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Radon Levels in Boone County, Missouri

EPA puts Boone County in Zone 2, its middle radon zone, and high results are common there: 42.9% of the 63 radon tests reported to CDC (2023) 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

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  • Share at 4+ pCi/L

    42.9%

    7.2 pts above MO

    Boone
    42.9%
    Missouri
    35.7%

    63 tests, 2023

  • Median result

    3.6pCi/L

    Below action level

    Boone
    3.6 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    63

    5th of 7 by tests

    Boone
    63
    St. Louis
    443

    Reported to CDC before any fix, 2023

  • 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

    3 of 7

    Middle half

    Boone
    42.9%
    Clay
    44.6%

    By share, of 7 with 30+ tests

Read a result for Boone County

Starts at Boone County's median, 3.6 pCi/L

3.6pCi/L

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

EPA’s reading of 3.6 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. Boone County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Boone County, At a glance

Boone County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Boone 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 Boone County, 2023

Share of reported tests at or above 4 pCi/L, by year, Boone County
Share of reported tests at or above 4 pCi/L, by year, Boone County
YearShare of reported tests at or above 4 pCi/L
201433.8%
201523.7%
201624.6%
201722.4%
201842.6%
201942.3%
202014.3%
202114.3%
202233.3%
202342.9%

2023: 42.9%. Across these years the share ran from 14.3% to 42.9%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 63 tests reported to CDC for Boone County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Boone County, Compared

Boone County radon figures, compared

Calculated by Radon411

In Boone County, about 4 in 10 reported tests in 2023 (27 of 63) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 9.5 points higher. Across 91 Missouri counties pooled together, 35.7% of tests reached that level, so Boone County runs 7.2 points above its state.

By share, Boone County is 3rd of 7 Missouri counties with 30 or more tests for the same period.

Year by year, 2014 opened at 33.8% and 2023 closed at 42.9% (up 9.1 points), with 2023 the high at 42.9%. Half the tests came in under 3.6 pCi/L and half over it; the single highest reached 25.1 pCi/L. Below the action level, 21 tests (33.3%) came in under 2 pCi/L, against 36.6% statewide, and 15 tests (23.8%) fell between 2 and 4, against 27.7% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 42.9% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential. CDC also counts 7 tests taken after mitigation in Boone County for the same period: tests in homes where a fix was already in.

The busiest year on file was 2022, with 129 tests reported; the quietest, 2020, had 21.

Share of reported tests at or above 4 pCi/L by year, Boone County against Missouri2014 to 2023, years with 30 or more tests: Boone County 33.8% to 42.9%, the state's pooled share 35.7% in 2023.
Boone CountyMissouri, pooled
Share of reported tests at or above 4 pCi/L by year, Boone County against Missouri: data table
YearTestsBoone County, at or above 4 pCi/LMissouri, pooled
20146533.8%34.4%
20155923.7%27.6%
20165724.6%29.8%
20174922.4%37.0%
20185442.6%42.1%
20217014.3%31.8%
202212933.3%40.8%
20236342.9%35.7%
Boone County against Missouri, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Boone County
Boone County6342.9%3.6 pCi/LThis county
Missouri, pooled91 counties, pooled1,41235.7%Not pooled−7.2 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−9.5 points
Clay Countyhighest in the state8344.6%3.6 pCi/L+1.7 points
St. Louis Countylowest in the state44322.6%2.0 pCi/L−20.3 points
Audrain County, MOborders it2100.0%9.7 pCi/L+57.1 points
Moniteau County, MOborders it475.0%6.8 pCi/L+32.1 points
Howard County, MOborders it250.0%5.5 pCi/L+7.1 points
Cole County, MOborders it2240.9%3.4 pCi/L−2.0 points
Cooper County, MOborders it333.3%3.6 pCi/L−9.6 points
Randolph County, MOborders it333.3%3.2 pCi/L−9.6 points
Callaway County, MOborders it1330.8%2.8 pCi/L−12.1 points
Where Boone County's reported results fell, 2023, beside Missouri and the United States
ResultBoone County testsBoone County shareMissouri shareU.S. shareAgainst Missouri
Under 2 pCi/L2133.3%36.6%41.4%−3.3 points
2 to 4 pCi/L1523.8%27.7%25.2%−3.9 points
4 pCi/L and above2742.9%35.7%33.4%+7.2 points
Boone County ranked among the 7 Missouri counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Clay County1 of 78344.6%3.6 pCi/L
Jackson County2 of 720444.1%3.4 pCi/L
Boone County3 of 76342.9%3.6 pCi/L
St. Charles County4 of 710340.8%3.4 pCi/L
Jefferson County5 of 73638.9%3.4 pCi/L
Greene County6 of 74827.1%2.9 pCi/L
St. Louis County7 of 744322.6%2.0 pCi/L
Boone County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
20236342.9%3.6 pCi/L25.1 pCi/L35.7%+9.6 points
202212933.3%2.2 pCi/L67.3 pCi/L40.8%+19.0 points
20217014.3%1.5 pCi/L19.4 pCi/L31.8%Level
20202114.3%1.8 pCi/L21.4 pCi/L33.2%−28.0 points
20192642.3%2.6 pCi/L24.1 pCi/L33.5%−0.3 points
20185442.6%3.3 pCi/L33.6 pCi/L42.1%+20.2 points
20174922.4%2.0 pCi/L38.9 pCi/L37.0%−2.2 points
20165724.6%1.9 pCi/L11.3 pCi/L29.8%+0.9 points
20155923.7%1.8 pCi/L11.8 pCi/L27.6%−10.1 points
20146533.8%2.3 pCi/L20.6 pCi/L34.4%First on file

