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 Jersey County, Illinois
EPA puts Jersey County in Zone 1, its highest radon zone, and high results are common there: 46.5% of the 129 radon tests reported to CDC (2017) came back 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
46.5%
12.8 pts above IL
- Jersey
- 46.5%
- Illinois
- 33.7%
129 tests, 2017
Median result
3.6pCi/L
Below action level
- Jersey
- 3.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2017
Tests reported
129
48th of 70 by tests
- Jersey
- 129
- Cook
- 26,937
Reported to CDC before any fix, 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 Illinois
27 of 70
Middle half
- Jersey
- 46.5%
- Stark
- 69.2%
By share, of 70 with 30+ tests
Read a result for Jersey County
Starts at Jersey County's median, 3.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.6 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. Jersey County's median reported result, 2017.
The data
Jersey County, At a glance
Jersey County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Jersey 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 Jersey County, 2017
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 18.6% |
| 2015 | 45.5% |
| 2017 | 46.5% |
2017: 46.5%. Across these years the share ran from 18.6% to 46.5%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 129 tests reported to CDC for Jersey County over 2017, 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: 2017. Measured data period: 2005 to 2017 (every CDC figure on file).
Jersey County, Compared
Jersey County radon figures, compared
Calculated by Radon411In Jersey County, about 5 in 10 reported tests in 2017 (60 of 129) were at or above EPA's action level. Against the national pool of 31.7%, the gap is 14.8 points higher. Across 93 Illinois counties pooled together, 33.7% of tests reached that level, so Jersey County runs 12.8 points above its state.
Of 3 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 25.6% (Macoupin County) to 35.9% (St. Charles County, MO). By share, Jersey County is 27th of 70 Illinois counties with 30 or more tests for the same period.
Year by year, 2014 opened at 18.6% and 2017 closed at 46.5% (up 27.9 points), with 2017 the high at 46.5%. Half the tests came in under 3.6 pCi/L and half over it; the single highest reached 19.5 pCi/L. Below the action level, 33 tests (25.6%) came in under 2 pCi/L, against 37.7% statewide, and 36 tests (27.9%) fell between 2 and 4, against 28.6% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 46.5% share point the same way here. USGS geology rates 100% of the county's land high radon potential.
The busiest year on file was 2014, with 129 tests reported; the quietest, 2015, had 66.
Jersey CountyIllinois, pooled
46.5% % of tests33.7% % of tests
| Year | Tests | Jersey County, at or above 4 pCi/L | Illinois, pooled |
|---|---|---|---|
| 2014 | 129 | 18.6% | 37.8% |
| 2015 | 66 | 45.5% | 36.6% |
| 2017 | 129 | 46.5% | 33.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Jersey County, Geology
The ground under Jersey County
PredictedMost of the ground under Jersey County is one class on USGS's geologic map: 99.6% of its land is high radon potential, with 0.4% moderate. All of it lies in the area the map calls Galesburg Plain, 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 |
|---|---|---|---|---|
| Galesburg Plain | Illinoian glacial deposits and loess over Paleozoic sedimentary rocks. | 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.
Jersey County beside the ground around it
Jersey County has more high-potential ground than Illinois as a whole: 99.6% of its land against 64.5%. Of the 5 counties that border it, 1 has more high-potential ground, Greene County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Jersey County, Local resources
Radon testing and mitigation in Jersey County
- IEMA-OHS Radon ProgramIEMA-OHS Radon Program, run by Illinois Emergency Management Agency and Office of Homeland Security, licenses or certifies radon professionals and states the rule for disclosing radon when a home is sold, and answers questions about testing and mitigation in Illinois.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 Illinois339 professionals are listed in Illinois.
What Illinois's program says
- Phone
- (800) 325-1245
- Licensing of radon professionals
The Agency also licenses and regulates the individuals who provide radon measurement and mitigation to the public.
