Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Benton County, Missouri
EPA puts Benton 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
Share at 4+ pCi/L
30.6%
0.0 pts above MO
- Benton
- 30.6%
- Missouri
- 30.6%
49 tests, 2008 to 2017
Median result
2.0pCi/L
Below action level
- Benton
- 2.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
49
57th of 72 by tests
- Benton
- 49
- 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
38 of 72
Middle half
- Benton
- 30.6%
- Atchison
- 69.9%
By share, of 72 with 30+ tests
Read a result for Benton County
Starts at Benton County's median, 2.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.0 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. Benton County's median reported result, 2008 to 2017.
The data
Benton County, At a glance
Benton County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Benton 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 Benton County, 2022
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 0.0% |
| 2015 | 40.0% |
| 2016 | 0.0% |
| 2017 | 33.3% |
| 2018 | 0.0% |
| 2019 | 50.0% |
| 2020 | 0.0% |
| 2021 | 50.0% |
| 2022 | 33.3% |
2022: 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 6 tests were reported to CDC for Benton 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).
Benton County, Compared
Benton County radon figures, compared
Calculated by Radon411In Benton County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (15 of 49) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 5.1 points lower. Pooled across 115 Missouri counties, the share is the same 30.6%.
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 49-test figure.
Of 4 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 21.1% (Morgan County) to 38.3% (Henry County). By share, Benton County is 38th of 72 Missouri counties with 30 or more tests for the same period.
Half the tests came in under 2.0 pCi/L and half over it; the single highest reached 14.1 pCi/L. Below the action level, 23 tests (46.9%) came in under 2 pCi/L, against 41.2% statewide, and 11 tests (22.4%) 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 30.6% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential.
The busiest year on file was 2018, with 6 tests reported; the quietest, 2016, had 1.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Benton County, Geology
The ground under Benton County
PredictedUSGS's geologic map puts all of Benton County's mapped land in one class: moderate radon potential. The map puts 76.2% of Benton County in the area it calls Salem Plateau and 12.9% in Osage Plains, with one smaller area beside them. USGS gives both 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 |
|---|---|---|---|---|
| Salem Plateau | Ordovician dolomite, sandstone, limestone, and shale. | Moderate | 11 | 76.2% |
| Osage Plains | Ordovician dolomite, sandstone, limestone, and shale. | Moderate | 11 | 12.9% |
| Springfield Plateau | Mississippian limestone, shale, and sandstone. | Moderate | 11 | 10.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Benton County beside the ground around it
Across Missouri 8.2% of the land is rated high; none of Benton County's is. Of the 6 counties that border it, none has as large a share of moderate-potential ground; Camden County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Benton County, Local resources
Radon testing and mitigation in Benton 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
Benton County, Questions
Questions about radon in Benton County
Are radon levels high in Benton County?
In 2022, 33.3% of the radon tests reported to CDC for Benton County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.4 pCi/L. Of 72 Missouri counties with 30 or more tests for the same period, 37 reported a higher share; pooled, the state comes to 30.6%.
Which counties border Benton County?
Benton County borders 6 counties: Morgan County, Hickory County, Henry County, Pettis County, Camden County and St. Clair County.
Products
Benton County, Products
Testing a home in Benton County
In Benton County, 30.6% of 49 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 Benton 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
Monitor
RadonPro Wi-Fi radon monitor with a built-in Geiger counter
- C-NRPP 2024/25: Not included
- Plug-in
- Wi-Fi
- Alarm
- Screen, app
First reading: Within 5 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Benton County, Bordering counties
Counties bordering Benton County
Calculated by Radon411- Radon levels in Henry CountyEPA zone 2
38.3%at or above 4 pCi/L
Median 3.4 pCi/L · 81 tests · 7.7 points above Benton County
- Radon levels in Pettis CountyEPA zone 2
37.9%at or above 4 pCi/L
Median 2.8 pCi/L · 132 tests · 7.3 points above Benton County
- Radon levels in Camden CountyEPA zone 2
22.9%at or above 4 pCi/L
Median 2.2 pCi/L · 763 tests · 7.7 points below Benton County
- Radon levels in Morgan CountyEPA zone 2
21.1%at or above 4 pCi/L
Median 2.2 pCi/L · 123 tests · 9.5 points below Benton County
- Radon levels in St. Clair CountyEPA zone 2
7.7%at or above 4 pCi/L
Median 1.5 pCi/L · 13 tests · 22.9 points below Benton County
- Radon levels in Hickory CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 2.0 pCi/L · 9 tests · 30.6 points below Benton County
Benton County, Cities and towns
Cities and towns in Benton County
Benton County is growing: the Census Bureau puts it at 20,536 residents on July 1, 2025, up 5.7% from 19,431 in 2020. That works out to 29 people per square mile of land. No town dominates: Warsaw, the largest, has 2,338 residents, 11.4% of the total. Reported testing is thin here: 49 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 Warsaw to Ionia, CDC publishes no figure by town: each reads Benton County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Warsaw | 2,338 | +5.2% | 11.4% |
| Lincoln | 1,197 | +4.7% | 5.8% |
| Cole Camp | 1,169 | +6.3% | 5.7% |
| Ioniaextends beyond Benton County | 79 | +5.3% | Counted whole |
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). A place that extends beyond Benton County is counted whole, so it has no share.
Benton County, Homes
Homes in Benton County
Of Benton County's 13,579 homes, 72% are detached houses, against 70% across Missouri; 23% are mobile homes. Half of its homes were built before 1984, close to Missouri's 1978: 15% date from before 1960 and 25% from 2000 or later. Owners live in 84% of the occupied homes (Missouri: 68%), so for most households a test and a fix are their own to order.
| Homes | Benton County | Missouri |
|---|---|---|
| Housing units | 13,579 | 2,809,501 |
| Detached houses | 72% | 70% |
| In buildings of 5 or more | 2% | 13% |
| Mobile homes | 23% | 5% |
| Built before 1960 | 15% | 28% |
| Built since 2000 | 25% | 21% |
| Middle year built | 1984 | 1978 |
| Owner-occupied | 84% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.