E cigarettes High concentrations of flavor chemicals are present in electronic cigarette refill fluids Scientific Reports Frontiers Diacetyl and Other Ketones in e Cigarette Aerosols: Some Important Sources and Contributing Factors A Kernel of Truth: Diacetyl, Popcorn Lung and E Liquids Dinner Lady Flavouring chemical in e cigarettes linked to severe respiratory disease South China Morning Post An updated overview of e cigarette impact on human health Respiratory Research Springer Nature Link