Locations and reports
Radon Levels in Illinois
What this means for you
- Your area: EPA rates 56 of Illinois's 102 classified counties Zone 1, the highest of its three radon zones. Zones are predictions for whole counties, and homes with elevated levels occur in all three zones.
- Local tests: CDC publishes Illinois's radon test results by county. Open your county below to see its figures.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
For Illinois, EPA's Map of Radon Zones places 56 of its 102 classified counties in Zone 1, highest predicted potential, a prediction for each county as a whole. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
102 of 102 counties classified
EPA classifies counties, not states. Of the 102 counties in Illinois with a zone, 56 are in Zone 1, 43 in Zone 2 and 3 in Zone 3.
- Zone 1: Highest predicted potentialgreater than 4 pCi/L56 of 102 counties · 54.9%
- Zone 2: Moderate predicted potential2 to 4 pCi/L43 of 102 counties · 42.2%
- Zone 3: Lower predicted potentialless than 2 pCi/L3 of 102 counties · 2.9%
An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
CDC publishes Illinois's radon test figures by county: 102 of its 102 counties have one. Each county's share is in the county list.
Illinois, In figures
Illinois in figures
What the published data says about Illinois, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places 56 of Illinois's 102 counties in Zone 1, 43 in Zone 2 and 3 in Zone 3.
Zone 1 counties, A to Z, begin with Adams County, Boone County and Brown County; the county section below lists all 56.
Compared
Calculated by Radon41155% of Illinois's counties with a zone on file are in Zone 1, a larger share than across all U.S. counties (34%). It is a share of counties, not of land, people or homes.
Reported tests
MeasuredCDC has no statewide testing figure for Illinois on file here.
102 of the 102 counties have a published county figure; the most tests in each one's latest year were reported for Cook County (10,990 in 2017), Champaign County (6,807 in 2017) and DuPage County (6,467 in 2017).
Local record
Illinois's radon program is the IEMA-OHS Radon Program, run by Illinois Emergency Management Agency and Office of Homeland Security; its contacts are under Local resources.
2 cities have a page setting the figures of the counties it lies in side by side: Rockford and St. Charles.
Illinois, Counties
Illinois counties by EPA zone
PredictedAll 102 counties, by the zone EPA predicts for each. Every county has its own report.
Zone 1: highest predicted potential56
- Adams County55.2% of reported tests at or above 4 pCi/L, 2017
- Boone County48.1% of reported tests at or above 4 pCi/L, 2017
- Brown County37.8% of reported tests at or above 4 pCi/L, 2017
- Bureau County58.6% of reported tests at or above 4 pCi/L, 2017
- Calhoun County66.7% of reported tests at or above 4 pCi/L, 2017
- Carroll County60.8% of reported tests at or above 4 pCi/L, 2017
- Cass County38.5% of reported tests at or above 4 pCi/L, 2017
- Champaign County50.2% of reported tests at or above 4 pCi/L, 2017
- Coles County38.6% of reported tests at or above 4 pCi/L, 2017
- De Witt County60.6% of reported tests at or above 4 pCi/L, 2017
- DeKalb County46.2% of reported tests at or above 4 pCi/L, 2017
- Douglas County42.7% of reported tests at or above 4 pCi/L, 2017
- Edgar County37.9% of reported tests at or above 4 pCi/L, 2017
- Ford County42.2% of reported tests at or above 4 pCi/L, 2017
- Fulton County64.6% of reported tests at or above 4 pCi/L, 2017
- Greene County0.0% of reported tests at or above 4 pCi/L, 2017
- Grundy County32.3% of reported tests at or above 4 pCi/L, 2017
- Hancock County43.5% of reported tests at or above 4 pCi/L, 2017
- Henderson County68.4% of reported tests at or above 4 pCi/L, 2017
- Henry County60.4% of reported tests at or above 4 pCi/L, 2017
- Iroquois County28.0% of reported tests at or above 4 pCi/L, 2017
- Jersey County38.9% of reported tests at or above 4 pCi/L, 2017
- Jo Daviess County57.2% of reported tests at or above 4 pCi/L, 2017
- Kane County43.9% of reported tests at or above 4 pCi/L, 2017
- Kendall County46.9% of reported tests at or above 4 pCi/L, 2017
- Knox County65.9% of reported tests at or above 4 pCi/L, 2017
