MTL or DTL: Mouth to Lung vs Direct to Lung Vape Guide 2019 Today's Fact Friday highlights an important truth. Both cigarettes and e cigarettes are harmful to your health. While some believe vaping is a safer alternative, studies show that one disposable vape can equal Mouth to Lung (MTL) Vs Direct Lung (DL) Inhale Explained E Cigarette Direct Vaping damages young people's lungs as much as smoking, study suggests Vaping The Guardian