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Radon Levels in Callaway County, Missouri

EPA puts Callaway County in Zone 2, its middle radon zone, and only 13 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

    28.9%

    1.9 pts below MO

    Callaway
    28.9%
    Missouri
    30.8%

    204 tests, 2007 to 2016

  • Median result

    1.8pCi/L

    Below action level

    Callaway
    1.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2007 to 2016

  • Tests reported

    204

    22nd of 72 by tests

    Callaway
    204
    St. Louis
    16,567

    Reported to CDC before any fix, 2007 to 2016

  • 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

    Callaway
    28.9%
    Atchison
    70.5%

    By share, of 72 with 30+ tests

Read a result for Callaway County

Starts at Callaway 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. Callaway County's median reported result, 2007 to 2016.

Interpret this reading

The data

Callaway County, At a glance

Callaway County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Callaway 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 Callaway County, 2023

Share of reported tests at or above 4 pCi/L, by year, Callaway County
Share of reported tests at or above 4 pCi/L, by year, Callaway County
YearShare of reported tests at or above 4 pCi/L
201471.4%
201511.1%
201640.0%
201733.3%
20180.0%
201950.0%
202014.3%
20210.0%
202234.5%
202330.8%

2023: 30.8%. Across these years the share ran from 0.0% to 71.4%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 13 tests were reported to CDC for Callaway 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

Callaway County, Compared

Callaway County radon figures, compared

Calculated by Radon411

Callaway County's 204 reported tests over the 2007 to 2016 laboratory totals had a middle value of 1.8 pCi/L and a maximum of 92.4 pCi/L, and 28.9% reached 4 pCi/L. Missouri as a whole (115 Missouri counties, pooled) comes to 30.8%: 1.9 points higher than here.

The newest figure, in 2023, counts only 13 tests (30.8% at or above 4 pCi/L), too few to compare, so this reading uses the 204-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 (70.5%) and Vernon County the lowest (9.1%).

Below the action level, 108 tests (52.9%) came in under 2 pCi/L, against 41.2% statewide, and 37 tests (18.1%) fell between 2 and 4, against 27.9% statewide. The busiest year on file was 2022, with 29 tests reported; the quietest, 2019, had 2.

EPA's 1993 zone map puts Callaway 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 14.5% in Osage County to 29.8% in Audrain County, with Cole County, Boone County and Montgomery County below Callaway County.

Callaway County against Missouri, the United States and nearby counties, 2007 to 2016, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Callaway County
Callaway County20428.9%1.8 pCi/LThis county
Missouri, pooled115 counties, pooled54,94630.8%Not pooled+1.9 points
United States, pooled2,666 counties, pooled1,939,02535.8%Not pooled+6.9 points
Atchison Countyhighest in the state8870.5%5.5 pCi/L+41.6 points
Vernon Countylowest in the state339.1%1.2 pCi/L−19.8 points
Audrain County, MOborders it12429.8%2.3 pCi/L+0.9 points
Cole County, MOborders it79025.7%2.2 pCi/L−3.2 points
Boone County, MOborders it4,49621.6%1.9 pCi/L−7.3 points
Montgomery County, MOborders it4316.3%1.6 pCi/L−12.6 points
Osage County, MOborders it5514.5%1.5 pCi/L−14.4 points
Where Callaway County's reported results fell, 2007 to 2016, laboratory, beside Missouri and the United States
ResultCallaway County testsCallaway County shareMissouri shareU.S. shareAgainst Missouri
Under 2 pCi/L10852.9%41.2%39.6%+11.7 points
2 to 4 pCi/L3718.1%27.9%24.6%−9.8 points
4 pCi/L and above5928.9%30.8%35.8%−1.9 points
Callaway County ranked among the 72 Missouri counties with 30 or more tests, by share at or above 4 pCi/L, 2007 to 2016, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Gasconade County37 of 723531.4%2.3 pCi/L
Benton County38 of 724231.0%1.9 pCi/L
Livingston County38 of 724231.0%2.2 pCi/L
Audrain County40 of 7212429.8%2.3 pCi/L
Ste. Genevieve County41 of 726229.0%2.5 pCi/L
Callaway County42 of 7220428.9%1.8 pCi/L
Jasper County43 of 7225628.5%2.0 pCi/L
Scott County44 of 724526.7%1.8 pCi/L
St. Louis County45 of 7216,56726.5%2.3 pCi/L
St. Charles County46 of 726,28726.2%2.2 pCi/L
Moniteau County47 of 727025.7%2.3 pCi/L
Callaway County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
20231330.8%2.8 pCi/L16.6 pCi/L35.7%−3.7 points
20222934.5%2.8 pCi/L32.0 pCi/L40.8%+34.5 points
2021120.0%1.4 pCi/L3.7 pCi/L31.8%−14.3 points
2020714.3%1.5 pCi/L7.9 pCi/L33.2%−35.7 points
2019250.0%4.0 pCi/L4.8 pCi/L33.5%+50.0 points
201820.0%0.7 pCi/L1.1 pCi/L42.1%−33.3 points
2017333.3%3.8 pCi/L10.0 pCi/L37.0%−6.7 points
2016540.0%2.4 pCi/L7.7 pCi/L29.8%+28.9 points
2015911.1%1.7 pCi/L4.8 pCi/L27.6%−60.3 points
2014771.4%5.7 pCi/L12.0 pCi/L34.4%First on file

