About Comparative study of lung toxicity of E cigarette ingredients to investigate E cigarette or vaping product associated lung injury ScienceDirect Propylene glycol, a component of electronic cigarette liquid, damages epithelial cells in human small airways Respiratory Research Springer Nature Link Cytotoxic and oxidative effects of commercially available propylene glycol (PG) and vegetable glycerin (VG): Common humectants in electronic cigarettes ScienceDirect VG PG Ratio Explained: Choosing the Right Vape Juice for Your Kit VSAVI E Liquids Vape Kits The combination of propylene glycol and vegetable glycerin e cigarette aerosols induces airway inflammation and mucus hyperconcentration Scientific Reports