Electronic Cigarette Use and Respiratory Symptoms in Chinese Adolescents in Hong Kong
To the Editor E-cigarettes are increasingly used, but their health effects remain unclear.The primary ingredients of e-cigarette liquid, propylene glycol and flavoring chemicals (e.g.diacetyl or diketone), are respiratory irritants and harmful to the lungs. 1 Well-documented respiratory toxicants such as particulate matters, volatile organic compounds and metals were found in ecigarette aerosol although in lower concentrations than conventional cigarettes. 2 Short-term adverse effects of airway resistance and inflammation have been observed in adults but null associations were also reported. 3Children are particularly vulnerable to respiratory pollutants yet no study has evaluated the respiratory effects of e-cigarettes in children.We assessed the association between e-cigarette use and respiratory symptoms in Chinese adolescents in Hong Kong. MethodsDuring 2012/13, we surveyed Secondary 1 (US Grade 7, typically aged 12) to Secondary 6 students from 75 randomly selected schools using an anonymous questionnaire based on the Global Youth Tobacco Survey. 4An invitation letter was sent to parents, and student participation was voluntary.Ethics approval was granted by a local institutional review board.A total of 45128 students (94.5% of all invited) were available for analysis after data cleaning.Smoking status was defined as never-smoking, experimental smoking (smoked once or a few times), exsmoking (smoking in the past but not now) and current smoking (smoked on ≥1 day in the past 30 days).E-cigarette use in the past 30 days (yes/no), respiratory symptoms (cough or phlegm) for 3 consecutive months in the past 12 months (yes/no), socio-demographic characteristics (sex, age, perceived family affluence) and secondhand smoke exposure were recorded.We weighted