I have tried removing as much geometry as I thought possible.
I fizzled with the idea of removing most of the inner part of the mask (the part which is against the villager's face) but I still want the mask to look good if it is used in a third person map or at close ups.
To retain the level of detail the mask has, quite a few polygons must be preserved. If you look at the mesh on the mask itself (both front and back) you can see it is quite messed up.
This is due to optimizing and it not noticeable in game.