Real Estate Agent’s Guide to Radon: What Every Agent Needs to Know

Real estate agents who understand radon protect their clients better, close more transactions, and significantly reduce their own post-closing liability exposure. Radon is the second leading cause of lung cancer in the United States — a material fact that must be handled competently in any residential transaction involving a ground-contact foundation. This guide covers everything a working agent needs to know: what radon is, how to advise buyers and sellers at each stage, how to structure contingency language, and what happens when transactions go sideways because of radon.

What Every Agent Must Know About Radon

You do not need to be a radon expert. You need to know enough to advise your clients correctly and recognize when professional testing and mitigation expertise is needed. The core facts:

• Radon is a naturally occurring radioactive gas produced by uranium decay in soil and rock — it enters homes through foundation cracks, joints, and penetrations under pressure differential
• EPA’s action level is 4.0 pCi/L — at or above this level, EPA recommends mitigation; between 2.0 and 4.0 pCi/L, EPA recommends considering mitigation
• Approximately 1 in 15 U.S. homes has radon above 4.0 pCi/L nationally; in Zone 1 states, that rate may be 1 in 3 or higher
• A properly installed active mitigation system reduces radon by 85–99% and costs $800–$2,500 — it solves the problem completely and does not prevent the home from selling
• Elevated radon that is mitigated does not materially affect home value; unmitigated elevated radon may create a price discount that typically exceeds mitigation cost

Disclosure Obligations: The Agent’s Duty

Real estate agents have disclosure obligations that extend to known material facts — and radon is a material fact. The specific obligation varies by state and by which party the agent represents:

Listing Agent Obligations

A listing agent who learns that a home has elevated radon — from the seller, from a prior test report, from a neighbor, or any other reliable source — has a duty to ensure this information is disclosed to buyers in jurisdictions with material defect disclosure requirements. The appropriate action:

• Advise the seller of their disclosure obligation and the consequences of non-disclosure
• Recommend the seller test if no current test results exist, and document this recommendation
• Recommend pre-listing mitigation if results are elevated, explaining the pricing and deal-certainty advantages
• Ensure that completed mitigation and test results are documented and available for buyer review during due diligence
• Never advise a seller to conceal or minimize known radon test results — this creates agent liability in addition to seller liability

Buyer’s Agent Obligations

A buyer’s agent working in any market where ground-contact foundations are common has a professional obligation to advise their client about radon risk and the value of radon testing. This includes:

• Recommending radon testing as part of the inspection process for any home with a basement, crawl space, or slab-on-grade foundation
• Including a radon contingency in the initial offer for any home in a Zone 1 or Zone 2 area (or any area where the agent’s experience suggests elevated radon is common)
• Helping the buyer understand test results and the mitigation process so decisions are made from an informed position
• Advising on the appropriate remedy request (seller installs mitigation, credit, or termination) based on the specific result and market context

Agent Liability for Non-Disclosure

Post-closing radon disputes are a growing source of real estate litigation. Buyers who discover elevated radon after closing — in homes where the agent or seller knew or should have known about elevated levels — have pursued claims against both sellers and their agents in multiple states. Agent liability theories include failure to disclose a material fact, fraudulent concealment, and negligent misrepresentation. Professional errors and omissions insurance typically covers these claims, but a covered claim still affects premiums and professional reputation.

The best liability protection for any agent is a clear, documented process: recommend testing, advise on contingency language, document all disclosures, and never suppress information the client has a right to know.

Advising Sellers: The Pre-Listing Conversation

The most valuable thing a listing agent can do regarding radon is have the pre-listing conversation. At the listing appointment or immediately after:

• Ask whether the home has ever been tested and what the results were — document the answer
• If never tested: recommend testing before listing in any Zone 1 county or in any state where radon is common. A $20 DIY charcoal canister test takes 48 hours and costs almost nothing relative to a failed transaction.
• If elevated results exist: explain the advantages of pre-listing mitigation (pricing control, deal certainty, negotiation leverage) vs. waiting for buyer discovery (reactive positioning, timeline pressure, deal risk)
• If a mitigation system is already installed: ensure complete documentation exists — the installer’s license number, installation date, system specs, and post-mitigation test result. This documentation is what distinguishes a “solved problem” from an “unknown ongoing condition” in a buyer’s mind.

