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Radon Levels in Gasconade County, Missouri

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

    31.8%

    1.2 pts above MO

    Gasconade
    31.8%
    Missouri
    30.6%

    44 tests, 2008 to 2017

  • Median result

    2.3pCi/L

    Below action level

    Gasconade
    2.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    44

    61st of 72 by tests

    Gasconade
    44
    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

    34 of 72

    Middle half

    Gasconade
    31.8%
    Atchison
    69.9%

    By share, of 72 with 30+ tests

Read a result for Gasconade County

Starts at Gasconade County's median, 2.3 pCi/L

2.3pCi/L

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

EPA’s reading of 2.3 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Gasconade County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Gasconade County, At a glance

Gasconade County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Gasconade 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 Gasconade County, 2023

Share of reported tests at or above 4 pCi/L, by year, Gasconade County
Share of reported tests at or above 4 pCi/L, by year, Gasconade County
YearShare of reported tests at or above 4 pCi/L
20140.0%
201550.0%
201620.0%
201762.5%
20190.0%
202216.7%
202350.0%

2023: 50.0%. Across these years the share ran from 0.0% to 62.5%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 2 tests were reported to CDC for Gasconade 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

Gasconade County, Compared

Gasconade County radon figures, compared

Calculated by Radon411

In Gasconade County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (14 of 44) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 3.9 points lower. Across 115 Missouri counties pooled together, 30.6% of tests reached that level, so Gasconade County runs 1.2 points above its state.

The newest figure, in 2023, counts only 2 tests (50.0% at or above 4 pCi/L), too few to compare, so this reading uses the 44-test figure.

Of 6 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 4 a smaller one; the spread is 12.8% (Montgomery County) to 36.8% (Warren County). By share, Gasconade County is 34th of 72 Missouri counties with 30 or more tests for the same period.

Half the tests came in under 2.3 pCi/L and half over it; the single highest reached 11.4 pCi/L. Below the action level, 17 tests (38.6%) came in under 2 pCi/L, against 41.2% statewide, and 13 tests (29.5%) fell between 2 and 4, against 28.1% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 31.8% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential.

The busiest year on file was 2017, with 8 tests reported; the quietest, 2019, had 1.

Gasconade County against Missouri, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Gasconade County
Gasconade County4431.8%2.3 pCi/LThis county
Missouri, pooled115 counties, pooled58,52530.6%Not pooled−1.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+3.9 points
Atchison Countyhighest in the state10369.9%5.6 pCi/L+38.1 points
Vernon Countylowest in the state348.8%0.9 pCi/L−23.0 points
Warren County, MOborders it28536.8%2.7 pCi/L+5.0 points
Franklin County, MOborders it75333.2%2.6 pCi/L+1.4 points
Osage County, MOborders it5215.4%1.5 pCi/L−16.4 points
Phelps County, MOborders it20414.7%1.5 pCi/L−17.1 points
Crawford County, MOborders it3414.7%1.5 pCi/L−17.1 points
Maries County, MOborders it2114.3%1.8 pCi/L−17.5 points
Montgomery County, MOborders it4712.8%1.6 pCi/L−19.0 points
Where Gasconade County's reported results fell, 2008 to 2017, laboratory, beside Missouri and the United States
ResultGasconade County testsGasconade County shareMissouri shareU.S. shareAgainst Missouri
Under 2 pCi/L1738.6%41.2%39.6%−2.6 points
2 to 4 pCi/L1329.5%28.1%24.7%+1.4 points
4 pCi/L and above1431.8%30.6%35.7%+1.2 points
Gasconade 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
Lincoln County29 of 7244433.6%2.2 pCi/L
Franklin County30 of 7275333.2%2.6 pCi/L
Greene County31 of 721,47032.7%2.5 pCi/L
Ralls County32 of 724332.6%2.7 pCi/L
Lewis County33 of 727132.4%2.6 pCi/L
Gasconade County34 of 724431.8%2.3 pCi/L
Christian County35 of 7243631.7%1.9 pCi/L
Newton County36 of 7216731.1%2.5 pCi/L
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
Gasconade County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
2023250.0%11.1 pCi/L19.6 pCi/L35.7%+33.3 points
2022616.7%1.2 pCi/L4.5 pCi/L40.8%+16.7 points
201910.0%3.3 pCi/L3.3 pCi/L33.5%−62.5 points
2017862.5%4.6 pCi/L8.7 pCi/L37.0%+42.5 points
2016520.0%3.1 pCi/L4.9 pCi/L29.8%−30.0 points
2015250.0%3.8 pCi/L6.7 pCi/L27.6%+50.0 points
201420.0%1.3 pCi/L2.0 pCi/L34.4%First on file

