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Radon Levels in Perry County, Missouri

EPA puts Perry County in Zone 2, its middle radon zone, and only 6 radon tests from it are on file with CDC (2022). 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

    37.8%

    7.2 pts above MO

    Perry
    37.8%
    Missouri
    30.6%

    82 tests, 2008 to 2017

  • Median result

    3.2pCi/L

    Below action level

    Perry
    3.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    82

    43rd of 72 by tests

    Perry
    82
    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

    22 of 72

    Middle half

    Perry
    37.8%
    Atchison
    69.9%

    By share, of 72 with 30+ tests

Read a result for Perry County

Starts at Perry County's median, 3.2 pCi/L

3.2pCi/L

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

EPA’s reading of 3.2 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. Perry County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Perry County, At a glance

Perry County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Perry 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 Perry County, 2022

Share of reported tests at or above 4 pCi/L, by year, Perry County
Share of reported tests at or above 4 pCi/L, by year, Perry County
YearShare of reported tests at or above 4 pCi/L
201433.3%
20150.0%
201671.4%
201733.3%
201866.7%
2019100.0%
202050.0%
2021100.0%
202233.3%

2022: 33.3%. 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 6 tests were reported to CDC for Perry County over 2022, 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: 2022. Measured data period: 2005 to 2022 (every CDC figure on file).

How to read these figures

Perry County, Compared

Perry County radon figures, compared

Calculated by Radon411

In Perry County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (31 of 82) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 2.1 points higher. Across 115 Missouri counties pooled together, 30.6% of tests reached that level, so Perry County runs 7.2 points above its state.

The newest figure, in 2022, counts only 6 tests (33.3% at or above 4 pCi/L), too few to compare, so this reading uses the 82-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 25.3% (Union County, IL) to 41.1% (St. Francois County). By share, Perry County is 22nd of 72 Missouri counties with 30 or more tests for the same period.

Half the tests came in under 3.2 pCi/L and half over it; the single highest reached 24.7 pCi/L. Below the action level, 26 tests (31.7%) came in under 2 pCi/L, against 41.2% statewide, and 25 tests (30.5%) 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 37.8% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential.

The busiest year on file was 2016, with 7 tests reported; the quietest, 2021, had 1.

Perry County against Missouri, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Perry County
Perry County8237.8%3.2 pCi/LThis county
Missouri, pooled115 counties, pooled58,52530.6%Not pooled−7.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−2.1 points
Atchison Countyhighest in the state10369.9%5.6 pCi/L+32.1 points
Vernon Countylowest in the state348.8%0.9 pCi/L−29.0 points
St. Francois County, MOborders it14641.1%2.9 pCi/L+3.3 points
Randolph County, ILborders it13440.3%3.2 pCi/L+2.5 points
Madison County, MOborders it2339.1%3.5 pCi/L+1.3 points
Cape Girardeau County, MOborders it25335.2%2.8 pCi/L−2.6 points
Ste. Genevieve County, MOborders it7431.1%2.5 pCi/L−6.7 points
Jackson County, ILborders it49228.5%2.3 pCi/L−9.3 points
Union County, ILborders it8725.3%1.9 pCi/L−12.5 points
Bollinger County, MOborders it60.0%1.4 pCi/L−37.8 points
Where Perry County's reported results fell, 2008 to 2017, laboratory, beside Missouri and the United States
ResultPerry County testsPerry County shareMissouri shareU.S. shareAgainst Missouri
Under 2 pCi/L2631.7%41.2%39.6%−9.5 points
2 to 4 pCi/L2530.5%28.1%24.7%+2.4 points
4 pCi/L and above3137.8%30.6%35.7%+7.2 points
Perry 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
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
Cape Girardeau County27 of 7225335.2%2.8 pCi/L
Perry County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
2022633.3%2.3 pCi/L8.7 pCi/L40.8%−66.7 points
20211100.0%8.2 pCi/L8.2 pCi/L31.8%+50.0 points
2020450.0%3.7 pCi/L20.9 pCi/L33.2%−50.0 points
20191100.0%24.5 pCi/L24.5 pCi/L33.5%+33.3 points
2018366.7%10.1 pCi/L11.1 pCi/L42.1%+33.4 points
2017333.3%3.6 pCi/L9.8 pCi/L37.0%−38.1 points
2016771.4%7.1 pCi/L15.5 pCi/L29.8%+71.4 points
201530.0%2.1 pCi/L2.6 pCi/L27.6%−33.3 points
2014633.3%2.2 pCi/L20.4 pCi/L34.4%First on file

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

Perry County, Geology

The ground under Perry County

Predicted

USGS's geologic map puts all of Perry 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 Perry 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.

Perry County beside the ground around it

Across Missouri 8.2% of the land is rated high; none of Perry County's is. Of the 8 counties that border it, 2 have more high-potential ground, Madison County the most at 68.2%.

Share of land by USGS radon potential: Perry County, the 8 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Perry CountyZone 2None100%None
Randolph County, ILZone 2None100%None
Bollinger CountyZone 26.3%93.7%None
Ste. Genevieve CountyZone 2None100%None
Jackson County, ILZone 2None100%None
Cape Girardeau CountyZone 217.1%82.9%None
Madison CountyZone 2None31.8%68.2%
Union County, ILZone 2None100%None
St. Francois CountyZone 2None68.8%31.2%
Missouri115 counties, pooled by land areaVaries5.8%86.0%8.2%

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

Local help

Perry County, Local resources

Radon testing and mitigation in Perry County

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

What it means

Perry County, Questions

Questions about radon in Perry County

Are radon levels high in Perry County?

In 2022, 33.3% of the radon tests reported to CDC for Perry County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.3 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, 21 reported a higher share; pooled, the state comes to 30.6%.

Which counties border Perry County?

Perry County borders 8 counties: Randolph County, IL, Bollinger County, MO, Ste. Genevieve County, MO, Jackson County, IL, Cape Girardeau County, MO, Madison County, MO, Union County, IL and St. Francois County, MO.

Products

Perry County, Products

Testing a home in Perry County

In Perry County, 37.8% of 82 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 Perry County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Perry County homes, compared

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Perry County, Bordering counties

Counties bordering Perry County

Calculated by Radon411

Perry County, Cities and towns

Cities and towns in Perry County

The Census Bureau estimates 19,093 residents in Perry County for July 1, 2025, 122 more than in 2020 (+0.6%). That works out to 40 people per square mile of land. Its largest town, Perryville, has 8,593 residents, 45.0% of the total. Together its 4 incorporated places hold 48.5% of those residents; the other 51.5% live outside any of them. Reported testing is thin here: 82 tests over 2008 to 2017, or 4.3 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.

From Perryville to Longtown, CDC publishes no figure by town: each reads Perry County's.

The cities and towns in Perry County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Perryville8,593+0.5%45.0%
Altenburg324−2.4%1.7%
Frohna242−0.8%1.3%
Longtown92+1.1%0.5%

4 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).

Perry County, Homes

Homes in Perry County

Perry County is a place of houses on their own lots: 78% of its 8,507 homes are detached single-family houses, against 70% across Missouri. Half of its homes were built before 1979, close to Missouri's 1978: 24% date from before 1960 and 20% from 2000 or later. Owners live in 78% of the occupied homes (Missouri: 68%), so for most households a test and a fix are their own to order.

Homes in Perry County, Missouri, 2019 to 2023
HomesPerry CountyMissouri
Housing units8,5072,809,501
Detached houses78%70%
In buildings of 5 or more6%13%
Mobile homes10%5%
Built before 196024%28%
Built since 200020%21%
Middle year built19791978
Owner-occupied78%68%

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