Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in De Witt County, Illinois
EPA puts De Witt County in Zone 1, its highest radon zone, and high results are common there: 57.1% of the 126 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
57.1%
23.4 pts above IL
- De Witt
- 57.1%
- Illinois
- 33.7%
126 tests, 2017
Median result
5.2pCi/L
Action level reached
- De Witt
- 5.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2017
Tests reported
126
49th of 70 by tests
- De Witt
- 126
- 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
9 of 70
Top quarter
- De Witt
- 57.1%
- Stark
- 69.2%
By share, of 70 with 30+ tests
Read a result for De Witt County
Starts at De Witt County's median, 5.2 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 5.2 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. De Witt County's median reported result, 2017.
The data
De Witt County, At a glance
De Witt County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of De Witt 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 De Witt County, 2017
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 73.3% |
| 2015 | 58.6% |
| 2017 | 57.1% |
2017: 57.1%. Across these years the share ran from 57.1% to 73.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 126 tests reported to CDC for De Witt 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).
De Witt County, Compared
De Witt County radon figures, compared
Calculated by Radon411More than half: 57.1% of the 126 radon tests reported to CDC for De Witt County in 2017 read at least 4 pCi/L. That places it 9th of 70 Illinois counties with 30 or more tests for the same period. That is 23.4 points above the 33.7% pooled from 93 Illinois counties.
The median result, 5.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 35.9 pCi/L. The rest split 11.9% under 2 pCi/L and 31.0% from 2 to 4 (Illinois: 37.7% and 28.6%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 57.1% share point the same way here.
No bordering county with a figure for the same period reported a higher share; the closest is Piatt County at 54.8%, the lowest Macon County at 38.8%. 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 2017, with 126 tests reported; the quietest, 2015, had 87.
Over 3 years of annual figures the share fell 16.2 points, from 73.3% in 2014 to 57.1% in 2017; its peak was 73.3% in 2014. Nationally, every county with a figure for the same period pools to 31.7%; De Witt County sits 25.4 points above it.
De Witt CountyIllinois, pooled
57.1% % of tests33.7% % of tests
| Year | Tests | De Witt County, at or above 4 pCi/L | Illinois, pooled |
|---|---|---|---|
| 2014 | 90 | 73.3% | 37.8% |
| 2015 | 87 | 58.6% | 36.6% |
| 2017 | 126 | 57.1% | 33.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
De Witt County, Geology
The ground under De Witt County
PredictedUSGS's geologic map puts all of De Witt County's mapped land in one class: high radon potential. The map puts 94.3% of De Witt County in the area it calls Bloomington Ridged Plain and 5.7% in Galesburg Plain. USGS gives both 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 |
|---|---|---|---|---|
| Bloomington Ridged Plain | Wisconsinan glacial deposits and loess over Paleozoic sedimentary rocks. | High | 13 | 94.3% |
| Galesburg Plain | Illinoian glacial deposits and loess over Paleozoic sedimentary rocks. | High | 13 | 5.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
De Witt County beside the ground around it
De Witt County has more high-potential ground than Illinois as a whole: 100% of its land against 64.5%. Of the 4 counties that border it, none has as large a share of high-potential ground; Macon County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
De Witt County, Local resources
Radon testing and mitigation in De Witt County
Listed radon businesses with an address in De Witt 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: Farmer City
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
De Witt County, Questions
Questions about radon in De Witt County
Are radon levels high in De Witt County?
In 2017, 57.1% of the radon tests reported to CDC for De Witt County, Illinois were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.2 pCi/L. Of 70 Illinois counties with 30 or more tests for the same period, 8 reported a higher share; pooled, the state comes to 33.7%.
Which counties border De Witt County?
De Witt County borders 4 counties: McLean County, Piatt County, Macon County and Logan County.
Products
De Witt County, Products
Testing a home in De Witt County
In De Witt County, 57.1% of 126 tests reported to CDC in 2017 reached 4 pCi/L, against 33.7% pooled across Illinois. In Zone 1 the year-round level in De Witt 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-1011 rechargeable radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
De Witt County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like De Witt County
Explore
De Witt County, Bordering counties
Counties bordering De Witt County
Calculated by Radon411- Radon levels in Piatt CountyEPA zone 1
54.8%at or above 4 pCi/L
Median 4.3 pCi/L · 279 tests · 2.3 points below De Witt County
- Radon levels in Logan CountyEPA zone 1
45.8%at or above 4 pCi/L
Median 3.4 pCi/L · 72 tests · 11.3 points below De Witt County
- Radon levels in McLean CountyEPA zone 1
42.5%at or above 4 pCi/L
Median 3.3 pCi/L · 4,548 tests · 14.6 points below De Witt County
- Radon levels in Macon CountyEPA zone 1
38.8%at or above 4 pCi/L
Median 3.1 pCi/L · 1,251 tests · 18.3 points below De Witt County
De Witt County, Cities and towns
Cities and towns in De Witt County
About 15,118 people live in De Witt County by the Census Bureau's estimate for July 1, 2025, 332 fewer than in 2020 (−2.1%). That works out to 38 people per square mile of land. Its largest town, Clinton, has 6,781 residents, 44.9% of the total. Together its 7 incorporated places hold 67.8% of those residents; the other 32.2% live outside any of them. CDC's 126 reported tests for 2017 work out to 8.3 per 1,000 residents (2025 estimate), close to Illinois' 10.9.
From Clinton to De Witt, CDC publishes no figure by town: each reads De Witt County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Clinton | 6,781 | −2.8% | 44.9% |
| Farmer City | 1,797 | −1.6% | 11.9% |
| Wapella | 497 | −2.7% | 3.3% |
| Waynesville | 369 | −2.1% | 2.4% |
| Weldon | 355 | −1.9% | 2.3% |
| Kenney | 297 | −0.3% | 2.0% |
| De Witt | 160 | Level | 1.1% |
7 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).
De Witt County, Homes
Homes in De Witt County
De Witt County is a place of houses on their own lots: 85% of its 7,312 homes are detached single-family houses, against 58% across Illinois. The homes are older than Illinois' as a whole: half were built before 1961 (1970 for Illinois), and 49% date from before 1960. Owners live in 77% of the occupied homes (Illinois: 67%), so for most households a test and a fix are their own to order.
| Homes | De Witt County | Illinois |
|---|---|---|
| Housing units | 7,312 | 5,443,501 |
| Detached houses | 85% | 58% |
| In buildings of 5 or more | 4% | 22% |
| Mobile homes | 5% | 2% |
| Built before 1960 | 49% | 38% |
| Built since 2000 | 10% | 16% |
| Middle year built | 1961 | 1970 |
| Owner-occupied | 77% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.