There is no relationship at all. For example- a clean room with no one in it might be class 100, while the addition of personnel will send it into other higher categories. however, suppose the filters supplying a room were thoroughly checked for leaks, and all significant leaks were sealed, this room is operating at maximum efficiency with respect to the filters, and since the filters are mechanical in nature, there is nothing the operator can do to change conditions in this area. The achievement of a particular class would relate to the number of air changes per hour as well as the scavenging design of the system.