The Boston Globe carries the story of a Cape Cod man fired by Scotts Lawn Care for smoking off the job; I have one comment on the story and one comment on the issue itself.
The story presents the matter as if it were one of first impression. In fact, Massachusetts has a law on the books making it illegal for any police officer or firefighter to smoke, on or off the job. The effective date of the law was January 1988, if memory serves, and it then forbade any smoking by anyone hired on or after that date as a police officer or firefighter. The mandatory penalty is dismissal. I recall at least one firing. I do recognize the public sector / private sector distinction, but a thorough article would have mentioned the law.
As for the issue itself, I think Scotts, Inc. is being hypocritical. Employees can't put poison in their own lungs. This from a company whose entire business revolves around dumping chemicals on grass as far and wide as it can.