Can being a "non-smoker" be a requirement for employment?
There is no federal regulation governing smoking at work or employment of smokers. Some states have laws that would protect a smokers' rights, making it illegal to discriminate against a prospective or current employee based on whether or not they smoke. Definitely check at your state level to be certain. The American Lung Association has (I believe) a comprehensive list: http://slati.lungusa.org/appendixf.asp