Personally, as a smoker, if my neighbors are uncomfortable, all they have to do is tell me. I only smoke outside, and never in front of the kids when they're playing (I'll take a walk down the block). We have ashtrays next to every door outside, but I'm the only one on this end of the building who smokes. I have no problem walking out to the parking lot to keep the smoke away from people's windows. As long as it's in a polite manner, I have no problem with it.
It seems odd to me that the smell is seeping into your house from so far away. A single cigarette from that distance isn't going to hold enough odor to make it through the air (let alone closed doors/windows) to your home. (unless this is a townhome where your doors are right next to each other?) I would check your insulation, ventilation and window/door seals to make sure something isn't out of sorts. Also, what age is your home? There could be something haywire somewhere that needs attention.
As far as air quality, I went through a company and bought a great air purifier for our house. Even though I don't smoke inside, my clothes still hold the odor and an hour in front of the purifier gets rid of it. (it's also great for pet odors, dirty dishes and poopy diapers) :D
In the end, your neighbor has every right to smoke anywhere on his/her property, but I'm confident that if you're honest and polite about it they won't have a problem smoking in a different spot.