A new JAMA Viewpoint article by investigators of California’s Collaborative Consortium on Thirdhand Smoke highlights the significance and implications of California Assembly Bill 455 (AB 455), the world’s first law requiring the disclosure of thirdhand smoke contamination in residential real estate transactions. Signed into law on October 3, 2025, AB 455 establishes a new legal framework recognizing thirdhand smoke as an environmental hazard comparable to asbestos, radon, or lead paint.
Thirdhand smoke refers to the toxic residues left behind when tobacco smoke or vaping aerosols settle on surfaces, dust, and building materials. These pollutants – many classified under California’s Proposition 65 as carcinogens or reproductive toxins – can persist for years and pose particular risks to children, the elderly, and immunocompromised individuals.
Under AB 455, sellers of single-family homes must disclose in writing any known indoor smoking, vaping, or thirdhand smoke contamination to prospective buyers. The law also mandates the California Department of Toxic Substances Control to update its Homeowner’s Guide to Environmental Hazards to include thirdhand smoke information, a task assigned to SDSU’s Center for Tobacco and the Environment.
“AB 455 broadens the scope of tobacco prevention and control,” said Dr. Matt, lead author of the article. “It recognizes that the toxic legacy of indoor smoking and vaping extends beyond personal behavior – it’s an environmental issue with real health and economic consequences.”
By classifying thirdhand smoke as a recognized environmental hazard, AB 455 sets a precedent that could influence housing, consumer protection, and tobacco policies nationwide. The law positions California once again at the forefront of public health innovation, expanding tobacco regulation into the realm of consumer protection and environmental justice.
Click here to read the full article.
Click here to read California Assembly Bill 455.
