almost every post in this thread is totally ridiculous, but I can only quote one.
so smoking italian cigars is somehow healthy?  get your head checked.
the chemicals they put in cigarettes are not to make them more addictive, its so that they burn quickly and evenly.  and no, the government doesn't put them in there to whatever nutcase said that.
TOBACCO INCREASES YOUR RISK FOR CANCER.  end of story.  whether it be a cigar or a cigarette.  but unlike cigars, cigarettes put tar in your lungs.  smoking weed puts a lot more tar in your lungs.  this site is filled with people who think that cigarettes are the devil but weed is ok...wrong.  weed has a shitload more tar, but not carcinogens.  tar makes it harder to breathe, but there's plenty of daily joint smokers who can run really fast.  sitting on your ass and doing nothing makes it harder to breathe when you are doing aerobic exercise too, but plenty of people do that.
tobacco in moderation is fine.  hell, you're young, smoke all you want.  your risk for cancer is so low right now it wouldn't make a difference.  however, prolonged use increases your risk for cancer.  but if you quit, the extra risk fades over time.  people who never smoke get cancer.  my advice is, don't smoke because its bad for you, but if you want to occassionally, it really doesn't matter as long as you're not running a lot for sports.
just don't get addicted.