Can smoking 3 cigrettes a day also kill?

Here's what long term smoking can do. It increases the risk of lung cancer, cardiovascular problems, suppressed immune system, etc. If smoking a pack a day can cause such problems, then smoking 2-3 cigarettes a day could do the same, though at a slower pace. This is a person to person basis, as some people are more prone to the aforementioned health problems due to family history or other underlying causes. It's hard to establish a minimum. I've known chain smokers who lived through their old age without such health problems, but it is not everyone's case. Remember, the damage is ulative, and only reversible up to a certain degree.