Air borne contamination is mainly derived from the personnel within the operation theatre area and due to their activities. The bacterial count in operation theatre is influenced by the number of individuals present, ventilation and air flow. Studies in a number of operation theatres have suggested that there is a general relationship between total air count and risk of infection.

Proper design and ventilation of operation theatres is the most important means of controlling air borne contamination and thus preventing air borne infection in operation theatre. The operation theatre should be segregated into zones: aseptic, clean, less clean and have mechanical ventilation.

Vertical clean air Laminar Flow is the most effective way to Control Microbe Levels in The Entire Operation Theatre. Compared to conventional turbulent ventilation, vertical laminar air flow can decrease the number of post-operative infections substantially. The advantages of an air exchange system for the entire operating theatre have been established conclusively in a number of studies. In laminar airflow system, the entire air mass circulates in one direction and displaces the existing air in the operating area. The first crucial step in vertical laminar flow takes place when incoming air is blown straight down through HEPA filters above the operating table (the downward airflow prevents air masses from mixing in the work area).

About 10 % to 30 % of the total air is vented out of room and being replaced by fresh air according to the good design of the AHU ( Air Handling Units ) System. Rest of the air in the room is re circulated, filtered and blown back into the room. In this way, increased amount of fresh air is not needed, which keeps energy costs down when compared to conventional Air conditioning systems.

When operations required extremely sterile conditions are performed everyday, effective air conditioning in operating theatres pays for itself quickly. Infections increase hospital stays by an average of two weeks, so improved hygiene and lower health care costs can cover the price difference between a conventional turbulent ventilation systems and laminar flow unit in just a few months when designed properly.