Radon testing is not required by any federal law in the United States. No national mandate compels homeowners to test their properties, and the EPA’s guidance on radon remains a recommendation, not a regulation. That said, your specific situation matters: several states do require radon testing or disclosure during home sales, and certain types of properties like schools, daycares, and HUD-assisted housing have their own rules.
No Federal Law Requires Testing
The EPA sets the action level for radon at 4 pCi/L (picocuries per liter) and recommends that any home at or above that level be fixed. Because there is no known safe level of radon exposure, the EPA also suggests considering mitigation for levels between 2 and 4 pCi/L. But these are recommendations. The federal government has never passed a law requiring homeowners to test.
This means the legal landscape is a patchwork. Whether you’re required to test depends on your state, the type of property, and whether a real estate transaction or government program is involved.
Real Estate Transactions Are Where Requirements Show Up
The most common scenario where radon testing becomes mandatory, or close to it, is when you’re buying or selling a home. Many states require real estate brokers to share radon information with buyers, though this often takes the form of a disclosure rather than a full test. HUD-owned properties and FHA-backed loans require radon advisory disclosures, and many relocation companies and brokerages require radon testing or specific disclosure statements as part of their internal policies.
The practical reality is that even in states without a testing mandate, radon testing has become a standard part of the home inspection process in high-radon areas. Buyers routinely request it, and sellers who skip it risk losing deals. If you’re buying a home, your lender or real estate agent can tell you whether testing is required or simply expected in your market.
Not every state has adopted these rules. California, for example, has not enacted legislation requiring sellers or landlords to provide specific radon information. In Canada, several provinces including Nova Scotia, New Brunswick, Quebec, and British Columbia include a radon line on property disclosure statements, and real estate agents have professional duties to inform clients about environmental conditions like radon.
States That Require Certified Professionals
Twenty states currently run their own credentialing programs for radon service providers. In these states, anyone offering radon testing or mitigation professionally must meet licensing or certification requirements. Those states are California, Colorado, Connecticut, Florida, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Minnesota, Nebraska, New Hampshire, New Jersey, Ohio, Pennsylvania, Rhode Island, Utah, Virginia, and West Virginia.
This doesn’t mean you can’t test your own home with a DIY kit in those states. Homeowner self-testing is generally allowed everywhere. The licensing rules apply to professionals who charge for the service. If you’re testing as part of a real estate transaction, though, most parties involved will want results from a certified tester.
Schools, Daycares, and Childcare Facilities
Radon testing in schools is mandatory in nine states: Colorado, Connecticut, Florida, New Jersey, New York, Oregon, Rhode Island, Virginia, and West Virginia. Rules for childcare centers vary further. Colorado requires new childcare facilities opened after January 2016 to complete radon tests within six months of occupancy. Illinois requires licensed day care centers, day care homes, and group day care homes to test for radon at least once every three years.
If your child attends a daycare or school and you’re concerned, check whether your state is on this list. In states without mandates, schools and childcare centers may still test voluntarily, and you can ask the facility directly for their most recent results.
HUD and Multi-Family Housing
HUD does not impose blanket radon testing requirements, but its guidance for projects undergoing environmental review strongly recommends testing using national standards. For buildings with existing mitigation systems, HUD wants documentation showing radon levels below 4 pCi/L with test results no older than two years, along with an ongoing maintenance plan. Buildings tested within five years must show results below the EPA’s action level.
Certain buildings are exempt from radon consideration: structures built on open piers with air between the lowest floor and the ground, and non-residential buildings occupied for fewer than four hours per day. Buildings with crawlspaces, utility tunnels, or parking garages do not qualify for the exemption.
Rental Properties and Landlord Obligations
There is no broad federal requirement for landlords to test rental properties for radon. However, most states require property owners to keep rental units “habitable,” meaning safe and fit for people to live in. If a tenant tests and finds high radon levels, the responsibility for fixing the problem generally falls on the building owner, since mitigation involves structural work the tenant isn’t authorized to do.
The EPA recommends that tenants who discover elevated radon inform the building owner in writing. Some states, like Maryland, offer government loan programs to help cover mitigation costs in limited-income housing. If you’re renting and worried about radon, a DIY test kit costing $15 to $30 can give you a baseline reading, and elevated results give you leverage to request action from your landlord.
New Construction Codes
Even though testing existing homes isn’t federally mandated, building codes increasingly require radon-resistant construction techniques in new homes. The International Residential Code includes radon control methods in Appendix F, and several national standards address radon-resistant rough-in components for single-family homes, townhouses, schools, and large buildings. Whether these code provisions are enforced depends on whether your local jurisdiction has adopted them.
Radon-resistant construction typically includes a gas-permeable layer beneath the foundation, sealed cracks, and a vent pipe that can be activated into a full mitigation system if post-construction testing shows elevated levels. Building a home with these features costs far less than retrofitting one later. If you’re building new, ask your builder whether local code requires radon-resistant techniques, or consider adding them regardless, especially if your area falls in a higher-risk EPA radon zone.