Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
Locations and reports
Radon Levels in Grundy County, Missouri
EPA puts Grundy 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
26.7%
Daviess County
- Daviess
- 26.7%
- Linn
- 18.9%
3 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
22.4%
Livingston County, 23 miles
- Livingston
- 22.4%
- Missouri
- 30.6%
Share at 4+ pCi/L, 49 tests, 2008 to 2017
Ground above low
100.0%
5.8 pts above Missouri
- Grundy
- 100.0%
- Missouri
- 94.2%
Share of land USGS rates moderate or high potential
Tests reported
27
Too few for a share
- Grundy
- 27
- 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 Grundy 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
Grundy County, At a glance
Grundy County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Grundy 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 Grundy County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 100.0% |
| 2015 | 0.0% |
| 2016 | 0.0% |
| 2017 | 50.0% |
| 2023 | 33.3% |
2023: 33.3%. 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 Grundy 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).
Grundy County, Compared
Grundy County radon figures, compared
Calculated by Radon411CDC's largest figure for Grundy County rests on 27 tests over the 2008 to 2017 laboratory totals, 10 of them at or above 4 pCi/L, so each test moves its share by 3.7 points and no rank or comparison is drawn from it. Results reached as high as 21.4 pCi/L, with a middle value of 2.8 pCi/L.
Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Daviess County reported the largest share at or above 4 pCi/L, 26.7%, and Linn County the smallest, 18.9%, with Livingston County at 22.4% between. Farther out, DeKalb County (47 miles away) at 24.2%, Adair County (51 miles away) at 27.2% and Macon County (57 miles away) at 19.4% 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 Grundy 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.
Grundy County, Geology
The ground under Grundy County
PredictedUSGS's geologic map puts all of Grundy 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.
Grundy County beside the ground around it
Across Missouri 8.2% of the land is rated high; none of Grundy County's is. Of the 6 counties that border it, 1 has more high-potential ground, Harrison County the most at 0.1%.
The map rates the ground, not the air in any home.
Local help
Grundy County, Local resources
Radon testing and mitigation in Grundy 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
Grundy County, Questions
Questions about radon in Grundy County
Are radon levels high in Grundy County?
In 2023, 33.3% of the radon tests reported to CDC for Grundy County, Missouri were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.3 pCi/L. Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Daviess County reported the largest share at or above 4 pCi/L, 26.7%, and Linn County the smallest, 18.9%, with Livingston County at 22.4% between.
Which counties border Grundy County?
Grundy County borders 6 counties: Livingston County, Daviess County, Mercer County, Sullivan County, Harrison County and Linn County.
Products
Grundy County, Products
Testing a home in Grundy County
No CDC figure names Grundy County; the nearest county with one, Livingston County (23 miles away), reported 22.4% 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 Grundy County; a long-term test tells the year-round average.
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
Monitor
EcoQube Flex battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Alarm
- Screen, app
Method: Ion chamber
First reading: Within 15 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Grundy County, Bordering counties
Counties bordering Grundy County
Calculated by Radon411- Radon levels in Sullivan CountyEPA zone 2
33.3%at or above 4 pCi/L
Median 1.4 pCi/L · 6 tests
- Radon levels in Harrison CountyEPA zone 2
29.2%at or above 4 pCi/L
Median 1.9 pCi/L · 24 tests
- Radon levels in Mercer CountyEPA zone 2
27.3%at or above 4 pCi/L
Median 1.7 pCi/L · 11 tests
- Radon levels in Daviess CountyEPA zone 2
26.7%at or above 4 pCi/L
Median 2.0 pCi/L · 30 tests
- Radon levels in Livingston CountyEPA zone 2
22.4%at or above 4 pCi/L
Median 2.1 pCi/L · 49 tests
- Radon levels in Linn CountyEPA zone 2
18.9%at or above 4 pCi/L
Median 1.8 pCi/L · 37 tests
Grundy County, Cities and towns
Cities and towns in Grundy County
Grundy County's population has barely moved since 2020: 9,744 residents on July 1, 2025 against 9,764 then, by the Census Bureau's estimates. That works out to 22 people per square mile of land. Trenton alone is home to 5,557 of them, 57.0% of the total. Together its 6 incorporated places hold 63.6% of those residents; the other 36.4% live outside any of them. Reported testing is thin here: 27 tests over 2008 to 2017, or 2.8 for every 1,000 residents (2025 estimate), where Missouri as a whole comes to 9.3.
From Trenton to Brimson, CDC publishes no figure by town: each reads Grundy County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Trenton | 5,557 | −0.2% | 57.0% |
| Spickard | 220 | −0.9% | 2.3% |
| Galt | 167 | Level | 1.7% |
| Laredo | 154 | −1.3% | 1.6% |
| Tindall | 49 | Level | 0.5% |
| Brimson | 48 | Level | 0.5% |
6 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).
Grundy County, Homes
Homes in Grundy County
Grundy County is a place of houses on their own lots: 81% of its 4,851 homes are detached single-family houses, against 70% across Missouri. The homes are older than Missouri's as a whole: half were built before 1962 (1978 for Missouri), and 47% date from before 1960. 69% 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 | Grundy County | Missouri |
|---|---|---|
| Housing units | 4,851 | 2,809,501 |
| Detached houses | 81% | 70% |
| In buildings of 5 or more | 4% | 13% |
| Mobile homes | 6% | 5% |
| Built before 1960 | 47% | 28% |
| Built since 2000 | 11% | 21% |
| Middle year built | 1962 | 1978 |
| Owner-occupied | 69% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.