It sounds to me you need to talk to the apartment management - there is obviously something wrong in the structural elements of the building.
BTW, who lived there first, you or the smoker? If it is you, I would complain loudly to the management about the problem. If not, well.........
I've lived in Nashville, TN for 21 years and have resided in 3 different apartment complexes. I've had this problem with every single one. The smoke odors usually seem to be coming from two main sources, the bathroom and the small closet where my water heater and central heat/air unit are located. If someone burns food, you can smell it, or if they are smoking pot, you can smell it also. These apartment complexes are mass produced and thrown up quicker than you can snap your fingers, and so I assume this is why odors are transferred from one apartment to another.
I've lived in my apartment for over three years and my neighbor downstairs has only been here a little over a year. I'd love to complain to management, but I can already predict what kind of response I would get here in the south. Heck, the lady that manages the place is a chain smoker herself! I don't think that she's going to have too much sympathy for me.