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 Jefferson County, Nebraska
EPA puts Jefferson County in Zone 1, its highest radon zone, and only 12 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
Share at 4+ pCi/L
67.4%
8.9 pts above NE
- Jefferson
- 67.4%
- Nebraska
- 58.5%
325 tests, 2008 to 2017
Median result
6.6pCi/L
Action level reached
- Jefferson
- 6.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
325
30th of 77 by tests
- Jefferson
- 325
- Douglas
- 8,556
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Nebraska
30 of 77
Middle half
- Jefferson
- 67.4%
- Clay
- 85.1%
By share, of 77 with 30+ tests
Read a result for Jefferson County
Starts at Jefferson County's median, 6.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 6.6 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. Jefferson County's median reported result, 2008 to 2017.
The data
Jefferson County, At a glance
Jefferson County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Jefferson 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 Jefferson County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 30.2% |
| 2015 | 66.7% |
| 2016 | 50.0% |
| 2017 | 66.7% |
| 2018 | 64.8% |
| 2019 | 43.1% |
| 2020 | 53.8% |
| 2021 | 56.3% |
| 2022 | 42.9% |
| 2023 | 75.0% |
2023: 75.0%. Across these years the share ran from 30.2% to 75.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 12 tests were reported to CDC for Jefferson 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).
Jefferson County, Compared
Jefferson County radon figures, compared
Calculated by Radon411More than half: 67.4% of the 325 radon tests reported to CDC for Jefferson County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 30th of 77 Nebraska counties with 30 or more tests for the same period. That is 8.9 points above the 58.5% pooled from 93 Nebraska counties.
The newest figure, in 2023, counts only 12 tests (75.0% at or above 4 pCi/L), too few to compare, so this reading uses the 325-test figure.
The median result, 6.6 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 46.7 pCi/L. The rest split 14.2% under 2 pCi/L and 18.5% from 2 to 4 (Nebraska: 18.6% and 22.8%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 67.4% share point the same way here.
All 4 of its bordering counties with figures ran higher, led by Fillmore County at 76.6%; the lowest of them, Thayer County, reported 68.2%. Statewide for the same period, Clay County reported the highest share (85.1%) and Cherry County the lowest (13.3%).
The busiest year on file was 2017, with 315 tests reported; the quietest, 2023, had 12.
Over 8 years of annual figures the share rose 26.1 points, from 30.2% in 2014 to 56.3% in 2021; its peak was 66.7% in 2015. Nationally, every county with a figure for the same period pools to 35.7%; Jefferson County sits 31.7 points above it. CDC also counts 15 tests taken after mitigation in Jefferson County for the same period: tests in homes where a fix was already in.
Jefferson CountyNebraska, pooled
56.3% % of tests34.9% % of tests
| Year | Tests | Jefferson County, at or above 4 pCi/L | Nebraska, pooled |
|---|---|---|---|
| 2014 | 159 | 30.2% | 50.5% |
| 2015 | 234 | 66.7% | 53.3% |
| 2016 | 210 | 50.0% | 47.4% |
| 2017 | 315 | 66.7% | 47.7% |
| 2018 | 213 | 64.8% | 44.5% |
| 2019 | 306 | 43.1% | 44.3% |
| 2020 | 78 | 53.8% | 42.2% |
| 2021 | 48 | 56.3% | 34.9% |
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 puts all of Jefferson County's mapped land in one class: high radon potential. All of it lies in the area the map calls Pre-Wisconsin glacial deposits, to which USGS gives a radon index of 13, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Pre-Wisconsin glacial deposits | Loess-mantled glacial drift. | High | 13 | 99.6% |
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
Jefferson County has more high-potential ground than Nebraska as a whole: 100% of its land against 40.9%. Of the 6 counties that border it, none has as large a share of high-potential ground; Fillmore County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Jefferson County, Local resources
Radon testing and mitigation in Jefferson County
Listed radon businesses with an address in Jefferson County:
- Office of Environmental Health Hazards & Indoor AirOffice of Environmental Health Hazards & Indoor Air, run by Nebraska Department of Health and Human Services, licenses or certifies radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Nebraska.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Some local programs distribute radon kits for free or a reduced cost.
