My boyfriend smokes tobacco. (Once in a while, he might roll a joint. It helps him relax. I don't mind it because it's not on a daily basis). Both my mother and his parents know about it. I actually worry more about the effects of tobacco.
Sometimes my mother visits us and there had been a couple of times, where he happened to do it in front of her knowing that she knows about it. My mom is a very discreet person and never said anything so far to indicate it had bothered her. I certainly thought it hadn't.
Recently though, and after watching some documentary about the effects of smoking in general, she told me she doesn't feel as comfortable. Boyfriend doesn't smoke right in her face and almost always asks if parents mind if visiting. His dad lets him smoke inside the house but my mom and his mom don't do that. Mom is concerned a lot and she wants to say something about it but she doesn't know how to approach it since it's not really her business whether he smokes or not. I don't want her to say anything but I don't want her to stop visiting either. I told her that I'd rather she never came by the house again than saying the wrong thing at the wrong time. I don't want this escalating. We are in our thirties.
My mom has an increased concern about my boyfriend's health because of the smoking and the fact that I am a passive smoker, which is understandable. People smoke. He is one of them. Do I particularly like that he smokes? NO. But I can't make him stop. I know my mom's concerns are valid and that she feels uncomfortable about it but she tends to be a bit stubborn about it and not wanting to drop the subject. (Not saying she's wrong but she tends to lecture me about it).
How do I address these concerns? If I decide to tell my boyfriend about it, how can I tell him to minimize conflict? Is there anything my mom can say next time she visits that won't make things awkward and potentially cause a fight?