Understanding The


Association of Home Appliance Manufacturers
Leading trade association of the home appliance industry, delivering value to consumers through leadership, education and advocacy.

AHAM represents manufacturers of major, portable and floor care home appliances, and suppliers to the industry. AHAM’s membership includes over 150 companies throughout the world.

AHAM is also a standards development organization, accredited by the American National Standards Institute (ANSI). The Association authors numerous appliance performance testing standards used by manufacturers, consumer organizations and governmental bodies to rate and compare appliances.


Clean Air Delivery Rate
CADR—Clean Air Delivery Rate—is the most important metric for measuring air cleaner performance.

The CADR indicates the volume of filtered air delivered by an air cleaner. In general, an air cleaner with a higher CADR will be able to remove pollutants from the air at a higher rate than an air cleaner with a lower CADR.

Certified Clean Air Delivery Rates are stated only by air cleaners that have undergone the AHAM Verifide® testing process, which verifies that manufacturers’ claims about the air cleaner’s capabilities are legitimate.

Air cleaners that carry the AHAM Verifide® Mark have a suggested room size based on 4.8 air changes per hour, which is the minimum equivalent air exchange necessary for an air cleaner to keep up with unfiltered air entering the room.


Air Changes per Hour
ACH is a way to tell how often the air in their room is circulated. A higher number of air changes presents more opportunities for pollutants to be removed.

For the air cleaner to be able to keep up with unfiltered air entering a room with the suggested room size, the air cleaner must deliver an amount of clean air (CADR) sufficient to deliver clean air in the room 4.84 times per hour.

The ACH calculation is based on an air cleaner’s ability to reduce the concentration of pollutants in a room appropriate for the air cleaner’s size by 80%. The calculation is based on one air change per hour, with a recirculation fan providing complete mixing of air in the room.

If the air cleaner will be used in a room larger than the suggested room size, the number of air changes per hour will be less than 4.8, and the pollutant concentration in the indoor air will be higher. The opposite applies if an air cleaner is used in a room smaller than the suggested room size where the actual air cleanings and circulation per hour will be greater than 4.8. An air cleaner with a higher CADR will be able to remove pollutants from the air at a higher rate than an air cleaner with a lower CADR.

Room Size

Suggested Room Size
The suggested room size on the packaging gives guidance on how large a room the product is best suited for. The air cleaner works best in a room with closed windows and doors.

The suggested room size for an air cleaner is based upon the CADR obtained for reducing engineered cigarette smoke concentrations. The room size is based upon the ability of the air cleaner to reduce the concentration of smoke particles by 80% in a room to a new steady-state when the air cleaner is operating.

The suggested room size is determined through the following formula: Room Size = (Certified Smoke CADR x 60)/(ACH x 8 Feet Ceiling).

Personal Up to 50 ft² (4.7 m²)
Small 51 – 99 ft² (4.7 – 9.2 m²)
Medium 100 – 155 ft² (9.3 – 14.4 m²)
Medium – Large 156 – 210 ft² (14.5 – 19.5 m²)
Large 200 – 349 ft² (18.6 – 32.4 m²)
Large – Extra Large 350 – 399 ft² (32.5 – 37.1 m²)
Extra Large Over 400 ft² (37.2 m²)

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