Operating rooms usually work with positive differential pressure in order to prevent the entry of
contaminated air from adjacent areas and so maintain asepsis. Nevertheless, the opening of doors
causes this pressure difference to disappear and means that contaminating agents can enter from
adjacent areas. As a result, a knowledge of air flow pattern behaviour during the door opening
and closing cycle is key to understanding the risk of infection and contamination in the operating
room. The objective of this study is to quantify the air flow that enters the operating room during
a complete door opening and closing cycle. We specifically study two operating rooms equipped
with a heating ventilating air conditioning system: one with turbulent air flow and the other with
laminar air flow. We assess the influence of the type of door - hinged and sliding – for different
origin values of flow exhaust fan regulation. In order to perform the measurements, a threedimensional
ultrasonic anemometer that measures the magnitude and direction of the instant
air velocity on the doorway of the door was used. Analysis of the results shows that the door
opening and closing process leads to air entering the operating room from the adjacent areas in all
of the cases studied, regardless of the ventilation system used. Sliding doors are seen to reduce the
amount of air entering from the adjacent area in all the scenarios tested. Sliding doors are thus
considered the preferred option in operating rooms.
