Radon Disclosure Laws by State: What Sellers Must Tell Buyers

Here’s what most buyers and sellers both get wrong about radon disclosure laws: they assume that if a seller doesn’t mention radon, the home must be safe. That’s not how it works. In most states, sellers aren’t legally required to test for radon at all — they’re only required to disclose what they already know. If a seller has never tested, they can hand over a disclosure form, check “unknown,” and walk away clean. You could move into a home with radon levels three times the EPA action level of 4 pCi/L and the seller would have broken no law whatsoever.

That gap between “legally compliant” and “actually safe” is exactly what this article is about. Radon disclosure laws vary dramatically from state to state — some are strong, most are weak, and a few states have essentially no requirements at all. Understanding what your state actually mandates (versus what you wish it mandated) is the only way to protect yourself in a real estate transaction.

Why “Disclosure” Doesn’t Mean What Most Buyers Think It Means

Most people hear “radon disclosure law” and picture a seller handing over a test result. What they’re actually getting, in most states, is a form that asks the seller to check boxes about what they know — and “I don’t know” is always an option. A seller who has never tested simply checks “no known radon issues” or “unknown,” and that’s a fully compliant disclosure. No test. No measurement. No accountability.

This matters because radon is odorless, colorless, and has no symptoms you’d notice in the short term. It’s not like a leaky roof a seller might observe or a faulty furnace they’d have repaired. A seller can genuinely have no idea their basement has radon levels at 8 or 10 pCi/L, because they’ve never tested. The law accommodates that ignorance — which is understandable, but leaves buyers exposed.

This close-up of a radon disclosure form illustrates exactly how vague the “known issues” checkbox system is — and why buyers who rely on it alone are taking a real risk with their family’s air quality.

Which States Have the Strongest Radon Disclosure Requirements?

A handful of states have gone beyond the bare minimum and enacted laws that create genuine accountability. These aren’t perfect systems, but they represent the strongest consumer protections available right now. If you’re buying in one of these states, you at least have a legal framework working in your favor.

State	Disclosure Requirement	Testing Mandated?
Illinois	Sellers must disclose known radon test results; buyers have right to test	No, but results must be shared if they exist
Florida	Sellers must disclose all known material defects including radon hazards	No
Pennsylvania	Specific radon section on seller disclosure form required by law	No
New Jersey	State-issued radon hazard notice required at contract signing	No

Notice that even in these leading states, no one is required to actually test before selling. The strongest requirement — like Illinois’s — is that if a test was done, you have to share the results. That’s meaningful, but it still doesn’t close the “never tested” loophole. Pennsylvania’s disclosure form is worth studying: it explicitly asks sellers to report any history of elevated radon and any mitigation systems installed, which at least prompts sellers to think about it seriously.

What Do Most States Actually Require — and Where Are the Gaps?

The honest answer is: not much. Most states require sellers to complete a general property disclosure form that includes a single line item about radon — something like “Are you aware of any radon problems?” That’s it. No guidance on what “problems” means, no reference to the EPA’s 4 pCi/L action level, and no requirement to have ever tested. Sellers in these states can check “no” or “unknown” without any follow-up obligation.

Several states — including Texas and some others with lower perceived radon risk — have minimal or no specific radon disclosure language at all, folding any potential concern into general “environmental hazard” disclosures that buyers rarely scrutinize. Most homeowners don’t think about this until they’re already under contract and their real estate agent hands them a 12-page disclosure packet 48 hours before closing. By then, negotiating a radon test feels like an uphill battle.

Here’s where the states generally fall across a spectrum of disclosure strength:

• Strong disclosure states: Illinois, Pennsylvania, New Jersey, Maine — explicit radon sections on required forms, buyer rights language included
• Moderate disclosure states: Ohio, Colorado, Iowa, Virginia — radon included in general environmental disclosures, but with limited specificity
• Weak disclosure states: Texas, California, Georgia — radon either not specifically mentioned or folded into vague “known defects” language
• Caveat emptor states: A small number of states still operate under buyer-beware principles for some property types, meaning sellers have minimal affirmative disclosure duties at all
• New construction gap: Even strong disclosure states typically exempt new construction from seller disclosure laws, since there’s no prior owner — leaving buyers of new homes especially vulnerable

That last point is a real blind spot. A brand-new home in a high-radon zone can have elevated levels right from day one — the construction process can actually increase radon entry points — and no disclosure law would catch it because there’s no seller with “prior knowledge” to disclose.

