Quote Originally Posted by MrNiceGuy420
cannabis does not negativey effect the lungs at all. tobacco bunches up your lungs and kills the air sacs in your lungs called aveoli. cannabis contains thc which open up the lungs, which is why its good for asthma, and cannabis smoke stays in your major air ways in your lungs unlike tobacco which goes deep into your lungs. ive been smoking for a while now and im more physically fit than i was before i started. i also know alot of jocks who smoke weed. if your worried about it, id invest in a vaporizer
You need to do more research. Smoked cannabis does indeed affect the lungs negatively. It's not associated with an increased risk of lung cancer, but it does raise people's likelihood of developing pulmonary infections such as bronchitis or pneumonia, causes irritation and inflammation, reduces vital (lung) capacity, diminishes oxygen saturation, and, over time, diminishes the elasticity of the alveoli. There are other negative pulmonary consequences, too. Any inhaled burning vegetable matter does this. If people could ingest THC alone without the rest of the cannabis combustion by-products, it'd be much better for their pulmonary health. But inhaled cannabis smoke is not good for the lungs.

Cannabis smoke, by the way, doesn't only stay in the major airways, or bronchial tubes/bronchioles. That is yet another persistent myth. The bronchial tubes and bronchioles aren't set up for 02-C02 gas-exchange. All inhalant transfer, whether we're talking about oxygen/air, anesthesia, cigarette smoke, cannabis smoke, or other inhalable recreational substances that we can't discuss here, occurs through the alveoli, the tiny air sacs. The other parts of the lungs are simply designed to expand to help transport the air or inhalants to the alveoli.