Many singers are smokers. They smoke because they cannot kick the cigarette butt or they need hoarse, husky, breathy, voices to suit their individual song needs. However, the trade-off is costly, as they can probably never regain their original tonal quality besides being addicted to smoke and inviting a plethora of vocal cord problems including but not limited to cancer. In the smoke-filled entertainment industry, it is uncommon to find a person who does not smoke. Nevertheless, classical vocalists, as a rule, never smoke.
My own view is that a singer should not smoke. Period.
Check out the below links for authoritative views. I hope it helps you to quit smoking and more especially if you are a singer or desire to be one.
2. Laryngeal And Voice Disorders (medical content reviewed by the Faculty of the Harvard Medical School)
[Accessed 25 Sept 2010]