First and foremost, let's keep this civil.
1. Bus and train usually pollute a lot less than a car, per person. Point stands, there is no need.
2. Really, spitting on me is your right? Well I believe it is my right not to be spat upon. Now who is right? Really, rights are not universal immutable objective facts, they are very subjective. For instance, I believe I have the right to kick the ass of anyone who spits on me on purpose. The law states otherwise, but the law is also a subjective set of arbitrary rules.
3. Yes, and I think it's unfair that smokers should take extra care while non-smoking polluters shouldn't. For extra reference by the way, at the bus stop I always make sure no-one is downwind or in my smoke when I light a cig.
4. That last thing was not a quote of mine, and nowhere am I making a stand that I am in my right to blow my smoke in your face. I'm merely stating that your right to bitch about it is limited. For I will take my right of bitching back about whatever you're doing that even remotely impedes my rights for clean air.
To take your previous example, you can't tell me I shouldn't spit in your face while you're spitting in mine all the time.