- LaSalle County45.8% of reported tests at or above 4 pCi/L, 2017
- Lee County43.8% of reported tests at or above 4 pCi/L, 2017
- Livingston County61.7% of reported tests at or above 4 pCi/L, 2017
- Logan County62.1% of reported tests at or above 4 pCi/L, 2017
- Macon County44.5% of reported tests at or above 4 pCi/L, 2017
- Marshall County63.9% of reported tests at or above 4 pCi/L, 2017
- Mason County21.4% of reported tests at or above 4 pCi/L, 2017
- McDonough County54.4% of reported tests at or above 4 pCi/L, 2017
- McLean County42.5% of reported tests at or above 4 pCi/L, 2017
- Menard County51.8% of reported tests at or above 4 pCi/L, 2017
- Mercer County68.2% of reported tests at or above 4 pCi/L, 2017
- Morgan County64.5% of reported tests at or above 4 pCi/L, 2017
- Moultrie County47.8% of reported tests at or above 4 pCi/L, 2017
- Ogle County62.5% of reported tests at or above 4 pCi/L, 2017
- Peoria County50.4% of reported tests at or above 4 pCi/L, 2017
- Piatt County51.7% of reported tests at or above 4 pCi/L, 2017
- Pike County25.0% of reported tests at or above 4 pCi/L, 2017
- Putnam County53.3% of reported tests at or above 4 pCi/L, 2017
- Rock Island48.3% of reported tests at or above 4 pCi/L, 2017
- Sangamon County52.2% of reported tests at or above 4 pCi/L, 2017
- Schuyler County43.9% of reported tests at or above 4 pCi/L, 2017
- Scott County50.0% of reported tests at or above 4 pCi/L, 2017
- Stark County80.5% of reported tests at or above 4 pCi/L, 2017
- Stephenson County63.2% of reported tests at or above 4 pCi/L, 2017
- Tazewell County46.4% of reported tests at or above 4 pCi/L, 2017
- Vermilion County48.8% of reported tests at or above 4 pCi/L, 2017
- Warren County50.0% of reported tests at or above 4 pCi/L, 2017
- Whiteside County43.1% of reported tests at or above 4 pCi/L, 2017
- Winnebago County44.2% of reported tests at or above 4 pCi/L, 2017
- Woodford County61.5% of reported tests at or above 4 pCi/L, 2017
Zone 2: moderate predicted potential43
- Bond County44.2% of reported tests at or above 4 pCi/L, 2017
- Christian County42.3% of reported tests at or above 4 pCi/L, 2017
- Clark County33.3% of reported tests at or above 4 pCi/L, 2017
- Clay County14.7% of reported tests at or above 4 pCi/L, 2017
- Clinton County36.4% of reported tests at or above 4 pCi/L, 2017
- Cook County20.2% of reported tests at or above 4 pCi/L, 2017
- Crawford County19.3% of reported tests at or above 4 pCi/L, 2017
- Cumberland County21.8% of reported tests at or above 4 pCi/L, 2017
- DuPage County33.7% of reported tests at or above 4 pCi/L, 2017
- Edwards County21.1% of reported tests at or above 4 pCi/L, 2017
- Effingham County37.9% of reported tests at or above 4 pCi/L, 2017
- Fayette County33.1% of reported tests at or above 4 pCi/L, 2017
- Franklin County19.6% of reported tests at or above 4 pCi/L, 2017
- Gallatin County33.3% of reported tests at or above 4 pCi/L, 2017
- Hamilton County23.3% of reported tests at or above 4 pCi/L, 2017
- Hardin County22.2% of reported tests at or above 4 pCi/L, 2017
- Jackson County28.5% of reported tests at or above 4 pCi/L, 2017
- Jasper County23.7% of reported tests at or above 4 pCi/L, 2017
- Jefferson County22.2% of reported tests at or above 4 pCi/L, 2017
- Johnson County14.6% of reported tests at or above 4 pCi/L, 2017
- Kankakee County42.5% of reported tests at or above 4 pCi/L, 2017
- Lake County30.2% of reported tests at or above 4 pCi/L, 2017
- Lawrence County18.8% of reported tests at or above 4 pCi/L, 2017
- Macoupin County34.8% of reported tests at or above 4 pCi/L, 2017
- Madison County37.4% of reported tests at or above 4 pCi/L, 2017
- Marion County20.6% of reported tests at or above 4 pCi/L, 2017
- McHenry County35.1% of reported tests at or above 4 pCi/L, 2017
- Monroe County44.2% of reported tests at or above 4 pCi/L, 2017
- Montgomery County36.9% of reported tests at or above 4 pCi/L, 2017
- Perry County27.7% of reported tests at or above 4 pCi/L, 2017
- Pope County0.0% of reported tests at or above 4 pCi/L, 2017
- Randolph County40.3% of reported tests at or above 4 pCi/L, 2017
- Richland County18.9% of reported tests at or above 4 pCi/L, 2017
