I recently read this article on smokers in the workplace. They are less productive overall and have a much higher incidence of sick days.
Many years ago when I was working at a major home improvement store I saw this first hand. There was a manager who, I swear, thought that his sole duty was to do his best at wearing a groove in the back aisle between the break room and the smoking area. This guy smoked so much that it was just about all he did.
Well give this article a read and let me know what you think.
Later all and have a productive day.