Impact of HVAC-Systems on the Dispersion of Infectious Aerosols in a Cardiac Intensive Care Unit

Abstract

At the end of 2019, a variation of a coronavirus, named SARS-CoV-2, has been identified as being responsible for a respiratory illness disease (COVID-19). Since ventilation is an important factor that influences airborne transmission, we proposed to study the impact of heating, ventilation and air-conditioning (HVAC) with a variable air volume (VAV) primary air system, on the dispersion of infectious aerosols, in a cardiac intensive care unit, using a transient simulation with computational fluid dynamics (CFD), based on the finite element method (FEM). We analyzed three scenarios that followed the dispersion of pathogen carrying expiratory droplets particles from coughing, from patients possibly infected with COVID-19, depending on the location of the patients in the intensive care unit. Our study provides the mechanism for spread of infectious aerosols, and possibly of COVID-19 infection, by air conditioning systems and also highlights important recommendations for disease control and optimization of ventilation in intensive care units, by increasing the use of outdoor air and the rate of air change, decreasing the recirculation of air and using high-efficiency particulate air (HEPA) filters. The CFD-FEM simulation approach that was applied in our study could also be extended to other targets, such as public transport, theaters, philharmonics and amphitheaters from educational units.

Removal of SARS-CoV-2 bioaerosols using ultraviolet air filtration

“…In conclusion, the emergence of SARS-CoV-2 has accelerated the development and adoption of air purification technologies. [4][5][6][7] In this study, viable virus was detected in the control runs without UV-C light activation or HEPA filtration. Using an UV-C light system with and without HEPA filtration eliminated SARS-CoV-2.…”

“…10 To date, we are unaware of any APS having been directly challenged with SARS-CoV-2 bioaerosols. [4][5][6][7] The APS successfully eliminated the virus within closely defined parameters reaching significance. Future studies should address the impact of APS on SARS-CoV-2 transmission in a clinical environment, considering challenges from virus emissions by patients to airflow patterns.…”

Air Disinfection for Airborne Infection Control with a Focus on COVID‐19: Why Germicidal UV is Essential†

“…The implication of this local, in‐room transmission pattern is that the current focus on high‐level air filtration in central HVAC systems is unlikely to be very helpful for COVID‐19 mitigation (17). There are other reasons to filter recirculated air, airborne particulates and pollen, for example.…”

The impact of heating, ventilation, and air conditioning design features on the transmission of viruses, including the 2019 novel coronavirus: a systematic review of ventilation and coronavirus

“…Seven studies, including modelling (n=4), epidemiological (n=2), and experimental and modelling (n=1) studies, examined the impact of airflow pattern on SARS-CoV-2/COVID-19 (n=6) and SARS-CoV/SARS (n=1). Settings analyzed included airplane cabins, 46 restaurants, [24][25]47 hospitals and healthcare facilities, [48][49][50] supermarkets, 26 and classrooms. 26 Two of the four modelling studies determined that the placement of ventilation grilles was important in the dispersion of infectious particles.…”

“…26 Two of the four modelling studies determined that the placement of ventilation grilles was important in the dispersion of infectious particles. 26,48 Results from Shao et al 26 showed that when the supply and exhaust grilles are near the infectious particle emitter, the infectious particles are less dispersed. You et al 46 found the infection risk in an airliner cabin to be lower when displacement ventilation was used compared to mixing ventilation.…”