The things they call respirators are not respirators. Operators operate, motivators motivate. The suffix -or is active, as in something that does something. The things called respirators do not respirate, they filter. I refuse to use the term in that way. Protect our language.
Ok, but the first usage was in the 1860's. The US military typically calls them masks. Currently it's the M50 Joint Service General Protective Mask.