Second-hand smoke

My whole apartment smells like cigarette smoke. It started in the bathroom of all places. The bathroom is right in the middle of the apartment and has no windows or doors to the outside. I first noticed it Friday night. I closed the door and left the vent on overnight in hopes it would be better in the morning. Nope. If anything, it was worse. Then I found out that the vent doesn't even go outside. It's re-circulating, so it just blew the air back into the room. Tell me, what is the point of these kind of vents? Can that even be called a vent? I went to my parents house for most of the day yesterday. Someone told me that vinager will get the smell out, so I left a bowl of vinager in the bathroom and once more closed the door. When I got home, it smelled like smoke and vinager, and the rest of my apartment was beginning to smell like an old hotel room. It's just been getting worse. The people who live below me are smokers, so I can only assume it's coming from them, but I don't know how it's getting into my home! I haven't had doors or windows open. It's aweful. I really need to move.