The combination of propylene glycol and vegetable glycerin e cigarette aerosols induces airway inflammation and mucus hyperconcentration Scientific Reports Toxicity of humectants propylene glycol and vegetable glycerin in electronic nicotine delivery systems ScienceDirect Batterie de cigarette lectronique pas cher, mod ou batterie de e cigarette pas cher Mon liquide Mon liquide E cigarettes aren't harmless, and combining them with cigarettes makes them even worse Study Summary