Propylene Glycol Vape (PG) Svapoebasta Predicting the pulmonary effects of long term e cigarette use: are the clouds clearing? European Respiratory Society Flavor induced inflammation and cytotoxicity in human aortic smooth muscle cells: Potential implications for E cigarette safety ScienceDirect Vaping is the act of inhaling a heated, aerosolized substance. It is critical to distinguish vaping from smoking. Smoking is the inhalation of a burned substance. The main difference between the two