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

Boone County, Geology

The ground under Boone County

Predicted

USGS's geologic map puts all of Boone County's mapped land in one class: moderate radon potential. The map puts 59.1% of Boone County in the area it calls Dissected Till Plains and 40.9% in Salem Plateau. USGS gives both a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Boone County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Dissected Till PlainsTill-covered Pennsylvanian sandstone, shale, and limestone.Moderate1159.1%
Salem PlateauOrdovician dolomite, sandstone, limestone, and shale.Moderate1140.9%

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

Boone County beside the ground around it

Across Missouri 8.2% of the land is rated high; none of Boone County's is. Of the 7 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: Boone County, the 7 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Boone CountyZone 2None100%None
Howard CountyZone 2None100%None
Callaway CountyZone 2None100%None
Cooper CountyZone 2None100%None
Moniteau CountyZone 2None100%None
Cole CountyZone 2None100%None
Audrain CountyZone 2None100%None
Randolph 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

Boone County, Local resources

Radon testing and mitigation in Boone County

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

What it means

Boone County, Questions

Questions about radon in Boone County

Are radon levels high in Boone County?

In 2023, 42.9% of the radon tests reported to CDC for Boone County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.6 pCi/L. Of 7 Missouri counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 35.7%.

Which counties border Boone County?

Boone County borders 7 counties: Howard County, Callaway County, Cooper County, Moniteau County, Cole County, Audrain County and Randolph County.

Products

Boone County, Products

Testing a home in Boone County

In Boone County, 42.9% of 63 tests reported to CDC in 2023 reached 4 pCi/L, against 35.7% pooled across Missouri. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Boone County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Boone County homes, compared

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Boone County, Bordering counties

Counties bordering Boone County

Calculated by Radon411

Boone County, Cities and towns

Cities and towns in Boone County

The Census Bureau estimates 191,746 residents in Boone County for July 1, 2025, 7,686 more than in 2020 (+4.2%). That works out to 280 people per square mile of land. Columbia alone is home to 130,851 of them, 68.2% of the total. CDC's 63 reported tests for 2023 work out to 0.3 per 1,000 residents (2025 estimate), close to Missouri's 0.2.

From Columbia to McBaine, CDC publishes no figure by town: each reads Boone County's.

The cities and towns in Boone County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Columbia130,851+3.6%68.2%
Ashland5,221+9.4%2.7%
Centraliaextends beyond Boone County4,767+4.5%Counted whole
Hallsville1,742+7.9%0.9%
Sturgeon957+4.4%0.5%
Harrisburg289+6.6%0.2%
Clarkextends beyond Boone County237−2.1%Counted whole
Rocheport211+3.9%0.1%
Hartsburg137+4.6%Under 0.1%
Pierpont68+6.3%Under 0.1%
Huntsdale30+7.1%Under 0.1%
McBaine16+14.3%Under 0.1%

12 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 Boone County is counted whole, so it has no share.

Boone County, Homes

Homes in Boone County

Of Boone County's 80,912 homes, 60% are detached houses, against 70% across Missouri; 19% are in buildings of five or more homes. Much of Boone County is recent building: 35% of its homes have gone up since 2000 and the middle year built is 1991, against 1978 for Missouri. 58% 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 Boone County, Missouri, 2019 to 2023
HomesBoone CountyMissouri
Housing units80,9122,809,501
Detached houses60%70%
In buildings of 5 or more19%13%
Mobile homes4%5%
Built before 196011%28%
Built since 200035%21%
Middle year built19911978
Owner-occupied58%68%

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