Certified radon companies in Illinois

Illinois has the strongest radon disclosure law in the country, so radon reaches every buyer in the state whether they asked about it or not.

Radon in Illinois

The Illinois Radon Awareness Act has been in force since 1 January 2008. Before a buyer is obligated under a contract for residential real property, the seller must hand over the state pamphlet, Radon Testing Guidelines for Real Estate Transactions, together with the Illinois Disclosure of Information on Radon Hazards. Every deal, not just the ones where somebody raises it.

That makes radon a routine part of a closing in Illinois rather than an optional extra, which is why the difference between a company that can measure and a company that can fix matters more here than almost anywhere else.

What a home sale in Illinois requires

The Act, 420 ILCS 46, requires the disclosure and the pamphlet. It expressly does not oblige a seller to test or to mitigate anything. A buyer who wants a number has to arrange the test themselves, usually inside the inspection period.

Certified for mitigation, 19 companies

Certified to install a radon reduction system in a home. Most of these also test.

Measurement only, 51 companies

Certified to measure radon but not to install the fix. Many are home inspectors who test as part of an inspection, which is how radon first comes up in most sales.

How this list is put together

Taken from the public directories of NRPP and NRSB, read 2026-09-01. Certified individuals are grouped into the company they list, and each company is tagged with what its people are certified for. Phone numbers and websites appear only where a registry publishes them; we do not fill the gaps from third-party data, because name matching gets it wrong often enough to put one firm's number on another firm's listing.

Listing is free and alphabetical. Nobody pays for position. Certifications expire and registries lag, so check a company's current standing before you hire. If something here is wrong, tell us and it gets fixed.

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