The only ones amongst my close friends and family who smoke are my in-laws. I have RAD that is triggered by cigarrette smoke, so I have always made a point to politely ask them not to smoke around me and if they light up, I have always left the room or walked away, and I never cared if it offended them or not.
With my children, I am very strict. I tell them under no certain terms can they smoke around or near my children. When we go to visit, (they live a few states away), we always get a hotel room, and if they come in from smoking and I can smell it heavily on them, I ask them to please wash their hands/change their shirt before handling my babies. I am especially glad that I have had this policy since day 1 as my DD1 is showing early signs of RAD.
I don't care that they are smokers, that is their decision, their life choice, and I respect that. DH and I have never asked them to quit, nor do we lecture them about the harm smoking can cause to their health. However, just as I respect their life choices, they in turn, must respect our decision to keep our and our children's exposure to cigarrette smoke and its remnants/ashes at a bare minimum and out of their little lungs.