Passive Electronic Cigarette Vapor Exposure in Children: A Systematic Review.

Adults of childbearing age have the highest rate of electronic cigarette (e-cigarette) use in the United States. Users perceive passive e-cigarette vapor exposure to be less harmful than passive conventional cigarette smoke exposure. We conducted a systematic review to understand the risks of passive e-cigarette vapor exposure in children. Data sources included PubMed, CINAHL, Web of Science, and Scopus. Eligibility criteria included studies published between 2010 and 2024 with (1) children ages 0-18 or animal models representing children and in vitro studies, (2) descriptive, experimental, and qualitative designs, and (3) a focus on passive e-cigarette vapor exposure. Two independent reviewers screened studies, with a third for arbitration. Thirty-three studies were included in this review. Emerging evidence, primarily from animal studies, suggests that passive e-cigarette vapor exposure is associated with poor respiratory, immunological, physical growth, and neurological effects. Air assessments noted increased particulate matter and concentrations of nicotine, metals, and volatile organic compounds. Parents were more likely to use e-cigarettes than non-parents, and a majority reported use in the home and car. Risk of bias assessment indicated that 23 of the 33 studies were rated as weak, highlighting methodological limitations in the current evidence base. More rigorously designed studies are needed to strengthen the evidence base. Passive e-cigarette vapor exposure may be harmful to children, and many parents seem unaware of this potential threat. Parents should be cautioned to minimize exposure until more is known.