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

Callaway County, Geology

The ground under Callaway County

Predicted

USGS's geologic map puts all of Callaway County's mapped land in one class: moderate radon potential. The map puts 64.0% of Callaway County in the area it calls Dissected Till Plains and 36.0% in Salem Plateau. USGS gives both a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Callaway County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Dissected Till PlainsTill-covered Pennsylvanian sandstone, shale, and limestone.Moderate1164.0%
Salem PlateauOrdovician dolomite, sandstone, limestone, and shale.Moderate1136.0%

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

Callaway County beside the ground around it

Across Missouri 8.2% of the land is rated high; none of Callaway County's is. Of the 5 counties that border it, none has as large a share of moderate-potential ground; Audrain County comes nearest at 100%.

Share of land by USGS radon potential: Callaway County, the 5 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Callaway CountyZone 2None100%None
Osage CountyZone 2None100%None
Cole CountyZone 2None100%None
Montgomery CountyZone 2None100%None
Boone CountyZone 2None100%None
Audrain 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

Callaway County, Local resources

Radon testing and mitigation in Callaway County

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

What it means

Callaway County, Questions

Questions about radon in Callaway County

Are radon levels high in Callaway County?

In 2023, 30.8% of the radon tests reported to CDC for Callaway County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.8 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 30.8%.

Which counties border Callaway County?

Callaway County borders 5 counties: Osage County, Cole County, Montgomery County, Boone County and Audrain County.

Products

Callaway County, Products

Testing a home in Callaway County

In Callaway County, 28.9% of 204 tests reported to CDC over the 2007 to 2016 laboratory totals reached 4 pCi/L, against 30.8% pooled across Missouri. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Callaway County; a long-term test tells the year-round average.

Test kits and monitors3

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Best radon monitors for Callaway County homes, compared

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Callaway County, Bordering counties

Counties bordering Callaway County

Calculated by Radon411

Callaway County, Cities and towns

Cities and towns in Callaway County

The Census Bureau estimates 45,765 residents in Callaway County for July 1, 2025, 1,426 more than in 2020 (+3.2%). That works out to 55 people per square mile of land. Jefferson City, the largest place on its list (42,489 residents in all), extends beyond Callaway County, so no share of the total is worked out for it. Reported testing is thin here: 204 tests over 2007 to 2016, or 4.5 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 8.8.

From Jefferson City to Kingdom City, CDC publishes no figure by town: each reads Callaway County's.

The cities and towns in Callaway County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Jefferson Cityextends beyond Callaway County42,489−0.1%Counted whole
Fulton12,853+2.0%28.1%
Holts Summit4,773+7.3%10.4%
Auxvasse1,029+2.6%2.2%
New Bloomfield747+9.5%1.6%
Mokane188+1.6%0.4%
Kingdom City135+3.8%0.3%

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 Callaway County is counted whole, so it has no share.

Callaway County, Homes

Homes in Callaway County

Of Callaway County's 18,596 homes, 73% are detached houses, against 70% across Missouri; 14% are mobile homes. Much of Callaway County is recent building: 30% of its homes have gone up since 2000 and the middle year built is 1988, against 1978 for Missouri. Owners live in 76% of the occupied homes (Missouri: 68%), so for most households a test and a fix are their own to order.

Homes in Callaway County, Missouri, 2019 to 2023
HomesCallaway CountyMissouri
Housing units18,5962,809,501
Detached houses73%70%
In buildings of 5 or more3%13%
Mobile homes14%5%
Built before 196018%28%
Built since 200030%21%
Middle year built19881978
Owner-occupied76%68%

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