It wouldn't really help if you breathed through your nose or mouth it still ets to your lungs. What I do when someone smokes around me is leave the room, it might seems rude at first but they'll understand :)
Sorry; I smoke, know it's bad for me and still do. But even I in my stupid action know Not to be Ignorant about harm done.. It's the same damage to Lungs,Heart,Stomach and on and on. Don't Do It! Yeah; Do as I say, Not as I Do.:-).