Why is my air purifier making noise and producing less airflow?

The filters are likely dirty, as high amounts of particles can block the filter pores and restrict airflow. Replace the filters — HEPA Filters should be replaced every year and the Pre-Filter and Enhanced Odor and VOC Filters every 3 months, though individual home conditions may require more frequent replacement. Use only Certified Genuine Honeywell Filters to ensure proper performance. (Page 9)