Electronic cigarettes (e-cigarettes) are hand-held battery powered devices that deliver a liquid which is heated and inhaled as an aerosol. The aerosol is commonly referred to as ‘vapour’, and the use of an e-cigarette is commonly referred to as ‘vaping’.

The liquid solution usually comprises propylene glycol and glycerol, with or without nicotine and flavours, which is stored in disposable or refillable cartridges, or a reservoir. The composition of the liquid solutions have been reported to contain flavourings and harmful substances such as heavy metals, volatile organic compounds and cancer-causing chemicals. E-cigarettes can contain nicotine, even if labelled “nicotine free”. They may also look like cigarettes, cigars, pipes, pens or memory sticks. Newer versions, called box or 'squonk' mods, are bulkier and box-like in shape...