PURPOSE: The popularity of electronic cigarettes (e-cigarettes) has grown exponentially over the past few years, and teenagers now prefer them to tobacco cigarettes. We determined whether exposure to e-cigarette vapour (e-vapour) adversely affects ion transport using human airway epithelial cell lines 16HBE14o- and Calu-3 and well-differentiated primary human bronchial epithelial cells (HBEs). METHODS: We concurrently measured fluorescent signals and short-circuit current (I RESULTS: We compared the effects of e-vapour to those of traditional cigarette smoke (CS) on the human airway cell models. In all three cell types, e-vapour, similar to CS, significantly reduced agonist-induced increases in Ca CONCLUSION: Our data suggest that e-vapour is not harmless and causes ion transport dysfunction similar to CS, thereby predisposing e-cigarette users to vaping-induced lung injury.