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 Calhoun County, Illinois
EPA puts Calhoun County in Zone 1, its highest radon zone, and only 6 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
46.3%
Pike County
- Pike
- 46.3%
- St. Charles
- 26.5%
5 of 6 neighbours have 30+ tests, 2008 to 2017
Nearest county
38.9%
Jersey County, 18 miles
- Jersey
- 38.9%
- Illinois
- 43.1%
Share at 4+ pCi/L, 90 tests, 2008 to 2017
Ground above low
100.0%
0.9 pts above Illinois
- Calhoun
- 100.0%
- Illinois
- 99.1%
Share of land USGS rates moderate or high potential
Tests reported
12
Too few for a share
- Calhoun
- 12
- Needed
- 30
2006 to 2015, laboratory
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Read a result for Calhoun 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
Calhoun County, At a glance
Calhoun County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Calhoun County in
USGS geologic potential: High across 99% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Calhoun County, 2008 to 2017, laboratory
CDC holds 6 reported tests for Calhoun County over the 2008 to 2017 laboratory totals, with a median of 4.5 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Calhoun County beside the counties around it is how this page reads it.
What these figures count
Only 6 tests were reported to CDC for Calhoun County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Calhoun County, Compared
Calhoun County radon figures, compared
Calculated by Radon411CDC's largest figure for Calhoun County rests on 12 tests over the 2006 to 2015 laboratory totals, 6 of them at or above 4 pCi/L, so each test moves its share by 8.3 points and no rank or comparison is drawn from it. Results reached as high as 11.0 pCi/L, with a middle value of 4.0 pCi/L.
Of the counties bordering it, 5 have a figure over the 2008 to 2017 laboratory totals: Pike County reported the largest share at or above 4 pCi/L, 46.3%, and St. Charles County, MO the smallest, 26.5%, with Pike County, MO at 40.0%, Jersey County at 38.9% and Lincoln County, MO at 33.6% between. Farther out, Macoupin County (40 miles away) at 34.8%, Morgan County (45 miles away) at 64.5% and Madison County (47 miles away) at 37.4% have figures too. Pooled across 102 Illinois counties, 43.1% of reported tests reached that level; across every county in the country with a figure, 35.7%.
Statewide for the same period, Stark County reported the highest share (80.5%) and Williamson County the lowest (13.3%). EPA's 1993 map puts Calhoun County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 99% of the county's land high radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Calhoun County, Geology
The ground under Calhoun County
PredictedMost of the ground under Calhoun County is one class on USGS's geologic map: 99.4% of its land is high radon potential, with 0.6% moderate. 99.4% 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 | 99.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Calhoun County beside the ground around it
Calhoun County has more high-potential ground than Illinois as a whole: 99.4% of its land against 64.5%. Of the 6 counties that border it, 3 have more high-potential ground, Greene County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Calhoun County, Local resources
Radon testing and mitigation in Calhoun 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
Calhoun County, Questions
Questions about radon in Calhoun County
Are radon levels high in Calhoun County?
Over the 2008 to 2017 laboratory totals, 66.7% of the radon tests reported to CDC for Calhoun County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.5 pCi/L. Of the counties bordering it, 5 have a figure over the 2008 to 2017 laboratory totals: Pike County reported the largest share at or above 4 pCi/L, 46.3%, and St. Charles County, MO the smallest, 26.5%, with Pike County, MO at 40.0%, Jersey County at 38.9% and Lincoln County, MO at 33.6% between.
Which counties border Calhoun County?
Calhoun County borders 6 counties: Jersey County, IL, Lincoln County, MO, Greene County, IL, St. Charles County, MO, Pike County, MO and Pike County, IL.
Products
Calhoun County, Products
Testing a home in Calhoun County
No CDC figure names Calhoun County; the nearest county with one, Jersey County (18 miles away), reported 38.9% 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 1 the year-round level in Calhoun 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
MonitorX-Sense
XR0B-SR battery digital radon monitor with an alarm
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Alpha spectrometry
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
Calhoun County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Calhoun County
Explore
Calhoun County, Bordering counties
Counties bordering Calhoun County
Calculated by Radon411- Radon levels in Pike County, ILEPA zone 1
46.3%at or above 4 pCi/L
Median 3.8 pCi/L · 108 tests
- Radon levels in Greene County, ILEPA zone 1
42.9%at or above 4 pCi/L
Median 3.5 pCi/L · 21 tests
- Radon levels in Pike County, MOEPA zone 2
40.0%at or above 4 pCi/L
Median 2.9 pCi/L · 35 tests
- Radon levels in Jersey County, ILEPA zone 1
38.9%at or above 4 pCi/L
Median 3.2 pCi/L · 90 tests
- Radon levels in Lincoln County, MOEPA zone 2
33.6%at or above 4 pCi/L
Median 2.2 pCi/L · 444 tests
- Radon levels in St. Charles County, MOEPA zone 2
26.5%at or above 4 pCi/L
Median 2.2 pCi/L · 7,001 tests
Calhoun County, Cities and towns
Cities and towns in Calhoun County
About 4,300 people live in Calhoun County by the Census Bureau's estimate for July 1, 2025, 99 fewer than in 2020 (−2.3%). That works out to 17 people per square mile of land. No town dominates: Hardin, the largest, has 779 residents, 18.1% of the total. Together its 5 incorporated places hold 33.6% of those residents; the other 66.4% live outside any of them. Reported testing is thin here: 12 tests over 2006 to 2015, or 2.8 for every 1,000 residents (2025 estimate), where Illinois as a whole comes to 7.8.
From Hardin to Hamburg, CDC publishes no figure by town: each reads Calhoun County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Hardin | 779 | −2.0% | 18.1% |
| Kampsville | 294 | −2.6% | 6.8% |
| Batchtown | 166 | −2.9% | 3.9% |
| Brussels | 111 | −1.8% | 2.6% |
| Hamburg | 95 | −3.1% | 2.2% |
5 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).
Calhoun County, Homes
Homes in Calhoun County
Calhoun County is a place of houses on their own lots: 82% of its 2,298 homes are detached single-family houses, against 58% across Illinois. Half of its homes were built before 1968, close to Illinois' 1970: 44% date from before 1960 and 14% from 2000 or later. Owners live in 89% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.
| Homes | Calhoun County | Illinois |
|---|---|---|
| Housing units | 2,298 | 5,443,501 |
| Detached houses | 82% | 58% |
| In buildings of 5 or more | 2% | 22% |
| Mobile homes | 11% | 2% |
| Built before 1960 | 44% | 38% |
| Built since 2000 | 14% | 16% |
| Middle year built | 1968 | 1970 |
| Owner-occupied | 89% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.