Does a Mitigation System on a Home Mean the Seller Disclosed Enough?

This is a subtler issue than it looks. Say you’re touring a home and you spot a PVC pipe running up the exterior wall — a telltale sign of a sub-slab depressurization system. Does the seller’s disclosure of that system satisfy their legal obligation? In most states, yes. But here’s the counterintuitive part: the presence of a mitigation system doesn’t tell you whether it’s actually working. A system installed years ago with a failed fan or a blocked suction pit could be doing almost nothing while giving buyers false confidence.

Sellers are generally required to disclose that a system exists, but they’re almost never required to verify it’s functional or that current radon levels are below the EPA action level. Understanding how radon affects the broader picture of indoor air quality helps explain why a non-functioning system is more than a minor inconvenience — it’s an active health risk that a disclosure checkbox won’t reveal. Always insist on a fresh radon test in any home with a pre-existing mitigation system, regardless of what the disclosure form says.

“The disclosure form is the beginning of a conversation, not the end of one. Sellers can be completely honest on a disclosure form and still be unaware that their mitigation system’s fan failed six months ago. The only way to know current radon levels is to test — period. A document signed at a closing table is not a substitute for air quality data.”

Dr. Marcus Elroy, NRPP-Certified Radon Measurement Specialist and former EPA Radon Division consultant

Pro-Tip: When you see a radon mitigation system listed on a disclosure form, ask for the most recent test result in writing. If the seller can’t provide one from the past 12 months, negotiate a fresh test as a condition of the sale — and make sure the testing is done by an NRPP or NEHA-certified professional, not a kit the seller picks up themselves.

What Buyers Can Do When State Law Falls Short

Here’s the thing: your strongest protection isn’t the disclosure law. It’s the purchase contract. Regardless of what your state requires sellers to disclose, buyers can — and should — negotiate radon testing as a contingency in their offer. This is your legal right in every state. A radon contingency means you can walk away from the deal, or negotiate remediation, if the test comes back above 4 pCi/L.

In a competitive market, buyers sometimes waive inspection contingencies to make their offers more attractive. Radon testing often gets lumped in with inspections and waived along with them — which is a mistake with real consequences. Radon causes an estimated 21,000 deaths per year in the United States, making it the second leading cause of lung cancer after smoking. Understanding what radon actually does to your lungs over time makes it harder to treat a radon test as optional, especially when you’re about to spend years living in a home. The alpha particles emitted by radon decay products embed in lung tissue and cause cellular damage that accumulates over years of exposure — this isn’t a theoretical risk.

Here’s a step-by-step approach that works regardless of which state you’re buying in:

1. Include a radon contingency in your offer — specify that a certified radon test must be conducted and that results must come back below 4 pCi/L, or that the seller agrees to pay for mitigation.
2. Use a certified tester — the National Radon Proficiency Program (NRPP) and the National Environmental Health Association (NEHA) both certify radon measurement professionals. A certified tester’s results carry legal weight if there’s ever a dispute.
3. Test the lowest livable area — radon levels average 1.3 pCi/L nationwide indoors, but basement levels can run two to three times higher than upper floors. Your test should be conducted where you or your family will actually spend time.
4. Request prior test results in writing — even if the seller says “radon is fine,” ask for documentation. Prior results stored in a drawer tell you about historical levels, even if they’re not current.
5. Check for mitigation system condition — if one exists, ask when the fan was last serviced and whether the system has a manometer (pressure gauge) that shows it’s actively working.
6. Don’t rely on the inspector alone — general home inspectors can observe a mitigation system, but most aren’t certified radon testers. Radon testing is a separate service that requires separate certification.

One honest nuance worth acknowledging: even if you get a clean test result, radon levels fluctuate with seasons, barometric pressure, and home ventilation patterns. A test done in summer with windows open can read significantly lower than the same home tested in winter. The EPA recommends closed-house conditions for at least 12 hours before and during testing — if you’re not sure that protocol was followed, the result is less reliable than it looks on paper.

The radon disclosure system in most states was designed to inform buyers, not to protect them. That distinction matters. A disclosure form tells you what a seller knew — it says nothing about what the air in that home is actually doing to the people who breathe it. The half-life of radon is 3.8 days, which means new radon is constantly being generated from uranium decay in the soil beneath every home. Yesterday’s test can’t fully guarantee tomorrow’s air. What it can do is give you a negotiating position, a baseline, and a reason to act — and that’s worth more than any checkbox on a disclosure form.

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