Illinois has 102 counties, with 56 classified as EPA Zone 1 (highest risk). With an average radon level of 7.51 pCi/L, Illinois state testing data reveals significantly elevated risks across multiple counties. Testing is highly recommended.
Considered by many to be a microcosm of the entire country, Illinois is the 25th most expansive state and the fifth most populous. The state also has a very commendable Radon program, dedicated to educating citizens about the risks associated with the deadly gas. According to the Illinois Radon program, 118,447 homes across the state were tested and more than 41 percent were found to have elevated levels above the recommended action point. Furthermore, the U.S. IEMA estimates nearly 1,200 Illinois citizens die from radon-related lung cancer each year. Long story short, it’s a pretty serious problem throughout the entire country – let alone just one state. You can find more information on Radon, testing and mitigation at the official Illinois government page.
Explore radon data organized by metro region, including average levels, hotspot cities, and local mitigation professionals.
Cities with the most user-submitted radon test data, ranked by number of submissions.
| City | Avg User Radon Level | Submissions |
|---|---|---|
| Buffalo Grove | 6.10 pCi/L | 10 |
| Crystal Lake | 7.25 pCi/L | 8 |
| Lake Zurich | 6.00 pCi/L | 7 |
| Grayslake | 5.00 pCi/L | 7 |
| New Lenox | 10.17 pCi/L | 6 |
| Park Ridge | 7.00 pCi/L | 6 |
| Arlington Heights | 6.17 pCi/L | 6 |
| Waterloo | 9.20 pCi/L | 5 |
| Palatine | 7.80 pCi/L | 5 |
| Round Lake | 7.80 pCi/L | 5 |
| Northbrook | 6.20 pCi/L | 5 |
| Mchenry | 11.00 pCi/L | 4 |
| Dekalb | 8.75 pCi/L | 4 |
| Columbia | 8.00 pCi/L | 4 |
| Lisle | 7.25 pCi/L | 4 |
| Normal | 7.25 pCi/L | 4 |
| Antioch | 7.00 pCi/L | 4 |
| Elk Grove Village | 7.00 pCi/L | 4 |
| Aurora | 6.75 pCi/L | 4 |
| Hoffman Estates | 6.75 pCi/L | 4 |
All 102 Illinois counties with their EPA radon zone classification and user-submitted average radon levels.
Browse radon data for individual cities across Illinois. Each city page includes user-submitted radon levels, local contractors, and mitigation resources.