Short answer: Radon is a colorless, odorless radioactive gas. EPA estimates it causes about 21,000 lung cancer deaths a year in the United States—the leading cause of lung cancer among people who have never smoked and the second leading cause overall (EPA health risk of radon). EPA and the U.S. Surgeon General recommend testing all homes below the third floor; fix the home if the result is 4 picocuries per liter (pCi/L) or higher, and consider fixing between 2 and 4 pCi/L (EPA Citizen’s Guide to Radon; EPA Map of Radon Zones). During a sale, EPA’s Home Buyer’s and Seller’s Guide (EPA 402/K-24/001, March 2024) says have the home tested, ask for prior results and mitigation records, and take steps against device interference (EPA Home Buyer’s and Seller’s Guide PDF). Some states add their own disclosure duties—Illinois’s Radon Awareness Act and Colorado’s SB23-206 are two examples (IEMA-OHS radon and real estate; Colorado Division of Real Estate SB23-206 advisory). Radon itself is a health and real-estate issue more than a standard named peril; sudden fire or storm damage to a mitigation fan may map to dwelling coverage, while gradual indoor-air problems usually do not—read your policy (TDI home insurance guide; NAIC homeowners guide).
This is a national explainer with federal EPA guidance and sample state disclosure rules, checked October 2026. Confirm your state radon office and any local disclosure forms before you buy, sell or lease.
Why EPA wants every home tested
EPA’s health-risk page summarizes Agency and National Academy of Sciences estimates: radon is responsible for about 21,000 lung cancer deaths each year (uncertainty range roughly 8,000 to 45,000 in the Agency’s 2003 assessment), about 2,900 of them among never-smokers. Smoking remains the leading cause of lung cancer; radon is number one among never-smokers and number two overall. Risk rises with radon concentration and with smoking together (EPA health risk of radon).
You cannot smell or see radon. Testing is the only way to know the level in a specific house. EPA’s Citizen’s Guide and Map of Radon Zones both say: test your home no matter which zone you live in. The Map of Radon Zones helps governments target resources and radon-resistant building codes; it is not a substitute for testing an individual home (EPA Map of Radon Zones; Citizen’s Guide).
| Source | What it recommends |
|---|---|
| EPA / Surgeon General (Citizen’s Guide) | Test all homes below the third floor; schools too |
| EPA action level | Fix at 4 pCi/L or higher; consider fixing between 2 and 4 pCi/L |
| EPA Map of Radon Zones | Use for targeting risk-reduction work—not to decide whether your house needs a test |
| Home Buyer’s and Seller’s Guide (402/K-24/001, Mar. 2024) | Test when buying or selling; save results; fix at ≥4 pCi/L |
Short-term kits (charcoal canisters, electret ion chambers and similar devices) give a quick reading; long-term tests better reflect a year-round average. For a sale, EPA’s buyer/seller guide lays out short-term options designed for the compressed timeline of a closing, plus a testing checklist and interference warnings (Home Buyer’s and Seller’s Guide PDF; find a test kit or professional).
Buying, selling and sample state disclosure rules
EPA recommends sellers test before listing and, if needed, lower radon levels so results are ready for buyers. Buyers should ask for recent results and any mitigation-system records. A buyer may reasonably request a new test if the last one is old (for example, not within about two years), the home was renovated, checklist items were missed, or the buyer plans to use a lower level than was tested (Home Buyer’s and Seller’s Guide PDF).
Federal EPA guidance is national; disclosure statutes are state-specific. Two published examples:
- Illinois: The Illinois Radon Awareness Act requires the seller of residential real property to give the buyer the IEMA-OHS pamphlet Radon Testing Guidelines for Real Estate Transactions and the Illinois Disclosure of Information on Radon Hazards. IEMA strongly recommends buyers have an indoor radon test before purchase or occupancy and mitigate elevated levels (IEMA-OHS radon and real estate; IEMA radon testing guidelines PDF).
- Colorado: SB23-206 (effective August 7, 2023) requires each residential sales contract to include a bold-faced Colorado Department of Public Health and Environment warning that strongly recommends indoor radon testing and mitigation of elevated levels, plus disclosure of known tests, concentrations, mitigation/remediation and whether a mitigation system is installed, and a copy of CDPHE’s radon brochure. Parallel landlord disclosures apply before a residential lease is signed (Colorado DRE SB23-206 advisory).
Check your own state radon office through EPA’s real-estate and state-contact resources before you rely on any form (EPA radon and real estate resources).
Mitigation and how homeowners insurance usually maps
If a test is at or above 4 pCi/L, EPA’s Consumer’s Guide to Radon Reduction walks through hiring a qualified mitigator—often a soil-suction / active soil-depressurization system with a fan and vent (EPA Consumer’s Guide to Radon Reduction). New homes with passive radon-resistant features should still be tested after occupancy; if levels stay above 4 pCi/L, a qualified mitigator can activate the system with a vent fan (Citizen’s Guide).
Radon concentration itself is not a classic named peril like fire or wind. A standard homeowners form is built around sudden covered perils to the dwelling and personal property, liability to others, and additional living expenses after a covered loss (TDI home insurance guide; NAIC homeowners guide). In practice that usually means:
- Paying a contractor to install or upgrade a mitigation system because of a high test result is typically a maintenance / health-improvement cost, not a claim.
- Sudden fire, lightning or storm damage to a mitigation fan, roof penetration or related building components may be treated like other dwelling damage—subject to your deductible and exclusions.
- Indoor-air, pollution and gradual-condition exclusions can limit bodily-injury or cleanup claims tied to long-term radon exposure—read the policy and ask your insurer in writing.
Keep test reports and mitigation invoices with your home records for buyers and for underwriting questions. Pair radon awareness with other winter indoor-air topics such as carbon monoxide alarms and smoke alarm laws. Find your state regulator via our state insurance rules hub.
Frequently asked questions
Does the EPA Map of Radon Zones tell me whether my house is safe?
No. EPA says the map helps target resources and building codes and should not be used to decide whether an individual home needs testing—test every home (EPA Map of Radon Zones).
What radon level should trigger mitigation?
EPA recommends fixing at 4 pCi/L or higher and considering a fix between 2 and 4 pCi/L (Citizen’s Guide; Home Buyer’s and Seller’s Guide).
Do sellers have to test for radon under federal law?
EPA strongly recommends testing when buying or selling, but mandatory seller disclosure and pamphlet rules are set by states (for example Illinois’s Radon Awareness Act and Colorado’s SB23-206) (IEMA-OHS; Colorado DRE; EPA buyer/seller guide).
Will homeowners insurance pay to install a radon mitigation system?
Usually not as a standalone claim for high radon alone—mitigation is typically a property-improvement cost. Sudden covered damage to the dwelling or to installed equipment may be treated differently; read your policy (TDI; NAIC).
Is radon the same issue as mold or carbon monoxide?
No. Radon is a radioactive soil gas measured in pCi/L; mold is a moisture/biological issue; carbon monoxide is a combustion byproduct with its own alarm standards—see our CO alarm guide and water-damage and mold claims guide.
Alishahi Insurance · 439 N Canon Dr, Penthouse, Beverly Hills, CA 90210 · (877) 711-4545 · CA License #4348151. General information only. This isn't legal, tax or financial advice or a coverage determination. Coverage depends on policy language and underwriting, and rules vary by state.