- Saline County0.0% of reported tests at or above 4 pCi/L, 2017
- Shelby County56.6% of reported tests at or above 4 pCi/L, 2017
- St. Clair County44.2% of reported tests at or above 4 pCi/L, 2017
- Union County0.0% of reported tests at or above 4 pCi/L, 2017
- Wabash County50.0% of reported tests at or above 4 pCi/L, 2017
- Washington County26.5% of reported tests at or above 4 pCi/L, 2017
- Wayne County15.1% of reported tests at or above 4 pCi/L, 2017
- White County29.4% of reported tests at or above 4 pCi/L, 2017
- Will County43.4% of reported tests at or above 4 pCi/L, 2017
- Williamson County8.4% of reported tests at or above 4 pCi/L, 2017
Illinois, Cities
Cities in Illinois with their own page
Radon data is published by county, not by city. Each city page sets the figures of the counties the city lies in side by side.
Illinois, Local resources
Local resources in Illinois
Who to ask in Illinois: the state's radon program, test kits and professionals.
IEMA-OHS Radon Program
Illinois Emergency Management Agency and Office of Homeland Security
Illinois’s radon program answers questions about testing, mitigation and the rules where you live.
- 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.
Test kits
Ask the program whether it has free or discounted kits, or compare kits you can buy.
Radon professionals
387 professionals are listed in Illinois.
Professionals in IllinoisIllinois, Questions
Questions about radon in Illinois
Common questions9 questions, answered from the figures above
Is radon a problem in Illinois?
EPA's Map of Radon Zones places 56 of the 102 Illinois counties it classifies in Zone 1, the highest predicted potential, 43 in Zone 2 and 3 in Zone 3. An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
How do I get a radon test in Illinois?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. The Illinois radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeFree and low-cost kits by stateIllinois radon program
Who does radon mitigation in Illinois?
Radon411's Illinois directory lists 387 certified radon companies. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional.
How radon mitigation worksWhat mitigation costsRadon professionals in Illinois
Which Illinois counties are in EPA radon Zone 1?
56 counties are in Zone 1: Adams County, Boone County, Brown County, Bureau County, Calhoun County, Carroll County, Cass County, Champaign County, and 48 more in the county table on this page. Zone 1 is EPA's class for highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. A zone is a prediction for a county, not a measurement of any home.
Radon in Adams CountyRadon in Boone CountyRadon in Brown County
Which Illinois counties have the highest radon?
102 of Illinois's 102 counties have an EPA radon zone published here. Radon411 will not rank counties on data it does not hold, and a zone is a prediction for an area rather than a measurement of any building.
What share of radon tests in Illinois are high?
CDC has published no statewide radon testing statistics for Illinois, so we cannot give a figure. Where CDC does publish one, the percentage describes radon tests reported to CDC, not homes.
Which EPA region is Illinois in?
Illinois is in EPA Region 5: Great Lakes.
Do I need to test my home in Illinois?
Yes, wherever you live in the state. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L.
Why does this page show coverage rather than one radon level for Illinois?
A statewide figure averages counties with very different geology and very different numbers of reported tests, so it hides more than it shows. The county report is the level at which the EPA zone, the geologic potential and the reported testing statistics are actually published, which is why the county table above links to every one of them.
What these figures mean if you own, buy, sell or rent
The zone counts on this page describe counties across Illinois. They are predictions for areas, and none of them measures your building.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Illinois, Products
Testing and mitigation products
Whatever the figures for Illinois show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Illinois / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.