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Radon Levels in Atchison County, Missouri

EPA puts Atchison County in Zone 1, its highest radon zone, and only 3 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

    69.9%

    39.3 pts above MO

    Atchison
    69.9%
    Missouri
    30.6%

    103 tests, 2008 to 2017

  • Median result

    5.6pCi/L

    Action level reached

    Atchison
    5.6 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    103

    39th of 72 by tests

    Atchison
    103
    St. Louis
    17,747

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Missouri

    1 of 72

    Top quarter

    Atchison
    69.9%
    Atchison
    69.9%

    By share, of 72 with 30+ tests

Read a result for Atchison County

Starts at Atchison County's median, 5.6 pCi/L

5.6pCi/L

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

EPA’s reading of 5.6 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Atchison County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Atchison County, At a glance

Atchison County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Atchison County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

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

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Atchison County, 2023

Share of reported tests at or above 4 pCi/L, by year, Atchison County
Share of reported tests at or above 4 pCi/L, by year, Atchison County
YearShare of reported tests at or above 4 pCi/L
201454.5%
201566.7%
201685.7%
201766.7%
2018100.0%
2019100.0%
202180.0%
202286.7%
2023100.0%

2023: 100.0%. Across these years the share ran from 54.5% to 100.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 3 tests were reported to CDC for Atchison 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

Atchison County, Compared

Atchison County radon figures, compared

Calculated by Radon411

More than half: 69.9% of the 103 radon tests reported to CDC for Atchison County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 1st of 72 Missouri counties with 30 or more tests for the same period. That is 39.3 points above the 30.6% pooled from 115 Missouri counties.

The newest figure, in 2023, counts only 3 tests (100.0% at or above 4 pCi/L), too few to compare, so this reading uses the 103-test figure.

The median result, 5.6 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 31.5 pCi/L. The rest split 12.6% under 2 pCi/L and 17.5% from 2 to 4 (Missouri: 41.2% and 28.1%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 69.9% share point the same way here.

2 of its 5 bordering counties with figures ran higher, led by Nemaha County, NE at 74.9%; Nodaway County reported 34.2%. Statewide for the same period, Andrew County reported the highest share (60.8%) and Vernon County the lowest (8.8%).

The busiest year on file was 2022, with 15 tests reported; the quietest, 2019, had 2.

Nationally, every county with a figure for the same period pools to 35.7%; Atchison County sits 34.2 points above it.

Atchison County against Missouri, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Atchison County
Atchison County10369.9%5.6 pCi/LThis county
Missouri, pooled115 counties, pooled58,52530.6%Not pooled−39.3 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−34.2 points
Andrew Countyhighest in the state15860.8%4.9 pCi/L−9.1 points
Vernon Countylowest in the state348.8%0.9 pCi/L−61.1 points
Nemaha County, NEborders it31574.9%8.7 pCi/L+5.0 points
Page County, IAborders it65371.7%7.2 pCi/L+1.8 points
Otoe County, NEborders it40269.9%6.5 pCi/LLevel
Fremont County, IAborders it20569.8%7.2 pCi/L−0.1 points
Holt County, MOborders it2962.1%4.9 pCi/L−7.8 points
Nodaway County, MOborders it22534.2%2.7 pCi/L−35.7 points
Where Atchison County's reported results fell, 2008 to 2017, laboratory, beside Missouri and the United States
ResultAtchison County testsAtchison County shareMissouri shareU.S. shareAgainst Missouri
Under 2 pCi/L1312.6%41.2%39.6%−28.6 points
2 to 4 pCi/L1817.5%28.1%24.7%−10.6 points
4 pCi/L and above7269.9%30.6%35.7%+39.3 points
Atchison 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
Atchison County1 of 7210369.9%5.6 pCi/L
Andrew County2 of 7215860.8%4.9 pCi/L
Buchanan County3 of 7257552.9%4.2 pCi/L
Saline County4 of 725549.1%3.7 pCi/L
Lafayette County5 of 7218446.7%3.5 pCi/L
Howell County6 of 7213845.7%3.5 pCi/L
Cass County7 of 7298845.5%3.5 pCi/L
Howard County8 of 726243.5%3.5 pCi/L
Marion County9 of 7228241.8%3.2 pCi/L
Barry County10 of 725541.8%3.1 pCi/L
Jefferson County11 of 722,65241.6%3.1 pCi/L
Atchison County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
20233100.0%14.7 pCi/L20.6 pCi/L35.7%+13.3 points
20221586.7%9.6 pCi/L24.8 pCi/L40.8%+6.7 points
2021580.0%4.7 pCi/L11.8 pCi/L31.8%−20.0 points
20192100.0%6.7 pCi/L8.1 pCi/L33.5%Level
20182100.0%7.3 pCi/L9.8 pCi/L42.1%+33.3 points
20171266.7%5.3 pCi/L24.3 pCi/L37.0%−19.0 points
2016785.7%11.9 pCi/L22.6 pCi/L29.8%+19.0 points
20151266.7%5.7 pCi/L12.3 pCi/L27.6%+12.2 points
20141154.5%4.0 pCi/L21.4 pCi/L34.4%First on file

