22 people have been hospitalized with vaping linked breathing problems. Doctors don't know why. Do you know what you're vaping? Propylene glycol (PG) and vegetable glycerin (VG) are the main liquids in vapes. When heated, these chemicals turn toxic and aren't safe to breathe. How to Properly Store E Liquids and Prevent Accidental Exposure of E Liquids to Children FDA Do you know what you're vaping? Cancer Institute NSW Nicotine poisoning and overdose: Symptoms, treatment, and prevention