Skip to content
RADON411

Locations and reports

Radon Levels in Adair County, Iowa

EPA puts Adair County in Zone 1, its highest radon zone, and high results are common there: 72.4% of the 98 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

    72.4%

    13.9 pts above IA

    Adair
    72.4%
    Iowa
    58.5%

    98 tests, 2008 to 2017

  • Median result

    9.3pCi/L

    Action level reached

    Adair
    9.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    98

    90th of 99 by tests

    Adair
    98
    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

    17 of 99

    Top quarter

    Adair
    72.4%
    Sioux
    84.2%

    By share, of 99 with 30+ tests

Read a result for Adair County

Starts at Adair County's median, 9.3 pCi/L

9.3pCi/L

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

EPA’s reading of 9.3 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. Adair County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Adair County, At a glance

Adair County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Adair County, 2008 to 2017, laboratory
Under 2 pCi/L: 11%2 to 4 pCi/L: 16%4 pCi/L and above: 73%

Of 98 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Adair County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1111.2%
2 to 4 pCi/L1616.3%
4 pCi/L and above7172.4%
What these figures count

These are the 98 tests reported to CDC for Adair 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

Adair County, Compared

Adair County radon figures, compared

Calculated by Radon411

More than half: 72.4% of the 98 radon tests reported to CDC for Adair County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 17th of 99 Iowa counties with 30 or more tests for the same period. That is 13.9 points above the 58.5% pooled from 99 Iowa counties.

The median result, 9.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 141.6 pCi/L. The rest split 11.2% under 2 pCi/L and 16.3% from 2 to 4 (Iowa: 21.8% and 19.7%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 72.4% share point the same way here.

2 of its 7 bordering counties with figures ran higher, led by Audubon County at 78.3%; Dallas County reported 58.5%. 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 Adair County went from 97 tests (2005 to 2014) to 98 (2008 to 2017), the share going from 73.2% to 72.4%.

Nationally, every county with a figure for the same period pools to 35.7%; Adair County sits 36.7 points above it. CDC also counts 6 tests taken after mitigation in Adair County for the same period: tests in homes where a fix was already in.

Adair County against Iowa, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Adair County
Adair County9872.4%9.3 pCi/LThis county
Iowa, pooled99 counties, pooled95,24558.5%Not pooled−13.9 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−36.7 points
Sioux Countyhighest in the state1,98284.2%10.7 pCi/L+11.8 points
Decatur Countylowest in the state8525.9%2.5 pCi/L−46.5 points
Audubon County, IAborders it18978.3%9.5 pCi/L+5.9 points
Cass County, IAborders it32777.4%8.1 pCi/L+5.0 points
Guthrie County, IAborders it25770.8%6.9 pCi/L−1.6 points
Adams County, IAborders it8165.4%6.1 pCi/L−7.0 points
Madison County, IAborders it31862.3%6.0 pCi/L−10.1 points
Union County, IAborders it13161.8%4.9 pCi/L−10.6 points
Dallas County, IAborders it2,35258.5%4.9 pCi/L−13.9 points
Where Adair County's reported results fell, 2008 to 2017, laboratory, beside Iowa and the United States
ResultAdair County testsAdair County shareIowa shareU.S. shareAgainst Iowa
Under 2 pCi/L1111.2%21.8%39.6%−10.6 points
2 to 4 pCi/L1616.3%19.7%24.7%−3.4 points
4 pCi/L and above7172.4%58.5%35.7%+13.9 points
Adair 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
Monona County12 of 9960374.6%7.0 pCi/L
Cherokee County13 of 9979574.5%7.6 pCi/L
Franklin County14 of 9931373.5%6.2 pCi/L
Jasper County15 of 9974673.3%8.2 pCi/L
Allamakee County16 of 9949273.2%7.0 pCi/L
Adair County17 of 999872.4%9.3 pCi/L
Buena Vista County18 of 9968872.1%6.9 pCi/L
Winnebago County19 of 9982971.9%6.7 pCi/L
Ida County20 of 9939971.7%7.4 pCi/L
Page County21 of 9965371.7%7.2 pCi/L
Greene County22 of 9914371.3%6.2 pCi/L
Adair County ten-year laboratory totals, against Iowa's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIowa, pooledChange from the row before
2008 to 20179872.4%9.3 pCi/L141.6 pCi/L58.5%+2.0 points
2007 to 20168170.4%9.9 pCi/L141.6 pCi/L58.6%−4.0 points
2006 to 20159074.4%8.8 pCi/L141.6 pCi/L59.4%+1.2 points
2005 to 20149773.2%8.9 pCi/L141.6 pCi/L59.6%First on file

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

Adair County, Geology

The ground under Adair County

Predicted

USGS's geologic map puts all of Adair 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 Adair 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.

Adair County beside the ground around it

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

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

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

Local help

Adair County, Local resources

Radon testing and mitigation in Adair 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

Adair County, Questions

Questions about radon in Adair County

Are radon levels high in Adair County?

Over the 2008 to 2017 laboratory totals, 72.4% of the radon tests reported to CDC for Adair County, Iowa were at or above 4 pCi/L, and the median reported pre-mitigation result was 9.3 pCi/L. Of 99 Iowa counties with 30 or more tests for the same period, 16 reported a higher share; pooled, the state comes to 58.5%.

Which counties border Adair County?

Adair County borders 7 counties: Adams County, Union County, Madison County, Cass County, Guthrie County, Dallas County and Audubon County.

Products

Adair County, Products

Testing a home in Adair County

In Adair County, 72.4% of 98 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 Adair 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

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

Explore

Adair County, Bordering counties

Counties bordering Adair County

Calculated by Radon411

Adair County, Cities and towns

Cities and towns in Adair County

About 7,403 people live in Adair County by the Census Bureau's estimate for July 1, 2025, 95 fewer than in 2020 (−1.3%). That works out to 13 people per square mile of land. Its largest town, Greenfield, has 2,070 residents, 28.0% of the total. Reported testing is thin here: 98 tests over 2008 to 2017, or 13.2 for every 1,000 residents (2025 estimate), where Iowa as a whole comes to 29.4.

From Greenfield to Bridgewater, CDC publishes no figure by town: each reads Adair County's.

The cities and towns in Adair County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Greenfield2,070+0.2%28.0%
Stuartextends beyond Adair County1,882+4.8%Counted whole
Adairextends beyond Adair County776−2.1%Counted whole
Fontanelle673−2.3%9.1%
Caseyextends beyond Adair County386+0.5%Counted whole
Orient352−3.3%4.8%
Bridgewater141−3.4%1.9%

7 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 Adair County is counted whole, so it has no share.

Adair County, Homes

Homes in Adair County

Adair County is a place of houses on their own lots: 86% of its 3,595 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 52% date from before 1960. 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 Adair County, Iowa, 2019 to 2023
HomesAdair CountyIowa
Housing units3,5951,427,175
Detached houses86%72%
In buildings of 5 or more3%14%
Mobile homes2%3%
Built before 196052%39%
Built since 200010%21%
Middle year built19581971
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.