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 Jo Daviess County, Illinois
EPA puts Jo Daviess County in Zone 1, its highest radon zone, and high results are common there: 45.0% of the 513 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
45.0%
11.3 pts above IL
- Jo Daviess
- 45.0%
- Illinois
- 33.7%
513 tests, 2017
Median result
3.5pCi/L
Below action level
- Jo Daviess
- 3.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2017
Tests reported
513
29th of 70 by tests
- Jo Daviess
- 513
- 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
32 of 70
Middle half
- Jo Daviess
- 45.0%
- Stark
- 69.2%
By share, of 70 with 30+ tests
Read a result for Jo Daviess County
Starts at Jo Daviess County's median, 3.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.5 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. Jo Daviess County's median reported result, 2017.
The data
Jo Daviess County, At a glance
Jo Daviess County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Jo Daviess 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 Jo Daviess County, 2017
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 55.3% |
| 2015 | 51.0% |
| 2016 | 100.0% |
| 2017 | 45.0% |
2017: 45.0%. Across these years the share ran from 45.0% to 100.0%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 513 tests reported to CDC for Jo Daviess 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).
Jo Daviess County, Compared
Jo Daviess County radon figures, compared
Calculated by Radon411In Jo Daviess County, about 5 in 10 reported tests in 2017 (231 of 513) were at or above EPA's action level. Against the national pool of 31.7%, the gap is 13.3 points higher. Across 93 Illinois counties pooled together, 33.7% of tests reached that level, so Jo Daviess County runs 11.3 points above its state.
Of 4 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 31.3% (Lafayette County, WI) to 62.9% (Carroll County). By share, Jo Daviess County is 32nd of 70 Illinois counties with 30 or more tests for the same period.
Year by year, 2014 opened at 55.3% and 2017 closed at 45.0% (down 10.3 points), with 2014 the high at 55.3%. Half the tests came in under 3.5 pCi/L and half over it; the single highest reached 59.5 pCi/L. Below the action level, 159 tests (31.0%) came in under 2 pCi/L, against 37.7% statewide, and 123 tests (24.0%) fell between 2 and 4, against 28.6% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 45.0% 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 900 tests reported; the quietest, 2016, had 6.
Jo Daviess CountyIllinois, pooled
45.0% % of tests33.7% % of tests
| Year | Tests | Jo Daviess County, at or above 4 pCi/L | Illinois, pooled |
|---|---|---|---|
| 2014 | 900 | 55.3% | 37.8% |
| 2015 | 288 | 51.0% | 36.6% |
| 2017 | 513 | 45.0% | 33.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Jo Daviess County, Geology
The ground under Jo Daviess County
PredictedUSGS's geologic map puts all of Jo Daviess County's mapped land in one class: high radon potential. The map puts 89.8% of Jo Daviess County in the area it calls Driftless Area and 9.9% in Galesburg Plain. USGS gives the first a radon index of 12 and the second 13, both in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Driftless Area | Cambrian sandstone and Ordovician limestone and dolostone. | High | 12 | 89.8% |
| Galesburg Plain | Illinoian glacial deposits and loess over Paleozoic sedimentary rocks. | High | 13 | 9.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Jo Daviess County beside the ground around it
Jo Daviess County has more high-potential ground than Illinois as a whole: 100% of its land against 64.5%. Of the 6 counties that border it, none has as large a share of high-potential ground; Dubuque County, IA comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Jo Daviess County, Local resources
Radon testing and mitigation in Jo Daviess County
Listed radon businesses with an address in Jo Daviess 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.
Listed radon professionals by town: East Dubuque
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
Jo Daviess County, Questions
Questions about radon in Jo Daviess County
Are radon levels high in Jo Daviess County?
In 2017, 45.0% of the radon tests reported to CDC for Jo Daviess County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.5 pCi/L. Of 70 Illinois counties with 30 or more tests for the same period, 31 reported a higher share; pooled, the state comes to 33.7%.
Which counties border Jo Daviess County?
Jo Daviess County borders 6 counties: Lafayette County, WI, Jackson County, IA, Carroll County, IL, Stephenson County, IL, Dubuque County, IA and Grant County, WI.
Products
Jo Daviess County, Products
Testing a home in Jo Daviess County
In Jo Daviess County, 45.0% of 513 tests reported to CDC in 2017 reached 4 pCi/L, against 33.7% pooled across Illinois. In Zone 1 the year-round level in Jo Daviess 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
MonitorAEGTEST
HOUND-3699 radon monitor with a 2.1-inch touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
First reading: Within 1 hour
Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Jo Daviess County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Jo Daviess County
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Jo Daviess County, Bordering counties
Counties bordering Jo Daviess County
Calculated by Radon411- Radon levels in Carroll County, ILEPA zone 1
62.9%at or above 4 pCi/L
Median 5.5 pCi/L · 210 tests · 17.9 points above Jo Daviess County
- Radon levels in Stephenson County, ILEPA zone 1
57.2%at or above 4 pCi/L
Median 4.8 pCi/L · 519 tests · 12.2 points above Jo Daviess County
- Radon levels in Grant County, WIEPA zone 1
44.3%at or above 4 pCi/L
Median 3.2 pCi/L · 167 tests · 0.7 points below Jo Daviess County
- Radon levels in Lafayette County, WIEPA zone 1
31.3%at or above 4 pCi/L
Median 2.6 pCi/L · 80 tests · 13.7 points below Jo Daviess County
- Radon levels in Jackson County, IAEPA zone 1
No CDC figure for 2017; its page reads it against its own neighbours.
- Radon levels in Dubuque County, IAEPA zone 1
No CDC figure for 2017; its page reads it against its own neighbours.
Jo Daviess County, Cities and towns
Cities and towns in Jo Daviess County
About 21,594 people live in Jo Daviess County by the Census Bureau's estimate for July 1, 2025, 496 fewer than in 2020 (−2.2%). That works out to 36 people per square mile of land. No town dominates: Galena, the largest, has 3,210 residents, 14.9% of the total. Together its 10 incorporated places hold 47.2% of those residents; the other 52.8% live outside any of them. Testing is reported here more often than across the state: CDC's 513 reported tests for 2017 come to 23.8 for every 1,000 residents (2025 estimate), against 10.9 for Illinois.
From Galena to Nora, CDC publishes no figure by town: each reads Jo Daviess County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Galena | 3,210 | −3.2% | 14.9% |
| Stockton | 1,669 | −3.6% | 7.7% |
| East Dubuque | 1,457 | −2.5% | 6.7% |
| Warren | 1,275 | −4.1% | 5.9% |
| Hanover | 824 | −4.2% | 3.8% |
| Elizabeth | 695 | −1.8% | 3.2% |
| Scales Mound | 419 | −3.5% | 1.9% |
| Apple River | 333 | −2.1% | 1.5% |
| Menominee | 211 | −0.9% | 1.0% |
| Nora | 109 | −0.9% | 0.5% |
10 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).
Jo Daviess County, Homes
Homes in Jo Daviess County
Jo Daviess County is a place of houses on their own lots: 83% of its 13,425 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1976, close to Illinois' 1970: 35% date from before 1960 and 17% from 2000 or later. Owners live in 82% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.
| Homes | Jo Daviess County | Illinois |
|---|---|---|
| Housing units | 13,425 | 5,443,501 |
| Detached houses | 83% | 58% |
| In buildings of 5 or more | 4% | 22% |
| Mobile homes | 2% | 2% |
| Built before 1960 | 35% | 38% |
| Built since 2000 | 17% | 16% |
| Middle year built | 1976 | 1970 |
| Owner-occupied | 82% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.