Mouth To Lung Vaping What Is It & Why Is It Still Important In 2019? If you vape, you inhale a lot of harmful substances. These can damage your heart and lungs. How to Inhale Vapor Do You Inhale Vape Or Keep It In Your Mouth Mouth to Lung (MTL) vs Direct to Lung (DTL) Vaping 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 The Difference Between Healthy Lungs and Smoker's Lungs