What is MTL Vaping? What Does Mouth to Lung Inhaling Mean? Mouth To Lung (MTL) Direct To Lung (DTL) Restricted Direct Lung (RDL) Vaping: What's The Difference? How To Inhale A Vape Properly: MTL, DTL & RDTL Vaping Explained Smoking and vaping are often compared, but neither is harmless. While they work differently, both can expose the lungs to addictive nicotine and harmful chemicals that impact breathing and overall health. Smoking