I found these descriptions on Google. I think the first is from a 1.0 item, when they were standard enemies in La Noscea.

A leather mask that filters out bad odors, as well as most poisonous gasses. Due to its odd shape, only goblins can wear it.
It sounds like they could be used for mining or something like that, but that doesn't explain why they wear them all the time.

They never take off their distinctive masks, and always bear seemingly unbearable packs on their back
Anything I've missed? Are they allergic to Miqo'te hair?

Thanks!