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

Atchison County, Geology

The ground under Atchison County

Predicted

USGS's geologic map puts all of Atchison County's mapped land in one class: high radon potential. All of it lies in the area the map calls Northwestern Dissected Till Plains, to which USGS gives a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under Atchison County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Northwestern Dissected Till PlainsPennsylvanian shales covered by thick loess.High1399.8%

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

Atchison County beside the ground around it

Atchison County has more high-potential ground than Missouri as a whole: 100% of its land against 8.2%. Of the 6 counties that border it, none has as large a share of high-potential ground; Fremont County, IA comes nearest at 100%.

Share of land by USGS radon potential: Atchison County, the 6 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Atchison CountyZone 1NoneNone100%
Nemaha County, NEZone 1NoneNone100%
Fremont County, IAZone 1NoneNone100%
Holt CountyZone 1NoneNone100%
Nodaway CountyZone 1None20.1%79.9%
Page County, IAZone 1NoneNone100%
Otoe County, NEZone 1NoneNone100%
Missouri115 counties, pooled by land areaVaries5.8%86.0%8.2%

The map rates the ground, not the air in any home.

Local help

Atchison County, Local resources

Radon testing and mitigation in Atchison County

Listed radon businesses with an address in Atchison County:

Listed radon professionals by town: Tarkio

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

What it means

Atchison County, Questions

Questions about radon in Atchison County

Are radon levels high in Atchison County?

In 2023, 100.0% of the radon tests reported to CDC for Atchison County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 14.7 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, none reported a higher share; pooled, the state comes to 30.6%.

Which counties border Atchison County?

Atchison County borders 6 counties: Nemaha County, NE, Fremont County, IA, Holt County, MO, Nodaway County, MO, Page County, IA and Otoe County, NE.

Products

Atchison County, Products

Testing a home in Atchison County

In Atchison County, 69.9% of 103 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 30.6% pooled across Missouri. In Zone 1 the year-round level in Atchison County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Atchison County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Atchison County

Explore

Atchison County, Bordering counties

Counties bordering Atchison County

Calculated by Radon411

Atchison County, Cities and towns

Cities and towns in Atchison County

About 5,175 people live in Atchison County by the Census Bureau's estimate for July 1, 2025, 132 fewer than in 2020 (−2.5%). Spread over its land, that is 9.5 people to the square mile. Its largest town, Tarkio, has 1,478 residents, 28.6% of the total. Together its 5 incorporated places hold 68.1% of those residents; the other 31.9% live outside any of them. Testing is reported here more often than across the state: CDC's 103 reported tests for 2008 to 2017 come to 19.9 for every 1,000 residents (2025 estimate), against 9.3 for Missouri.

From Tarkio to Watson, CDC publishes no figure by town: each reads Atchison County's.

The cities and towns in Atchison County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Tarkio1,478−2.2%28.6%
Rock Port1,246−2.4%24.1%
Fairfax627−2.9%12.1%
Westboro113−3.4%2.2%
Watson58−1.7%1.1%

5 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).

Atchison County, Homes

Homes in Atchison County

Atchison County is a place of houses on their own lots: 87% of its 2,726 homes are detached single-family houses, against 70% across Missouri. The homes are older than Missouri's as a whole: half were built before 1957 (1978 for Missouri), and 54% date from before 1960. 74% 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 Atchison County, Missouri, 2019 to 2023
HomesAtchison CountyMissouri
Housing units2,7262,809,501
Detached houses87%70%
In buildings of 5 or more2%13%
Mobile homes2%5%
Built before 196054%28%
Built since 20007%21%
Middle year built19571978
Owner-occupied74%68%

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