Understanding E Cigarette Liquids: Key Ingredients Explained Vibe Medina It's NOT just water vapor. Vaping exposes your lungs to harmful chemicals and can affect your overall health. This Vaping Awareness Month, get the facts and free support to quit. Text READY Monopropylene Glycol (USP EP) Union DIY Union Vape 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.