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Radon Levels in Adair County, Missouri

EPA puts Adair County in Zone 2, its middle radon zone, and only 4 radon tests from it are on file with CDC (2023). 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

    27.2%

    3.4 pts below MO

    Adair
    27.2%
    Missouri
    30.6%

    92 tests, 2008 to 2017

  • Median result

    1.8pCi/L

    Below action level

    Adair
    1.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    92

    41st of 72 by tests

    Adair
    92
    St. Louis
    17,747

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Missouri

    42 of 72

    Middle half

    Adair
    27.2%
    Atchison
    69.9%

    By share, of 72 with 30+ tests

Read a result for Adair County

Starts at Adair County's median, 1.8 pCi/L

1.8pCi/L

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

EPA’s reading of 1.8 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Adair County's median reported result, 2008 to 2017.

Interpret this reading

The data

Adair County, At a glance

Adair County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Adair County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Adair County, 2023

Share of reported tests at or above 4 pCi/L, by year, Adair County
Share of reported tests at or above 4 pCi/L, by year, Adair County
YearShare of reported tests at or above 4 pCi/L
201427.8%
201528.6%
20160.0%
2017100.0%
20180.0%
20200.0%
20210.0%
202230.0%
20230.0%

2023: 0.0%. Across these years the share ran from 0.0% to 100.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 4 tests were reported to CDC for Adair County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.

Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Adair County, Compared

Adair County radon figures, compared

Calculated by Radon411

Adair County's 92 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.8 pCi/L and a maximum of 30.7 pCi/L, and 27.2% reached 4 pCi/L. Missouri as a whole (115 Missouri counties, pooled) comes to 30.6%: 3.4 points higher than here.

The newest figure, in 2023, counts only 4 tests (0.0% at or above 4 pCi/L), too few to compare, so this reading uses the 92-test figure.

Among its state's counties it ranks 42nd of 72 Missouri counties with 30 or more tests for the same period. Statewide for the same period, Atchison County reported the highest share (69.9%) and Vernon County the lowest (8.8%).

Below the action level, 47 tests (51.1%) came in under 2 pCi/L, against 41.2% statewide, and 20 tests (21.7%) fell between 2 and 4, against 28.1% statewide. The busiest year on file was 2014, with 18 tests reported; the quietest, 2020, had 1.

EPA's 1993 zone map puts Adair County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.

Next door, the shares run from 18.9% in Linn County to 19.4% in Macon County, with Macon County and Linn County below Adair County.

Adair County against Missouri, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Adair County
Adair County9227.2%1.8 pCi/LThis county
Missouri, pooled115 counties, pooled58,52530.6%Not pooled+3.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+8.5 points
Atchison Countyhighest in the state10369.9%5.6 pCi/L+42.7 points
Vernon Countylowest in the state348.8%0.9 pCi/L−18.4 points
Sullivan County, MOborders it633.3%1.4 pCi/L+6.1 points
Putnam County, MOborders it933.3%1.8 pCi/L+6.1 points
Macon County, MOborders it3619.4%1.7 pCi/L−7.8 points
Linn County, MOborders it3718.9%1.8 pCi/L−8.3 points
Scotland County, MOborders it1816.7%1.4 pCi/L−10.5 points
Schuyler County, MOborders it119.1%1.0 pCi/L−18.1 points
Knox County, MOborders it100.0%1.9 pCi/L−27.2 points
Where Adair County's reported results fell, 2008 to 2017, laboratory, beside Missouri and the United States
ResultAdair County testsAdair County shareMissouri shareU.S. shareAgainst Missouri
Under 2 pCi/L4751.1%41.2%39.6%+9.9 points
2 to 4 pCi/L2021.7%28.1%24.7%−6.4 points
4 pCi/L and above2527.2%30.6%35.7%−3.4 points
Adair County ranked among the 72 Missouri counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Ste. Genevieve County37 of 727431.1%2.5 pCi/L
Benton County38 of 724930.6%2.0 pCi/L
Audrain County39 of 7212729.9%2.5 pCi/L
Scott County40 of 725129.4%2.2 pCi/L
Jasper County41 of 7225129.1%2.0 pCi/L
Adair County42 of 729227.2%1.8 pCi/L
Lawrence County43 of 727027.1%1.8 pCi/L
Callaway County44 of 7219227.1%1.7 pCi/L
Daviess County45 of 723026.7%2.0 pCi/L
St. Charles County46 of 727,00126.5%2.2 pCi/L
St. Louis County47 of 7217,74726.3%2.3 pCi/L
Adair County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
202340.0%2.0 pCi/L3.5 pCi/L35.7%−30.0 points
20221030.0%2.4 pCi/L14.3 pCi/L40.8%+30.0 points
202190.0%1.1 pCi/L2.5 pCi/L31.8%Level
202010.0%1.2 pCi/L1.2 pCi/L33.2%Level
201840.0%0.7 pCi/L2.7 pCi/L42.1%−100.0 points
20174100.0%10.1 pCi/L14.2 pCi/L37.0%+100.0 points
201650.0%2.6 pCi/L3.8 pCi/L29.8%−28.6 points
2015728.6%2.3 pCi/L5.8 pCi/L27.6%+0.8 points
20141827.8%1.5 pCi/L9.8 pCi/L34.4%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: moderate radon potential. All of it lies in the area the map calls Dissected Till Plains, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Adair County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Dissected Till PlainsTill-covered Pennsylvanian sandstone, shale, and limestone.Moderate11100%

