Second-hand exposure at home to vaping devices such as e-cigarettes may be linked to a heightened risk of bronchitis symptoms and shortness of breath in young adults.
Vaping is becoming increasingly popular despite the little evidence about the possible health effects of second-hand exposure to nicotine vapour from e-cigarettes and other vaping devices, said the researchers.
Although second-hand exposure to particulate matter from e-cigarettes is lower than that from conventional cigarettes, levels of ultrafine particles in e-cigarette aerosol can be higher. This aerosol also contains volatile compounds and metals known to harm lung tissue.
If these findings prove causal, there would be a “compelling rationale” for banning the use of e-cigarettes and other vaping devices in public spaces, conclude the researchers.
The research has been published online in the respiratory journal, Thorax.
The impact of vaping
The researchers drew on information supplied by 2090 participants in the Southern California Children’s Health Study to understand the impact on respiratory health from vaping and other conventional methods.
The study collected information annually on respiratory health, active and second-hand nicotine vaping, and conventional tobacco and cannabis smoke exposure in the household from 2014, when participants were 17, on average, to 2019.
Participants were considered to have bronchitis symptoms if they reported any of the following:
- bronchitis in the previous 12 months,
- daily cough in the morning for three consecutive months,
- daily cough at other times of the day for three months in a row,
- congestion or phlegm that wasn’t cold symptoms.
Furthermore, a wheeze was based on self-reported wheezing or whistling in the chest during the previous 12 months. And shortness of breath was based on experiencing this when hurrying on level ground or walking up a slight hill.
Understanding the researchers’ findings
The prevalence of second-hand nicotine vapour increased by 12% to 16% between 2014 and 2019, whilst the prevalence of second-hand smoking fell from 27% to 21%. Past 30-day active use of cigarettes and cannabis rose over the study period.
Most participants (76%-93%) who were exposed to second-hand nicotine vaping during any of the study years were also more likely to actively use tobacco or cannabis products themselves or be exposed to second-hand smoking.
The prevalence of self-reported wheeze and bronchitis symptoms rose from 12% to 15% and from 19.5% to 26%, respectively. The prevalence of shortness of breath didn’t show any clear trend over time, ranging from 16.5% to 18%.
Compared with participants who hadn’t been exposed to second-hand nicotine vaping, those who had were more likely to report bronchitis symptoms and shortness of breath but not wheeze.
After adjusting for second-hand smoking and cannabis exposure, and active vaping or smoking, those exposed to second-hand nicotine vaping were 40% more likely to report bronchitis symptoms and 53% more likely to report shortness of breath.
When the analysis was restricted to the 1181 participants who reported no personal vaping or smoking in the past 30 days, the researchers found stronger associations emerging. These participants were more than twice as likely to report a wheeze, three times as likely to report bronchitis symptoms, and twice as likely to report shortness of breath as those who hadn’t been exposed to second-hand nicotine vaping after adjusting for demographic factors and second-hand smoking/cannabis exposure.
Whilst, this is an observational study, and as such, can’t establish cause, the findings are similar in magnitude to those observed for second-hand smoking, said the researchers.
Banning e-cigarettes in public
The researchers suggested that if causal can be proved in future studies, then a ban on vaping in public would be warranted.
“If causal, reduction of second-hand e-cigarette exposure in the home would reduce the burden of respiratory symptoms and would provide a compelling rationale for regulation of e-cigarette use in public places,” they wrote.
In a linked editorial, Drs Anna Lucia Fuentes and Laura Crotty Alexander of, respectively, the University of California San Diego and the San Diego Healthcare System, pointed out that vaping devices were originally marketed as a lower health risk nicotine replacement.
“But increasing evidence points to the contrary,” they said. “Even more concerning is that marketing has targeted the vulnerable adolescent population, with 78% of middle school and high school students exposed to at least one e-cigarette advertisement between 2014 and 2016.”
They added: “Some may be comforted by studies that argue that nicotine use has not increased with the rise of vaping. However, it is important to note that the nicotine content reported on product labels and what is chemically measured can vary widely.
“This means that users may be unaware of what they are truly vaping and thus are at risk of unwittingly becoming nicotine addicts.”
They concluded: “While the association is not causation, this study is the first to describe the negative effects of second-hand nicotine vape exposure on respiratory symptoms.
“More work needs to be done to prove that this exposure directly causes harm. Ultimately, this is a public health concern that—if not addressed—has the potential to negatively affect our population, including those who are most vulnerable.”