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 Jefferson County, Kansas
EPA puts Jefferson County in Zone 2, its middle radon zone, and 39.6% of its 53 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
39.6%
7.6 pts above KS
- Jefferson
- 39.6%
- Kansas
- 32.0%
53 tests, 2022
Median result
2.4pCi/L
Below action level
- Jefferson
- 2.4 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2022
Tests reported
53
28th of 38 by tests
- Jefferson
- 53
- Johnson
- 5,240
Reported to CDC before any fix, 2022
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 Kansas
14 of 38
Middle half
- Jefferson
- 39.6%
- Mitchell
- 57.4%
By share, of 38 with 30+ tests
Read a result for Jefferson County
Starts at Jefferson County's median, 2.4 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.4 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. Jefferson County's median reported result, 2022.
The data
Jefferson County, At a glance
Jefferson County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Jefferson County is a
USGS geologic potential: Moderate across 71% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Jefferson County, 2022
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2016 | 40.4% |
| 2017 | 36.6% |
| 2018 | 32.7% |
| 2019 | 33.8% |
| 2020 | 30.0% |
| 2021 | 44.7% |
| 2022 | 39.6% |
2022: 39.6%. Across these years the share ran from 30.0% to 44.7%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 53 tests reported to CDC for Jefferson 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).
Jefferson County, Compared
Jefferson County radon figures, compared
Calculated by Radon411In Jefferson County, about 4 in 10 reported tests in 2022 (21 of 53) were at or above EPA's action level. Against the national pool of 23.9%, the gap is 15.7 points higher. Across 96 Kansas counties pooled together, 32.0% of tests reached that level, so Jefferson County runs 7.6 points above its state.
Of 4 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 25.8% (Douglas County) to 41.7% (Atchison County). By share, Jefferson County is 14th of 38 Kansas counties with 30 or more tests for the same period.
Year by year, 2016 opened at 40.4% and 2022 closed at 39.6% (about level), with 2021 the high at 44.7%. Half the tests came in under 2.4 pCi/L and half over it; the single highest reached 15.5 pCi/L. Below the action level, 25 tests (47.2%) came in under 2 pCi/L, against 45.8% statewide, and 7 tests (13.2%) fell between 2 and 4, against 22.1% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 39.6% share point the same way here. USGS geology rates 71% of the county's land moderate radon potential.
The busiest year on file was 2021, with 228 tests reported; the quietest, 2022, had 53.
Jefferson CountyKansas, pooled
39.6% % of tests32.0% % of tests
| Year | Tests | Jefferson County, at or above 4 pCi/L | Kansas, pooled |
|---|---|---|---|
| 2016 | 57 | 40.4% | 35.4% |
| 2017 | 71 | 36.6% | 37.3% |
| 2018 | 104 | 32.7% | 37.3% |
| 2019 | 68 | 33.8% | 33.7% |
| 2020 | 60 | 30.0% | 31.3% |
| 2021 | 228 | 44.7% | 31.8% |
| 2022 | 53 | 39.6% | 32.0% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Jefferson County, Geology
The ground under Jefferson County
PredictedUSGS's geologic map splits Jefferson County: 70.7% of its land is moderate radon potential and 29.3% high. The map puts 70.7% of Jefferson County in the area it calls Glaciated Area and 29.3% in Glacial Drift. USGS gives the first a radon index of 9, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Glaciated Area | Glacial till underlain by Pennsylvanian and Permian marine and nonmarine sedimentary shale, sandstone, limestone, coal. | Moderate | 9 | 70.7% |
| Glacial Drift | Glacial drift and loess of varying thickness, largely locally derived from underlying and nearby Paleozoic sedimentary rocks. | High | 12 | 29.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Jefferson County beside the ground around it
Kansas as a whole has more high-potential ground than Jefferson County: 59.9% of its land, against 29.3% here. Of the 5 counties that border it, 3 have more high-potential ground, Atchison County the most at 93.5%.
