51 decibels -- that's all you'll hear as this ultra quiet air purifier captures 96% of pollen, mold spores, dust and other large airborne particles from your air. The quietest air purifier in its class (based on the AHAM certified air purifier group for a room size of 91-115 square feet). Perfect for offices, nurseries, small bedrooms and other spaces 10 square feet or less. Air Cleaner Machine Type: Filtrete™; CADR: 67 (smoke); 51 (dust); 58 (pollen); Maximum Room Size (Square Footage): 100 sq. ft..