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Radon Levels in Hancock County, Iowa

EPA puts Hancock County in Zone 1, its highest radon zone, and high results are common there: 64.5% of the 640 radon tests reported to CDC (2008 to 2017, laboratory totals) 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

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  • Share at 4+ pCi/L

    64.5%

    6.0 pts above IA

    Hancock
    64.5%
    Iowa
    58.5%

    640 tests, 2008 to 2017

  • Median result

    5.5pCi/L

    Action level reached

    Hancock
    5.5 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    640

    38th of 99 by tests

    Hancock
    640
    Polk
    10,945

    Reported to CDC before any fix, 2008 to 2017

  • 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 Iowa

    50 of 99

    Middle half

    Hancock
    64.5%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Hancock County

Starts at Hancock County's median, 5.5 pCi/L

5.5pCi/L

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

EPA’s reading of 5.5 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. Hancock County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Hancock County, At a glance

Hancock County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Hancock 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 Hancock County, 2008 to 2017, laboratory

Reported results by concentration band, Hancock County, 2008 to 2017, laboratory
Under 2 pCi/L: 15%2 to 4 pCi/L: 21%4 pCi/L and above: 64%

Of 640 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Hancock County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L9414.7%
2 to 4 pCi/L13320.8%
4 pCi/L and above41364.5%
What these figures count

These are the 640 tests reported to CDC for Hancock County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Hancock County, Compared

Hancock County radon figures, compared

Calculated by Radon411

More than half: 64.5% of the 640 radon tests reported to CDC for Hancock County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 50th of 99 Iowa counties with 30 or more tests for the same period. That is 6.0 points above the 58.5% pooled from 99 Iowa counties.

The median result, 5.5 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 189.1 pCi/L. The rest split 14.7% under 2 pCi/L and 20.8% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 64.5% share point the same way here.

6 of its 7 bordering counties with figures ran higher, led by Franklin County at 73.5%; Cerro Gordo County reported 59.0%. Statewide for the same period, Sioux County reported the highest share (84.2%) and Decatur County the lowest (25.9%).

CDC's ten-year totals for Hancock County went from 530 tests (2005 to 2014) to 640 (2008 to 2017), the share going from 67.2% to 64.5%.

Nationally, every county with a figure for the same period pools to 35.7%; Hancock County sits 28.8 points above it. CDC also counts 54 tests taken after mitigation in Hancock County for the same period: tests in homes where a fix was already in.

Hancock County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Hancock County
Hancock County64064.5%5.5 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled−6.0 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−28.8 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+19.7 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−38.6 points
Franklin County, IAborders it31373.5%6.2 pCi/L+9.0 points
Winnebago County, IAborders it82971.9%6.7 pCi/L+7.4 points
Humboldt County, IAborders it38570.1%7.0 pCi/L+5.6 points
Worth County, IAborders it15467.5%6.0 pCi/L+3.0 points
Wright County, IAborders it29266.8%6.2 pCi/L+2.3 points
Kossuth County, IAborders it43466.1%5.7 pCi/L+1.6 points
Cerro Gordo County, IAborders it1,66259.0%4.8 pCi/L−5.5 points
Where Hancock County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultHancock County testsHancock County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L9414.7%21.8%39.6%−7.1 points
2 to 4 pCi/L13320.8%19.7%24.7%+1.1 points
4 pCi/L and above41364.5%58.5%35.7%+6.0 points
Hancock County ranked among the 99 Iowa counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Wright County45 of 9929266.8%6.2 pCi/L
Winneshiek County46 of 991,07166.4%6.2 pCi/L
Kossuth County47 of 9943466.1%5.7 pCi/L
Warren County48 of 991,51366.0%6.3 pCi/L
Adams County49 of 998165.4%6.1 pCi/L
Hancock County50 of 9964064.5%5.5 pCi/L
Polk County51 of 9910,94564.4%5.6 pCi/L
Hamilton County52 of 9925264.3%5.5 pCi/L
Hardin County53 of 9934962.8%5.6 pCi/L
Fayette County54 of 9974662.7%5.6 pCi/L
Clayton County55 of 9931062.6%5.8 pCi/L
Hancock County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 201764064.5%5.5 pCi/L189.1 pCi/L58.5%−0.5 points
2007 to 201661165.0%5.6 pCi/L189.1 pCi/L58.6%−1.8 points
2006 to 201559666.8%5.8 pCi/L189.1 pCi/L59.4%−0.4 points
2005 to 201453067.2%6.0 pCi/L189.1 pCi/L59.6%First on file

