Aerodynamic analysis and airborne transmission research of SARS-CoV-2
The world has fully returned to normalcy after the disruption caused by COVID-19 in the past few years. However, even after the pandemic, our behaviors and attitude have been transformed as the public strives for safer living conditions in certain ways.
Prof. Zhi NING (Professor of the Division of Environment and Sustainability, HKUST) is one of the earliest scientists who discovered the airborne transmission of SARS-CoV-2, through studying the aerosol concentrations in two Wuhan Hospitals in early 2020. This study played a pivotal role in guiding the World Health Organization (WHO) and governments to formulate the public health policies globally, as it has been referenced as one of the first evidence proving the airborne transmission capability of the virus.
As an expert in air pollution measurement and modeling, Prof. NING led a research team to investigate the aerodynamic nature of SARS-CoV-2 by measuring viral RNA in aerosols in different areas of Renmin Hospital of Wuhan University and Wuchang Fangcang Field Hospital in February and March 2020, based on the limited pre-existing research on aerosol transmission (Yu et al., 2014) [1].
Sampling airborne SARS-CoV-2 at 30 different sites, traditional aerosol capture devices were deployed to gather total suspended particles (TSP), size-segregated particles, and deposition-based samples. The findings from Phase 1 indicated high viral aerosol concentrations in non-ventilated medical staff areas but well-ventilated ICU rooms showed lower concentrations conversely, elucidating a critical transmission route in the medical environment. The sampling of Phase 2 was conducted after the implementation of rigorous sanitization procedures such as comprehensive disinfection with 5% hydrogen peroxide and alcohol, thus resulted in undetectable viral concentrations. The results suggest that the virus can be transported through human movement and eventually resuspended in the air during activities like walking or protective apparel removal, hence the virus-laden aerosol can be transferred from patient areas to medical staff areas through the air. The study also reveals the bimodal nature (0.25 to 2.5 microns) of SARS-CoV-2 aerosol in its airborne form.
Concluding from the findings, the team highlighted the importance of implementing rigorous sterilization, proper ventilation, and crowd management measures to mitigate the risk of airborne SARS-CoV-2 infection in both medical and public settings at the early stage of the global COVID-19 pandemic. This study has had an impact on guidelines related to ventilation and sanitation, particularly in medical settings and public restrooms. It has also influenced more than 10 global policy documents including those of the European Commission, European Parliament, Government of the Netherlands, and Scottish Government.
The impact of this study endures beyond the pandemic, as it has not only influenced public behaviors such as mask-wearing and crowd avoidance, but also served as an inspiration for technological innovations, namely two patented applications focusing on virus detection and prevention[2][3], to drive socio-economic transformations for healthier living conditions in long term.
References:
Yu et al., Clinical Infectious Diseases, 58: 683-686 (2014).
Method of detecting virus particles and kits therefor, Patent Application Number: PCT/EP2021/064857, 2021.
Virus-like particles for preventing the spreading and lowering the infection rate of viruses, Patent No.: US 11,564,892 B2, 2023.
