Hey folks, sorry to bother y'all, but through my research I couldn't find anything pertaining to the topic so here's my question:

There's kind of a sweet smelling gas that comes up through my vents in my apartment style building downtown (does not smell like rotten eggs or sewage), it's not there all the time and has been going on for the last 6 months, I called Atco initially because I thought it was a gas leak (it was not). I've smelt this smell walking through my neighborhood on occasion so i know it's not just a my building problem. It's quite a foul smell, if anyone could offer any insight into what this might be, I'd be eternally grateful.