A systematic review of the health risks from passive exposure to electronic cigarette vapour.

Electronic cigarettes (ECs) have recently become popular around the world, and their safety is being widely discussed in the scientific literature. Previous studies have examined the chemicals in e-liquids and vapour, and demonstrated that the aerosol from ECs can contain toxic chemicals that are harmful to health. However, little is known about the potential adverse health effects of passive exposure to EC vapour. The aim of this paper is to summarise and review all studies that have examined potential adverse health effects of passive exposure from inhaling EC vapour. Specifically, our research objectives were to describe 1) the absolute impact of passive exposure from inhaling vapour when compared with background, and 2) the relative impact of passive exposure from inhaling vapour when compared with passive exposure from inhaling conventional cigarette smoke.