[sgtnoodle]

It seems like a burner left on a dry pot or pan could easily do that.

Grills with PTFE coated utensils.

Commercial kitchens using specialized ovens and PTFE lined pans could be constantly putting out fumes.

Our propane pizza oven gets up to about 400C on the stone, and hotter at the flames. I don't think there's ever any PTFE near it, though. There do exist "non-stick" pizza peels, though, so someone could do that. The thing with peels on pizza stones is that their edges tend to grind down. I probably eat a miniscule amount of aluminum each time we make pizza.