The ornamental design for an airtreatmentappliance, substantially as shown and described.
FIG. 1 is a top isometric view of an air treatment appliance, showing our new design.
FIG. 2 is a bottom isometric view thereof.
FIG. 3 is a front elevational view thereof.
FIG. 4 is a rear elevational view thereof.
FIG. 5 is a left side elevational view thereof.
FIG. 6 is a right side elevational view thereof.
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
Stippling and tangency lines in the drawings represent the three-dimensional contours of the design, and are not intended to indicate surface decoration. The broken lines in the drawings illustrate portions of the air treatment appliance and form no part of the claimed design.