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Radon Levels in Fillmore County, Minnesota

EPA puts Fillmore County in Zone 1, its highest radon zone, and high results are common there: 53.4% of the 118 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    53.4%

    18.8 pts above MN

    Fillmore
    53.4%
    Minnesota
    34.6%

    118 tests, 2023

  • Median result

    4.2pCi/L

    Action level reached

    Fillmore
    4.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    118

    27th of 62 by tests

    Fillmore
    118
    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

    18 of 62

    Middle half

    Fillmore
    53.4%
    Renville
    75.7%

    By share, of 62 with 30+ tests

Read a result for Fillmore County

Starts at Fillmore County's median, 4.2 pCi/L

4.2pCi/L

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

EPA’s reading of 4.2 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Fillmore County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Fillmore County, At a glance

Fillmore County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Fillmore 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 Fillmore County, 2023

Share of reported tests at or above 4 pCi/L, by year, Fillmore County
Share of reported tests at or above 4 pCi/L, by year, Fillmore County
YearShare of reported tests at or above 4 pCi/L
201463.5%
201556.7%
201660.7%
201759.0%
201857.6%
201966.7%
202053.9%
202152.0%
202252.9%
202353.4%

2023: 53.4%. Across these years the share ran from 52.0% to 66.7%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 118 tests reported to CDC for Fillmore 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

Fillmore County, Compared

Fillmore County radon figures, compared

Calculated by Radon411

More than half: 53.4% of the 118 radon tests reported to CDC for Fillmore County in 2023 read at least 4 pCi/L. That places it 18th of 62 Minnesota counties with 30 or more tests for the same period. That is 18.8 points above the 34.6% pooled from 86 Minnesota counties.

The median result, 4.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 78.1 pCi/L. The rest split 20.3% under 2 pCi/L and 26.3% from 2 to 4 (Minnesota: 36.6% and 28.9%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 53.4% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Houston County at 47.8%, the lowest Winona County at 38.8%. 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 2014, with 373 tests reported; the quietest, 2019, had 36.

Over 10 years of annual figures the share fell 10.1 points, from 63.5% in 2014 to 53.4% in 2023; its peak was 66.7% in 2019. Nationally, every county with a figure for the same period pools to 33.4%; Fillmore County sits 20.0 points above it.

Share of reported tests at or above 4 pCi/L by year, Fillmore County against Minnesota2014 to 2023, years with 30 or more tests: Fillmore County 63.5% to 53.4%, the state's pooled share 34.6% in 2023.
Fillmore CountyMinnesota, pooled
Share of reported tests at or above 4 pCi/L by year, Fillmore County against Minnesota: data table
YearTestsFillmore County, at or above 4 pCi/LMinnesota, pooled
201437363.5%42.9%
201529156.7%43.6%
201622460.7%37.0%
201721259.0%38.2%
201812557.6%38.3%
20193666.7%36.1%
202015453.9%31.8%
202110252.0%33.1%
202210452.9%31.6%
202311853.4%34.6%
Fillmore County against Minnesota, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Fillmore County
Fillmore County11853.4%4.2 pCi/LThis county
Minnesota, pooled86 counties, pooled22,44934.6%Not pooled−18.8 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−20.0 points
Renville Countyhighest in the state3775.7%6.3 pCi/L+22.3 points
Lake Countylowest in the state783.8%1.3 pCi/L−49.6 points
Houston County, MNborders it11347.8%3.5 pCi/L−5.6 points
Olmsted County, MNborders it85446.1%3.7 pCi/L−7.3 points
Mower County, MNborders it9145.1%3.7 pCi/L−8.3 points
Winona County, MNborders it13938.8%3.0 pCi/L−14.6 points
Where Fillmore County's reported results fell, 2023, beside Minnesota and the United States
ResultFillmore County testsFillmore County shareMinnesota shareU.S. shareAgainst Minnesota
Under 2 pCi/L2420.3%36.6%41.4%−16.3 points
2 to 4 pCi/L3126.3%28.9%25.2%−2.6 points
4 pCi/L and above6353.4%34.6%33.4%+18.8 points
Fillmore 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
Polk County13 of 629060.0%4.7 pCi/L
Sibley County13 of 625560.0%5.0 pCi/L
Nobles County15 of 624158.5%4.7 pCi/L
McLeod County16 of 6213155.7%4.7 pCi/L
Redwood County17 of 623154.8%4.6 pCi/L
Fillmore County18 of 6211853.4%4.2 pCi/L
Jackson County19 of 624452.3%4.1 pCi/L
Becker County20 of 624652.2%4.1 pCi/L
Steele County21 of 6214051.4%4.0 pCi/L
Pope County22 of 625550.9%4.2 pCi/L
Goodhue County23 of 6221849.5%3.9 pCi/L
Fillmore County radon tests by year, against Minnesota's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMinnesota, pooledChange from the row before
202311853.4%4.2 pCi/L78.1 pCi/L34.6%+0.5 points
202210452.9%4.1 pCi/L32.1 pCi/L31.6%+0.9 points
202110252.0%4.0 pCi/L54.6 pCi/L33.1%−1.9 points
202015453.9%4.3 pCi/L29.2 pCi/L31.8%−12.8 points
20193666.7%6.0 pCi/L23.4 pCi/L36.1%+9.1 points
201812557.6%6.2 pCi/L93.7 pCi/L38.3%−1.4 points
201721259.0%5.7 pCi/L74.8 pCi/L38.2%−1.7 points
201622460.7%5.5 pCi/L43.8 pCi/L37.0%+4.0 points
201529156.7%4.4 pCi/L59.7 pCi/L43.6%−6.8 points
201437363.5%5.7 pCi/L90.2 pCi/L42.9%First on file

