Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Marshall County, Kansas
EPA puts Marshall County in Zone 1, its highest radon zone, and 31.8% of its 66 reported radon tests (2022) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
31.8%
0.2 pts below KS
- Marshall
- 31.8%
- Kansas
- 32.0%
66 tests, 2022
Median result
1.9pCi/L
Below action level
- Marshall
- 1.9 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2022
Tests reported
66
25th of 38 by tests
- Marshall
- 66
- Johnson
- 5,240
Reported to CDC before any fix, 2022
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Kansas
21 of 38
Middle half
- Marshall
- 31.8%
- Mitchell
- 57.4%
By share, of 38 with 30+ tests
Read a result for Marshall County
Starts at Marshall County's median, 1.9 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.9 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. Marshall County's median reported result, 2022.
The data
Marshall County, At a glance
Marshall County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Marshall County in
USGS geologic potential: High across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Marshall County, 2022
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2016 | 42.9% |
| 2017 | 50.8% |
| 2018 | 51.9% |
| 2019 | 63.0% |
| 2020 | 67.4% |
| 2021 | 63.6% |
| 2022 | 31.8% |
2022: 31.8%. Across these years the share ran from 31.8% to 67.4%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 66 tests reported to CDC for Marshall County over 2022, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2022. Measured data period: 2016 to 2022 (every CDC figure on file).
Marshall County, Compared
Marshall County radon figures, compared
Calculated by Radon411In Marshall County, about 3 in 10 reported tests in 2022 (21 of 66) were at or above EPA's action level. Against the national pool of 23.9%, the gap is 7.9 points higher. Across 96 Kansas counties pooled together, 32.0% of tests reached that level, so Marshall County runs 0.2 points below its state.
Of 3 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 25.2% (Pottawatomie County) to 76.8% (Gage County, NE). By share, Marshall County is 21st of 38 Kansas counties with 30 or more tests for the same period.
Year by year, 2016 opened at 42.9% and 2022 closed at 31.8% (down 11.1 points), with 2020 the high at 67.4%. Half the tests came in under 1.9 pCi/L and half over it; the single highest reached 41.0 pCi/L. Below the action level, 33 tests (50.0%) came in under 2 pCi/L, against 45.8% statewide, and 12 tests (18.2%) fell between 2 and 4, against 22.1% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 31.8% share point the same way here. USGS geology rates 100% of the county's land high radon potential. CDC also counts 7 tests taken after mitigation in Marshall County for the same period: tests in homes where a fix was already in.
The busiest year on file was 2021, with 99 tests reported; the quietest, 2019, had 27.
Marshall CountyKansas, pooled
| Year | Tests | Marshall County, at or above 4 pCi/L | Kansas, pooled |
|---|---|---|---|
| 2016 | 49 | 42.9% | 35.4% |
| 2017 | 65 | 50.8% | 37.3% |
| 2018 | 54 | 51.9% | 37.3% |
| 2020 | 46 | 67.4% | 31.3% |
| 2021 | 99 | 63.6% | 31.8% |
| 2022 | 66 | 31.8% | 32.0% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Marshall County, Geology
The ground under Marshall County
PredictedMost of the ground under Marshall County is one class on USGS's geologic map: 99.6% of its land is high radon potential, with 0.4% moderate. The map puts 58.3% of Marshall County in the area it calls Glacial Drift and 41.3% in Mid-Continent Rift Zone. USGS gives both a radon index of 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Glacial Drift | Glacial drift and loess of varying thickness, largely locally derived from underlying and nearby Paleozoic sedimentary rocks. | High | 12 | 58.3% |
| Mid-Continent Rift Zone | Faulted and fractured Permian limestone, dolomite, shale, and sandstone related to the Mid-Continent Rift zone. | High | 12 | 41.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Marshall County beside the ground around it
Marshall County has more high-potential ground than Kansas as a whole: 99.6% of its land against 59.9%. Of the 6 counties that border it, 2 have more high-potential ground, Gage County, NE the most at 100%.
The map rates the ground, not the air in any home.
Local help
Marshall County, Local resources
Radon testing and mitigation in Marshall County
- Kansas Radon ProgramKansas Radon Program answers questions about testing, mitigation and the rules in Kansas.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Kansas178 professionals are listed in Kansas.
