Most vapes contain toxic chemicals that are bad for your health. Some are added to make the vapes taste or smell nice, and others are created when the battery heats the liquid. 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. The combination of propylene glycol and vegetable glycerin e cigarette aerosols induces airway inflammation and mucus hyperconcentration Scientific Reports PG vs VG: What They Are and How to Use Them