Skip to content
RADON411

Locations and reports

Radon Levels in Adams County, Iowa

EPA puts Adams County in Zone 1, its highest radon zone, and high results are common there: 65.4% of the 81 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

    65.4%

    6.9 pts above IA

    Adams
    65.4%
    Iowa
    58.5%

    81 tests, 2008 to 2017

  • Median result

    6.1pCi/L

    Action level reached

    Adams
    6.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    81

    96th of 99 by tests

    Adams
    81
    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

    49 of 99

    Middle half

    Adams
    65.4%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Adams County

Starts at Adams County's median, 6.1 pCi/L

6.1pCi/L

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

EPA’s reading of 6.1 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. Adams County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Adams County, At a glance

Adams County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Adams County, 2008 to 2017, laboratory
Under 2 pCi/L: 7%2 to 4 pCi/L: 27%4 pCi/L and above: 66%

Of 81 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Adams County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L67.4%
2 to 4 pCi/L2227.2%
4 pCi/L and above5365.4%
What these figures count

These are the 81 tests reported to CDC for Adams 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

Adams County, Compared

Adams County radon figures, compared

Calculated by Radon411

More than half: 65.4% of the 81 radon tests reported to CDC for Adams County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 49th of 99 Iowa counties with 30 or more tests for the same period. That is 6.9 points above the 58.5% pooled from 99 Iowa counties.

The median result, 6.1 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 40.7 pCi/L. The rest split 7.4% under 2 pCi/L and 27.2% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 65.4% share point the same way here.

4 of its 7 bordering counties with figures ran higher, led by Cass County at 77.4%; Ringgold County reported 28.7%. 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 Adams County went from 58 tests (2005 to 2014) to 81 (2008 to 2017), the share going from 65.5% to 65.4%.

Nationally, every county with a figure for the same period pools to 35.7%; Adams County sits 29.7 points above it.

Adams County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Adams County
Adams County8165.4%6.1 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled−6.9 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−29.7 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+18.8 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−39.5 points
Cass County, IAborders it32777.4%8.1 pCi/L+12.0 points
Adair County, IAborders it9872.4%9.3 pCi/L+7.0 points
Page County, IAborders it65371.7%7.2 pCi/L+6.3 points
Montgomery County, IAborders it23367.4%6.1 pCi/L+2.0 points
Union County, IAborders it13161.8%4.9 pCi/L−3.6 points
Taylor County, IAborders it23560.9%4.6 pCi/L−4.5 points
Ringgold County, IAborders it8728.7%2.6 pCi/L−36.7 points
Where Adams County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultAdams County testsAdams County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L67.4%21.8%39.6%−14.4 points
2 to 4 pCi/L2227.2%19.7%24.7%+7.5 points
4 pCi/L and above5365.4%58.5%35.7%+6.9 points
Adams 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
Grundy County44 of 9950166.9%6.9 pCi/L
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
Adams County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 20178165.4%6.1 pCi/L40.7 pCi/L58.5%−3.6 points
2007 to 20167169.0%6.1 pCi/L36.3 pCi/L58.6%+1.4 points
2006 to 20156867.6%6.2 pCi/L36.3 pCi/L59.4%+2.1 points
2005 to 20145865.5%6.9 pCi/L36.3 pCi/L59.6%First on file

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

Adams County, Geology

The ground under Adams County

Predicted

USGS's geologic map puts all of Adams 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 Adams 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.

Adams County beside the ground around it

On high-potential ground Adams 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; Adair County comes nearest at 100%.

Share of land by USGS radon potential: Adams County, the 7 counties bordering it and Iowa
AreaEPA zoneLow potentialModerate potentialHigh potential
Adams CountyZone 1NoneNone100%
Taylor CountyZone 1NoneNone100%
Adair CountyZone 1NoneNone100%
Montgomery CountyZone 1NoneNone100%
Union CountyZone 1NoneNone100%
Page CountyZone 1NoneNone100%
Cass CountyZone 1NoneNone100%
Ringgold CountyZone 1NoneNone100%
Iowa99 counties, pooled by land areaVariesNone1.2%98.8%

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

Local help

Adams County, Local resources

Radon testing and mitigation in Adams 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

Adams County, Questions

Questions about radon in Adams County

Are radon levels high in Adams County?

Over the 2008 to 2017 laboratory totals, 65.4% of the radon tests reported to CDC for Adams County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.1 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 48 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Adams County?

Adams County borders 7 counties: Taylor County, Adair County, Montgomery County, Union County, Page County, Cass County and Ringgold County.

Products

Adams County, Products

Testing a home in Adams County

In Adams County, 65.4% of 81 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 Adams 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

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

Explore

Adams County, Bordering counties

Counties bordering Adams County

Calculated by Radon411

Adams County, Cities and towns

Cities and towns in Adams County

About 3,617 people live in Adams County by the Census Bureau's estimate for July 1, 2025, 93 fewer than in 2020 (−2.5%). Spread over its land, that is 8.5 people to the square mile. Its largest town, Corning, has 1,511 residents, 41.8% of the total. CDC's 81 reported tests for 2008 to 2017 work out to 22.4 per 1,000 residents (2025 estimate), close to Iowa's 29.4.

From Corning to Carbon, CDC publishes no figure by town: each reads Adams County's.

The cities and towns in Adams County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Corning1,511−3.4%41.8%
Lenoxextends beyond Adams County1,364+1.9%Counted whole
Prescott186−2.6%5.1%
Nodaway71−2.7%2.0%
Carbon33Level0.9%

5 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 Adams County is counted whole, so it has no share.

Adams County, Homes

Homes in Adams County

Adams County is a place of houses on their own lots: 84% of its 1,892 homes are detached single-family houses, against 72% across Iowa. The homes are older than Iowa's as a whole: half were built before 1954 (1971 for Iowa), and 56% date from before 1960. Owners live in 77% of the occupied homes (Iowa: 72%), so for most households a test and a fix are their own to order.

Homes in Adams County, Iowa, 2019 to 2023
HomesAdams CountyIowa
Housing units1,8921,427,175
Detached houses84%72%
In buildings of 5 or more3%14%
Mobile homes10%3%
Built before 196056%39%
Built since 200014%21%
Middle year built19541971
Owner-occupied77%72%

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