I'm 23 and been smoking regularly for about 3 years now and just this last week have been coughing up black phlegm. Now I have done a ton of researching (including this site) which seems to indicate while (obviously) inhaling smoke isn't safe, on the marijuana side it isn't nearly as potentially damaging as say cigarettes. I've also seen a lot of indication that this tends to occur more when you are sick or have a cold, as this is your bodies way of ridding your lugs of the tar in an attempt to help. On the flip side though, some people still say the opposite. I use to smoke cigarettes, but not many a day and have since quit for about a year now (I'll never touch them again). I've always had chest pain but after a magnitude of tests (I'm persistant) including an EKG of my heart, they diagnosed me with Chostral Chondritis.I work out actively, I eat heathly, and basically smoke marijuana now to help with my anxiety and depression (which I am so helpful for). I've heard a vaporizor may be the best plan on action for the "safest" way to smoke marijuana, but just wanted to make sure this isn't a more severe thing I should go checked out. Thank you for your time.