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Radon Levels in Henry County, Iowa

EPA puts Henry County in Zone 1, its highest radon zone, and high results are common there: 46.4% of the 168 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    46.4%

    12.1 pts below IA

    Henry
    46.4%
    Iowa
    58.5%

    168 tests, 2008 to 2017

  • Median result

    3.4pCi/L

    Below action level

    Henry
    3.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    168

    83rd of 99 by tests

    Henry
    168
    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

    84 of 99

    Lowest quarter

    Henry
    46.4%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Henry County

Starts at Henry County's median, 3.4 pCi/L

3.4pCi/L

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

EPA’s reading of 3.4 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. Henry County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Henry County, At a glance

Henry County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Henry County, 2008 to 2017, laboratory
Under 2 pCi/L: 26%2 to 4 pCi/L: 28%4 pCi/L and above: 46%

Of 168 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Henry County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L4325.6%
2 to 4 pCi/L4728.0%
4 pCi/L and above7846.4%
What these figures count

These are the 168 tests reported to CDC for Henry 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

Henry County, Compared

Henry County radon figures, compared

Calculated by Radon411

In Henry County, about 5 in 10 reported tests over the 2008 to 2017 laboratory totals (78 of 168) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 10.7 points higher. Across 99 Iowa counties pooled together, 58.5% of tests reached that level, so Henry County runs 12.1 points below its state.

Of 6 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 32.1% (Van Buren County) to 54.9% (Washington County). By share, Henry County is 84th of 99 Iowa counties with 30 or more tests for the same period.

Half the tests came in under 3.4 pCi/L and half over it; the single highest reached 37.3 pCi/L. Below the action level, 43 tests (25.6%) came in under 2 pCi/L, against 21.8% statewide, and 47 tests (28.0%) fell between 2 and 4, against 19.7% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 46.4% share point the same way here. USGS geology rates 100% of the county's land high radon potential. CDC also counts 10 tests taken after mitigation in Henry County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Henry County went from 216 tests (2005 to 2014) to 168 (2008 to 2017), the share going from 47.2% to 46.4%.

Henry County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Henry County
Henry County16846.4%3.4 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled+12.1 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−10.7 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+37.8 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−20.5 points
Washington County, IAborders it1,18654.9%4.6 pCi/L+8.5 points
Louisa County, IAborders it9652.1%4.1 pCi/L+5.7 points
Des Moines County, IAborders it43651.1%4.2 pCi/L+4.7 points
Lee County, IAborders it35143.6%3.2 pCi/L−2.8 points
Jefferson County, IAborders it84133.5%2.6 pCi/L−12.9 points
Van Buren County, IAborders it5632.1%2.3 pCi/L−14.3 points
Where Henry County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultHenry County testsHenry County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L4325.6%21.8%39.6%+3.8 points
2 to 4 pCi/L4728.0%19.7%24.7%+8.3 points
4 pCi/L and above7846.4%58.5%35.7%−12.1 points
Henry 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
Des Moines County79 of 9943651.1%4.2 pCi/L
Delaware County80 of 9952050.0%4.0 pCi/L
Black Hawk County81 of 993,22348.4%3.8 pCi/L
Dubuque County82 of 993,77546.8%3.6 pCi/L
Muscatine County83 of 9995446.5%3.7 pCi/L
Henry County84 of 9916846.4%3.4 pCi/L
Clarke County85 of 9912045.8%3.5 pCi/L
Appanoose County86 of 9911745.3%3.7 pCi/L
Scott County87 of 993,52044.3%3.3 pCi/L
Lee County88 of 9935143.6%3.2 pCi/L
Davis County89 of 998542.4%3.1 pCi/L
Henry County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 201716846.4%3.4 pCi/L37.3 pCi/L58.5%Level
2007 to 201616846.4%3.5 pCi/L66.0 pCi/L58.6%−2.8 points
2006 to 201518749.2%3.9 pCi/L66.0 pCi/L59.4%+2.0 points
2005 to 201421647.2%3.5 pCi/L66.0 pCi/L59.6%First on file

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

Henry County, Geology

The ground under Henry County

Predicted

USGS's geologic map puts all of Henry County's mapped land in one class: high radon potential. All of it lies in the area the map calls Loess-Covered Drift Plains, to which USGS gives a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under Henry County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Loess-Covered Drift PlainsPre-Illinoian and Illinoian glacial deposits, and loess.High13100%

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

Henry County beside the ground around it

On high-potential ground Henry County is close to Iowa as a whole: 100% of its land against 98.8%. Of the 6 counties that border it, none has as large a share of high-potential ground; Des Moines County comes nearest at 100%.

Share of land by USGS radon potential: Henry County, the 6 counties bordering it and Iowa
AreaEPA zoneLow potentialModerate potentialHigh potential
Henry CountyZone 1NoneNone100%
Des Moines CountyZone 1NoneNone100%
Jefferson CountyZone 1NoneNone100%
Washington CountyZone 1NoneNone100%
Louisa CountyZone 1NoneNone100%
Van Buren CountyZone 1None8.8%91.2%
Lee CountyZone 1None0.1%99.9%
Iowa99 counties, pooled by land areaVariesNone1.2%98.8%

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

Local help

Henry County, Local resources

Radon testing and mitigation in Henry County

Listed radon businesses with an address in Henry County:

Listed radon professionals by town: Mount Pleasant

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

Henry County, Questions

Questions about radon in Henry County

Are radon levels high in Henry County?

Over the 2008 to 2017 laboratory totals, 46.4% of the radon tests reported to CDC for Henry County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.4 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 83 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Henry County?

Henry County borders 6 counties: Des Moines County, Jefferson County, Washington County, Louisa County, Van Buren County and Lee County.

Products

Henry County, Products

Testing a home in Henry County

In Henry County, 46.4% of 168 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 Henry 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

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

Explore

Henry County, Bordering counties

Counties bordering Henry County

Calculated by Radon411

Henry County, Cities and towns

Cities and towns in Henry County

Henry County has been losing residents: from 20,450 in 2020 to 19,349 on July 1, 2025, a fall of 5.4% by the Census Bureau's estimates. That works out to 45 people per square mile of land. Its largest town, Mount Pleasant, has 8,500 residents, 43.9% of the total. Reported testing is thin here: 168 tests over 2008 to 2017, or 8.7 for every 1,000 residents (2025 estimate), where Iowa as a whole comes to 29.4.

From Mount Pleasant to Coppock, CDC publishes no figure by town: each reads Henry County's.

The cities and towns in Henry County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Mount Pleasant8,500−8.3%43.9%
New London1,850−3.2%9.6%
Winfield1,004−2.6%5.2%
Wayland932−2.9%4.8%
Salem381−4.3%2.0%
Olds165−4.1%0.9%
Hillsboro160−3.0%0.8%
Rome111−2.6%0.6%
Westwood95−5.0%0.5%
Coppockextends beyond Henry County35−2.8%Counted whole

10 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 Henry County is counted whole, so it has no share.

Henry County, Homes

Homes in Henry County

Henry County is a place of houses on their own lots: 79% of its 8,442 homes are detached single-family houses, against 72% across Iowa. Half of its homes were built before 1966, close to Iowa's 1971: 43% date from before 1960 and 13% from 2000 or later. 74% of occupied homes are lived in by their owner (Iowa: 72%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Henry County, Iowa, 2019 to 2023
HomesHenry CountyIowa
Housing units8,4421,427,175
Detached houses79%72%
In buildings of 5 or more6%14%
Mobile homes5%3%
Built before 196043%39%
Built since 200013%21%
Middle year built19661971
Owner-occupied74%72%

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