LAMINAR FLOW HOODS 1 The critical principle of using LAHs is that nothing interrupts the flow of air between the HEPA filter and the sterile object. The SPACE between the HEPA FILTER and the STERILE OBJECT is known as the __ 2 Materials placed within the laminar flow hood disturb the patterned flow of air blowing from the HEPA filter. This __ created behind an object could potentially extend outside the hood pulling or ALLOWING CONTAMINATED ROOM AIR into the ASEPTIC WORKING AREA. 3 It is advisable to work with objects at least __ inches from the sides and front edge of the hood without blocking air vents, so that unobstructed airflow is maintained between the HEPA filter and sterile objects.