N One Crystal Cube Engngs Vape The Effects and Safety of Propylene Glycol & Vegetable Glycerine Pod Salt UK Vaping propylene glycol and vegetable glycerine may lead to lung inflammation Researchers at the University of California, Riverside, found that heating propylene glycol, the main ingredient in most e cigarette liquids, can produce two toxic chemicals, methylglyoxal and acetaldehyde, which damage lung cells. Using