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

Fillmore County, State data

Minnesota's own radon test data

Measured

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

59.6%

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

Median result

4.6 pCi/L

Average result

6.6 pCi/L

Tests behind these figures

100 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.

Fillmore County, Geology

The ground under Fillmore County

Predicted

USGS's geologic map puts all of Fillmore County's mapped land in one class: high radon potential. The map puts 81.3% of Fillmore County in the area it calls Driftless Section and 18.2% in Dissected Till Plains. USGS gives both a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under Fillmore County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Driftless SectionOrdivician carbonates and sandstones.High1281.3%
Dissected Till PlainsPre-Wisconsinan glacial deposits derived from limestone, dolomite, sandstone, shale, locally covered by Wisconsinan loess.High1218.2%

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

Fillmore County beside the ground around it

Fillmore 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; Olmsted County comes nearest at 100%.

Share of land by USGS radon potential: Fillmore County, the 6 counties bordering it and Minnesota
AreaEPA zoneLow potentialModerate potentialHigh potential
Fillmore CountyZone 1NoneNone100%
Howard County, IAZone 1NoneNone100%
Olmsted CountyZone 1NoneNone100%
Winona CountyZone 1NoneNone100%
Houston CountyZone 1NoneNone100%
Winneshiek County, IAZone 1NoneNone100%
Mower CountyZone 1NoneNone100%
Minnesota87 counties, pooled by land areaVariesNone38.9%61.1%

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

Local help

Fillmore County, Local resources

Radon testing and mitigation in Fillmore County

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

Fillmore County, Questions

Questions about radon in Fillmore County

Are radon levels high in Fillmore County?

In 2023, 53.4% of the radon tests reported to CDC for Fillmore County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.2 pCi/L. Of 62 Minnesota counties with 30 or more tests for the same period, 17 reported a higher share; pooled, the state comes to 34.6%.

Which counties border Fillmore County?

Fillmore County borders 6 counties: Howard County, IA, Olmsted County, MN, Winona County, MN, Houston County, MN, Winneshiek County, IA and Mower County, MN.

Products

Fillmore County, Products

Testing a home in Fillmore County

In Fillmore County, 53.4% of 118 tests reported to CDC in 2023 reached 4 pCi/L, against 34.6% pooled across Minnesota. In Zone 1 the year-round level in Fillmore 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

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

Explore

Fillmore County, Bordering counties

Counties bordering Fillmore County

Calculated by Radon411

Fillmore County, Cities and towns

Cities and towns in Fillmore County

The Census Bureau estimates 21,540 residents in Fillmore County for July 1, 2025, 305 more than in 2020 (+1.4%). That works out to 25 people per square mile of land. Chatfield, the largest place on its list (3,018 residents in all), extends beyond Fillmore County, so no share of the total is worked out for it. CDC's 118 reported tests for 2023 work out to 5.5 per 1,000 residents (2025 estimate), close to Minnesota's 3.9.

From Chatfield to Whalan, CDC publishes no figure by town: each reads Fillmore County's.

The 12 largest cities and towns in Fillmore County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Chatfieldextends beyond Fillmore County3,018+0.5%Counted whole
Spring Valley2,431−0.9%11.3%
Rushford1,849−0.8%8.6%
Preston1,318−0.2%6.1%
Harmony1,028−2.0%4.8%
Rushford Village796+0.4%3.7%
Lanesboro712−1.9%3.3%
Mabel700−2.1%3.2%
Wykoff437+1.2%2.0%
Fountain400−1.5%1.9%
Canton313+0.6%1.5%
Peterson226−2.6%1.0%
  • Ostrander
  • Whalan

14 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 Fillmore County is counted whole, so it has no share.

Fillmore County, Homes

Homes in Fillmore County

Fillmore County is a place of houses on their own lots: 84% of its 9,669 homes are detached single-family houses, against 66% across Minnesota. The homes are older than Minnesota's as a whole: half were built before 1966 (1978 for Minnesota), and 46% date from before 1960. Owners live in 82% of the occupied homes (Minnesota: 72%), so for most households a test and a fix are their own to order.

Homes in Fillmore County, Minnesota, 2019 to 2023
HomesFillmore CountyMinnesota
Housing units9,6692,519,538
Detached houses84%66%
In buildings of 5 or more7%19%
Mobile homes3%3%
Built before 196046%29%
Built since 200021%22%
Middle year built19661978
Owner-occupied82%72%

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