What are the health risks of smoking in moderation?

Everybody knows how bad smoking is for you. Countless studies have linked it to lung cancer, oral cancer, and emphysema. However, as far as I know, these studies have focused on the long term effects on people who smoke a great deal – say, a cigarette or two every day for thirty years.

Have there been any studies done on the health risks of moderate smoking? Say, a cigarette or two once a month? Are the risks the same? It seems to me that, if done in moderation, the risk of smoking-related cancer would lower to the point where smoking would be about as dangerous as driving a car, considering how many automobile accidents there are.

This is mainly speculation, so if someone could clear things up for me I’d be grateful.