Is it fair to ask smokers you live with not to smoke around you?

I think you're stuck with this problem for a while. It is "their" home and it will be their home after you leave. You are the short-term tenant, and you came after they did, so you knew the situation when you went into it. I'm glad your mother is trying to help you, but you really don't have any right to force her partner to take his cigarettes somewhere else. if he was a decent person he would go outside to smoke, but it's his choice and he's obviously chosen to look after his own wants before considering anyone else. Open your bedroom window to keep some fresh air coming into the room. Keep your door closed and lay a towel across the bottom of the door to stop smoke from coming in the crack underneath. You will be able to keep your room relatively smoke-free that way. You room can be your haven when smoking is going on downstairs. I understand your difficulty with quitting when everyone around you is smoking, so I think all you can do is to tough it out and find a job ASAP so that you can get your own place. Or find a non-smoking friend to share an apartment with until you can afford your own. Remember, though, that even once you do quit there will always be smokers in your world, so maybe living in this condition right now is a good test of your willpower.