Thanks, our fans do vent out of the apartment, at least. Our setup looks a lot like the janky ones you hear about that just vent into a wall, but when you open the cabinet above the microwave there's a duct that merges with the dryer exhaust on the way out of the unit to an exterior vent. It's a bit annoying to hear it running every time I'm cooking, but I figure it's worth it to be inhaling a bit less toxic fumes.

I dont know about everywhere, but at least a few places i've lived it was required by law/code to have it vent outside if it was a gas stove.