This is where I came in. A billion years ago, in the 80s, when there was a surge of evidence against the tobacco companies, the bacterial content of their tobacco was studied... and while found to be interesting, the possibility of transmission through air flow knocking the little buggers off the leaf, through a filter and into your mouth (behind the burning coal, which kills almost everything) was found to be entirely inconclusive.What was conclusive though is that tobacco containing *mold* was exceedingly dangerous. Mold spores don't "stick" to the leaf, they just sit on it like dust. And mold spores very often have an outer casing which can survive temperatures much, much higher than the approximately 400 degrees F that burning dry tobacco leaf generates. Suck some of those up and you can end up with a fungal infection in your bronchia and/or lungs that is extremely difficult to get rid of and very, very unpleasant.