Advice on smoking and motivating SO to quit?

So I recently started dating a wonderful guy who I'm quickly falling for. He's a smoker and I am not. He's asked if I mind, I just say no, but it actually does bother me, especially with my nasal problems.I don't want this issue to define the future of my relationship but I would like for him to quit smoking. Regardless of the sex and good times this feels like a hindrance, although I feel selfish for wanting him to quit.Thoughts?