Propylene glycol, a component of electronic cigarette liquid, damages epithelial cells in human small airways Respiratory Research Springer Nature Link Heated Tobacco Products, Cigarettes, and E Cigarettes: What's the Difference PMI Science E Cigarettes, Vapes, and other Electronic Nicotine Delivery Systems (ENDS) FDA Heated Tobacco Products and E cigarettes What's the difference? Dailynewsegypt View of a ClopiNette store in Paris, France on August 23, 2012. ClopiNette stores sell electronic cigarettes, also known as e cigarettes to help the consumers to quit smoking. The electrical device simulates Am I Allergic to Electronic Cigarettes? E Cigarette Reviews and Rankings