There is as much evidence to back the outright "denying" as there is to back supporting global warming. As to those theorizing that this is about government control... well... let's see, the federal government just classified the breath you exhale as a poison. How far a reach do you think THAT gives the government over you in the public domain. Think second hand smoke.
I see where you're getting at. I offer this argument (the Libertarian one):
While I am all for you being able to smoke and kill yourself slowly. I'd rather not have the same done to me. Second hand smoke exists and it kills. (It's been proven). So, when you smoke around me in public places such as restaurants and slowly take away from my life, you are violating my rights as a human being.
Therefore, you should have to move to a new area of the restaurant, perhaps a smoker area where you all can smoke together and not breach my rights.
The Government although considered to be evil by many, it is necessary. We need them to step in and make such measures at points in order to protect our rights.
Also, the situation you are talking about already exists among the states that border the mexican border.