FIG. 1 is a front left top perspective view of a respirator bag which embodies my design; FIG. 2 is a rear right top perspective view thereof; FIG. 3 is a front right bottom perspective view thereof; FIG. 4 is a front right top perspective view thereof with the cover open; FIG. 5 is a rear left top perspective view thereof with the cover open; and, FIG. 6 is a front right bottom perspective view thereof with the cover open.