FIG. 1 is a front perspective view of an air purifier showing my new design;
FIG. 2 is a rear perspective 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 of thereof; and,
FIG. 8 is a bottom plan view thereof.
The broken lines in the drawings illustrate the portions of the air purifier which form no part of the claimed design.