Not in caves though, I seldom set foot in them, its man made places for me
I find the smell unpleasant, though this does disperse. Worse, I think, are the dog-ends. I hope if you do have to smoke underground that you take your rubbish out with you!
A point worth thinking about. If smoking in caves is an alien activity for the cave environment, then in ancient mine workings, dating back to pre-Raleigh times, it is equally alien. The miners had no such vice when the oldest workings were created.
Of course, in mines where smoking did take place, the clay-pipes thrown away by miners are valuable dating evidence. Will there ever be a way of dating dog-ends? I suspect not.
Putting the whole debate into perspective, smoking has only existed on this island for some 400 years. That's considerably less than the period between the rise and fall of the Roman Empire, and only about as long as the Roman occupation of this island. The sooner we kick this 'new' habit of smoking, the better for everyone! Historically, the people of Britain have been exclusively non-smokers for a much longer period than the time over which the habit has developed.
Perhaps in a thousand years time, historians will view smoking as a quaint little activity, performed by humans in those bad old days when we seemed to take a curious delight in abusing ourselves and others.