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

Hancock County, Geology

The ground under Hancock County

Predicted

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

USGS's geologic areas under Hancock County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Des Moines LobeCalcareous loamy till derived from shale, limestone, dolomite, sandstone.High12100%

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

Hancock County beside the ground around it

On high-potential ground Hancock County is close to Iowa as a whole: 100% of its land against 98.8%. Of the 7 counties that border it, none has as large a share of high-potential ground; Cerro Gordo County comes nearest at 100%.

Share of land by USGS radon potential: Hancock County, the 7 counties bordering it and Iowa
AreaEPA zoneLow potentialModerate potentialHigh potential
Hancock CountyZone 1NoneNone100%
Winnebago CountyZone 1NoneNone100%
Wright CountyZone 1NoneNone100%
Cerro Gordo CountyZone 1NoneNone100%
Kossuth CountyZone 1NoneNone100%
Worth CountyZone 1NoneNone100%
Humboldt CountyZone 1NoneNone100%
Franklin CountyZone 1NoneNone100%
Iowa99 counties, pooled by land areaVariesNone1.2%98.8%

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

Local help

Hancock County, Local resources

Radon testing and mitigation in Hancock County

What Iowa's program says
Phone
(515) 281-4928
Licensing of radon professionals
Iowa’s radon program approves applications for persons who wish to become certified to perform radon testing or credentialed to perform mitigation and laboratories that provide radon testing devices and analytical services.
Disclosure when a home is sold or rented
However, per Iowa Code chapters 543B.9 and 543B.18 and Iowa Administrative Code 193E Chapter 14 administered by the Iowa Real Estate Commission, a seller must disclose any known tests for the presence of radon and if yes, provide the date of last report and the result(s).

What it means

Hancock County, Questions

Questions about radon in Hancock County

Are radon levels high in Hancock County?

Over the 2008 to 2017 laboratory totals, 64.5% of the radon tests reported to CDC for Hancock County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.5 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 49 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Hancock County?

Hancock County borders 7 counties: Winnebago County, Wright County, Cerro Gordo County, Kossuth County, Worth County, Humboldt County and Franklin County.

Products

Hancock County, Products

Testing a home in Hancock County

In Hancock County, 64.5% of 640 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 58.5% pooled across Iowa. In Zone 1 the year-round level in Hancock 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

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

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Hancock County, Bordering counties

Counties bordering Hancock County

Calculated by Radon411

Hancock County, Cities and towns

Cities and towns in Hancock County

About 10,528 people live in Hancock County by the Census Bureau's estimate for July 1, 2025, 235 fewer than in 2020 (−2.2%). That works out to 18 people per square mile of land. Forest City, the largest place on its list (4,143 residents in all), extends beyond Hancock County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 640 reported tests for 2008 to 2017 come to 60.8 for every 1,000 residents (2025 estimate), against 29.4 for Iowa.

From Forest City to Goodell, CDC publishes no figure by town: each reads Hancock County's.

The cities and towns in Hancock County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Forest Cityextends beyond Hancock County4,143−3.0%Counted whole
Garner3,029−0.9%28.8%
Britt1,981−2.8%18.8%
Kanawha630−3.7%6.0%
Klemme424−3.4%4.0%
Corwith253−4.2%2.4%
Crystal Lake240−5.5%2.3%
Woden185−3.6%1.8%
Goodell138−2.1%1.3%

9 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). A place that extends beyond Hancock County is counted whole, so it has no share.

Hancock County, Homes

Homes in Hancock County

Hancock County is a place of houses on their own lots: 87% of its 5,120 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1959 (1971 for Iowa), and 51% date from before 1960. Owners live in 82% of the occupied homes (Iowa: 72%), so for most households a test and a fix are their own to order.

Homes in Hancock County, Iowa, 2019 to 2023
HomesHancock CountyIowa
Housing units5,1201,427,175
Detached houses87%72%
In buildings of 5 or more5%14%
Mobile homes3%3%
Built before 196051%39%
Built since 200010%21%
Middle year built19591971
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.