INFECTION CONTROL
Bacteria
100 200 300 400 500
0 8:00 9:00 10:00 Time Figure 3: Effectiveness of a portable air cleaner to reduce peak suspended bacteria concentration.
Reducing airborne bacterial concentration Reduction of the peak morning concentration of airborne bacterial numbers is expected to contribute to a reduction in hospital infections. Potential engineering controls include ventilation (local exhaust
ventilation or general ventilation), air filtration (e.g., use of a filter installed in an AHU), or use of a portable air cleaner. In this context, ventilation, which works by diluting the airborne particles, is an energy-intensive technique, making it less appealing. In the present study, a portable air cleaner
11:00 12:00 OFF ON OFF ON
Occupants OFF
10 15 20
0 5
was tested in a clinic for its effectiveness in reducing the peak airborne microbial concentration. Specifically, indoor suspended bacteria concentrations were measured continuously in situ under the conditions of alternating the air cleaner between the ON and OFF modes. The effect of air cleaner use on suspended
bacteria concentration and the number of occupants versus elapsed time are shown in Figure 3. As seen previously in Figure 1, the concentration of suspended bacteria rose with increasing occupant numbers. However, the concentration of suspended bacteria fell when the air cleaner was in operation. These results confirmed that this air cleaner was an effective additional control method.
Conclusion Transmission of infectious diseases through the inhalation of airborne microbes is a public health problem that may pose substantial risk to healthcare workers and raise the risk of nosocomial infection in hospital waiting rooms. This study demonstrated that a portable air cleaner reduced the indoor concentration of suspended microbes during high-occupancy periods in waiting rooms, and may therefore serve as valuable auxiliary equipment for use in hospital settings.
Providing insights into the vast field of healthcare engineering and facility management
30 IFHE DIGEST 2013
Suspended bacteria [cfu/m3 ]
Number of occupants
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