I am sorry you are dealing with this. I know first hand how you feel. My mother was very similar. She smoked heavily for years and died just over a year ago at the age of 59 from lung cancer. I miss her so much. I'm not saying this to worry you, I just want you to hear my story.
I was very frustrated with my mom. She always complained about being sick but wouldn't quit smoking, and many times she was just looking for attention. It became the "boy who called wolf" scenario. Well, ,one day she didn't come to my boy's hockey games (she always did) and I thought she was just looking for attention. THis was the in the beginning of December. She only lived 5 minutes away from me so we talked regularly, but I noticed she wasn't coming over as much. She told me on the phone she had the flu and a bit of pleurisy. I called her everyday up until Christmas day. I kept telling her if she wasn't feeling better to go back to the doc. She wouldn't, said she was scared, etc. I would get angry and think it was just an attention ploy. Christmas day she showed up for dinner with her husband who had just finished cancer treatments himself six months prior. I couldn't believe the condition of my mother and this had taken place in just one month or so. She had lost weight, was visibly in pain and talking nonsence off and on. I immediately called my brother in Florida (26 hours away) to come home. I had begged my mom on Christmas day to let me take her to emergency, but she wouldn't go unless my brother was home. He drove the full 26 hours and I took my mom in by ambulance. It was lung and brain cancer, she lived until January 31st, 3 days after my birthday. My brother and i spent everyday with her. I still had to work and look after my family, but my brother would go over all day and take care of her ,I would go over in the evenings. I miss her. I feel guilty for not believing her this last time. I feel sad that she must have known she was dying and just couldn't face it. I'm angry that she didn't really tell me how bad it was, nor her husband. Her husband didn't see it though. It's hard to explain.
Anyway, if you can get past your frustration (which I understand) try to just enjoy your mom for who and what she is. How old are you? Maybe you could stay with a close relative who doesn't smoke. I can understand not wanting to be around that smoke, but it doesn't sound like she's going to give it up. My mom coughed and sputtered every morning terribly, but just couldn't quit.
Best wishes to you and I hope everything works out for you. My heart goes out to you.
Take care, Michelle