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Radon Levels in Oregon County, Missouri

EPA puts Oregon County in Zone 2, its middle radon zone, and only 1 radon test from it is on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Highest bordering

    45.7%

    Howell County

    Howell
    45.7%

    1 of 7 neighbours have 30+ tests, 2008 to 2017

  • Nearest county

    45.7%

    Howell County, 27 miles

    Howell
    45.7%
    Missouri
    30.6%

    Share at 4+ pCi/L, 138 tests, 2008 to 2017

  • Ground above low

    100.0%

    5.8 pts above Missouri

    Oregon
    100.0%
    Missouri
    94.2%

    Share of land USGS rates moderate or high potential

  • Tests reported

    3

    Too few for a share

    Oregon
    3
    Needed
    30

    2008 to 2017, laboratory

  • 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

Read a result for Oregon County

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 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.

Interpret this readingWhat a fix costs

The data

Oregon County, At a glance

Oregon County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Oregon 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 Oregon County, 2023

Share of reported tests at or above 4 pCi/L, by year, Oregon County
Share of reported tests at or above 4 pCi/L, by year, Oregon County
YearShare of reported tests at or above 4 pCi/L
2016100.0%
20170.0%
2019100.0%
20200.0%
202250.0%
2023100.0%

2023: 100.0%. 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 1 test was reported to CDC for Oregon 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

Oregon County, Compared

Oregon County radon figures, compared

Calculated by Radon411

CDC's largest figure for Oregon County rests on 3 tests over the 2008 to 2017 laboratory totals, 1 of them at or above 4 pCi/L, so each test moves its share by 33.3 points and no rank or comparison is drawn from it. Results reached as high as 7.7 pCi/L, with a middle value of 2.0 pCi/L.

Howell County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 45.7% of its tests at or above 4 pCi/L. Farther out, Texas County (53 miles away) at 19.3%, Butler County (55 miles away) at 21.2% and Phelps County (85 miles away) at 14.7% have figures too. Pooled across 115 Missouri counties, 30.6% of reported tests reached that level; across every county in the country with a figure, 35.7%.

Statewide for the same period, Atchison County reported the highest share (69.9%) and Vernon County the lowest (8.8%). EPA's 1993 map puts Oregon County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.

Missouri, the United States and the counties around Oregon County, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedian
Missouri, pooled115 counties, pooled58,52530.6%Not pooled
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled
Atchison Countyhighest in the state10369.9%5.6 pCi/L
Vernon Countylowest in the state348.8%0.9 pCi/L
Fulton County, ARborders it250.0%5.9 pCi/L
Randolph County, ARborders it250.0%3.2 pCi/L
Howell County, MOborders it13845.7%3.5 pCi/L
Ripley County, MOborders it1030.0%3.0 pCi/L
Shannon County, MOborders it1926.3%1.3 pCi/L
Carter County, MOborders it425.0%2.8 pCi/L
Sharp County, ARborders it520.0%1.8 pCi/L
The nearest Missouri counties to Oregon County with 30 or more tests, 2008 to 2017, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Howell County27 mi13845.7%3.5 pCi/L
Texas County53 mi5719.3%1.3 pCi/L
Butler County55 mi3321.2%1.9 pCi/L
Phelps County85 mi20414.7%1.5 pCi/L
Crawford County89 mi3414.7%1.5 pCi/L
Pulaski County90 mi10718.7%1.3 pCi/L
Taney County91 mi14637.0%3.0 pCi/L
Webster County91 mi10320.4%1.6 pCi/L
Oregon County radon tests by year, against Missouri's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMissouri, pooledChange from the row before
20231100.0%9.7 pCi/L9.7 pCi/L35.7%+50.0 points
2022250.0%10.0 pCi/L17.1 pCi/L40.8%+50.0 points
202010.0%3.3 pCi/L3.3 pCi/L33.2%−100.0 points
20191100.0%14.2 pCi/L14.2 pCi/L33.5%+100.0 points
201710.0%1.3 pCi/L1.3 pCi/L37.0%−100.0 points
20162100.0%6.3 pCi/L7.7 pCi/L29.8%First on file

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

Oregon County, Geology

The ground under Oregon County

Predicted

USGS's geologic map puts all of Oregon 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 Oregon 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.

Oregon County beside the ground around it

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

Share of land by USGS radon potential: Oregon County, the 7 counties bordering it and Missouri
AreaEPA zoneLow potentialModerate potentialHigh potential
Oregon CountyZone 2None100%None
Howell CountyZone 2None100%None
Carter CountyZone 2None100%None
Fulton County, ARZone 2None100%None
Ripley CountyZone 29.7%90.3%None
Shannon CountyZone 2None100%None
Randolph County, ARZone 228.9%71.1%None
Sharp County, ARZone 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

Oregon County, Local resources

Radon testing and mitigation in Oregon County

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

What it means

Oregon County, Questions

Questions about radon in Oregon County

Are radon levels high in Oregon County?

In 2023, 100.0% of the radon tests reported to CDC for Oregon County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 9.7 pCi/L. Howell County, the one bordering county with a figure over the 2008 to 2017 laboratory totals, reported 45.7% of its tests at or above 4 pCi/L.

Which counties border Oregon County?

Oregon County borders 7 counties: Howell County, MO, Carter County, MO, Fulton County, AR, Ripley County, MO, Shannon County, MO, Randolph County, AR and Sharp County, AR.

Products

Oregon County, Products

Testing a home in Oregon County

No CDC figure names Oregon County; the nearest county with one, Howell County (27 miles away), reported 45.7% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Oregon County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Oregon County homes, compared

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Oregon County, Bordering counties

Counties bordering Oregon County

Calculated by Radon411

Oregon County, Cities and towns

Cities and towns in Oregon County

The Census Bureau estimates 8,709 residents in Oregon County for July 1, 2025, 104 more than in 2020 (+1.2%). That works out to 11 people per square mile of land. Its largest town, Thayer, has 1,898 residents, 21.8% of the total. Together its 3 incorporated places hold 32.1% of those residents; the other 67.9% live outside any of them. Reported testing is thin here: 3 tests over 2008 to 2017, or 0.3 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.

From Thayer to Koshkonong, CDC publishes no figure by town: each reads Oregon County's.

The cities and towns in Oregon County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Thayer1,898+1.6%21.8%
Alton702+0.1%8.1%
Koshkonong198+1.0%2.3%

3 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).

Oregon County, Homes

Homes in Oregon County

Oregon County is a place of houses on their own lots: 78% of its 4,332 homes are detached single-family houses, against 70% across Missouri. Half of its homes were built before 1979, close to Missouri's 1978: 26% date from before 1960 and 21% from 2000 or later. Owners live in 77% of the occupied homes (Missouri: 68%), so for most households a test and a fix are their own to order.

Homes in Oregon County, Missouri, 2019 to 2023
HomesOregon CountyMissouri
Housing units4,3322,809,501
Detached houses78%70%
In buildings of 5 or more1%13%
Mobile homes16%5%
Built before 196026%28%
Built since 200021%21%
Middle year built19791978
Owner-occupied77%68%

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