The general altitude smokers and addicts demonstrate is similar to his altitude. They generally believe that they can handle the smoking until the addiction overshadows them. I know that you cannot do much if he does not listen to your advice, but the general tendency here is that he is going to end up as an addict, if he is not yet one. I can only advice you to let him see the consequences and negative effects of what he is doing. Once in a while, talk about it. Do not insist on it to the extent where it sounds like you are nagging. Speak softly, but use strong words. Let him know that he is eventually going to become an addict if he does not stop now. I hope he listens to you.