Radon Levels in Illinois
Illinois is classified as an EPA Zone 1 state with a high risk for radon. Average indoor radon levels range from 2 to 6 pCi/L, and approximately 30% of Illinois homes test above the EPA action level of 4.0 pCi/L.
Illinois Radon Summary
High Radon Risk State
Illinois is among the higher-risk states for residential radon. The Illinois Department of Health strongly recommends that all residents test their homes. If you have not tested your home, consider ordering a test kit or radon detector today.
Key Facts About Radon in Illinois
- Illinois is one of the higher-risk Midwest states for radon
- The Illinois Emergency Management Agency actively manages the radon program
- All counties in northern Illinois are EPA Zone 1
- Illinois requires radon-resistant new construction in Zone 1 areas
Illinois Testing Requirements & Recommendations
Illinois requires sellers to disclose radon test results to buyers. Testing strongly recommended before home purchase.
The Illinois Radon Awareness Act governs contractor certification in the state.
Major Cities in Illinois
Radon levels can vary significantly within Illinois depending on local geology. All residents — regardless of city — should test their specific home, as neighborhood-level radon varies independently of broader state and county averages.
What Should Illinois Residents Do?
Test Your Home
Use a short-term charcoal test kit ($15–$25) for an initial reading, or a continuous radon detector for ongoing monitoring. Test in your basement or lowest livable area.
Understand Your Result
If your result is below 2.0 pCi/L: monitor periodically. Between 2.0–4.0 pCi/L: consider mitigation. Above 4.0 pCi/L: the EPA recommends mitigation. Above 8.0 pCi/L: take action promptly.
Hire a Certified Contractor if Needed
Look for NRPP or NRSB-certified radon mitigation contractors in Illinois. Mitigation systems typically cost $800–$2,500 and can reduce radon levels by 50–99%.
Verify with a Follow-Up Test
After mitigation, test again to confirm the system is working. Retest every 2 years, or after significant home renovations.
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