There is unequivocal evidence that regular cannabis smoking causes acute lung inflammation, but what are the long-term consequences? “There is unequivocal evidence that habitual or regular marijuana smoking is not harmless and causes respiratory symptoms and airway inflammation.” If you take biopsies from the airways of those that smoke crack, cannabis, or tobacco, compared to nonsmokers, there is significantly more damage in the lungs of crack smokers, marijuana smokers, and tobacco smokers. And, the levels of damage seemed comparable—especially between the marijuana smokers and tobacco smokers—which is remarkable, since the tobacco smokers were smoking about a pack a day, whereas the marijuana smokers were only smoking about 20 joints a week, rather than 25 cigarettes a day. And those smoking crack were just doing a gram or two a week. So, to see similar rates of damage between marijuana smokers and cigarette smokers suggests each joint is way worse than each cigarette….