ISO 14644-3:2005 specifies test methods for designated classification of airborne particulate cleanliness and for characterizing the performance of cleanrooms and clean zones. Performance tests are specified for two types of cleanrooms and clean zones: those with unidirectional flow and those with non-unidirectional flow, in three possible occupancy states: as-built, at-rest and operational.

ISO 14644-3:2005 is not applicable to the measurement of products or of processes in cleanrooms or separative devices.