Importantly, many researchers in this field have argued that there is no safe level of secondhand smoke exposure, and due to significant overlap in important carcinogens between secondhand and thirdhand smoke, it can be argued that there is no safe level of thirdhand smoke exposure either.

Pulmonology Advisor: Why is the risk for thirdhand smoke exposure particularly high in children?

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Mr Drehmer: Young children are at risk for increased exposure because they typically spend greater amounts of time at home, have smaller bodies, crawl on the ground and on furniture where thirdhand smoke has settled, and often put their hands and toys — which may be contaminated with thirdhand smoke particles — into their mouths.  

Pulmonology Advisor: What are implications for clinicians in terms of how to advise patients and parents about these risks?

Mr Drehmer: Advising parents to avoid smoking in the presence of their children is necessary, but not sufficient, because it fails to account for children’s exposure to thirdhand smoke. Parents should be advised to keep homes and cars completely smoke-free, even at times when children are not present. 

Thirdhand smoke residue remains on surfaces long after smoking takes place and thirdhand smoke sticks to the hair, skin, and clothing of smokers. Therefore, the only way to fully protect household members from exposure to tobacco smoke is for all household smokers to quit smoking. We refer to this concept as the “Cessation Imperative.” 

Prioritizing the topic of thirdhand smoke when speaking with parents who smoke can be particularly helpful for clinicians when encouraging smoke-free home and car policies, and it can increase the likelihood that parents accept assistance to quit smoking, such as nicotine replacement therapy and enrollment in the free tobacco quitline available in each state.  

Dr Northrup: Similar to clinicians advising patients to avoid smoking and secondhand smoke exposure, clinicians should feel confident advising patients that the safest course of action is to avoid and minimize time spent in environments where smoking and/or vaping occurs and to avoid exposure to aged-tobacco and aged-nicotine byproducts, such as carcinogens and other toxicants. 

This advice is especially true for populations potentially more vulnerable to thirdhand smoke exposure, such as pregnant women, children, and individuals who are immunocompromised. To assist patients who wish to quit tobacco or nicotine, clinicians may wish to incorporate patients’ concerns about exposing other members of their household to thirdhand smoke into discussions about consequences of continued smoking. 

Pulmonology Advisor: What should be next steps in this area in terms of research or otherwise?

Mr Drehmer: Policy changes are needed to make indoor spaces where people live and work free from both secondhand and thirdhand exposure to tobacco smoke. The US Department of Housing and Urban Development recently implemented a smoke-free policy in public housing that will help reduce the risk of being exposed to thirdhand smoke in units previously occupied by smokers. Expansion of smoke-free policies to include all multiunit housing is necessary to protect residents from secondhand and thirdhand smoke exposure.  

Making changes in electronic medical record systems to efficiently document [whether] homes and cars are smoke free would encourage more discussions about preventing thirdhand smoke exposure. One of the very best ways for a healthcare system to address this problem is to systematically screen all patients for smoking and exposure to tobacco smoke and provide evidence-based assistance to all household smokers to help them quit smoking.

Dr Northrup: Research support and interest has grown significantly in the past 2 decades and much work is still needed to quantify the risks from long-term thirdhand smoke exposure, as well as to understand the mechanisms by which this exposure causes harm. 

Dr Matt: Other important areas to focus on include:

  • prevention of thirdhand smoke pollution and exposure
  • closing gaps in the protection of nonsmokers
  • better implementation of smoking bans
  • expanding smoking prohibitions
  • remediation/clean-up of polluted environments
  • exposure pathways (dermal, ingestion, inhalation)
  • disease mechanisms
  • dose-response relationships
  • specific markers of thirdhand smoke pollution and exposure

Dr Hovell: You could argue that suppression of secondhand smoke exposure is the best means of preventing thirdhand smoke exposure.3 Suppression of both may contribute to successful cessation. Cessation requires curtailment of all public spaces [where] tobacco smoke is allowed — ditto for all private spaces where mothers and children ever frequent, indoors or out. Finally, taxes should be raised on the tobacco industry, including all imports, to curtail the industry overall and offer alternative investments to kill the industry.

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  1. Northrup TF, Jacob P III, Benowitz NL, et al. Thirdhand smoke: state of the science and a call for policy expansion. Public Health Rep. 2016;131(2): 233-238.
  2. Drehmer JE, Hipple Walters B, Nabi-Burza E, Winickoff JP. Guidance for the clinical management of thirdhand smoke exposure in the child health care setting. J Clin Outcomes Manag. 2017;24(12):551-559.
  3. Hovell MF, Hughes SC. The behavioral ecology of secondhand smoke exposure: a pathway to complete tobacco control. Nicotine Tob Res. 2009;11(11):1254-1264.