An air-handling unit designed for use in surgical theatres to produce a directed, non-turbulent flow of clean air and thereby provide an area free of contaminants to reduce the possibility of infection to the patient. The air is filtered, usually through a high-efficiency particulate air (HEPA) filter, to remove particulate matter and microorganisms. The unit is fixed, often built-in, typically to the ceiling, and provides a curtain of fast moving air around the perimeter of the area which will form an outer wall and help delineate between the "sterile" and "non-sterile" operation area. An operating light or light system may be mounted to this unit or within the specified area.