YSK that your above-range microwave likely contains a charcoal air filter at the top where the fan blows out recirculating air when the fan is on. Replacing this inexpensive filter can remove cooking odors from your kitchen.
from /r/YouShouldKnow
YSK，您的微波爐上面很可能在頂部有一個木炭空氣過濾器，當風扇打開時，風扇會將循環空氣吹出。更換這種廉價的過濾器可以去除廚房中的烹飪氣味。