• Tobacco and the lung

For several decades, it has been well known that smoking causes irreversible obstructive lung damage in adults1 and is associated with mild airway obstruction and slowed lung function development in adolescents.2 Despite the more than 1% per year decline in age-standardised tobacco smoke exposure between 2010 and 2019, the Global Burden of Diseases, Injuries and Risk Factors Study reported that tobacco (smoked, secondhand and chewing) was the leading risk factor globally for attributable deaths, accounting for 8.71 million deaths, that is, 15.4% of all deaths in 2019.3 This smoking landscape did not yet consider the e-cigarette, invented by Chinese Pharmacist Hon Lik in the early 2000s.E-cigarettes have risen steadily in popularity worldwide, in part due to their interest as an alternative to cigarettes and as a tool for smoking cessation, given their depiction as safer than cigarettes. The devices are now available in multiple formats and models, and in various flavours attractive to young consumers.

The apparent safety of e-cigarettes has been called into question in recent years. In 2021, an integrative review based on epidemiological—mostly cross-sectional—and laboratory studies concluded that there exists a real relationship between e-cigarette use and chronic obstructive pulmonary disease (COPD) among adults and asthma among adolescents, mostly high school students.4 Cross-sectional studies suffer from lack of temporality and reverse causation. Two of the studies, though, were longitudinal and showed increased risks of chronic bronchitis, COPD, emphysema and lung function decline among e-cigarette users. Despite the public health issue of e-cigarette use in young consumers, longitudinal population cohorts focusing on respiratory health and considering other tobacco product uses are scarce. …