.6% pooled across Minnesota. In Zone 1 the year-round level in Winona 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

Winona County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Winona County

Explore

Winona County, Bordering counties

Counties bordering Winona County

Calculated by Radon411

Winona County, Cities and towns

Cities and towns in Winona County

The Census Bureau estimates 50,523 residents in Winona County for July 1, 2025, 867 more than in 2020 (+1.7%). That works out to 81 people per square mile of land. Winona alone is home to 26,530 of them, 52.5% of the total. CDC's 139 reported tests for 2023 work out to 2.8 per 1,000 residents (2025 estimate), close to Minnesota's 3.9.

From Winona to Minneiska, CDC publishes no figure by town: each reads Winona County's.

The 12 largest cities and towns in Winona County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Winona26,530+2.1%52.5%
La Crescentextends beyond Winona County5,261−1.5%Counted whole
Goodview4,122+0.3%8.2%
St. Charles4,090+1.5%8.1%
Lewiston1,514−0.7%3.0%
Stockton837+1.2%1.7%
Rollingstone703+3.4%1.4%
Altura463−0.4%0.9%
Dakota288−0.7%0.6%
Utica274−1.4%0.5%
Minnesota City188−1.6%0.4%
Elba132−0.8%0.3%
  • Minneiska (part)

13 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 Winona County is counted whole, so it has no share.

Winona County, Homes

Homes in Winona County

Of Winona County's 21,763 homes, 66% are detached houses, against 66% across Minnesota; 17% are in buildings of five or more homes. The homes are older than Minnesota's as a whole: half were built before 1970 (1978 for Minnesota), and 41% date from before 1960. 69% 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 in Winona County, Minnesota, 2019 to 2023
HomesWinona CountyMinnesota
Housing units21,7632,519,538
Detached houses66%66%
In buildings of 5 or more17%19%
Mobile homes4%3%
Built before 196041%29%
Built since 200017%22%
Middle year built19701978
Owner-occupied69%72%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.