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Radon Levels in Clinton County, Iowa

EPA puts Clinton County in Zone 1, its highest radon zone, and high results are common there: 52.7% of the 1,375 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

    52.7%

    5.8 pts below IA

    Clinton
    52.7%
    Iowa
    58.5%

    1,375 tests, 2008 to 2017

  • Median result

    4.3pCi/L

    Action level reached

    Clinton
    4.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,375

    15th of 99 by tests

    Clinton
    1,375
    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

    76 of 99

    Lowest quarter

    Clinton
    52.7%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Clinton County

Starts at Clinton County's median, 4.3 pCi/L

4.3pCi/L

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

EPA’s reading of 4.3 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. Clinton County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Clinton County, At a glance

Clinton County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Clinton County, 2008 to 2017, laboratory
Under 2 pCi/L: 20%2 to 4 pCi/L: 27%4 pCi/L and above: 53%

Of 1,375 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Clinton County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L28220.5%
2 to 4 pCi/L36926.8%
4 pCi/L and above72452.7%
What these figures count

These are the 1,375 tests reported to CDC for Clinton 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

Clinton County, Compared

Clinton County radon figures, compared

Calculated by Radon411

More than half: 52.7% of the 1,375 radon tests reported to CDC for Clinton County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 76th of 99 Iowa counties with 30 or more tests for the same period. That is 5.8 points below the 58.5% pooled from 99 Iowa counties.

The median result, 4.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 65.6 pCi/L. The rest split 20.5% under 2 pCi/L and 26.8% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 52.7% share point the same way here.

3 of its 7 bordering counties with figures ran higher, led by Carroll County, IL at 60.8%; Scott County reported 44.3%. 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 Clinton County went from 1,310 tests (2005 to 2014) to 1,375 (2008 to 2017), the share going from 55.1% to 52.7%.

Nationally, every county with a figure for the same period pools to 35.7%; Clinton County sits 17.0 points above it. CDC also counts 131 tests taken after mitigation in Clinton County for the same period: tests in homes where a fix was already in.

Clinton County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Clinton County
Clinton County1,37552.7%4.3 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled+5.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−17.0 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+31.5 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−26.8 points
Carroll County, ILborders it43160.8%5.1 pCi/L+8.1 points
Cedar County, IAborders it76560.4%5.0 pCi/L+7.7 points
Jones County, IAborders it55559.3%5.1 pCi/L+6.6 points
Jackson County, IAborders it1,05652.7%4.1 pCi/LLevel
Rock Island County, ILborders it3,73648.3%3.8 pCi/L−4.4 points
Whiteside County, ILborders it64147.0%3.7 pCi/L−5.7 points
Scott County, IAborders it3,52044.3%3.3 pCi/L−8.4 points
Where Clinton County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultClinton County testsClinton County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L28220.5%21.8%39.6%−1.3 points
2 to 4 pCi/L36926.8%19.7%24.7%+7.1 points
4 pCi/L and above72452.7%58.5%35.7%−5.8 points
Clinton 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
Dallas County71 of 992,35258.5%4.9 pCi/L
Pottawattamie County72 of 991,86857.4%4.7 pCi/L
Washington County73 of 991,18654.9%4.6 pCi/L
Bremer County74 of 9995753.0%4.3 pCi/L
Jackson County75 of 991,05652.7%4.1 pCi/L
Clinton County76 of 991,37552.7%4.3 pCi/L
Louisa County77 of 999652.1%4.1 pCi/L
Buchanan County78 of 9956451.2%4.1 pCi/L
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
Clinton County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 20171,37552.7%4.3 pCi/L65.6 pCi/L58.5%+0.3 points
2007 to 20161,32052.4%4.3 pCi/L870.6 pCi/L58.6%−2.9 points
2006 to 20151,41355.3%4.5 pCi/L870.6 pCi/L59.4%+0.2 points
2005 to 20141,31055.1%4.5 pCi/L870.6 pCi/L59.6%First on file

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

Clinton County, Geology

The ground under Clinton County

Predicted

USGS's geologic map puts all of Clinton County's mapped land in one class: high radon potential. 99.1% 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 Clinton County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Loess-Covered Drift PlainsPre-Illinoian and Illinoian glacial deposits, and loess.High1399.1%
Paleozoic PlateauOrdovician carbonate and Cambrian sandstone bedrock covered by varying amounts of Quaternary glacial deposits and loess.High130.5%

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

Clinton County beside the ground around it

On high-potential ground Clinton 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; Jackson County comes nearest at 100%.

Share of land by USGS radon potential: Clinton County, the 7 counties bordering it and Iowa
AreaEPA zoneLow potentialModerate potentialHigh potential
Clinton CountyZone 1NoneNone100%
Scott CountyZone 1NoneNone100%
Jackson CountyZone 1NoneNone100%
Rock Island County, ILZone 1NoneNone100%
Cedar CountyZone 1NoneNone100%
Whiteside County, ILZone 1NoneNone100%
Carroll County, ILZone 1NoneNone100%
Jones CountyZone 1NoneNone100%
Iowa99 counties, pooled by land areaVariesNone1.2%98.8%

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

Local help

Clinton County, Local resources

Radon testing and mitigation in Clinton 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

Clinton County, Questions

Questions about radon in Clinton County

Are radon levels high in Clinton County?

Over the 2008 to 2017 laboratory totals, 52.7% of the radon tests reported to CDC for Clinton County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.3 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 75 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Clinton County?

Clinton County borders 7 counties: Scott County, IA, Jackson County, IA, Rock Island County, IL, Cedar County, IA, Whiteside County, IL, Carroll County, IL and Jones County, IA.

Products

Clinton County, Products

Testing a home in Clinton County

In Clinton County, 52.7% of 1,375 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 Clinton 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

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

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Clinton County, Bordering counties

Counties bordering Clinton County

Calculated by Radon411

Clinton County, Cities and towns

Cities and towns in Clinton County

About 46,002 people live in Clinton County by the Census Bureau's estimate for July 1, 2025, 429 fewer than in 2020 (−0.9%). That works out to 66 people per square mile of land. Clinton alone is home to 24,049 of them, 52.3% of the total. CDC's 1,375 reported tests for 2008 to 2017 work out to 29.9 per 1,000 residents (2025 estimate), close to Iowa's 29.4.

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

The 12 largest cities and towns in Clinton County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Clinton24,049−1.6%52.3%
Maquoketaextends beyond Clinton County6,027−1.6%Counted whole
DeWitt5,704+3.4%12.4%
Camanche4,557−0.3%9.9%
Wheatland763−2.2%1.7%
Grand Mound601−2.8%1.3%
Delmar539−1.1%1.2%
Lost Nation425−1.4%0.9%
Charlotte386−0.8%0.8%
Calamus346−2.3%0.8%
Goose Lake249Level0.5%
Low Moor240−3.2%0.5%
  • Welton
  • Andover
  • Toronto

15 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 Clinton County is counted whole, so it has no share.

Clinton County, Homes

Homes in Clinton County

Clinton County is a place of houses on their own lots: 77% of its 21,590 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1958 (1971 for Iowa), and 53% date from before 1960. 73% 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 Clinton County, Iowa, 2019 to 2023
HomesClinton CountyIowa
Housing units21,5901,427,175
Detached houses77%72%
In buildings of 5 or more11%14%
Mobile homes1%3%
Built before 196053%39%
Built since 200012%21%
Middle year built19581971
Owner-occupied73%72%

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