We have the same problem in SG, except our neighbours are not only filthy ( food offerings left to rot in their front yard, incense sticks and CNY sparklers thrown about on the front lawn's of residents' houses, including ours, burning of offerings in their yard which is adjacent to ours....list goes on. ) One of our neighbours is moving to get away from the problem but we are here for another year....so I bought a good pedestal fan, faced it toward the direction of the burning crap and smoke, and turned it on full. I do this every time the old fella burns his incense and lights his bonfire in the metal bin. Forget religion, it is a health hazard as you are inhaling second hand smoke. If you have the time and money to sue, then one could argue that in court. I friend of mine is lives in Sha Tin had the same problem with her neighbour smoking constantly in the tiny bathroom which faced onto hers.