The map rates the ground, not the air in any home.
Local help
Jefferson County, Local resources
Radon testing and mitigation in Jefferson 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
Jefferson County, Questions
Questions about radon in Jefferson County
Are radon levels high in Jefferson County?
In 2022, 39.6% of the radon tests reported to CDC for Jefferson County, Kansas were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.4 pCi/L. Of 38 Kansas counties with 30 or more tests for the same period, 13 reported a higher share; pooled, the state comes to 32.0%.
Which counties border Jefferson County?
Jefferson County borders 5 counties: Atchison County, Leavenworth County, Jackson County, Douglas County and Shawnee County.
Products
Jefferson County, Products
Testing a home in Jefferson County
In Jefferson County, 39.6% of 53 tests reported to CDC in 2022 reached 4 pCi/L, against 32.0% pooled across Kansas. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Jefferson 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
Hello Radon C battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- 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
Jefferson County, Bordering counties
Counties bordering Jefferson County
Calculated by Radon411- Radon levels in Atchison CountyEPA zone 1
41.7%at or above 4 pCi/L
Median 3.3 pCi/L · 60 tests · 2.1 points above Jefferson County
- Radon levels in Shawnee CountyEPA zone 2
34.5%at or above 4 pCi/L
Median 2.6 pCi/L · 388 tests · 5.1 points below Jefferson County
- Radon levels in Leavenworth CountyEPA zone 1
26.8%at or above 4 pCi/L
Median 1.9 pCi/L · 515 tests · 12.8 points below Jefferson County
- Radon levels in Douglas CountyEPA zone 1
25.8%at or above 4 pCi/L
Median 1.8 pCi/L · 868 tests · 13.8 points below Jefferson County
- Radon levels in Jackson CountyEPA zone 1
23.8%at or above 4 pCi/L
Median 2.7 pCi/L · 21 tests · 15.8 points below Jefferson County
Jefferson County, Cities and towns
Cities and towns in Jefferson County
Jefferson County's population has barely moved since 2020: 18,296 residents on July 1, 2025 against 18,330 then, by the Census Bureau's estimates. That works out to 34 people per square mile of land. No town dominates: Oskaloosa, the largest, has 1,060 residents, 5.8% of the total. Together its 8 incorporated places hold 33.6% of those residents; the other 66.4% live outside any of them. Reported testing is thin here: 53 tests over 2022, or 2.9 for every 1,000 residents (2025 estimate), where Kansas as a whole comes to 6.2.
From Oskaloosa to Winchester, CDC publishes no figure by town: each reads Jefferson County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Oskaloosa | 1,060 | −3.3% | 5.8% |
| Valley Falls | 1,055 | −2.9% | 5.8% |
| Perry | 848 | −0.1% | 4.6% |
| McLouth | 832 | −2.9% | 4.5% |
| Meriden | 709 | −3.9% | 3.9% |
| Ozawkie | 617 | −2.8% | 3.4% |
| Nortonville | 579 | −3.8% | 3.2% |
| Winchester | 440 | −3.1% | 2.4% |
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).
Jefferson County, Homes
Homes in Jefferson County
Jefferson County is a place of houses on their own lots: 88% of its 8,004 homes are detached single-family houses, against 72% across Kansas. Half of its homes were built before 1977, close to Kansas' 1975: 27% date from before 1960 and 19% from 2000 or later. Owners live in 85% of the occupied homes (Kansas: 67%), so for most households a test and a fix are their own to order.
| Homes | Jefferson County | Kansas |
|---|---|---|
| Housing units | 8,004 | 1,285,221 |
| Detached houses | 88% | 72% |
| In buildings of 5 or more | 1% | 13% |
| Mobile homes | 7% | 4% |
| Built before 1960 | 27% | 33% |
| Built since 2000 | 19% | 20% |
| Middle year built | 1977 | 1975 |
| Owner-occupied | 85% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.