You cannot see or smell it, but radon can affect the health and value of your Crystal Lake home. Whether you are getting a property ready to list or preparing to buy, you want clear, local guidance you can trust. This primer breaks down what radon is, Crystal Lake’s risk profile, how to test, how to fix high results, what Illinois law requires, and simple steps to improve overall indoor air quality. Let’s dive in.
Radon basics and Crystal Lake risk
What radon is and why it matters
Radon is a colorless, odorless radioactive gas that forms naturally in soil and rock, and long-term exposure increases lung cancer risk. Illinois public health authorities identify radon as a serious, preventable hazard in homes. The U.S. Environmental Protection Agency uses an action level of 4.0 pCi/L, recommending you fix homes at or above that level and consider mitigation between 2 and 4 pCi/L. Learn more about radon and health from IEMA’s radon overview and see the EPA’s action guidance and zone map on the EPA radon page.
McHenry County risk at a glance
McHenry County is classified as an EPA Zone 2 county, which predicts average indoor screening levels between 2 and 4 pCi/L. Even on the same block, levels can vary because of soil pathways, foundation type, and small construction differences. The safest approach is simple: test every home. The McHenry County Department of Health offers low-cost short-term test kits and local guidance on its radon program page.
How to test a home
Short-term vs. long-term tests
Short-term radon tests run 2 to 90 days and provide a quick snapshot, which is why they are common in real estate. Long-term tests run more than 90 days and give a better picture of your year-round average. If a short-term test is elevated, plan a follow-up and consider long-term testing when time allows. For details, see the CDC’s testing guidance.
Where and how to place detectors
Test the lowest lived-in level of the home in a regularly used room. Keep kits 20 inches to 6 feet above the floor, away from windows, doors, exterior walls, kitchens, and bathrooms. For short-term tests, maintain “closed-house” conditions by keeping windows and exterior doors closed for 12 hours before and during the test. Always follow the kit instructions closely.
Real estate timing and documentation
When testing as part of a sale, use a qualified or state-licensed professional and keep all documentation. If an initial short-term test is 4.0 pCi/L or higher, confirm with a second short-term test or a long-term test. If the average of two short-term tests is 4.0 pCi/L or higher, or any long-term test is 4.0 pCi/L or higher, plan to mitigate. The EPA’s real estate resources outline best practices for buyers and sellers.
What testing costs locally
DIY kits typically cost about $10 to $50, and professional tests often run about $100 to $300. McHenry County’s Health Department sells low-cost short-term kits and maintains lists of licensed measurement professionals. If your home has never been tested, or you have finished a basement or renovated, testing now is a smart move.
If your levels are high: mitigation
Proven fixes for most homes
The most common solution for basements or slabs is active sub-slab depressurization, which uses a pipe and a quiet fan to draw soil gas from under the foundation and vent it above the roofline. Crawlspaces are often treated with a sealed membrane and venting. Sealing cracks helps, but it is usually a supporting step rather than a standalone fix. See common methods in this radon mitigation guide.
Cost, effectiveness, and follow-up
Properly designed systems can reduce radon by up to about 99 percent and typically cost less than many major home projects. Contractor-installed systems often range from roughly $800 to $2,500, depending on your home’s foundation, size, and layout. Fans run continuously, so plan for minimal operating costs and verify results with post-installation testing. For a cost overview, visit the EPA’s mitigation cost page.
Hire a licensed Illinois professional
In Illinois, measurement and mitigation professionals are licensed through IEMA. Ask for a written estimate, system description, references, and post-mitigation test results. You can find licensed providers and statewide guidance through the IEMA Radon Program.
Illinois disclosures and local help
Illinois law requires sellers to give buyers the state pamphlet “Radon Testing Guidelines for Real Estate Transactions” and the standardized “Disclosure of Information on Radon Hazards” before the buyer is obligated under a contract. Sellers must share any radon test results they have. The law does not require sellers to test or fix radon before closing. You can review the Radon Awareness Act in the Illinois code via FindLaw’s statute page.
In practice, buyers often request a radon test during the inspection period. If results are elevated, the parties negotiate next steps, which can include seller-paid mitigation before closing, a price concession, or other agreed terms. Local support is available through the McHenry County Department of Health and the IEMA Radon Program if you need kits, lists of licensed pros, or consumer education.
Beyond radon: healthier indoor air
Improving overall indoor air quality helps your home feel better and can reduce health risks from other pollutants.
- Maintain combustion appliances and install working carbon monoxide detectors on each level and outside sleeping areas.
- Keep indoor humidity around 30 to 50 percent with exhaust fans and dehumidifiers as needed to discourage mold.
- Improve filtration by upgrading central HVAC filters as your system allows and using portable HEPA units in key rooms.
- Reduce sources by avoiding indoor smoking, choosing low-emission paints and cleaners, controlling moisture, and venting combustion appliances to the outdoors.
For a user-friendly overview of indoor air quality basics, review the EPA’s IAQ guide.
Ready to discuss radon testing during your purchase or how mitigation might affect your listing strategy in Crystal Lake? Reach out to the Judy Gibbons Group for local insights, trusted referrals, and negotiation-forward guidance tailored to your goals.
FAQs
What is radon and why is it a concern in Illinois homes?
- Radon is a naturally occurring radioactive gas that can build up indoors, and long-term exposure raises lung cancer risk; Illinois homes commonly test at or above the EPA action level of 4.0 pCi/L, so every home should be tested.
How do you test a Crystal Lake home during a sale?
- Use a qualified or state-licensed tester during the inspection period, maintain closed-house conditions, and follow up if a short-term test is high so you can make informed decisions before closing.
What does a radon mitigation system look like and how much does it cost?
- Most systems use a discreet pipe and a quiet fan to vent soil gas above the roofline, and typical installation ranges from roughly $800 to $2,500 with a follow-up test to confirm results.
Are sellers required to fix high radon in Illinois?
- Sellers must provide the state pamphlet, the radon disclosure, and any known test results, but they are not required to test or mitigate; outcomes are usually negotiated during the inspection contingency.
Does finishing a basement change radon levels?
- It can change how you use the space and your exposure, so test before finishing and again after, then retest every two years or after major renovations to be sure levels remain low.
