Hospital isolation rooms are vital for the containment (when under negative pressure) of patients with, or the protection (when under positive pressure) of patients, from airborne infectious agents. Such facilities were essential for the management of highly contagious patients during the 2003 severe acute respiratory syndrome (SARS) outbreaks and the more recent 2009 A/H1N1 influenza pandemic. Many different types of door designs are used in the construction of such isolation rooms, which may be related to the space available and affordability. Using colored food dye as a tracer, the qualitative effects of door-opening motions on the dissemination of potentially contaminated air into and out of a single isolation room were visualized and filmed using Reynolds-number-equivalent, small-scale, water-tank models fitted with programmable door-opening and moving human figure motions. Careful scaling considerations involved in the design and construction of these water-tank models enabled these results to be accurately extrapolated to the full-scale situation. Four simple types of door design were tested: variable speed single and double, sliding and hinged doors, in combination with the moving human figure. The resulting video footage was edited, synchronized and presented in a series of split-screen formats. From these experiments, it is clear that double-hinged doors pose the greatest risk of leakage into or out of the room, followed by (in order of decreasing risk) single-hinged, double-sliding and single-sliding doors. The relative effect of the moving human figure on spreading any potential contamination was greatest with the sliding doors, as the bulk airflows induced were large relative to those resulting from these door-opening motions. However, with the hinged doors, the airflows induced by these door-opening motions were significantly greater. Further experiments involving a simulated ventilated environment are required, but from these findings alone, it appears that sliding-doors are far more effective for hospital isolation room containment.

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a b s t r a c tNegative pressure isolation rooms are used to house patients with highly contagious diseases (e.g. with airborne diseases) and to contain emitted pathogens to reduce the risk for cross-infection in hospitals. Airflows induced by door opening motion and healthcare worker passage can, however, transport the potentially pathogen laden air across the doorway. In this study airflow patterns across the isolation room doorway induced by the operation of single hinged and sliding doors with simulated human passage were examined. Smoke visualizations demonstrated that the hinged door opening generated a greater flow across the doorway than the sliding door. Tracer gas measurements showed that the examined ventilation rates (6 and 12 air changes per hour) had only a small effect on the air volume exchange across the doorway with the hinged door. The results were more variable with the sliding door. Supply-exhaust flow rate differential reduced the door motion-induced air transfer significantly with both door types. The experiments showed that the passage induced substantial air volume transport through the doorway with both door types. However, overall, the sliding door performed better in all tested scenarios, because the door-opening motion itself generated relatively smaller air volume exchange across the doorway, and hence should be the preferred choice in the design of isolation rooms.

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