My own little experiment
I remembered a commercial from years ago the other say while enjoying some shisha. When I thought of the commercial I thought about the health reports that compared smoking hookah to smoking cigarettes. The commercial I speak of was for a toothpaste called Topal or Topol I think. It was a toothpaste designed for smokers and it showed a man taking a drag of a cigarette and blowing the smoke into a hankerchief. After doing so he held it up to show that it had a nasty looking yellowish-brown stain on it from the exhaled cigarette smoke. Back when I smoked cigarettes I tried that and sure enough there was the same yellowish-brown stain on a paper towel (yes it was a low rent comparison but it worked! LOL)
So while I was enjoying my session I felt the need to be a little scientific. I picked up a paper towel and taking my usual big hit I blew the smoke through the paper towel. Interestingly enough there was no stain or mark on the towel at all. I took 4 more hits and blew each one into the towel and still no stain. I got bored with this experiment after that and just relaxed and enjoyed.
I'm going to try exhaling through a towel for an entire session and see if it leaves a stain. I wonder about the results so far. Is it tar that caused the yellowish-brown stain on the hankerchief in the commercial (and the paper towel when I recreated it)? If so this experiment has to prove that hookah smoke has no or at least far less tar in it than cigarette smoke.
I'll get back to you on a full session exhalation result, maybe tonight.