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

Gasconade County, Geology

The ground under Gasconade County

Predicted

USGS's geologic map puts all of Gasconade County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Salem Plateau, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Gasconade County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Salem PlateauOrdovician dolomite, sandstone, limestone, and shale.Moderate11100%

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

Gasconade County beside the ground around it

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

Share of land by USGS radon potential: Gasconade County, the 7 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Gasconade CountyZone 2None100%None
Osage CountyZone 2None100%None
Franklin CountyZone 2None100%None
Warren CountyZone 2None100%None
Montgomery CountyZone 2None100%None
Crawford CountyZone 2None100%None
Maries CountyZone 2None100%None
Phelps 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

Gasconade County, Local resources

Radon testing and mitigation in Gasconade County

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

What it means

Gasconade County, Questions

Questions about radon in Gasconade County

Are radon levels high in Gasconade County?

In 2023, 50.0% of the radon tests reported to CDC for Gasconade County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 11.1 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, 33 reported a higher share; pooled, the state comes to 30.6%.

Which counties border Gasconade County?

Gasconade County borders 7 counties: Osage County, Franklin County, Warren County, Montgomery County, Crawford County, Maries County and Phelps County.

Products

Gasconade County, Products

Testing a home in Gasconade County

In Gasconade County, 31.8% of 44 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 Gasconade County; a long-term test tells the year-round average.

Test kits and monitors3

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Best radon monitors for Gasconade County homes, compared

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Gasconade County, Bordering counties

Counties bordering Gasconade County

Calculated by Radon411

Gasconade County, Cities and towns

Cities and towns in Gasconade County

Gasconade County's population has barely moved since 2020: 14,784 residents on July 1, 2025 against 14,763 then, by the Census Bureau's estimates. That works out to 28 people per square mile of land. No town dominates: Owensville, the largest, has 2,802 residents, 19.0% of the total. Reported testing is thin here: 44 tests over 2008 to 2017, or 3.0 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.

From Owensville to Morrison, CDC publishes no figure by town: each reads Gasconade County's.

The cities and towns in Gasconade County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Owensville2,802−0.2%19.0%
Hermann2,221+1.7%15.0%
Blandextends beyond Gasconade County505−0.8%Counted whole
Rosebud396+1.3%2.7%
Gasconade168−1.2%1.1%
Morrison94−1.1%0.6%

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

Gasconade County, Homes

Homes in Gasconade County

Gasconade County is a place of houses on their own lots: 80% of its 7,597 homes are detached single-family houses, against 70% across Missouri. Half of its homes were built before 1974, close to Missouri's 1978: 34% date from before 1960 and 18% from 2000 or later. Owners live in 81% of the occupied homes (Missouri: 68%), so for most households a test and a fix are their own to order.

Homes in Gasconade County, Missouri, 2019 to 2023
HomesGasconade CountyMissouri
Housing units7,5972,809,501
Detached houses80%70%
In buildings of 5 or more3%13%
Mobile homes11%5%
Built before 196034%28%
Built since 200018%21%
Middle year built19741978
Owner-occupied81%68%

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