I got through a 600 puff vape a week, then I started coughing up a brown substance' The effect of e cigarettes on smoking cessation and cigarette smoking initiation: An evidence based rapid review and meta analysis Cardiopulmonary Impact of Electronic Cigarettes and Vaping Products: A Scientific Statement From the American Heart Association Circulation The impact of e cigarette exposure on different organ systems: A review of recent evidence and future perspectives ScienceDirect The Cochrane Review of behavioural interventions for smoking cessation, explained ASH E cigarettes around 95% less harmful than tobacco estimates landmark review GOV.UK