- Compare kits
- Professionals in Nebraska116 professionals are listed in Nebraska.
Listed radon professionals by town: Fairbury
What Nebraska's program says
- Phone
- (402) 471-1005
- Licensing of radon professionals
If radon testing is done in schools, offices, or other places of work, it must be done by a licensed radon measurement business.
What it means
Jefferson County, Questions
Questions about radon in Jefferson County
Are radon levels high in Jefferson County?
In 2023, 75.0% of the radon tests reported to CDC for Jefferson County, Nebraska were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.0 pCi/L. Of 77 Nebraska counties with 30 or more tests for the same period, 29 reported a higher share; pooled, the state comes to 58.5%.
Which counties border Jefferson County?
Jefferson County borders 6 counties: Thayer County, NE, Washington County, KS, Gage County, NE, Saline County, NE, Fillmore County, NE and Republic County, KS.
Products
Jefferson County, Products
Testing a home in Jefferson County
In Jefferson County, 67.4% of 325 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 58.5% pooled across Nebraska. In Zone 1 the year-round level in Jefferson 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
MonitorINKBIRD
INK-RD3 battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
First reading: Within 24 hours
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
Jefferson County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Jefferson County
Explore
Jefferson County, Bordering counties
Counties bordering Jefferson County
Calculated by Radon411- Radon levels in Fillmore County, NEEPA zone 1
76.6%at or above 4 pCi/L
Median 6.8 pCi/L · 175 tests · 9.2 points above Jefferson County
- Radon levels in Gage County, NEEPA zone 1
69.7%at or above 4 pCi/L
Median 6.8 pCi/L · 567 tests · 2.3 points above Jefferson County
- Radon levels in Saline County, NEEPA zone 1
69.4%at or above 4 pCi/L
Median 6.2 pCi/L · 242 tests · 2.0 points above Jefferson County
- Radon levels in Thayer County, NEEPA zone 1
68.2%at or above 4 pCi/L
Median 5.6 pCi/L · 110 tests · 0.8 points above Jefferson County
- Radon levels in Washington County, KSEPA zone 1
No CDC figure for 2008 to 2017; its page reads it against its own neighbours.
- Radon levels in Republic County, KSEPA zone 1
No CDC figure for 2008 to 2017; its page reads it against its own neighbours.
Jefferson County, Cities and towns
Cities and towns in Jefferson County
About 7,070 people live in Jefferson County by the Census Bureau's estimate for July 1, 2025, 190 fewer than in 2020 (−2.6%). That works out to 12 people per square mile of land. Fairbury alone is home to 3,812 of them, 53.9% of the total. Together its 9 incorporated places hold 70.3% of those residents; the other 29.7% live outside any of them. Testing is reported here more often than across the state: CDC's 325 reported tests for 2008 to 2017 come to 46.0 for every 1,000 residents (2025 estimate), against 21.2 for Nebraska.
From Fairbury to Steele City, CDC publishes no figure by town: each reads Jefferson County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Fairbury | 3,812 | −4.1% | 53.9% |
| Plymouth | 359 | −1.1% | 5.1% |
| Diller | 267 | +7.2% | 3.8% |
| Daykin | 153 | −1.9% | 2.2% |
| Endicott | 110 | −1.8% | 1.6% |
| Jansen | 101 | −1.0% | 1.4% |
| Reynolds | 62 | Level | 0.9% |
| Harbine | 52 | −1.9% | 0.7% |
| Steele City | 51 | −1.9% | 0.7% |
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).
Jefferson County, Homes
Homes in Jefferson County
Jefferson County is a place of houses on their own lots: 82% of its 3,664 homes are detached single-family houses, against 72% across Nebraska. The homes are older than Nebraska's as a whole: half were built before 1949 (1975 for Nebraska), and 59% date from before 1960. 72% of occupied homes are lived in by their owner (Nebraska: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Jefferson County | Nebraska |
|---|---|---|
| Housing units | 3,664 | 855,631 |
| Detached houses | 82% | 72% |
| In buildings of 5 or more | 9% | 17% |
| Mobile homes | 2% | 3% |
| Built before 1960 | 59% | 32% |
| Built since 2000 | 7% | 22% |
| Middle year built | 1949 | 1975 |
| Owner-occupied | 72% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.