Air Treatment Device

FIG. 1 is a top, front, left perspective view of an air treatment device showing our new design; FIG. 2 is a front elevation view thereof; FIG. 3 is a rear elevation view thereof; FIG. 4 is a right elevation view thereof; FIG. 5 is a left elevation view thereof; FIG. 6 is a top plan view thereof; and, FIG. 7 is a bottom plan view thereof. The broken lines depicting the remainder of the air treatment device show features that form no part of the claimed design.