- Disclosure when a home is sold or rented
Illinois Radon Awareness Act - This is the legislation that requires the seller to provide to the buyer of any interest in residential real property the IEMA-OHS pamphlet entitled "Radon Testing Guidelines for Real Estate Transactions" and the Illinois Disclosure of Information on Radon Hazards.
What it means
Jersey County, Questions
Questions about radon in Jersey County
Are radon levels high in Jersey County?
In 2017, 46.5% of the radon tests reported to CDC for Jersey County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.6 pCi/L. Of 70 Illinois counties with 30 or more tests for the same period, 26 reported a higher share; pooled, the state comes to 33.7%.
Which counties border Jersey County?
Jersey County borders 5 counties: Calhoun County, IL, Greene County, IL, Macoupin County, IL, St. Charles County, MO and Madison County, IL.
Products
Jersey County, Products
Testing a home in Jersey County
In Jersey County, 46.5% of 129 tests reported to CDC in 2017 reached 4 pCi/L, against 33.7% pooled across Illinois. In Zone 1 the year-round level in Jersey 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
Monitor
EcoBlu plug-in digital radon monitor with a display
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
Method: Ion chamber
First reading: Within 10 minutes
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
Jersey County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Jersey County
Explore
Jersey County, Bordering counties
Counties bordering Jersey County
Calculated by Radon411- Radon levels in St. Charles County, MOEPA zone 2
35.9%at or above 4 pCi/L
Median 2.8 pCi/L · 398 tests · 10.6 points below Jersey County
- Radon levels in Madison County, ILEPA zone 2
29.5%at or above 4 pCi/L
Median 2.6 pCi/L · 5,214 tests · 17.0 points below Jersey County
- Radon levels in Macoupin County, ILEPA zone 2
25.6%at or above 4 pCi/L
Median 2.2 pCi/L · 258 tests · 20.9 points below Jersey County
- Radon levels in Greene County, ILEPA zone 1
0.0%at or above 4 pCi/L
Median 2.7 pCi/L · 12 tests · 46.5 points below Jersey County
- Radon levels in Calhoun County, ILEPA zone 1
No CDC figure for 2017; its page reads it against its own neighbours.
Jersey County, Cities and towns
Cities and towns in Jersey County
About 21,160 people live in Jersey County by the Census Bureau's estimate for July 1, 2025, 333 fewer than in 2020 (−1.5%). That works out to 57 people per square mile of land. Its largest town, Jerseyville, has 8,409 residents, 39.7% of the total. Reported testing is thin here: 129 tests over 2017, or 6.1 for every 1,000 residents (2025 estimate), where Illinois as a whole comes to 10.9.
From Jerseyville to Otterville, CDC publishes no figure by town: each reads Jersey County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Jerseyville | 8,409 | +1.0% | 39.7% |
| Brightonextends beyond Jersey County | 2,162 | −2.4% | Counted whole |
| Grafton | 773 | +18.7% | 3.7% |
| Elsah | 539 | +2.7% | 2.5% |
| Medoraextends beyond Jersey County | 365 | −1.9% | Counted whole |
| Fieldon | 159 | −5.9% | 0.8% |
| Fidelity | 96 | −4.0% | 0.5% |
| Otterville | 82 | −4.7% | 0.4% |
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). A place that extends beyond Jersey County is counted whole, so it has no share.
Jersey County, Homes
Homes in Jersey County
Jersey County is a place of houses on their own lots: 86% of its 9,884 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1975, close to Illinois' 1970: 34% date from before 1960 and 22% from 2000 or later. Owners live in 78% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.
| Homes | Jersey County | Illinois |
|---|---|---|
| Housing units | 9,884 | 5,443,501 |
| Detached houses | 86% | 58% |
| In buildings of 5 or more | 3% | 22% |
| Mobile homes | 6% | 2% |
| Built before 1960 | 34% | 38% |
| Built since 2000 | 22% | 16% |
| Middle year built | 1975 | 1970 |
| Owner-occupied | 78% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.