Smoking is bad, yes we all know that.
<b>However</b>, this is real life people. Your children will grow up and be exposed to it in one situation or another. My mother was extremely caution of smokers when I was a child (she wouldn't let me sit at the smokey end of a fireplace during camping trips, left any restaurant that even smelled like a hint of smoke, and I can't remember her ever having a single smoking friend), however now that I have a job and 1/2 of my co-workers smoke (including my boss) it is not something I can discriminate against.
People can do what they want with their bodies, and I have to respect that. Thankfully I live in California where smoking isn't allowed within 30 feet of the building and all my friends know not to smoke around me, but at times I can still smell it. On my last clinic appointment I specifically asked MY doctor about "third-hand smoke", and he told me no specific harm can come from just smelling it on someones' breath/clothing.
As CF'ers it is easy to hate on people who abuse their lungs. I used to look at smokers and truely HATE them, but now I know what a tough habit it really is to kick. Regardless of whether they want to quit or not (and most do), we have to respect others' decisions.