Hojo, you are such a silly little angry man.
If you put 2 and 2 together you could draw the conclusion that marijuana smoke may be harmful, but at least it's got some anti-cancer THC in there.
Additionally, a pot smoker is probably inhaling a lot less smoke over the course of the day, week, year, lifetime, than the average cigarette smoker (who smokes 30 cigarettes per day).
So, if you take the added benefit of THC and couple it with the reduced ammount of smoke consumed by marijuana smokers, smoking pot doesn't seem to be nearly as harmful as tobacco use. Of course, there's no way to prove this other than rigorous unbiased scientific study.
But if someone really wanted to clean up their lungs they could switch to from smoking to vaporizing, or eating it. In your case hojo, I would suggest going directly to the marijuana enemas, and maybe even some douching for good measure.