The Clean Air Delivery Rate indicates the volume of air filtered through an air purifier. This number is typically certified by the AHAM, Association of Home Appliance Manufacturers.
The three numbers on the AHAM Seal (typically found on the back of the purifier packaging) indicate the three CADR numbers: tobacco smoke, pollen and smoke (and ususally in that order).
This higher the numbers, the faster the purifier filters the air.
It's important to know the CADR for the air purifier before you purchase as it is a great indicator on how effective the purifier really is.
Keep in mind however, that not all air purifiers have a CADR. CADR readings are mostly for filter-based purifiers like the IQAir Air Purifier or Blueair Air Purifier , not for UV light purifiers like the Air Oasis Air Purifier or Biozone.
UV Light Purifiers do not take in massive amounts of air to circulate and filter out pollen, smoke and allergens, they send cleaning 'agents' out into the space to purify the air outside of the purifier. A totally different type of technology which is why it does not have the same kind of ratings or certifications.
To learn more about CADR ratings, visit the AHAM website by clicking here.