Radon zones in Illinois
Last updated
EPA’s Map of Radon Zones places 102 Illinois counties in its three radon potential zones: 56 in Zone 1 (highest), 43 in Zone 2 (moderate), and 3 in Zone 3 (low).
What this means for Illinois homes
Most Illinois counties fall in Zone 1. EPA predicts average indoor screening levels above 4 pCi/L across much of Illinois, so elevated radon is common. Testing is especially worthwhile here, and radon-resistant construction features make sense for new homes.
EPA’s guidance is the same everywhere: test your home, fix it if the level is 4 pCi/L or higher, and consider fixing between 2 and 4 pCi/L. The zone map is from 1993 and should not be used to decide whether a single home needs testing.
Illinois radon program
EPA lists the following state contact for Illinois: IL Emergency Management Agency Radon Program, phone 217-782-4977. Website: iema.illinois.gov/nrs/radon.html. State programs can tell you about local testing data, free or discounted test kits, disclosure rules for home sales, and credentialed radon professionals.
Illinois counties and their EPA radon zones
| County | EPA radon zone |
|---|---|
| Adams County | Zone 1 |
| Alexander County | Zone 3 |
| Bond County | Zone 2 |
| Boone County | Zone 1 |
| Brown County | Zone 1 |
| Bureau County | Zone 1 |
| Calhoun County | Zone 1 |
| Carroll County | Zone 1 |
| Cass County | Zone 1 |
| Champaign County | Zone 1 |
| Christian County | Zone 2 |
| Clark County | Zone 2 |
| Clay County | Zone 2 |
| Clinton County | Zone 2 |
| Coles County | Zone 1 |
| Cook County | Zone 2 |
| Crawford County | Zone 2 |
| Cumberland County | Zone 2 |
| De Witt County | Zone 1 |
| DeKalb County | Zone 1 |
| Douglas County | Zone 1 |
| DuPage County | Zone 2 |
| Edgar County | Zone 1 |
| Edwards County | Zone 2 |
| Effingham County | Zone 2 |
| Fayette County | Zone 2 |
| Ford County | Zone 1 |
| Franklin County | Zone 2 |
| Fulton County | Zone 1 |
| Gallatin County | Zone 2 |
| Greene County | Zone 1 |
| Grundy County | Zone 1 |
| Hamilton County | Zone 2 |
| Hancock County | Zone 1 |
| Hardin County | Zone 2 |
| Henderson County | Zone 1 |
| Henry County | Zone 1 |
| Iroquois County | Zone 1 |
| Jackson County | Zone 2 |
| Jasper County | Zone 2 |
| Jefferson County | Zone 2 |
| Jersey County | Zone 1 |
| Jo Daviess County | Zone 1 |
| Johnson County | Zone 2 |
| Kane County | Zone 1 |
| Kankakee County | Zone 2 |
| Kendall County | Zone 1 |
| Knox County | Zone 1 |
| Lake County | Zone 2 |
| LaSalle County | Zone 1 |
| Lawrence County | Zone 2 |
| Lee County | Zone 1 |
| Livingston County | Zone 1 |
| Logan County | Zone 1 |
| Macon County | Zone 1 |
| Macoupin County | Zone 2 |
| Madison County | Zone 2 |
| Marion County | Zone 2 |
| Marshall County | Zone 1 |
| Mason County | Zone 1 |
| Massac County | Zone 3 |
| McDonough County | Zone 1 |
| McHenry County | Zone 2 |
| McLean County | Zone 1 |
| Menard County | Zone 1 |
| Mercer County | Zone 1 |
| Monroe County | Zone 2 |
| Montgomery County | Zone 2 |
| Morgan County | Zone 1 |
| Moultrie County | Zone 1 |
| Ogle County | Zone 1 |
| Peoria County | Zone 1 |
| Perry County | Zone 2 |
| Piatt County | Zone 1 |
| Pike County | Zone 1 |
| Pope County | Zone 2 |
| Pulaski County | Zone 3 |
| Putnam County | Zone 1 |
| Randolph County | Zone 2 |
| Richland County | Zone 2 |
| Rock Island County | Zone 1 |
| Saline County | Zone 2 |
| Sangamon County | Zone 1 |
| Schuyler County | Zone 1 |
| Scott County | Zone 1 |
| Shelby County | Zone 2 |
| St. Clair County | Zone 2 |
| Stark County | Zone 1 |
| Stephenson County | Zone 1 |
| Tazewell County | Zone 1 |
| Union County | Zone 2 |
| Vermilion County | Zone 1 |
| Wabash County | Zone 2 |
| Warren County | Zone 1 |
| Washington County | Zone 2 |
| Wayne County | Zone 2 |
| White County | Zone 2 |
| Whiteside County | Zone 1 |
| Will County | Zone 2 |
| Williamson County | Zone 2 |
| Winnebago County | Zone 1 |
| Woodford County | Zone 1 |
County names follow the 2020 Census. Zones from the EPA Map of Radon Zones (text version). Rows marked “zone of” use the zone EPA gave the predecessor or surrounding county.
Next steps: read how to test your home, check a result with the level calculator, or look up a single address by ZIP code.