How radon certification differs by state
Radon is regulated state by state, and the differences are substantive. In some states, performing radon measurement or mitigation for compensation requires a state-issued license. In others, no state license exists and national certification is the operative credential.
A contractor credentialed correctly in one state may not be credentialed for the state your property is in — which matters constantly in bistate metros.
States that license radon work directly
Where a state issues its own radon license, that license is what governs whether the work may legally be performed for compensation there, and it is the credential to verify first. Illinois licenses radon measurement and mitigation professionals through IEMA-OHS. Minnesota licenses through the Department of Health. Ohio licenses through the Department of Health. Pennsylvania requires certification through the Department of Environmental Protection. Kentucky licenses through the Department for Public Health. Iowa and Nebraska each credential radon professionals through their state programs.
In every one of those states, measurement and mitigation are distinct credentials. A firm holding one does not automatically hold the other, and that distinction is the single most common credential mistake homeowners make.
States that rely on national certification
Wisconsin, Michigan, and Colorado do not license radon professionals at the state level. Their state programs instead direct homeowners toward nationally certified professionals credentialed through NRPP or NRSB.
That does not make those states unregulated in any meaningful sense for a homeowner — it changes what you verify. In a certification state, ask for the national certification number, confirm the category covers mitigation, and confirm it is current.
Why this matters most at state lines
Several of the metros served here span state boundaries. The Quad Cities sit on both sides of the Mississippi. Omaha and Council Bluffs are one housing market across two states. Cincinnati draws from three.
A contractor licensed in one of those states cannot lawfully perform the work for compensation on the other side unless they also hold that state's credential. Many firms hold both and work the whole metro legitimately — the question to ask is specific: what is your credential number for the state my property is in?
Disclosure rules differ too
Licensing is not the only thing that varies. Several states have specific residential disclosure requirements around radon, including providing a state publication before a purchase agreement is signed.
What is consistent across the states served here is what none of them do: none of them compels a seller to test, and none sets a concentration at which a seller must install a system before closing. Disclosure obligations and installation obligations are different things.
State certification differences: common questions
How do I check a state license?
Ask for the license number and the exact name it is issued under, then verify it with the state agency that issues it rather than accepting a document from the contractor. State radon programs maintain the authoritative records, and licenses expire — a number without a current status is not verification.
My contractor is licensed in the next state over. Is that enough?
Not for work performed for compensation on a property in your state. Radon credentials do not carry across state lines. Plenty of firms in bistate metros hold credentials on both sides — ask specifically for the one covering your property's state and confirm it is current.
Is a state license better than national certification?
They serve different functions rather than ranking against each other. A state license is a legal authorization to perform the work for compensation in that state. A national certification is evidence of examined competence and continuing education. In licensed states you need the license; in certification states the national credential is what is available and it is substantive.
Keep reading
- NRPP certification — What the credential covers and how to verify it before hiring.
- NRSB certification — The second national credential — what it covers and how to check it.
- How to choose a radon contractor — The four-step screen: credential, diagnostic, written design, verified result.
- Why experience matters — Where judgment beats procedure, and how to test for it.
- All homeowner guides — every decision page in one place.
Find out whether your state licenses radon work. If it does, verify that license. If it does not, verify the national certification. In a bistate metro, ask which state the credential covers before comparing anything else.
Sources
- U.S. EPA — Radon
- U.S. EPA — A Citizen’s Guide to Radon
- U.S. EPA — Consumer’s Guide to Radon Reduction
Get contractors credentialed for your state
Requests route by ZIP to independent businesses holding the credential that state requires — which resolves the bistate question before it comes up.