E cigarettes can emit formaldehyde at high levels under conditions that have been reported to be non averse to users Scientific Reports Structure of the electronic cigarette. The electronic cigarette is a Download Scientific Diagram E cigarette aerosols of propylene glycol impair BK channel activity and parameters of mucociliary function American Journal of Physiology Lung Cellular and Molecular Physiology American Physiological Society Vgtol electronic cigarette: e liquids without PG J Well Flavorants and Propylene Glycol From e Cigarettes Form Harmful Irritants When Combined Hawai'i Public Health Institute