Abstract: An airlock (purge chamber) which functions as an intermediate area between a contaminated area and a clean area where contaminated air may be purged before a person enters the clean area. The airlock (10) is a double-walled circular structure having an outside wall (20) with a single air intake (31) at its top and multiple air discharge ducts (37) spaced around the full 360 degree circumference of its base. The airlock (10) has an inner wall (24) with multiple air intake openings (perforations) (38) across its inner ceiling (26) and around its sides (24), providing a primary purge air flow (34) into the ceiling (26) of the inner wall (24) and down through the airlock (10) and a secondary air flow (32) into the side air intake openings (perforations) (38) and down through the airlock (10). Outgoing purge air (36) flows down through the floor (28) of the inner wall (24) and out the discharge ducts (37) at the base (27) of the outer wall (20) of the airlock (10).