Tout savoir sur le propylne glycol dans les cigarettes lectroniques What is Propylene Glycol (PG) in Vape? Understanding E Cigarette Liquids: Key Ingredients Explained Vibe Medina 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