Those must be some terribly insulated apartments(I've lived in a few btw) but I think this guy is way over exaggerating the situation. My guess is he's gotten a whiff here and there and like many people he probably doesn't like or agree with medicinal cannabis so he's going to make a big deal out of this. I wonder if he's ever talked to the neighbor? If it's that bad maybe he can ask his neighbor to use his bathroom with the exhaust fan on? I know if someone came knocking on my door whether I was legal or not and made a complaint of this nature I'd try to do what I could to appease the guy.