Propylene Glycol Vape (PG) Svapoebasta E cigarettes and the ob gyn: Key safety information for prenatal counseling Contemporary OB GYN WellnessWednesday Is Vaping Safer than Smoking? Why this May Not be the Case In a bid to quit smoking, many are turning to vaping instead. But is it truly safer? If you've 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.