What is the Clean Air Delivery Rate?
The Clean Air Delivery Rate, or CADR for short, of an air purifier is a numerical value assigned to an air purifier based on independent tests performed for the Association of Home Appliance Manufacturers (or AHAM). AHAM has been measuring the CADRs of air cleaners since the 1980s.What can be confusing is the fact that air purifying filters are not all created equal, which is why CADR ratings vary. What you do need to know however, is there should ALWAYS be three figures: one for dust, pollen, and one for smoke.
CADR ratings are an excellent guide on how efficient any given model is at dealing with the above contaminants. For instance, if cigarette smoke is an issue for you over pollen, you will need to look for a higher rating in that.
In other words, the CADR is an attempt to provide a uniform, objective standard by which potential buyers can easily evaluate the effectiveness of an air cleaner.
Given the potentially bewildering variety of air purifiers available in the marketplace, such a standard is highly desirable. AHAM's own literature on CADR also emphasizes that CADR ratings are valid "regardless of the particle removal technology utilized," so it does not matter whether the purifier uses, for example, a HEPA filter or an ionizer. CADR measures only the end results.
Note that CADR testing (PDF) is applied only to portable air purifiers, not to large whole-house purifiers, which require a different method to measure their effectiveness.