Quote Originally Posted by melodious fellow
The swimmer definitely takes in more air in that one big breath than the toker does in that one big hit, but the toker is sitting on his ass while the swimmer is using ALOT of O2 and much faster, yeah?

I guess one could exhale completely and then inhale just smoke until they ran out of lung capacity (some head shops sell gas masks that do this) but most people release a carb and suck down some fresh air before their lungs are filled to capacity, yeah?

So unless you are using a gas mask, holding hits, even up to 45 seconds or so (who the hell does that anyway?) shouldn't cause oxygen deprivation, it will just fuck up your lungs, yeah?

any pulmonologists?

peace
Well... remember that the smoke contains carbon monoxide (CO), which binds to hemoglobine more than 200 times strongly than oxigen... so, while holding a lungful of smoke the CO is binding (and thus busying) the hemoglobine, and even after you exhale the smoke, the CO remains bound to the hemoglobine. So, the available hemoglobine goes lower and it diminishes the O2 transportation rate, causing oxigen deprivation.