How are they not being courteous to him? They are smoking in their own apartment, not his.
I would leave them alone.
Buy 3 or 4 bottles of Febreeze.
Buy zip ties.
Walk up to their doorstep of their apartment...
Quickly pull tight zip ties on each bottle, throw on ground by door and run.
Problem solved... at least for a while. Or will at least get the point across.