This study sucks balls, it doesn't say anything that I wouldn't have guessed. I want to know what is the health risks of smoking once a month versus once a week or once a day or once every 30 minutes? Cigarettes will have you relentlessly forcing shit down your throat at all hours of the day. My roomate is constantly rippin butts as soon as he wakes up and last thing before he goes to bed.  I'm conviced that this is what makes them so bad. Weed, if you're coughing up black shit I'd say, "damn I better take a day off". You don't do that with cigarettes, you never listen to your body at all because it is an actual addiction. You smoke and smoke and smoke and never give your body a damn break, see what I mean? Obviously smoking weed isn't good for your lungs, if you are trying to argue that you might as well dip your blunts in bleach before you hit them.