Never write or say this.
It is just a mask. There is no other kind but that worn on the face (except figuratively).
Face mask is as silly as foot shoe or head hat.
As these twenty different senses of mask that are listed in the Oxford English Dictionary will attest:
- image of a face worn by an actor
- representation of a human or animal head
- grotesque representation of a face worn at carnivals etc.
- facial expression concealing emotion, giving false impression
- human face resembling a mask
- protective covering for the face
- surgical dressing for the face
- medical device placed over the mouth and nose
- gauze or fibre covering for mouth and nose
- gas mask
- swimmer or diver’s watertight shield for the eyes
- face disguised by cosmetics
- cosmetic preparation for the face
- likeness of someone’s face in clay or wax, especially from a mould
- stylised representation of a face
- face, head or skinned head of a fox or other animal
- mouth of a dragonfly larva
- marking on the face of an animal
- blotchy discoloration on the face of pregnant woman
Please do wear a mask, but refer to it properly.