News that the child smokes, causes only negative emotions. However you should not follow their tastes. Better couple of days to calm down, and already then to begin to take actions. The main thing in this question is not to show authoritarianism.
In the beginning it is worth picking up a right moment for a conversation. You have to calm down already enough, and the child - is located to a conversation. For example, it can be done during joint walk or after viewing the family movie. Do not begin a conversation with threats, the increased tones or other manifestation of aggression.
Reasons and harm to health
You have to show to the child that are very concerned and really want to help him. For a start you need to find out the reason which the child began to smoke. Suggest the child to explain independently why he does it. It seems "I do not know answers" or "just like that" are not accepted. Ask the child to tell everything that he knows about harm of cigarettes.
Explain to him that what strong would not be the reason, smoking of that is not necessary. Long-term consequences are much stronger, than he can imagine. Tell him real examples of how people perished from this habit. It is also possible to place emphasis on communication with an opposite sex – very few people like to talk to the person from whom blows as nicotine. If you smoke, then your words can not hook on the child. The personal example is incredibly important in the course of education of children. However there are receptions which will help and in this case. For example, you can suggest it to throw together. At the same time all will have a benefit. Also you can tell about negative consequences on the example of own experience. For example, that at you it is bad with breath or that you spend too much money.
Personal example
Surely let the child know that you are not going to abuse him or to lecture somehow. Show that you really very much worry the incident. However you cannot just remain indifferent, but also will not dare to press his opinion. It really helps as the child will begin to feel that you do not try to influence him somehow. Show a personal example that the healthy lifestyle is cool. If the child likes to roller-skate, go together with him. If he prefers basketball, then descend somehow in the evening to leave a ball in a basket. Other case - simple suspicions that the child began to smoke (for example, the smell on clothes and hair appeared). In this case it is worth organizing an explanatory conversation earlier. It is easier to get rid of this addiction when it only began to appear. It is the best of all to place emphasis that the strong personality will never obey to influence of any bad habit. The created person is much stronger than it. If the child wants to become the real man (or the real woman), then he should get rid of it.