Cannabis can be a great thing, but lets not lie to ourselves either. Burnt carbon can be torture on lungs and livers in excess. There is NO evidence that I have found that leads me to believe it causes cancer, however it can decrease lung capacity, although not TOO much, Micheal Phelps proved that already. Still, when smoking is part of your daily routine, sometimes it makes sense to stop for a while, just to cleanse the toxins out of your body. Further, no offense to some of the amazing hydro growers...