i'm not doing this right now, but i'm going to have to search the case law for examples where second-hand smoke - and specifically second-hand marijuana smoke - is considered an "uninhabitable" situation.

A landlord is responsible for providing and maintaining a residential complex, including the rental units in it, in a good state of repair and fit for habitation and for complying with health, safety, housing and maintenance standards. 

i don't know if there is precedent around this, but i'm willing to make a novel argument - and push it to divisional court - if i have to.

a unit full of second-hand smoke should be considered unfit for habitation.