Radon disclosure during real-estate transactions — state-by-state

Mandatory-disclosure states (sellers MUST disclose known radon results)

Illinois — IL Public Act 095-0210 requires sellers to provide a Radon Disclosure form before contract.

New Jersey — Radon Hazard Disclosure required by NJ statute on every residential resale.

Florida — radon notice required in every real-estate contract; doesn't require testing, only the disclosure language.

Several others (RI, IA, MN, etc.) have variant rules. Always check your state's real-estate-commission disclosure form.

States with no mandatory disclosure

About half the country. Sellers may legally not mention prior radon test results even if they had elevated readings.

Common-law fraud rules still apply: a seller who actively conceals (paints over a radon-mitigation system pipe) can be sued post-closing. But passive non-disclosure in non-mandatory states is generally legal.

What to ask for during inspection

Add a radon test contingency. Cost: $25-150 for a 48-hour short-term test. Some inspectors include it; many add it as a la carte.

If radon was previously tested, ask the seller for the test reports (date, location of test, result in pCi/L).

If a mitigation system is installed, ask: when was it installed, by whom, has it been re-tested since, where's the system maintenance log.

EPA action level: 4.0 pCi/L. WHO recommends 2.7 pCi/L. The lower the better; mitigation is straightforward and affordable ($800-2,500 for active sub-slab depressurization).

What zipradar shows

EPA Radon Zone classification (1-3) per ZIP code — the regional risk indicator. See /topic/radon/[zip]/.

Zone 1 = highest predicted potential (>4 pCi/L average indoor); Zone 2 = moderate (2-4 pCi/L); Zone 3 = low (<2 pCi/L).

Zone classification is regional + advisory, NOT a substitute for testing your specific home. Side-by-side homes can have very different radon levels.