This portable air cleaner is recommended for filtering the air in a closed room as large as 168 square feet (12 by 14 feet). As it continuously circulates a room’s air–about six times per hour–it employs two filters to remove smoke, pollen, dust, animal dander, dust mites, molds, bacteria, viruses, and odors. Especially useful for asthmatics and allergy sufferers, the cleaner contains a true HEPA filter that is at least 99.97 percent effective at trapping extremely tiny particles (as small as 0.3 microns) while a prefilter reduces odors. Honeywell’s IntelliCheck system permits monitoring the filters’ lives. Each filter has a button. Pressing a button activates a light, which blinks or shines steadily. One blink indicates that the filter has lots of life remaining, two blinks means less life, three blinks means even less, and a steady light indicates the filter needs changing. The HEPA filter lasts one to three years; the prefilter, three months. Filter replacement is simple, and replacement filters can be ordered separately. The air cleaner has three speeds, and all are exceptionally quiet for an air cleaner this large and powerful. It carries a five-year warranty against defects.