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Radon Levels in Pettis County, Missouri

EPA puts Pettis 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

    37.9%

    7.3 pts above MO

    Pettis
    37.9%
    Missouri
    30.6%

    132 tests, 2008 to 2017

  • Median result

    2.8pCi/L

    Below action level

    Pettis
    2.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    132

    33rd of 72 by tests

    Pettis
    132
    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

    21 of 72

    Middle half

    Pettis
    37.9%
    Atchison
    69.9%

    By share, of 72 with 30+ tests

Read a result for Pettis County

Starts at Pettis County's median, 2.8 pCi/L

2.8pCi/L

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

EPA’s reading of 2.8 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. Pettis County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Pettis County, At a glance

Pettis County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Pettis 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 Pettis County, 2023

Share of reported tests at or above 4 pCi/L, by year, Pettis County
Share of reported tests at or above 4 pCi/L, by year, Pettis County
YearShare of reported tests at or above 4 pCi/L
201442.9%
201514.3%
20160.0%
201733.3%
201857.1%
2019100.0%
20200.0%
202114.3%
202233.3%
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 Pettis 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

Pettis County, Compared

Pettis County radon figures, compared

Calculated by Radon411

In Pettis County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (50 of 132) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 2.2 points higher. Across 115 Missouri counties pooled together, 30.6% of tests reached that level, so Pettis County runs 7.3 points above its state.

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 132-test figure.

Of 7 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 21.1% (Morgan County) to 49.1% (Saline County). By share, Pettis County is 21st of 72 Missouri counties with 30 or more tests for the same period.

Half the tests came in under 2.8 pCi/L and half over it; the single highest reached 51.1 pCi/L. Below the action level, 50 tests (37.9%) came in under 2 pCi/L, against 41.2% statewide, and 32 tests (24.2%) 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 37.9% 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 12 tests reported; the quietest, 2020, had 3.

Pettis County against Missouri, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Pettis County
Pettis County13237.9%2.8 pCi/LThis county
Missouri, pooled115 counties, pooled58,52530.6%Not pooled−7.3 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−2.2 points
Atchison Countyhighest in the state10369.9%5.6 pCi/L+32.0 points
Vernon Countylowest in the state348.8%0.9 pCi/L−29.1 points
Saline County, MOborders it5549.1%3.7 pCi/L+11.2 points
Lafayette County, MOborders it18446.7%3.5 pCi/L+8.8 points
Cooper County, MOborders it9041.1%2.6 pCi/L+3.2 points
Henry County, MOborders it8138.3%3.4 pCi/L+0.4 points
Benton County, MOborders it4930.6%2.0 pCi/L−7.3 points
Johnson County, MOborders it26425.8%1.9 pCi/L−12.1 points
Morgan County, MOborders it12321.1%2.2 pCi/L−16.8 points
Where Pettis County's reported results fell, 2008 to 2017, laboratory, beside Missouri and the United States
ResultPettis County testsPettis County shareMissouri shareU.S. shareAgainst Missouri
Under 2 pCi/L5037.9%41.2%39.6%−3.3 points
2 to 4 pCi/L3224.2%28.1%24.7%−3.9 points
4 pCi/L and above5037.9%30.6%35.7%+7.3 points
Pettis 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
Pike County16 of 723540.0%2.9 pCi/L
Clay County17 of 723,43839.2%3.1 pCi/L
Ray County18 of 7210838.9%2.5 pCi/L
Henry County19 of 728138.3%3.4 pCi/L
Clinton County20 of 7210538.1%2.8 pCi/L
Pettis County21 of 7213237.9%2.8 pCi/L
Perry County22 of 728237.8%3.2 pCi/L
Platte County23 of 721,78937.8%3.0 pCi/L
Taney County24 of 7214637.0%3.0 pCi/L
Laclede County25 of 724637.0%2.3 pCi/L
Warren County26 of 7228536.8%2.7 pCi/L
Pettis County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
202340.0%2.4 pCi/L3.7 pCi/L35.7%−33.3 points
2022933.3%3.3 pCi/L17.2 pCi/L40.8%+19.0 points
2021714.3%2.8 pCi/L7.7 pCi/L31.8%+14.3 points
202030.0%0.9 pCi/L2.4 pCi/L33.2%−100.0 points
20195100.0%7.3 pCi/L8.7 pCi/L33.5%+42.9 points
2018757.1%4.2 pCi/L13.7 pCi/L42.1%+23.8 points
20171233.3%3.0 pCi/L19.7 pCi/L37.0%+33.3 points
201640.0%1.0 pCi/L3.3 pCi/L29.8%−14.3 points
2015714.3%2.4 pCi/L6.7 pCi/L27.6%−28.6 points
2014742.9%2.7 pCi/L9.8 pCi/L34.4%First on file