Advising Buyers: Testing and Contingency Guidance

When representing buyers, the radon conversation should happen at or before the offer stage — not after the inspection reveals a problem that the contract doesn’t protect against. Recommended approach:

• Inform the buyer about radon risk in the specific county and foundation type of the home being considered
• Recommend including a radon contingency in the initial offer — explain that adding it after the fact is typically not possible and that waiving it introduces real health and financial risk
• Advise the buyer to hire a certified radon measurement professional (NRPP or NRSB, or state-licensed where required) rather than attempting DIY testing in a transaction context — certified testing produces results that are unambiguous in a negotiation
• When results come back elevated, help the buyer frame the response: what remedy to request, in what timeline, with what documentation requirements

Handling Elevated Radon Mid-Transaction

When a buyer’s radon test returns elevated results, the transaction enters a defined negotiation phase. As the agent — for either party — your job is to keep the transaction on track while ensuring your client’s interests are protected:

When Representing the Buyer

• Obtain a mitigation quote from a local certified contractor — this grounds the remedy request in real numbers and demonstrates buyer good faith
• Prepare a written contingency response specifying the preferred remedy (seller installs, seller credits, or buyer terminates)
• If seller installs: specify that closing is contingent on post-mitigation test results below the contract threshold, with test conducted by a certified professional independent of the installing contractor
• If seller credits: specify the credit amount (typically 1.0–1.5x the mitigation quote) and confirm the buyer is comfortable handling post-closing mitigation

When Representing the Seller

• Counsel the seller not to view elevated radon as a deal-killer — a properly installed system resolves the issue completely and is typically the path of least resistance for preserving the transaction
• Help the seller obtain mitigation quotes immediately — a quick response signals good faith and keeps the transaction moving
• Advise the seller on timeline: if installation and post-mitigation testing must be completed before closing, work backward from the closing date to ensure feasibility
• Ensure all mitigation documentation is provided to the buyer’s agent before closing — incomplete documentation at closing creates a final-day obstacle

Frequently Asked Questions

Do real estate agents have to disclose radon?

Agents who know or have reasonable cause to know about elevated radon in a property have a duty to disclose this information to buyers in most states, under either radon-specific disclosure statutes or general material defect disclosure obligations. Agents should never suppress or minimize known radon information — the liability exposure from non-disclosure far exceeds the cost of addressing the issue transparently.

Should I recommend radon testing for every buyer?

Yes, for any home with a ground-contact foundation — basement, crawl space, or slab-on-grade. This includes virtually all single-family homes and many condominiums on ground-level or below-grade units. The testing cost ($15–$30 DIY, $100–$400 professional) is negligible relative to the cost of not knowing — and the agent’s exposure to post-closing liability for failure to recommend testing is real.

Can elevated radon kill a real estate deal?

Elevated radon can terminate a transaction if: (1) the buyer has a radon contingency and the seller declines to remediate; or (2) the buyer loses confidence in the property when elevated radon is discovered mid-inspection. The best protection against deal termination is pre-listing mitigation by the seller, which eliminates radon as a negotiating issue entirely. When discovered mid-transaction, prompt professional mitigation with post-mitigation testing almost always preserves the deal at minimal cost relative to the purchase price.

What should I tell my clients about existing mitigation systems?

An existing mitigation system is a positive feature — it signals the previous owner identified and addressed the issue. Buyers should verify: (1) the system is operational (check the U-tube manometer — liquid should be displaced); (2) post-mitigation test documentation confirms results below 4.0 pCi/L; (3) the system was installed by a certified contractor (documentation should include license number and installation date); and (4) a current radon test confirms the system is still performing — fan performance degrades over time and new entry pathways can develop.