Propylene glycol in e cigarettes might keep us healthy, says researchers What Is Monopropylene Glycol Used For? The Chemistry Blog Electronic cigarette vapors from propylene glycol or glycerol alone Download Scientific Diagram Researchers at the University of California, Riverside, found that heating propylene glycol, the main ingredient in most e cigarette liquids, can produce two toxic chemicals, methylglyoxal and acetaldehyde, which damage lung cells. Using