Somewhere there's an air intake for the building my office is in. I think when the weather cools off, whoever runs the ventilation must open some vents somewhere to bring fresh air inside. Judging from the smell in my office, those vents must be somewhere that smokers congregate. Either that or someone in this building is smoking where they shouldn't be. The last few days there's been that old, trashy second-hand smoky smell all over the place. Ick.
I think I'm going to have to get one of those air freshener things or cover up this vent in my office.