This is very similiar to my situation I had in Nevada. First and foremost, don't let the trolls on this thread get you down.
In your lease, does it have an area for non smoking, as well as consequences for violating the lease? If it does, and you can prove they are smoking, and can also prove the landlord knows they are smoking (go there with the landlord while they're smoking, etc) then you can sue the landlord for not upholding the lease. If you can't prove this at all, then I don't think you can really do anything about if you want to stay there.
The problem the landlord doesn't understand is, if you leave, the only person that is going to be happy in that situation is a smoker. I'm pretty sure the majority of tenants now a days are non-smokers, so because of their carelessness/laziness they're actually hurting their situation financially by not taking care of it.
It may be time to get a consultation from a lawyer just to see what they say about it.