This topic is one I feel strongly about in many different ways, too many ways to go into, really.
Some folks here think I am a pretty smart guy - those folks are going to be staring at their monitors, slack-jawed in disbelief when I share this little revelation: I started smoking at age 18 to get a break. To date, it is about the stupidest reason I have yet come across for someone to start smoking.
Back in high school, my first job was Wendy's. Being upward-bound, I decided to go through the management training when I graduated. Hourly employees got their scheduled breaks as required by law, but managers really couldn't take a break at the time. The smokers could wander out back and grab a cigarette, but if you didn't smoke you didn't have a reason to stand around out back.
After about a month of managing, I started smoking. It was fairly harmless at first, but now I smoke a pack a day.
As much as I resent having certain liberties stripped from me (Colorado recently adopted a statewide smoking ban, I think it's illegal to smoke within 20' of any public door, or something like that), I also recognize that I would benefit greatly by quitting.
As far as smoking in the field goes, if I am permitted to smoke while working, I do. Once drywall is up and the air isn't flowing as freely, I stop smoking indoors. I quietly worry when guys light up after paint - just because I don't smoke inside doesn't mean I leave them in the car, and the last thing I want is to be blamed for the smell when I didn't contribute to it.
I now work for a company that does schools and hospitals, and when push comes to shove I comply with the rules - I am smart enough to know that my job is more valuable than a cigarette. I find it a little ironic that I can't smoke inside a porta-potty on school grounds, when all sorts of other foul activities are encouraged there, but irony does not undo a rule.
I have lost one friend and one aunt to smoking, and my wife doesn't smoke. Every once in a while, I have a pain taking a breath. Heck, I have a chronic sinus infection that probably would go away if I were to quit. I have plenty of reasons to quit, just no willpower. I look forward to the day. FWIW, I nearly quit when working at the school, so a non-smoking jobsite might just be the kick in the pants several folks need.
Please do not quote this post and respond, I'm just sharing a viewpoint.