Same here; we have a gas stove and a useless range hood above it. I guess it's supposed to filter it? Or previous owner installed it just to skirt the requirements ;-<
I've had that for two apartments in a row. The most it can do is direct fumes to the ceiling instead of in your face. Incredibly little effect, when I then need to had the windows open with a box fan for a few hours any time I pan-fry anything. It's very frustrating, as those fumes could have been caught and exhausted from the source with much less exchange of air.