>While tobacco is an obvious factor, it's not the only one. There is the paper which wraps the tobacco, the filter, and potentially even something from the match used to light the cigarette. They are minor factors, no doubt, but factors none-the-less.

Even more suspect, IMO, are the various chemicals they mix into the tobacco, to make it burn more evenly, or faster... I've compared a Marlboro against an American American natural brand, and the former is burning about three times faster, even unattended. Occasionally you see a little spark of something in the ember. Best phosphorus money can buy, or just the best gunpowder?

Not to mention the polymer particles from the filter.

Those who saw me know that I roll my own, using a glueless paper, with plain natural (just fermented) tobacco, no additives. I bet autopsy will show I've died healthier than an average smoker :).