What's in a vape: nicotine and other harmful chemicals Is Propylene Glycol Dangerous to Inhale? Safety and Use in E Cigarettes SMOKO E Cigarettes Health Effects of E Cigarettes Kansas Health Institute EVALI: New information on vaping induced lung injury Harvard Health How Much is Vaping Bad For You? Health Risks Explained 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