Yeah those masks are for dust-protection only. if you have a dry, fibreglassed helmet, and say you would dremel it, that thing would only protect you grom the dust from bondo and the nasty fibreglass paritcles
i havew some of these aswell, but a respirator of course.
I like to wear them when dremeling instead of a respirator because they are more 'handy' on my face.