Radon questions, answered
Are radon inspections required in Illinois?
Not at sale. Illinois requires sellers to give buyers the IEMA radon pamphlet and disclosure form, and the law says it does not require the seller to test or mitigate.[1] IEMA strongly recommends all homebuyers test.[2] See home sales.
How common is high radon in Rockford?
Our tally of IEMA-OHS public measurement data for Winnebago County found 8,595 licensee-reported tests, about 37% at or above 4 pCi/L (years covered not stated).[3] Winnebago County is EPA Radon Zone 1.[4] The only way to know your home's level is to test.
Is a radon level of 3.4 pCi/L safe?
It's below the 4.0 pCi/L action level, but EPA says levels below 4 pCi/L still pose some risk and suggests considering a fix between 2 and 4 pCi/L.[5]
What is the most effective radon mitigation method?
IEMA-OHS says the most common technique is sub-slab depressurization, which does not require major renovations.[6] The right design depends on your foundation. Ask a licensed mitigator.
Why do radon results change?
EPA notes that radon levels vary from day to day and season to season. A long-term test (over 90 days) better reflects your year-round average than a short-term test.[5]
Who can test or install radon systems in Illinois?
Only people licensed by IEMA-OHS may do radon testing or mitigation for compensation.[7] Check names in the licensee lookup.
Where can I get a test kit in Winnebago County?
The Winnebago County Health Department sells kits (815-720-4100), and its page says the price includes return postage and lab analysis. Kits are also sold at many hardware and building stores.[8]
How much does mitigation cost?
IEMA-OHS says an active system typically costs $1,000 to $1,500 installed, and the fan averages about $100 a year to run.[6] See cost.
Do I need a test after a system is installed?
Yes. IEMA-OHS says post-mitigation testing must be performed.[6] Illinois rules generally keep the mitigator from doing both the before and after measurements unless an independent person measures.[9]
Do you test homes or install systems?
No. This is an independent information and referral site. We don't perform testing or mitigation, and we aren't a licensed radon contractor. See how we work.
Will you sell my information?
No. Your inquiry goes to the site operator only. We won't share it with any company unless we first tell you the company's name and you agree. See privacy.
Sources
- Illinois Radon Awareness Act, 420 ILCS 46 (Sec. 10 seller disclosure; Sec. 26 tenants)
- IEMA, “Radon Testing Guidelines for Real Estate Transactions” (PDF)
- IEMA-OHS radon results dashboard (public measurement data; Winnebago counts tallied Nov 14, 2026)
- U.S. EPA, Map of Radon Zones (PDF)
- U.S. EPA, “A Citizen’s Guide to Radon” (PDF)
- IEMA-OHS, “What is Radon?” (cost, fan energy, action level, SSD)
- Radon Industry Licensing Act, 420 ILCS 44 (Sec. 25 license requirement)
- Winnebago County Health Department, Radon
- 32 Ill. Adm. Code 422 (licensing rules; 422.70(j) independent measurement)
Sources reviewed November 14, 2026.