While some of us would argue that stoners make ideal (and docile) neighbors, not everyone is dying to live in a cloud of someone else's smoke. "We don't smoke cigarettes and don't begrudge people that smoke, ahem, other things, we just don't want to smell it in our house," one beleaguered renter wrote in to Apartment Therapy's recurring "Ask Alice" etiquette column in response to new neighbors who are constantly lighting up.
After leaving a "lighthearted note" explaining that the smells waft through shared walls, the renters concluded that their neighbors "just don't care" about the irritation they're causing everyone else. So what to do? Rat them out to the management, of course! (It's a non-smoking building, according to the author of the question.) As "Alice" puts it, "You already let them know—nicely—that their habits are bothering you and they ignored it. I see no reason you need to bend over backwards trying to help these guys out when they can't be bothered to go outside to smoke."
Seems more than fair to us, but if you'd like to try a gentler route first, maybe try gifting them with a vaporizer?