Ah.. ive been smokin for about 4 years now, always through a bong. I never touch tobacco cause i think its a terrible habit to start. Ive always beleived that bong is one of the best ways to smoke, although a vaporizer is better. But still, the water in a bong does filter a lot of chemicals and tar from the smoke. I really haven't noticed anything in the lungs department so far. Although i see my brother who is a tobacco smoker basically hack up a lung every morning. Well hope it helps.. Peace.