Short-term kit
Radon Short Term Test Kit short-term charcoal radon test kit, lab fee included
- Lab fee included
Method: Charcoal
In home: 2 to 7 days
Locations and reports
Radon Levels in Marshall County, Kentucky
EPA puts Marshall County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 10.6% of 85 (2008 to 2017, laboratory totals) reached 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
10.6%
33.1 pts below KY
- Marshall
- 10.6%
- Kentucky
- 43.7%
85 tests, 2008 to 2017
Median result
1.5pCi/L
Below action level
- Marshall
- 1.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
85
39th of 69 by tests
- Marshall
- 85
- Jefferson
- 6,590
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Rank in Kentucky
68 of 69
Lowest quarter
- Marshall
- 10.6%
- Meade
- 68.4%
By share, of 69 with 30+ tests
Read a result for Marshall County
Starts at Marshall County's median, 1.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.5 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, 2008 to 2017.
The data
Marshall County, At a glance
Marshall County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 69% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Marshall County, 2008 to 2017, laboratory
Under 2 pCi/L: 56%2 to 4 pCi/L: 33%4 pCi/L and above: 11%
Of 85 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 48 | 56.5% |
| 2 to 4 pCi/L | 28 | 32.9% |
| 4 pCi/L and above | 9 | 10.6% |
What these figures count
These are the 85 tests reported to CDC for Marshall County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Marshall County, Compared
Marshall County radon figures, compared
Calculated by Radon411Marshall County reports fewer high tests than Kentucky overall. 10.6% of its 85 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 33.1 points below the 43.7% pooled from 120 Kentucky counties.
Ordered from highest share down, it comes 68th of 69 Kentucky counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 35.7%; Marshall County sits 25.1 points below it.
Trigg County, the one bordering county with a figure for the same period, reported 22.2%. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 10.6% share point the same way here.
Half the tests came in under 1.5 pCi/L and half over it; the single highest reached 9.3 pCi/L. The rest split 56.5% under 2 pCi/L and 32.9% from 2 to 4 (Kentucky: 33.2% and 23.1%).
CDC's ten-year totals for Marshall County went from 85 tests (2005 to 2014) to 85 (2008 to 2017), the share going from 11.8% to 10.6%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Marshall County, Geology
The ground under Marshall County
PredictedUSGS's geologic map splits Marshall County: 68.5% of its land is low radon potential and 31.5% moderate. The map puts 68.5% of Marshall County in the area it calls Jackson Purchase and 31.5% in Mississippian Plateau. USGS gives the first a radon index of 6, in the low band (5 to 8), and the second 11, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Jackson Purchase | Cretaceous and Tertiary marine and continental gravels, sands, silts, and clays, overlain by alluvium and loess. | Low | 6 | 68.5% |
| Mississippian Plateau | Mississippian marine limestones, dolomites, marine sandstones, siltstones, and shales. | Moderate | 11 | 31.5% |
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
Across Kentucky 18.2% of the land is rated high; none of Marshall County's is. Of the 6 counties that border it, 1 has more high-potential ground, Calloway County the most at 2.2%.
The map rates the ground, not the air in any home.
Local help
Marshall County, Local resources
Radon testing and mitigation in Marshall County
- Kentucky's radon programKentucky Board of Radon SafetyKentucky's radon program answers questions about testing, mitigation and the rules in Kentucky.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 Kentucky8 professionals are listed in Kentucky.
What Kentucky's program says
- Phone
- 502-782-2782
- Radon@ky.gov
What it means
Marshall County, Questions
Questions about radon in Marshall County
Are radon levels high in Marshall County?
Over the 2008 to 2017 laboratory totals, 10.6% of the radon tests reported to CDC for Marshall County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.5 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 67 reported a higher share; pooled, the state comes to 43.7%.
Which counties border Marshall County?
Marshall County borders 6 counties: Lyon County, Calloway County, Livingston County, Trigg County, Graves County and McCracken County.
Products
Marshall County, Products
Testing a home in Marshall County
In Marshall County, 10.6% of 85 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 43.7% pooled across Kentucky. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Marshall County.
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
MonitorX-Sense
XR0B-SR battery digital radon monitor with an alarm
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- 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
Marshall County, Bordering counties
Counties bordering Marshall County
Calculated by Radon411- Radon levels in Lyon CountyEPA zone 2
35.7%at or above 4 pCi/L
Median 2.5 pCi/L · 14 tests · 25.1 points above Marshall County
- Radon levels in Calloway CountyEPA zone 3
22.2%at or above 4 pCi/L
Median 2.4 pCi/L · 27 tests · 11.6 points above Marshall County
- Radon levels in Trigg CountyEPA zone 2
22.2%at or above 4 pCi/L
Median 2.4 pCi/L · 45 tests · 11.6 points above Marshall County
- Radon levels in McCracken CountyEPA zone 3
21.4%at or above 4 pCi/L
Median 1.6 pCi/L · 28 tests · 10.8 points above Marshall County
- Radon levels in Graves CountyEPA zone 3
8.3%at or above 4 pCi/L
Median 1.5 pCi/L · 24 tests · 2.3 points below Marshall County
- Radon levels in Livingston CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 1.3 pCi/L · 11 tests · 10.6 points below Marshall County
Marshall County, Cities and towns
Cities and towns in Marshall County
Marshall County's population has barely moved since 2020: 31,659 residents on July 1, 2025 against 31,689 then, by the Census Bureau's estimates. That works out to 105 people per square mile of land. No town dominates: Benton, the largest, has 4,718 residents, 14.9% of the total. Together its 3 incorporated places hold 24.7% of those residents; the other 75.3% live outside any of them. Reported testing is thin here: 85 tests over 2008 to 2017, or 2.7 for every 1,000 residents (2025 estimate), where Kentucky as a whole comes to 6.3.
From Benton to Hardin, CDC publishes no figure by town: each reads Marshall County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Benton | 4,718 | −1.0% | 14.9% |
| Calvert City | 2,510 | −0.3% | 7.9% |
| Hardin | 581 | Level | 1.8% |
3 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: 76% of its 16,461 homes are detached single-family houses, against 68% across Kentucky. Half of its homes were built before 1984, close to Kentucky's 1982: 16% date from before 1960 and 22% from 2000 or later. Owners live in 82% of the occupied homes (Kentucky: 68%), so for most households a test and a fix are their own to order.
| Homes | Marshall County | Kentucky |
|---|---|---|
| Housing units | 16,461 | 2,010,655 |
| Detached houses | 76% | 68% |
| In buildings of 5 or more | 5% | 12% |
| Mobile homes | 15% | 11% |
| Built before 1960 | 16% | 22% |
| Built since 2000 | 22% | 24% |
| Middle year built | 1984 | 1982 |
| Owner-occupied | 82% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.