What is Clean air delivery rate (CADR)?

Clean air delivery rate, shortened to CADR, is the volume of clean air a purifier pushes into a room in an hour, measured in cubic metres per hour. It tells you how fast the air in a space of a given size is replaced, so a large open-plan room needs more delivery than a bedroom to keep up with a steady source of pollution. AirDoctor states a CADR of 944.64, while Air Health lists 713.58 and Airthereal 319.41.