Vaping and smoking together increases lung cancer risk fourfold 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 Lung Injuries Associated with Use of Vaping Products FDA Mouth to Lung (MTL) Vs Direct Lung (DL) Inhale Explained E Cigarette Direct