I grew up in row houses in Baltimore County and I really can't believe that any amount of smoking that the neighbors do can permeate into your home. I've had that smoke smell in a house twice and one time it turned out to be some water damage behind a wall and the rotting wall board smelled like heavy smoke. The last time it turned out to be a dirty fireplace. It was very bad that time and all it took was to clean all the soot and ash out of there left over from winter fires. Do you have a fireplace that might be the source of your odors? Good luck.