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 Harrison County, Missouri
EPA puts Harrison 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
Highest bordering
28.7%
Ringgold County
- Ringgold
- 28.7%
- Decatur
- 25.9%
3 of 7 neighbours have 30+ tests, 2008 to 2017
Nearest county
26.7%
Daviess County, 27 miles
- Daviess
- 26.7%
- Missouri
- 30.6%
Share at 4+ pCi/L, 30 tests, 2008 to 2017
Ground above low
100.0%
5.8 pts above Missouri
- Harrison
- 100.0%
- Missouri
- 94.2%
Share of land USGS rates moderate or high potential
Tests reported
24
Too few for a share
- Harrison
- 24
- Needed
- 30
2008 to 2017, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Harrison County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
The data
Harrison County, At a glance
Harrison County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Harrison 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 Harrison County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 20.0% |
| 2016 | 0.0% |
| 2017 | 33.3% |
| 2018 | 0.0% |
| 2020 | 0.0% |
| 2021 | 100.0% |
| 2023 | 0.0% |
2023: 0.0%. 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 3 tests were reported to CDC for Harrison 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).
Harrison County, Compared
Harrison County radon figures, compared
Calculated by Radon411CDC's largest figure for Harrison County rests on 24 tests over the 2008 to 2017 laboratory totals, 7 of them at or above 4 pCi/L, so each test moves its share by 4.2 points and no rank or comparison is drawn from it. Results reached as high as 25.5 pCi/L, with a middle value of 1.9 pCi/L.
Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Ringgold County, IA reported the largest share at or above 4 pCi/L, 28.7%, and Decatur County, IA the smallest, 25.9%, with Daviess County at 26.7% between. Farther out, DeKalb County (39 miles away) at 24.2%, Livingston County (46 miles away) at 22.4% and Nodaway County (47 miles away) at 34.2% have figures too. Pooled across 115 Missouri counties, 30.6% of reported tests reached that level; across every county in the country with a figure, 35.7%.
Statewide for the same period, Atchison County reported the highest share (69.9%) and Vernon County the lowest (8.8%). EPA's 1993 map puts Harrison County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Harrison County, Geology
The ground under Harrison County
PredictedMost of the ground under Harrison County is one class on USGS's geologic map: 99.9% of its land is moderate radon potential, with 0.1% high. 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 | 99.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Harrison County beside the ground around it
On high-potential ground Harrison County is close to Missouri as a whole: 0.1% of its land against 8.2%. Of the 7 counties that border it, 3 have more high-potential ground, Ringgold County, IA the most at 100%.
The map rates the ground, not the air in any home.
Local help
Harrison County, Local resources
Radon testing and mitigation in Harrison 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
Harrison County, Questions
Questions about radon in Harrison County
Are radon levels high in Harrison County?
In 2023, 0.0% of the radon tests reported to CDC for Harrison County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L. Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Ringgold County, IA reported the largest share at or above 4 pCi/L, 28.7%, and Decatur County, IA the smallest, 25.9%, with Daviess County at 26.7% between.
Which counties border Harrison County?
Harrison County borders 7 counties: Daviess County, MO, Gentry County, MO, Mercer County, MO, Worth County, MO, Grundy County, MO, Decatur County, IA and Ringgold County, IA.
Products
Harrison County, Products
Testing a home in Harrison County
No CDC figure names Harrison County; the nearest county with one, Daviess County (27 miles away), reported 26.7% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Harrison 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
MonitorAEGTEST
HOUND-3786 rechargeable radon monitor with a 3.5-inch color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
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
Harrison County, Bordering counties
Counties bordering Harrison County
Calculated by Radon411- Radon levels in Gentry County, MOEPA zone 2
41.7%at or above 4 pCi/L
Median 3.5 pCi/L · 24 tests
- Radon levels in Grundy County, MOEPA zone 2
37.0%at or above 4 pCi/L
Median 2.8 pCi/L · 27 tests
- Radon levels in Ringgold County, IAEPA zone 1
28.7%at or above 4 pCi/L
Median 2.6 pCi/L · 87 tests
- Radon levels in Mercer County, MOEPA zone 2
27.3%at or above 4 pCi/L
Median 1.7 pCi/L · 11 tests
- Radon levels in Daviess County, MOEPA zone 2
26.7%at or above 4 pCi/L
Median 2.0 pCi/L · 30 tests
- Radon levels in Decatur County, IAEPA zone 1
25.9%at or above 4 pCi/L
Median 2.5 pCi/L · 85 tests
- Radon levels in Worth County, MOEPA zone 2
9.1%at or above 4 pCi/L
Median 1.5 pCi/L · 11 tests
Harrison County, Cities and towns
Cities and towns in Harrison County
The Census Bureau estimates 8,281 residents in Harrison County for July 1, 2025, 123 more than in 2020 (+1.5%). That works out to 11 people per square mile of land. Its largest town, Bethany, has 2,956 residents, 35.7% of the total. Reported testing is thin here: 24 tests over 2008 to 2017, or 2.9 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.
From Bethany to Mount Moriah, CDC publishes no figure by town: each reads Harrison County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Bethany | 2,956 | +1.6% | 35.7% |
| Ridgeway | 378 | +1.1% | 4.6% |
| Gilman Cityextends beyond Harrison County | 337 | +1.8% | Counted whole |
| Cainsville | 285 | +1.1% | 3.4% |
| Eagleville | 283 | +1.4% | 3.4% |
| New Hampton | 228 | +1.8% | 2.8% |
| Blythedale | 212 | +1.4% | 2.6% |
| Mount Moriah | 76 | +1.3% | 0.9% |
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 Harrison County is counted whole, so it has no share.
Harrison County, Homes
Homes in Harrison County
Harrison County is a place of houses on their own lots: 78% of its 4,023 homes are detached single-family houses, against 70% across Missouri. The homes are older than Missouri's as a whole: half were built before 1969 (1978 for Missouri), and 41% date from before 1960. 73% 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 | Harrison County | Missouri |
|---|---|---|
| Housing units | 4,023 | 2,809,501 |
| Detached houses | 78% | 70% |
| In buildings of 5 or more | 3% | 13% |
| Mobile homes | 8% | 5% |
| Built before 1960 | 41% | 28% |
| Built since 2000 | 19% | 21% |
| Middle year built | 1969 | 1978 |
| Owner-occupied | 73% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.