Abstract: A method of assembling a personal air purifying respirator includes assembling a housing including a blower disposed therein, a filter cavity, and an outlet manifold; installing a filter on the housing; attaching a filter cover to the housing with the filter cover disposed over the filter, wherein the filter cover defines an air inlet; and testing the filter including energizing the blower, introducing a testing aerosol into the air inlet, and measuring air exiting the outlet manifold.