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 Ralls County, Missouri
EPA puts Ralls 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
Share at 4+ pCi/L
34.6%
3.8 pts above MO
- Ralls
- 34.6%
- Missouri
- 30.8%
52 tests, 2007 to 2016
Median result
2.7pCi/L
Below action level
- Ralls
- 2.7 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2007 to 2016
Tests reported
52
56th of 72 by tests
- Ralls
- 52
- St. Louis
- 16,567
Reported to CDC before any fix, 2007 to 2016
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
29 of 72
Middle half
- Ralls
- 34.6%
- Atchison
- 70.5%
By share, of 72 with 30+ tests
Read a result for Ralls County
Starts at Ralls County's median, 2.7 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.7 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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. Ralls County's median reported result, 2007 to 2016.
The data
Ralls County, At a glance
Ralls County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Ralls 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 Ralls County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 0.0% |
| 2015 | 0.0% |
| 2016 | 40.0% |
| 2021 | 25.0% |
| 2022 | 100.0% |
| 2023 | 50.0% |
2023: 50.0%. 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 2 tests were reported to CDC for Ralls 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).
Ralls County, Compared
Ralls County radon figures, compared
Calculated by Radon411In Ralls County, about 3 in 10 reported tests over the 2007 to 2016 laboratory totals (18 of 52) were at or above EPA's action level. Against the national pool of 35.8%, the gap is 1.2 points lower. Across 115 Missouri counties pooled together, 30.8% of tests reached that level, so Ralls County runs 3.8 points above its state.
The newest figure, in 2023, counts only 2 tests (50.0% at or above 4 pCi/L), too few to compare, so this reading uses the 52-test figure.
Of 5 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 24.3% (Monroe County) to 45.8% (Pike County, IL). By share, Ralls County is 29th of 72 Missouri counties with 30 or more tests for the same period.
Half the tests came in under 2.7 pCi/L and half over it; the single highest reached 285.3 pCi/L. Below the action level, 19 tests (36.5%) came in under 2 pCi/L, against 41.2% statewide, and 15 tests (28.8%) fell between 2 and 4, against 27.9% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 34.6% 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 5 tests reported; the quietest, 2014, had 1.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Ralls County, Geology
The ground under Ralls County
PredictedUSGS's geologic map puts all of Ralls 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.
Ralls County beside the ground around it
Across Missouri 8.2% of the land is rated high; none of Ralls County's is. Of the 5 counties that border it, 3 have more high-potential ground, Pike County, IL the most at 99.9%.
The map rates the ground, not the air in any home.
Local help
Ralls County, Local resources
Radon testing and mitigation in Ralls 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
Ralls County, Questions
Questions about radon in Ralls County
Are radon levels high in Ralls County?
In 2023, 50.0% of the radon tests reported to CDC for Ralls County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.9 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, 28 reported a higher share; pooled, the state comes to 30.8%.
Which counties border Ralls County?
Ralls County borders 5 counties: Marion County, MO, Pike County, MO, Audrain County, MO, Monroe County, MO and Pike County, IL.
Products
Ralls County, Products
Testing a home in Ralls County
In Ralls County, 34.6% of 52 tests reported to CDC over the 2007 to 2016 laboratory totals reached 4 pCi/L, against 30.8% pooled across Missouri. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Ralls 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
MonitorAranet
Radon Plus battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Approved
- Battery
- Bluetooth
- Alarm
- Screen, app
Method: Ion chamber
First reading: Within 10 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Ralls County, Bordering counties
Counties bordering Ralls County
Calculated by Radon411- Radon levels in Pike County, ILEPA zone 1
45.8%at or above 4 pCi/L
Median 3.8 pCi/L · 96 tests · 11.2 points above Ralls County
- Radon levels in Pike County, MOEPA zone 2
41.2%at or above 4 pCi/L
Median 3.0 pCi/L · 34 tests · 6.6 points above Ralls County
- Radon levels in Marion County, MOEPA zone 2
40.7%at or above 4 pCi/L
Median 3.1 pCi/L · 273 tests · 6.1 points above Ralls County
- Radon levels in Audrain County, MOEPA zone 2
29.8%at or above 4 pCi/L
Median 2.3 pCi/L · 124 tests · 4.8 points below Ralls County
- Radon levels in Monroe County, MOEPA zone 2
24.3%at or above 4 pCi/L
Median 1.7 pCi/L · 37 tests · 10.3 points below Ralls County
Ralls County, Cities and towns
Cities and towns in Ralls County
The Census Bureau estimates 10,444 residents in Ralls County for July 1, 2025, 92 more than in 2020 (+0.9%). That works out to 22 people per square mile of land. Hannibal, the largest place on its list (16,804 residents in all), extends beyond Ralls County, so no share of the total is worked out for it. Reported testing is thin here: 52 tests over 2007 to 2016, or 5.0 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 8.8.
From Hannibal to Rensselaer, CDC publishes no figure by town: each reads Ralls County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Hannibalextends beyond Ralls County | 16,804 | −1.5% | Counted whole |
| Vandaliaextends beyond Ralls County | 3,029 | −11.2% | Counted whole |
| Monroe Cityextends beyond Ralls County | 2,714 | +2.0% | Counted whole |
| New London | 981 | +4.8% | 9.4% |
| Perry | 686 | +2.5% | 6.6% |
| Center | 542 | +1.1% | 5.2% |
| Rensselaer | 249 | Level | 2.4% |
7 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 Ralls County is counted whole, so it has no share.
Ralls County, Homes
Homes in Ralls County
Ralls County is a place of houses on their own lots: 76% of its 5,036 homes are detached single-family houses, against 70% across Missouri. Half of its homes were built before 1982, close to Missouri's 1978: 21% date from before 1960 and 23% from 2000 or later. Owners live in 86% of the occupied homes (Missouri: 68%), so for most households a test and a fix are their own to order.
| Homes | Ralls County | Missouri |
|---|---|---|
| Housing units | 5,036 | 2,809,501 |
| Detached houses | 76% | 70% |
| In buildings of 5 or more | 3% | 13% |
| Mobile homes | 18% | 5% |
| Built before 1960 | 21% | 28% |
| Built since 2000 | 23% | 21% |
| Middle year built | 1982 | 1978 |
| Owner-occupied | 86% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.