Understanding AHAM and CADR Charts
How to Interpret AHAM's CADR Ratings
Certified Clean Air Delivery Rate (CADR) - Recognized by the U.S. Environmental Protection Agency and the American Lung Association, the CADR is independently measured by the Association of Home Appliance Manufacturers (AHAM) to enable consumers to compare air purifiers with regard to performance in eliminating tobacco smoke, dust and pollen.
All of the manufacturers voluntarily participate in the AHAM certification program for room air cleaners. This standardized measurement system - known as the Clean Air Delivery Rate, or CADR - determines how well an air cleaner reduces pollutants such as tobacco smoke, dust, and pollen. From air cleaner to air cleaner, compare the CADR numbers listed next to each model number.
First, look at suggested room size. Then refer to the tobacco smoke, dust, and pollen CADR numbers. The higher the numbers, the faster the unit filters the pollutants out of the air. If from one unit to the other the ratings are the same, their air filtering performance is similar.
In basic terms, the higher the number (rating), the more clean air delivered.
Follow AHAM's 2/3 Rule:
You'll always want a unit with a tobacco smoke CADR at least 2/3 your room's area.
For example, a 10 ft x 12 ft room - 120 square feet (sqft) - would require an air cleaner with a tobacco smoke CADR of at least 80. If your room size is smaller, the unit will simply clean the air more often or faster. If you have ceilings higher than 8', you'll want an air cleaner rated for a larger room.
CADR Performance Measurement Parameters
Example of CADR performance measurement:
Room Size Calculation
Room size square footage is calculated using the following formula:
Square feet of room = Smoke CADR value x 1.55
This formula is based on the CADR requirement to remove 80% of smoke particles on a continuous steady state basis, assuming one room air exchange per hour.