Short-term kit
PicoCan short-term charcoal canister radon test
- Lab fee included
Method: Charcoal
In home: 48 to 96 hours
Locations and reports
Radon Levels in Randolph County, Missouri
EPA puts Randolph County in Zone 2, its middle 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
Share at 4+ pCi/L
17.2%
13.4 pts below MO
- Randolph
- 17.2%
- Missouri
- 30.6%
58 tests, 2008 to 2017
Median result
1.8pCi/L
Below action level
- Randolph
- 1.8 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
58
51st of 72 by tests
- Randolph
- 58
- St. Louis
- 17,747
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Missouri
64 of 72
Lowest quarter
- Randolph
- 17.2%
- Atchison
- 69.9%
By share, of 72 with 30+ tests
Read a result for Randolph County
Starts at Randolph County's median, 1.8 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.8 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Randolph County's median reported result, 2008 to 2017.
The data
Randolph County, At a glance
Randolph County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Randolph 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 Randolph County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 25.0% |
| 2015 | 33.3% |
| 2016 | 20.0% |
| 2018 | 50.0% |
| 2019 | 0.0% |
| 2021 | 0.0% |
| 2022 | 0.0% |
| 2023 | 33.3% |
2023: 33.3%. Across these years the share ran from 0.0% to 50.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 3 tests were reported to CDC for Randolph 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).
Randolph County, Compared
Randolph County radon figures, compared
Calculated by Radon411Randolph County's 58 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.8 pCi/L and a maximum of 21.1 pCi/L, and 17.2% reached 4 pCi/L. Missouri as a whole (115 Missouri counties, pooled) comes to 30.6%: 13.4 points higher than here.
The newest figure, in 2023, counts only 3 tests (33.3% at or above 4 pCi/L), too few to compare, so this reading uses the 58-test figure.
Among its state's counties it ranks 64th of 72 Missouri counties with 30 or more tests for the same period. Statewide for the same period, Atchison County reported the highest share (69.9%) and Vernon County the lowest (8.8%).
Below the action level, 31 tests (53.4%) came in under 2 pCi/L, against 41.2% statewide, and 17 tests (29.3%) fell between 2 and 4, against 28.1% statewide. The busiest year on file was 2022, with 8 tests reported; the quietest, 2019, had 1.
EPA's 1993 zone map puts Randolph County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Next door, the shares run from 19.4% in Macon County to 43.5% in Howard County.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Randolph County, Geology
The ground under Randolph County
PredictedUSGS's geologic map puts all of Randolph 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.
Randolph County beside the ground around it
Across Missouri 8.2% of the land is rated high; none of Randolph 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%.
The map rates the ground, not the air in any home.
Local help
Randolph County, Local resources
Radon testing and mitigation in Randolph 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
Randolph County, Questions
Questions about radon in Randolph County
Are radon levels high in Randolph County?
In 2023, 33.3% of the radon tests reported to CDC for Randolph County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.2 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, 63 reported a higher share; pooled, the state comes to 30.6%.
Which counties border Randolph County?
Randolph County borders 7 counties: Howard County, Macon County, Chariton County, Monroe County, Shelby County, Boone County and Audrain County.
Products
Randolph County, Products
Testing a home in Randolph County
In Randolph County, 17.2% of 58 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 Randolph County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
MonitorX-Sense
XR0A-SR battery digital radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Randolph County, Bordering counties
Counties bordering Randolph County
Calculated by Radon411- Radon levels in Howard CountyEPA zone 2
43.5%at or above 4 pCi/L
Median 3.5 pCi/L · 62 tests · 26.3 points above Randolph County
- Radon levels in Audrain CountyEPA zone 2
29.9%at or above 4 pCi/L
Median 2.5 pCi/L · 127 tests · 12.7 points above Randolph County
- Radon levels in Shelby CountyEPA zone 2
24.1%at or above 4 pCi/L
Median 1.7 pCi/L · 29 tests · 6.9 points above Randolph County
- Radon levels in Monroe CountyEPA zone 2
23.3%at or above 4 pCi/L
Median 1.5 pCi/L · 30 tests · 6.1 points above Randolph County
- Radon levels in Boone CountyEPA zone 2
21.7%at or above 4 pCi/L
Median 1.9 pCi/L · 4,767 tests · 4.5 points above Randolph County
- Radon levels in Macon CountyEPA zone 2
19.4%at or above 4 pCi/L
Median 1.7 pCi/L · 36 tests · 2.2 points above Randolph County
- Radon levels in Chariton CountyEPA zone 2
13.3%at or above 4 pCi/L
Median 1.7 pCi/L · 15 tests · 3.9 points below Randolph County
Randolph County, Cities and towns
Cities and towns in Randolph County
Randolph County's population has barely moved since 2020: 24,513 residents on July 1, 2025 against 24,462 then, by the Census Bureau's estimates. That works out to 51 people per square mile of land. Moberly alone is home to 13,719 of them, 56.0% of the total. Reported testing is thin here: 58 tests over 2008 to 2017, or 2.4 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.
From Moberly to Clifton Hill, CDC publishes no figure by town: each reads Randolph County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Moberly | 13,719 | +1.0% | 56.0% |
| Huntsville | 1,362 | −0.8% | 5.6% |
| Higbee | 442 | −1.3% | 1.8% |
| Clarkextends beyond Randolph County | 237 | −2.1% | Counted whole |
| Cairo | 203 | −1.0% | 0.8% |
| Renick | 150 | Level | 0.6% |
| Jacksonville | 123 | Level | 0.5% |
| Clifton Hill | 84 | −1.2% | 0.3% |
8 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 Randolph County is counted whole, so it has no share.
Randolph County, Homes
Homes in Randolph County
Of Randolph County's 10,811 homes, 74% are detached houses, against 70% across Missouri; 13% are mobile homes. Half of its homes were built before 1974, close to Missouri's 1978: 32% date from before 1960 and 19% from 2000 or later. 70% 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 | Randolph County | Missouri |
|---|---|---|
| Housing units | 10,811 | 2,809,501 |
| Detached houses | 74% | 70% |
| In buildings of 5 or more | 4% | 13% |
| Mobile homes | 13% | 5% |
| Built before 1960 | 32% | 28% |
| Built since 2000 | 19% | 21% |
| Middle year built | 1974 | 1978 |
| Owner-occupied | 70% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.