What is MTL Vaping? What Does Mouth to Lung Inhaling Mean? Everything we know about the outbreak of mysterious vaping related diseases Mouth to Lung (MTL) vs. Direct to Lung (DTL) Exxus Exxus Vape Vaping is often marketed as a safer alternative to smoking. But scientific research is increasingly showing that inhaling aerosolized chemicals can still damage the lungs. Studies have identified E cigarette or Vaping Product