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

Across Missouri 8.2% of the land is rated high; none of Adair County's is. Of the 7 counties that border it, none has as large a share of moderate-potential ground; Knox County comes nearest at 100%.

Share of land by USGS radon potential: Adair County, the 7 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Adair CountyZone 2None100%None
Schuyler CountyZone 2None100%None
Macon CountyZone 2None100%None
Knox CountyZone 2None100%None
Sullivan CountyZone 2None100%None
Putnam CountyZone 2None100%None
Scotland CountyZone 2None100%None
Linn CountyZone 2None100%None
Missouri115 counties, pooled by land areaVaries5.8%86.0%8.2%

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 Missouri's program says
Phone
573-751-6102
Email
radon@health.mo.gov

What it means

Adair County, Questions

Questions about radon in Adair County

Are radon levels high in Adair County?

In 2023, 0.0% of the radon tests reported to CDC for Adair County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, 41 reported a higher share; pooled, the state comes to 30.6%.

Which counties border Adair County?

Adair County borders 7 counties: Schuyler County, Macon County, Knox County, Sullivan County, Putnam County, Scotland County and Linn County.

Products

Adair County, Products

Testing a home in Adair County

In Adair County, 27.2% of 92 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 30.6% pooled across Missouri. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Adair County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Adair County homes, compared

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Adair County, Bordering counties

Counties bordering Adair County

Calculated by Radon411

Adair County, Cities and towns

Cities and towns in Adair County

The Census Bureau estimates 25,684 residents in Adair County for July 1, 2025, 408 more than in 2020 (+1.6%). That works out to 45 people per square mile of land. Kirksville alone is home to 17,863 of them, 69.5% of the total. Reported testing is thin here: 92 tests over 2008 to 2017, or 3.6 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.

From Kirksville to Gibbs, 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
Kirksville17,863+1.9%69.5%
Greentopextends beyond Adair County391+3.2%Counted whole
Novinger386+0.8%1.5%
Brashear240+0.4%0.9%
Millard78Level0.3%
Gibbs71Level0.3%

6 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

Of Adair County's 11,380 homes, 68% are detached houses, against 70% across Missouri; 8% are mobile homes. Half of its homes were built before 1973, close to Missouri's 1978: 32% date from before 1960 and 15% from 2000 or later. 61% of occupied homes are lived in by their owner (Missouri: 68%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Adair County, Missouri, 2019 to 2023
HomesAdair CountyMissouri
Housing units11,3802,809,501
Detached houses68%70%
In buildings of 5 or more7%13%
Mobile homes8%5%
Built before 196032%28%
Built since 200015%21%
Middle year built19731978
Owner-occupied61%68%

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