Living in a 1920s rowhome where the neighbors house shares a brick masonry wall eith mine. Occassionally I can smell smoke from then smoking so much so obviously there is somewhere in this shared wall that smoke is getting through. They have central air and I do not so I assume they have more positive air pressure on their side, forcing the smoky air through. The walls have a plaster skim coat but the space in the ceiling i assume is where the smell may be getting through. Any ideas for confirming my theory or dealing with the situation aside from ripping out the ceiling and maybe putting spray foam along the bricks?