Background Globally, a surge in electronic cigarette (e-cigarette) use has been observed in recent years, with youth being the most susceptible group. Given their recent emergence, studies assessing the health consequences of using e-cigarettes and exposure to their secondhand aerosols (SHA) are limited. Hence, this study sought to assess associations between e-cigarette use and household exposure to SHA from e-cigarettes with asthma symptoms among adolescents. Methods A school-based cross-sectional study was conducted by enrolling high school students (n = 1565; aged 16–19 years) in Kuwait. Participants self-completed a questionnaire on tobacco products use (e-cigarettes and cigarettes) and asthma symptoms. Current e-cigarette use and cigarette smoking were defined as any use in the past 30 days. Household exposure to SHA from e-cigarettes in the past 7 days was reported as none (0 days), infrequent (1–2 days), and frequent (≥ 3 days). Asthma symptoms included current (past 12 months) wheeze, current asthma (history of clinical diagnosis and current wheeze and/or medication use), and current symptoms of uncontrolled asthma (≥ 4 attacks of wheeze, ≥ 1 night per week sleep disturbance from wheeze, and/or wheeze affecting speech). Associations were assessed using Poisson regression with robust variance estimation, and adjusted prevalence ratios (aPRs) and 95% confidence intervals (CIs) were estimated. Results Among the analytical study sample (n = 1345), current e-cigarette use and cigarette smoking was reported by 369 (27.4%) and 358 (26.6%) participants, respectively. Compared to never e-cigarette users and never cigarette smokers, current e-cigarette users with no history of cigarette smoking had increased prevalence of current wheeze (aPR = 1.54, 95% CI 1.01–2.45) and current asthma (aPR = 1.85, 95% CI 1.03–3.41). Moreover, the frequency of exposure to household SHA from e-cigarettes was associated with asthma symptoms. For example, compared to those with no exposure to household SHA, frequent exposure to household SHA was associated with current wheeze (aPR = 1.30, 95% CI 1.04–1.59), current asthma (aPR = 1.56, 95% CI 1.13–2.16), and current uncontrolled asthma symptoms (aPR = 1.88, 95% CI 1.35–2.62). Conclusions E-cigarette use and their household SHA exposure were independently associated with asthma symptoms among adolescents. Hence, such observations indicate that e-cigarette use and passive exposure to their aerosols negatively impact respiratory health among adolescents.

INTRODUCTION Use of tobacco products among adolescents is a major global public health concern. Given the changing landscape of tobacco product use and the lack of epidemiologic data to inform tobacco prevention and control strategies in Kuwait, this study sought to estimate the prevalence and patterns of electronic cigarette (e-cigarette), conventional cigarette, and hookah use among adolescents in Kuwait. Moreover, exposure to secondhand smoke (SHS) and secondhand aerosol (SHA) from e-cigarettes was assessed. METHODS This cross-sectional study enrolled high school students (n=1565; 16-19 years) across Kuwait. Current (past 30-day) use of e-cigarettes, conventional cigarettes, and hookah were assessed through self-reported data. Additionally, current (past 7-day) exposure to SHS and SHA in households and public places were ascertained. Associations were evaluated using Poisson regression, and adjusted prevalence ratios (APRs) and 95% confidence intervals (CIs) were estimated. RESULTS Overall, 26.4% (402/1525), 25.1% (383/1525), and 20.9% (318/1525) of the study participants were current e-cigarette users, conventional cigarette smokers, and hookah smokers, respectively. Current use of any tobacco product was reported by 35.1% (535/1525) of the total study participants. The prevalence of concurrent triple use of 'e-cigarettes, conventional cigarettes, and hookah' was estimated to be 12.8% (195/1525). Also, among the study participants, 41.9% (619/1479) were exposed to household SHS, 32.0% (469/1465) were exposed to household SHA, and 62.2% (916/1472) were exposed to SHS and/or SHA in public places. Male adolescents were more likely than females to be current e-cigarette users (APR=5.19; 95% CI: 4.09-6.57), conventional cigarette smokers (APR=5.42; 95% CI: 4.26-6.90), and hookah smokers (APR=3.43; 95% CI: 2.72-4.32). CONCLUSIONS A substantial proportion of adolescents in Kuwait are currently using tobacco products and being exposed to SHS/SHA. The findings emphasize the need to continue monitoring all forms of tobacco product use among adolescents and to strengthen tobacco prevention and control programs.