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ObjectiveTo assess the effectiveness of aerosol filtration by portable air cleaning devices with high efficiency particulate air (HEPA) filters used in addition to standard building heating ventilation and air-conditioning (HVAC). MethodsTest rooms, including a hospital single-patient room, were filled with test aerosol to simulate aerosol movement. Aerosol counts were measured over time with various portable air cleaning devices and room ventilation systems to quantify the aerosol concentration reduction rate and overall clearance rate. ResultsPortable air cleaners were very effective in removing aerosols, especially for the devices with high flow rate. In a small control room, the aerosols were cleared 4 to 5 times faster with portable air cleaners than the room with HVAC alone. A single bed hospital room equipped with an excellent ventilation rate ([~] 14 air changes per hour) can clear the aerosols in 20 minutes. However, with the addition of two air cleaners, the clearance time became 3 times faster (in 6 minutes and 30 seconds). ConclusionsPortable air cleaning devices with HEPA filtration were highly effective at removing aerosols. To clear aerosols (above 90% clearance) in under 10 minutes requires around 25 air changes per hour; readily feasible with air cleaners. Inexpensive portable air cleaning devices should be considered for small and enclosed spaces in health care settings such as inpatient rooms, personal protective equipment donning/doffing stations, and staff tea rooms. Portable air cleaners are particularly important where there is limited ability to reduce aerosol transmission with building HVAC ventilation.
RESUMEN
ObjectiveTo describe COVID-19 infections amongst healthcare workers at the Royal Melbourne Hospital from 1st July to 31st August 2020 DesignProspective observational study SettingA 550 bed tertiary referral hospital in metropolitan Melbourne ParticipantsAll healthcare workers identified with COVID-19 infection in the period of interest Results262 healthcare worker infections were identified over 9 weeks. 68.3% of infected healthcare workers were nurses and the most affected locations were the geriatric and rehabilitation wards. Clusters of infection occurred in staff working in wards with patients known to have COVID-19 infection. Staff infections peaked when COVID-19 infected inpatient numbers were highest, and density of patients and certain patient behaviours were noted by staff to be linked to possible transmission events. Three small outbreaks on other wards occurred but all were recognised and brought under control. Availability of rapid turn-around staff testing, and regular review of local data and obtaining feedback from staff helped identify useful interventions which were iteratively implemented. Attention to staff wellbeing was critical to the response and a comprehensive support service was implemented. Conclusion(s)A comprehensive multimodal approach to containment was instituted with iterative refinement based on frontline workers observations and ongoing analysis of local data in real time. O_TEXTBOXThe known: Healthcare workers are a group recognized to be at risk of acquisition of infection in the workplace during the current COVID-19 pandemic The new: This describes the experience of the largest Australian outbreak to date of COVID- 19 infection amongst healthcare workers in a hospital environment The implications: This paper should assist healthcare services to prepare for surges in COVID-19 infection to help limit future transmissions to healthcare workers C_TEXTBOX