Air Volume Migration from Negative Pressure Isolation Rooms during Entry/Exit

Containment testing of isolation rooms

“…Prescribed minimum pressure differentials in national and international standards, however, vary considerably. This is probably because pressure differential has not, as yet, been shown to be a direct measure of containment, 1 and few studies have been done to test the efficacy of isolation precautions. 2 The 1994 tuberculosis guidelines from the Centers for Disease Control and Prevention (CDC) in the United States, referenced in many current national and international guidelines and publications concerning hospital isolation measures, recommended at least 0.25 Pa (0.001 inches of water) less pressure in an isolation room with respect to corridor.…”

Health and safety risk assessment methodology to calculate reverse airflow tolerance in a biosafety level 3 (BSL-3) or airborne infection isolation room (AII) environment

“…In this paper, the author proposes a practical mathematical approach that not only validates Hayden's et al (1998) premise but takes it a step further. The proposed model calculates how much air displacement and contaminant leakage occurs during a power outage that may result in a momentary positive pressure reversal and compares the degree of contaminant leakage that would occur through door gaps before opening the door during momentary pressure reversal versus the contaminant leakage that would occur when the door is opened to exit the area.…”

“…In this example, V = 1.7 × 0.3 × 0.15 = 0.08 m 3 (i.e., a person of 76.5 kg, since 1 m 3 = 100 × 100 × 100 cm 3 = 1,000 litre of water, assuming human body density has an average density equal to that of water) Per Bush and Eames (1998), 1 to 3 or a person walking at speed 1 m/s (2.2 MPH). Thus, movement of people in a room plays a significant part in disturbing the flow and also in transporting infected air from one place to another (Hayden et al, 1998).…”

“…A NIOSH funded study used a tracer gas in a simulated differentially pressurised setting to examine the magnitude of air volume migration (AVM) when a swinging door was opened and closed, when a sliding door was opened and closed and when a mannequin was passed through either of the doorways (Hayden et al, 1998). Hayden noted that there are currently no documented data available that demonstrate the level of AVM from a negative-pressure isolation room but that by knowing the level of AVM during entry/exit through a doorway where there can be airborne contaminant migration across the boundary, an assessment of the risk of transmission of airborne infectious disease is made possible.…”

The Influence of the Bed with a Semiopen Hood on Bacteria Removal in a Negative-Pressure Isolation Room

“…There are many studies on air conditioning in negativepressure isolation rooms in recent years, such as Hay Den II et al [1] who experimentally investigated the air volume migration from negative-pressure isolation rooms during entry/exit. Phillips et al [2] studied and analyzed the age-ofair and the patient comfort in the negative-pressure isolation room.…”