California has become the first state to require sellers of single-family homes to disclose thirdhand smoke—the toxic residue left behind by cigarettes and vapes on walls, carpets, and furniture. A new law, Assembly Bill 455, written by Assemblymember Liz Ortega and signed by Governor Gavin Newsom, took effect on January 1. It requires home sellers to tell buyers if a property may contain this smoke residue. The law was driven by years of research from San Diego State University and other California labs, which showed that tobacco chemicals can stick to indoor surfaces long after smoking stops, as reported by LegiScan.
What the law requires
Under AB 455, sellers now have a specific disclosure duty. They must tell buyers in writing if they have actual knowledge that a home has residue from smoking tobacco or nicotine products, or a history of occupants smoking or vaping inside, according to LegiScan. The statute spells out that “residue from smoking” includes chemical buildup that may be suggested by a lingering tobacco smell or by test results showing elevated nicotine on surfaces or in dust. The bill also orders the Department of Toxic Substances Control to update the Homeowners’ Guide to Environmental Hazards and hands that work to San Diego State University’s Center for Tobacco and the Environment.
Why scientists pushed for disclosure
Public health researchers argue that thirdhand smoke is more than a stale odor. It is a mix of nicotine, tobacco-specific nitrosamines and other toxic chemicals, some of which appear on California’s Prop 65 list, that bind to fabrics, drywall and dust and can hang around for years, according to UCSF. Scientists say that means a home can keep exposing people long after the last cigarette is stubbed out.
San Diego State University and members of the California Thirdhand Smoke Research Consortium supplied much of the evidence lawmakers relied on, and those researchers say children, pregnant people and people with respiratory conditions are especially vulnerable to long-term exposure, per SDSU. Their work helped convince legislators to treat thirdhand smoke as an environmental hazard that buyers deserve to know about before they sign on the dotted line.
Legal and market consequences
Because AB 455 creates a formal disclosure requirement, a seller who knowingly keeps quiet about thirdhand smoke could face civil claims from buyers who want remediation or damages, according to Steve Lopez Law. Folding thirdhand smoke into the same thick stack of paperwork that already covers hazards such as lead or asbestos could change how offers and escrows get negotiated.
In some transactions, SDSU researchers and other experts say cleanup may require more than a good scrub. Bringing a property back into shape can mean ripping out carpets, replacing upholstery or even taking down sections of drywall rather than relying on standard cleaning, which can add thousands of dollars to what it costs to close a sale.
Where the law stops and what’s next
There is a big carve-out. AB 455 applies to single-family residential sales, not to most rental units or multi-unit buildings. That leaves many renters without the same kind of upfront information, according to the bill text and researcher commentary. Experts at the Thirdhand Smoke Resource Center say this gap matters because people living in lower-income and multi-unit housing are often the most likely to face lingering contamination…