What Kansas's program says
- Phone
- (800) 693-5343
What it means
Marshall County, Questions
Questions about radon in Marshall County
Are radon levels high in Marshall County?
In 2022, 31.8% of the radon tests reported to CDC for Marshall County, Kansas were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.9 pCi/L. Of 38 Kansas counties with 30 or more tests for the same period, 20 reported a higher share; pooled, the state comes to 32.0%.
Which counties border Marshall County?
Marshall County borders 6 counties: Nemaha County, KS, Pawnee County, NE, Pottawatomie County, KS, Washington County, KS, Riley County, KS and Gage County, NE.
Products
Marshall County, Products
Testing a home in Marshall County
In Marshall County, 31.8% of 66 tests reported to CDC in 2022 reached 4 pCi/L, against 32.0% pooled across Kansas. In Zone 1 the year-round level in Marshall County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
Monitor
EcoBlu plug-in digital radon monitor with a display
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
Method: Ion chamber
First reading: Within 10 minutes
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
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Marshall County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Marshall County
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Marshall County, Bordering counties
Counties bordering Marshall County
Calculated by Radon411- Radon levels in Gage County, NEEPA zone 1
76.8%at or above 4 pCi/L
Median 6.6 pCi/L · 82 tests · 45.0 points above Marshall County
- Radon levels in Nemaha County, KSEPA zone 1
64.3%at or above 4 pCi/L
Median 7.3 pCi/L · 28 tests · 32.5 points above Marshall County
- Radon levels in Washington County, KSEPA zone 1
43.8%at or above 4 pCi/L
Median 3.3 pCi/L · 16 tests · 12.0 points above Marshall County
- Radon levels in Pawnee County, NEEPA zone 1
42.9%at or above 4 pCi/L
Median 3.7 pCi/L · 21 tests · 11.1 points above Marshall County
- Radon levels in Riley County, KSEPA zone 1
31.3%at or above 4 pCi/L
Median 1.9 pCi/L · 800 tests · 0.5 points below Marshall County
- Radon levels in Pottawatomie County, KSEPA zone 1
25.2%at or above 4 pCi/L
Median 1.7 pCi/L · 206 tests · 6.6 points below Marshall County
Marshall County, Cities and towns
Cities and towns in Marshall County
About 9,852 people live in Marshall County by the Census Bureau's estimate for July 1, 2025, 168 fewer than in 2020 (−1.7%). That works out to 11 people per square mile of land. Its largest town, Marysville, has 3,385 residents, 34.4% of the total. Together its 9 incorporated places hold 66.2% of those residents; the other 33.8% live outside any of them. CDC's 66 reported tests for 2022 work out to 6.7 per 1,000 residents (2025 estimate), close to Kansas' 6.2.
From Marysville to Oketo, CDC publishes no figure by town: each reads Marshall County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Marysville | 3,385 | −1.7% | 34.4% |
| Blue Rapids | 909 | −2.0% | 9.2% |
| Frankfort | 718 | −1.0% | 7.3% |
| Waterville | 644 | −2.6% | 6.5% |
| Axtell | 405 | +2.0% | 4.1% |
| Beattie | 198 | −1.5% | 2.0% |
| Summerfield | 122 | −3.2% | 1.2% |
| Vermillion | 79 | +1.3% | 0.8% |
| Oketo | 62 | −1.6% | 0.6% |
9 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).
Marshall County, Homes
Homes in Marshall County
Marshall County is a place of houses on their own lots: 87% of its 4,758 homes are detached single-family houses, against 72% across Kansas. The homes are older than Kansas' as a whole: half were built before 1960 (1975 for Kansas), and 50% date from before 1960. Owners live in 83% of the occupied homes (Kansas: 67%), so for most households a test and a fix are their own to order.
| Homes | Marshall County | Kansas |
|---|---|---|
| Housing units | 4,758 | 1,285,221 |
| Detached houses | 87% | 72% |
| In buildings of 5 or more | 4% | 13% |
| Mobile homes | 6% | 4% |
| Built before 1960 | 50% | 33% |
| Built since 2000 | 13% | 20% |
| Middle year built | 1960 | 1975 |
| Owner-occupied | 83% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.