Place the purifier on a level surface. Grasp the purifier's front grill cover and pull it toward you to remove it.
Pull the filter cartridge out of the purifier. Remove the plastic bag from the filter. Place the filter into the purifier and snap the plastic clip down over the hook on the filter cartridge to secure the cartridge inside the purifier.
Snap the grill cover back on the front of the purifier. Press it into place until it locks. Plug the power cord into an outlet.
Select the operating speed you prefer. The purifier has low, medium and high options. Slide the switch to the preferred speed. Holmes recommends setting the filter to medium speed for regular filtering and turning it up to high when many contaminants are detected in the air. The low setting offers quieter operation when it's necessary.
Check the filter's condition every three to four weeks. Replace the filter when it is visibly dirty.