Hi Ron, This thread started because for the last 10 years I have been hearing anecdotal evidence of a connection between stopping smoking and the diagnoses of PD. Several references to this possiblity have been made in recent postings, prompting me to instigate the straw poll. I can't speak for anyone else, but I am not suggesting that stopping smoking causes PD. In fact I would have no problem with rejecting that possibility out of hand. It may be, however, that some active component (nicotine?) masks PD symptoms (or even slows the progress of the disease). In this instance quitting smoking would have the apparent affect of accelerating the onset of PD. The straw poll is an attempt to put a figure to the juxtaposition of quitting and PD diagnosis in terms of this list. As regards possible smog connections, this can't be possible. I mean PD isn't confined to the Los Angeles area is it. *grin* Dennis.