IS smoking illegal?

Ok so here's the case as I see it. Research has shown that smoking over time can and will kill you. There are great debates over whether or not people should be allowed to kill themsleves, commit suicide.
To choose to smoke is in essence choosing to kill yourself in this way. Many people may not agree, but only because they are afraid to die, and are addicted. Addicted; it doesn't mean to want, to desire, to choose... no it means to use or face painful consequences. Smoking kills you, in horrible, but slow long-term fashion. I do not beleive that living or dieing should be a legal decision, it is a personal decision.
So a person has a right to kill themsleves if they choose, it is not illegal as of yet. I mean how could you make it illegal, who would you charge with attempted self-murder except for unsuccesful suicides, and if they wanted to kill themsleves before, going to jail for it is NOT going to make it better. So making smoking illegal for personal health matters just won't hold water.
Yet... second-hand smoke has also been proven to be fatal over time. If a person was knowingly poisoning someone esle over a long period of time and that person eventually died from some disease resulting from the poison, would not the person doing the poisoning be held responsible? Is that not murder? How can cigarette smoking be denied as attempted murder? Or deadly assault? Murder, assault, whatever you call it, it IS illegal. So what the fuck is going on here?