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

Pettis County, Geology

The ground under Pettis County

Predicted

USGS's geologic map puts all of Pettis County's mapped land in one class: moderate radon potential. The map puts 68.6% of Pettis County in the area it calls Salem Plateau and 31.4% in Osage Plains. USGS gives both a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Pettis County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Salem PlateauOrdovician dolomite, sandstone, limestone, and shale.Moderate1168.6%
Osage PlainsOrdovician dolomite, sandstone, limestone, and shale.Moderate1131.4%

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

Pettis County beside the ground around it

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

Share of land by USGS radon potential: Pettis County, the 7 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Pettis CountyZone 2None100%None
Cooper CountyZone 2None100%None
Saline CountyZone 2None100%None
Johnson CountyZone 2None100%None
Benton CountyZone 2None100%None
Morgan CountyZone 2None100%None
Lafayette CountyZone 2None100%None
Henry 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

Pettis County, Local resources

Radon testing and mitigation in Pettis County

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

What it means

Pettis County, Questions

Questions about radon in Pettis County

Are radon levels high in Pettis County?

In 2023, 0.0% of the radon tests reported to CDC for Pettis County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.4 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, 20 reported a higher share; pooled, the state comes to 30.6%.

Which counties border Pettis County?

Pettis County borders 7 counties: Cooper County, Saline County, Johnson County, Benton County, Morgan County, Lafayette County and Henry County.

Products

Pettis County, Products

Testing a home in Pettis County

In Pettis County, 37.9% of 132 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 Pettis County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Pettis County homes, compared

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Pettis County, Bordering counties

Counties bordering Pettis County

Calculated by Radon411

Pettis County, Cities and towns

Cities and towns in Pettis County

The Census Bureau estimates 44,254 residents in Pettis County for July 1, 2025, 1,243 more than in 2020 (+2.9%). That works out to 65 people per square mile of land. Sedalia alone is home to 22,621 of them, 51.1% of the total. Reported testing is thin here: 132 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 Sedalia to Ionia, CDC publishes no figure by town: each reads Pettis County's.

The cities and towns in Pettis County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Sedalia22,621+4.0%51.1%
Windsorextends beyond Pettis County2,869+3.5%Counted whole
La Monte1,018+1.2%2.3%
Green Ridge601+28.1%1.4%
Smithton508+0.6%1.1%
Houstonia201+1.0%0.5%
Hughesville151+0.7%0.3%
Ioniaextends beyond Pettis County79+5.3%Counted whole

8 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 Pettis County is counted whole, so it has no share.

Pettis County, Homes

Homes in Pettis County

Pettis County is a place of houses on their own lots: 79% of its 18,608 homes are detached single-family houses, against 70% across Missouri. Half of its homes were built before 1974, close to Missouri's 1978: 33% date from before 1960 and 18% from 2000 or later. 70% 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 Pettis County, Missouri, 2019 to 2023
HomesPettis CountyMissouri
Housing units18,6082,809,501
Detached houses79%70%
In buildings of 5 or more8%13%
Mobile homes6%5%
Built before 196033%28%
Built since 200018%21%
Middle year built19741978
Owner-occupied70%68%

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