What term refers to the space between the HEPA filter and the sterile product being prepared in a laminar flow workbench?

The Direct Compounding Area is the critical area within the ISO class 5 primary engineering control where critical sites are exposed to unidirectional HEPA-filtered air. The buffer area is an area where the preparation and staging of components and supplies used when compounding. The critical area is an ISO class 5 environment, and the critical site is a location that includes any component or fluid pathway surfaces.