Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Shelby County, Missouri
EPA puts Shelby County in Zone 2, its middle radon zone, and only 2 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
Highest bordering
41.8%
Marion County
- Marion
- 41.8%
- Randolph
- 17.2%
5 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
23.3%
Monroe County, 21 miles
- Monroe
- 23.3%
- Missouri
- 30.6%
Share at 4+ pCi/L, 30 tests, 2008 to 2017
Ground above low
100.0%
5.8 pts above Missouri
- Shelby
- 100.0%
- Missouri
- 94.2%
Share of land USGS rates moderate or high potential
Tests reported
29
Too few for a share
- Shelby
- 29
- Needed
- 30
2008 to 2017, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Shelby County
Starts at EPA's action level
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
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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.
The data
Shelby County, At a glance
Shelby County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Shelby County is a
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 Shelby County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 33.3% |
| 2015 | 0.0% |
| 2016 | 0.0% |
| 2021 | 0.0% |
| 2022 | 0.0% |
| 2023 | 0.0% |
2023: 0.0%. Across these years the share ran from 0.0% to 33.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 2 tests were reported to CDC for Shelby 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).
Shelby County, Compared
Shelby County radon figures, compared
Calculated by Radon411CDC's largest figure for Shelby County rests on 29 tests over the 2008 to 2017 laboratory totals, 7 of them at or above 4 pCi/L, so each test moves its share by 3.4 points and no rank or comparison is drawn from it. Results reached as high as 7.7 pCi/L, with a middle value of 1.7 pCi/L.
Of the counties bordering it, 5 have a figure over the 2008 to 2017 laboratory totals: Marion County reported the largest share at or above 4 pCi/L, 41.8%, and Randolph County the smallest, 17.2%, with Lewis County at 32.4%, Monroe County at 23.3% and Macon County at 19.4% between. Farther out, Ralls County (35 miles away) at 32.6%, Adair County (39 miles away) at 27.2% and Audrain County (42 miles away) at 29.9% 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 Shelby 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.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Shelby County, Geology
The ground under Shelby County
PredictedUSGS's geologic map puts all of Shelby County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Dissected Till Plains, to which USGS gives a radon index of 11, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Dissected Till Plains | Till-covered Pennsylvanian sandstone, shale, and limestone. | Moderate | 11 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Shelby County beside the ground around it
Across Missouri 8.2% of the land is rated high; none of Shelby County's is. Of the 6 counties that border it, 2 have more high-potential ground, Lewis County the most at 9.1%.
The map rates the ground, not the air in any home.
Local help
Shelby County, Local resources
Radon testing and mitigation in Shelby County
- Missouri Radon ProgramMissouri Radon Program, run by Missouri Department of Health and Senior Services, offers free or discounted test kits, and answers questions about testing and mitigation in Missouri.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Free radon test kits are available for Missouri residents (limit one per household).
- Compare kits
- Professionals in Missouri27 professionals are listed in Missouri.
What Missouri's program says
- Phone
- 573-751-6102
- radon@health.mo.gov
What it means
Shelby County, Questions
Questions about radon in Shelby County
Are radon levels high in Shelby County?
In 2023, 0.0% of the radon tests reported to CDC for Shelby County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.8 pCi/L. Of the counties bordering it, 5 have a figure over the 2008 to 2017 laboratory totals: Marion County reported the largest share at or above 4 pCi/L, 41.8%, and Randolph County the smallest, 17.2%, with Lewis County at 32.4%, Monroe County at 23.3% and Macon County at 19.4% between.
Which counties border Shelby County?
Shelby County borders 6 counties: Monroe County, Knox County, Marion County, Macon County, Lewis County and Randolph County.
Products
Shelby County, Products
Testing a home in Shelby County
No CDC figure names Shelby County; the nearest county with one, Monroe County (21 miles away), reported 23.3% 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 Shelby County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorForensics Detectors
FD-65-RADON rechargeable radon detector with a color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Shelby County, Bordering counties
Counties bordering Shelby County
Calculated by Radon411- Radon levels in Marion CountyEPA zone 2
41.8%at or above 4 pCi/L
Median 3.2 pCi/L · 282 tests
- Radon levels in Lewis CountyEPA zone 2
32.4%at or above 4 pCi/L
Median 2.6 pCi/L · 71 tests
- Radon levels in Monroe CountyEPA zone 2
23.3%at or above 4 pCi/L
Median 1.5 pCi/L · 30 tests
- Radon levels in Macon CountyEPA zone 2
19.4%at or above 4 pCi/L
Median 1.7 pCi/L · 36 tests
- Radon levels in Randolph CountyEPA zone 2
17.2%at or above 4 pCi/L
Median 1.8 pCi/L · 58 tests
- Radon levels in Knox CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 1.9 pCi/L · 10 tests
Shelby County, Cities and towns
Cities and towns in Shelby County
About 5,870 people live in Shelby County by the Census Bureau's estimate for July 1, 2025, 220 fewer than in 2020 (−3.6%). That works out to 12 people per square mile of land. Its largest town, Shelbina, has 1,550 residents, 26.4% of the total. Together its 6 incorporated places hold 52.5% of those residents; the other 47.5% live outside any of them. Reported testing is thin here: 29 tests over 2008 to 2017, or 4.9 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.
From Shelbina to Leonard, CDC publishes no figure by town: each reads Shelby County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Shelbina | 1,550 | −3.6% | 26.4% |
| Clarence | 720 | −2.2% | 12.3% |
| Shelbyville | 497 | −4.1% | 8.5% |
| Hunnewell | 133 | −3.6% | 2.3% |
| Bethel | 126 | −4.5% | 2.1% |
| Leonard | 55 | −3.5% | 0.9% |
6 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).
Shelby County, Homes
Homes in Shelby County
Shelby County is a place of houses on their own lots: 78% of its 2,952 homes are detached single-family houses, against 70% across Missouri. The homes are older than Missouri's as a whole: half were built before 1968 (1978 for Missouri), and 42% date from before 1960. 75% 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 | Shelby County | Missouri |
|---|---|---|
| Housing units | 2,952 | 2,809,501 |
| Detached houses | 78% | 70% |
| In buildings of 5 or more | 4% | 13% |
| Mobile homes | 12% | 5% |
| Built before 1960 | 42% | 28% |
| Built since 2000 | 14% | 21% |
| Middle year built | 1968 | 1978 |
| Owner-occupied | 75% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.