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 McDonough County, Illinois
EPA puts McDonough County in Zone 1, its highest radon zone, and high results are common there: 55.7% of the 210 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
55.7%
22.0 pts above IL
- McDonough
- 55.7%
- Illinois
- 33.7%
210 tests, 2017
Median result
4.3pCi/L
Action level reached
- McDonough
- 4.3 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2017
Tests reported
210
42nd of 70 by tests
- McDonough
- 210
- 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
12 of 70
Top quarter
- McDonough
- 55.7%
- Stark
- 69.2%
By share, of 70 with 30+ tests
Read a result for McDonough County
Starts at McDonough County's median, 4.3 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.3 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. McDonough County's median reported result, 2017.
The data
McDonough County, At a glance
McDonough County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of McDonough 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 McDonough County, 2017
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 56.3% |
| 2015 | 45.1% |
| 2017 | 55.7% |
2017: 55.7%. Across these years the share ran from 45.1% to 56.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 210 tests reported to CDC for McDonough 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).
McDonough County, Compared
McDonough County radon figures, compared
Calculated by Radon411More than half: 55.7% of the 210 radon tests reported to CDC for McDonough County in 2017 read at least 4 pCi/L. That places it 12th of 70 Illinois counties with 30 or more tests for the same period. That is 22.0 points above the 33.7% pooled from 93 Illinois counties.
The median result, 4.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 16.2 pCi/L. The rest split 22.9% under 2 pCi/L and 21.4% from 2 to 4 (Illinois: 37.7% and 28.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 55.7% share point the same way here.
1 of its 3 bordering counties with figures ran higher, led by Fulton County at 64.6%; Hancock County reported 33.3%. Statewide for the same period, Stark County reported the highest share (69.2%) and Williamson County the lowest (8.4%).
The busiest year on file was 2014, with 357 tests reported; the quietest, 2017, had 210.
Over 3 years of annual figures the share held within 2 points, from 56.3% in 2014 to 55.7% in 2017; its peak was 56.3% in 2014. Nationally, every county with a figure for the same period pools to 31.7%; McDonough County sits 24.0 points above it.
McDonough CountyIllinois, pooled
55.7% % of tests33.7% % of tests
| Year | Tests | McDonough County, at or above 4 pCi/L | Illinois, pooled |
|---|---|---|---|
| 2014 | 357 | 56.3% | 37.8% |
| 2015 | 213 | 45.1% | 36.6% |
| 2017 | 210 | 55.7% | 33.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
McDonough County, Geology
The ground under McDonough County
PredictedUSGS's geologic map puts all of McDonough County's mapped land in one class: high radon potential. 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 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
McDonough County beside the ground around it
McDonough County has more high-potential ground than Illinois as a whole: 100% of its land against 64.5%. Of the 5 counties that border it, none has as large a share of high-potential ground; Fulton County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
McDonough County, Local resources
Radon testing and mitigation in McDonough County
Listed radon businesses with an address in McDonough 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: Macomb, Industry
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
McDonough County, Questions
Questions about radon in McDonough County
Are radon levels high in McDonough County?
In 2017, 55.7% of the radon tests reported to CDC for McDonough County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.3 pCi/L. Of 70 Illinois counties with 30 or more tests for the same period, 11 reported a higher share; pooled, the state comes to 33.7%.
Which counties border McDonough County?
McDonough County borders 5 counties: Schuyler County, Hancock County, Fulton County, Warren County and Henderson County.
Products
McDonough County, Products
Testing a home in McDonough County
In McDonough County, 55.7% of 210 tests reported to CDC in 2017 reached 4 pCi/L, against 33.7% pooled across Illinois. In Zone 1 the year-round level in McDonough 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
lüft plug-in radon and indoor air quality monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Wi-Fi, Bluetooth
- App only
First reading: Within 90 minutes
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
McDonough County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like McDonough County
Explore
McDonough County, Bordering counties
Counties bordering McDonough County
Calculated by Radon411- Radon levels in Fulton CountyEPA zone 1
64.6%at or above 4 pCi/L
Median 5.8 pCi/L · 144 tests · 8.9 points above McDonough County
- Radon levels in Warren CountyEPA zone 1
50.0%at or above 4 pCi/L
Median 3.6 pCi/L · 42 tests · 5.7 points below McDonough County
- Radon levels in Hancock CountyEPA zone 1
33.3%at or above 4 pCi/L
Median 2.8 pCi/L · 63 tests · 22.4 points below McDonough County
- Radon levels in Schuyler CountyEPA zone 1
No CDC figure for 2017; its page reads it against its own neighbours.
- Radon levels in Henderson CountyEPA zone 1
No CDC figure for 2017; its page reads it against its own neighbours.
McDonough County, Cities and towns
Cities and towns in McDonough County
About 25,916 people live in McDonough County by the Census Bureau's estimate for July 1, 2025, 1,212 fewer than in 2020 (−4.5%). That works out to 44 people per square mile of land. Macomb alone is home to 14,530 of them, 56.1% of the total. CDC's 210 reported tests for 2017 work out to 8.1 per 1,000 residents (2025 estimate), close to Illinois' 10.9.
From Macomb to Sciota, CDC publishes no figure by town: each reads McDonough County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Macomb | 14,530 | −5.4% | 56.1% |
| Bushnell | 2,600 | −3.6% | 10.0% |
| Colchester | 1,070 | −3.4% | 4.1% |
| Blandinsville | 544 | −3.5% | 2.1% |
| Plymouthextends beyond McDonough County | 416 | −4.4% | Counted whole |
| Prairie City | 392 | −3.2% | 1.5% |
| Industry | 383 | −3.5% | 1.5% |
| Good Hope | 349 | −3.1% | 1.3% |
| Bardolph | 203 | −2.9% | 0.8% |
| Tennessee | 98 | −2.0% | 0.4% |
| Sciota | 32 | −3.0% | 0.1% |
11 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 McDonough County is counted whole, so it has no share.
McDonough County, Homes
Homes in McDonough County
Of McDonough County's 13,598 homes, 65% are detached houses, against 58% across Illinois; 18% are in buildings of five or more homes. Half of its homes were built before 1966, close to Illinois' 1970: 42% date from before 1960 and 13% from 2000 or later. 62% of occupied homes are lived in by their owner (Illinois: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | McDonough County | Illinois |
|---|---|---|
| Housing units | 13,598 | 5,443,501 |
| Detached houses | 65% | 58% |
| In buildings of 5 or more | 18% | 22% |
| Mobile homes | 5% | 2% |
| Built before 1960 | 42% | 38% |
| Built since 2000 | 13% | 16% |
| Middle year built | 1966 | 1970 |
| Owner-occupied | 62% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.