Current Smokefree Policies Don’t Protect Us from Thirdhand Smoke–But They Could

Public health policies implemented since the 1970s have increasingly aligned with scientific evidence linking secondhand smoke exposure to significant health risks in nonsmokers. These policies have resulted in the adoption of laws that prohibit indoor smoking in various settings such as indoor workplaces, public transportation, government buildings, hospitals, schools, restaurants, and bars. These measures have been instrumental in protecting public health, saving lives, and reducing healthcare spending by billions of dollars. However, current smokefree policies focus directly on secondhand smoke and do not adequately address the risks posed by thirdhand smoke, the chemical residue from tobacco smoke that lingers even after smoking has ceased. 

A recent analysis conducted by more than 20 researchers from the Collaborative Research Consortium on Thirdhand Smoke, published in the journal Tobacco Control in June 2023, revealed the limitations of existing smokefree policies in addressing thirdhand smoke.

Over the past two decades, extensive research conducted in laboratories and communities has demonstrated the pervasiveness, persistence, and toxicity of thirdhand smoke residue. Thirdhand smoke comprises hundreds of chemicals, including 26 that the state of California classifies as cancer-causing or linked to birth defects and reproductive harm. Some of the most toxic constituents include benzene, benzopyrene, cadmium, lead, and formaldehyde.

These chemicals are carcinogenic, exacerbate asthma and other respiratory diseases, damage DNA, and interfere with wound healing, to name a few of the known detrimental health effects. Moreover, thirdhand smoke disproportionately affects already vulnerable populations, with children, older individuals, and those with compromised immune systems facing the highest risk due to their reduced immune defenses. Low-income communities, which exhibit higher smoking rates, also experience disproportionate exposure to this chemical residue.

By targeting only secondhand smoke, existing policies allow thirdhand smoke to persist and continue to harm the public. The team of researchers, led by Drs. Georg Matt from San Diego State University and Neal Benowitz from University of California, San Francisco, propose expanding current smokefree policies to incorporate thirdhand smoke to not only safeguard the public from commercial tobacco byproducts but also foster new partnerships and garner broader public support for this critical cause.

From a public health perspective, five key distinctions between second- and thirdhand smoke underscore the need for expanding smokefree policies. First, thirdhand smoke persists in reservoirs, contaminating entire indoor environments by adhering to surfaces, accumulating in dust, and infiltrating building materials, furniture, carpets, and clothing. Second, thirdhand smoke can remain for years even after a smoker has quit or left the premises, as the chemical residue accumulated months earlier cannot be eliminated by later smoking bans. Third, thirdhand smoke can be encountered through inhalation, ingestion, or skin contact, expanding the pathways of exposure compared to secondhand smoke. Fourth, thirdhand smoke is transported not only through air but also through physical movement of items such as used clothing or furniture that harbor reservoirs of thirdhand smoke, allowing movement of toxic pollutants from one location to another. Lastly, removing thirdhand smoke is significantly more challenging as it becomes embedded in walls, carpets, and furniture, rendering traditional remediation methods ineffective.

According to Dr. Georg Matt, lead author of the Tobacco Control paper, the Consortium researchers view existing smokefree policies as a crucial foundation that, if expanded, could address thirdhand smoke effectively. “Based on the research about the characteristics and properties of thirdhand smoke, as well as the risk of harm to humans, we propose four key policy recommendations to better protect the public. First, the goal of smokefree policies should be to create indoor environments free of all tobacco smoke pollutants, including both secondhand and thirdhand smoke. Second, to prevent the creation of thirdhand smoke reservoirs, no exceptions or loopholes should be allowed in indoor smoking bans. Third, policies should incorporate mechanisms for identifying thirdhand smoke reservoirs in indoor environments, either through disclosure or testing. Consumers would greatly benefit from knowing if a home or car they intend to purchase or lease has a history of tobacco smoke pollution. Last, efforts should be made to address and clean up thirdhand smoke residue in contaminated spaces. Policy discussions must tackle the issue of assigning responsibility for the costs associated with thirdhand smoke cleanup. Given that tobacco companies have long been aware of the toxic residue left behind by tobacco smoke and yet have failed to advise smokers against indoor smoking, they bear a degree of responsibility for the remediation of thirdhand smoke residue.”

The Consortium researchers have reached the conclusion that thirdhand smoke is distinct from secondhand smoke in ways that should inform how smokefree policies are crafted. Furthermore, they agree that current smokefree policies focus on secondhand smoke, largely overlooking the long-term health and economic consequences of the toxic residue it generates. Despite this limitation, current smokefree policies provide a solid foundation upon which comprehensive thirdhand smoke policies could be built. Matt says: “Only by including thirdhand smoke in our smokefree policies can we fully protect people from the toxic legacy of tobacco use in indoor environments.”

The Collaborative Consortium on Thirdhand Smoke is funded by a grant from the California Tobacco-Related Disease Research Program (TRDRP), which is supported by a tobacco tax enacted by voters through Propositions 99 of 1988 and 56 of 2016.  

Click here to read the research study.

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