Great question and a lot of interesting responses. I am a former smoker who quit 4 years ago after smoking for 35 years. I never smoked inside my home, never smoked inside my car when other people were present, and did not smoke in bars (I don't drink) or restaurants. I could easily facilitate my habit by going out to the garage or outside for a smoke. Both of my kids grew up healthy and neither has any problems from 2nd hand smoke. Me, I am dying from the effects of my former habit. That's the price I have to pay for my bad behavior. Hopefully, I can be an example for others to quit now before it is too late. This debate, however, goes much deeper than that.
I think this is simply a case of common sense. If you have 3 smokers in a car with a non-smoker and all 3 are puffing away with the windows up - yeah, the non-smoker is probably going to have some problems with 2nd hand smoke. If you have 3 smokers in a car puffing away with the windows up and a non-smoker in a car in the next lane - no, the non-smoker is not going to have any problems with 2nd hand smoke.
Since quitting, I have never had any smoker ever blow smoke directly into my face. As a matter of fact, rarely do I ever smell cigarette smoke. I do notice the polluted air I have to breathe because of all of the traffic. I do notice the difficulty I have breathing when people wear obscene amounts of perfume and calogne. I do have problems breathing when I walk into stores that burn incense and sell scented candles. I now notice that my nose and lungs are assaulted by all kinds of toxic fumes and odors and most of them don't come from smokers.
I am not condoning smoking. You need to quit and you know it. I don't have the right to tell you to quit nor do I have the right to judge you because you smoke. Like another responder stated, since you don't fit into that perfect human category, people are going to treat you like a second class citizen. Society treats the overweight, the sick, the mentally impaired, the not-so-attractive, the not-so-wealthy, anyone who eats meat, anyone who doesn't eat meat, all the same way. We are all second class citizens who must stand and be judged by those who believe they are perfect. That's just the sorry way things are in this country. It's too bad we are all so judgemental of others and choose to ostracize instead of understand. I hope you do quit the habit someday. I know how difficult it is. I also fully support your right to smoke. As long as it is legal, then you should be able to do it without condemnation and criticism.