Performance testing of engineering controls of airborne infection isolation rooms by tracer gas techniques

Abstract

The ventilation performance of airborne infection isolation rooms (AIIRs) was assessed in three Finnish hospitals by examining the air change rate, contaminant removal efficiency and leakage of contaminants outside the isolation room by using tracer gas techniques. Results showed that infectious agents can escape from the AIIR during egress despite high ventilation rates in the AIIR and anteroom (air change rate, 4–24 h−1) and the pressure difference between the AIIR and corridor was −0.2 to −29 Pa. The control of impurities was often ineffective due to inappropriate direction of air flows and air moving from the patient towards the health care worker and anteroom. Although an anteroom reduces leakage of infectious agents to the corridor significantly, it does not prevent this completely when healthcare workers move between the AIIR and corridor. To enhance the protection of AIIRs, it is especially important to pay attention to the air distribution and removal efficiency of impurities in AIIRs and anterooms. Performance of AIIRs should be tested regularly, especially among older AIIRs.

Airflow patterns through single hinged and sliding doors in hospital isolation rooms – Effect of ventilation, flow differential and passage

“…In the closely related baseline study performed without ventilation, Kal-liom€ aki et al [20] found out that moving against the opening direction of the single hinged door, the passage amplified the doorway flows resulting in a higher air volume transfer across the doorway compared to the other passage direction. However, Hayden et al [18] and Kokkonen et al [25] did not find any significant effect of the passage direction on the air volume migration across the isolation room doorway when realistic ventilation rates were used. Fig.…”

“…Enhanced usage has led to increased interest in containment testing and to door operation induced air and contaminant transport [19e34]. A wide variety of different methods have been used to study the issue, including: computational fluid dynamics (CFD) [23,26,30e32,34], small-scale models [19,22,24,29], full-scale models [20] and field studies [21,25,27,28,32,33].…”

Adaptive Wall-Based Attachment Ventilation: A Comparative Study on Its Effectiveness in Airborne Infection Isolation Rooms with Negative Pressure

“…A pressure outlet at –10 Pa is used for the outlets. The tracer gas (i.e., contaminants) is assumed to be released from the heads of the patients in the ward [24] , [44] . Based on the literature, given the most unfavorable conditions for the environment of medical staff in an isolation ward, the rate of contaminants generated is 0.7 L·s -1 under steady conditions [45] , [46] and 10 L·s -1 for 2 s with a frequency of 40 counts per hour under unsteady conditions [47] , [48] , [49] .…”

“…In different national regulations and the World Health Organization (WHO) recommendations, ACHs range from 6 to 15 h –1 [12] , [18] , [19] , [20] , [21] , [22] , [23] . Field test studies have also shown that new isolation rooms do not always comply with an ACH of 12 h–1, and as many as 21% (3/14) of tested isolation rooms violated the lowest requirement of 6 h –1 for existing buildings [24] . Lower ACHs are used in order to conserve energy [25] , [26] .…”

Effectiveness of directional airflow in reducing containment failures in hospital isolation rooms generated by door opening

“…They found that increasing pressure differentials reduced the door opening and care provider movement induced contaminant transfer across the doorway. Kokkonen et al (2014) carried out performance testing of airborne infection isolation rooms (AIIRs) by tracer gas techniques in real hospital settings. They found that up to 1.7 m 3 of air can migrate to an anteroom during door opening and movement of a HCW through the doorway.…”