Abstract

Although the airborne transmission route of SARS-CoV-2 was acknowledged by early 2021—more than a year into the pandemic—we had expected that improved ventilation would help intercept transmission chains. However, the pandemic persisted, intensified, and resulted in significantly more deaths. Long-range transmission likely played a predominant role, while transmission in poorly ventilated spaces may have sustained the pandemic, particularly during the spread of the Delta and Omicron variants. In contrast, a predominantly short-range airborne transmission route might not sustain high transmissivity, as observed in the Omicron outbreaks in late 2022 in Chinese cities under lockdown. To better understand and address these dynamics, I will begin by analyzing several outbreaks, introduce a revised Wells-Riley formulation for multi-virion aerosols, and propose two new concepts of clean air equivalents and universal quanta generation profiles. This approach will enable the development of building dilution rate profiles, offering a potential strategy to mitigate and prevent future pandemics.

Biography

Yuguo Li is a Chair Professor of Building Environment at The University of Hong Kong. His research spans city climate, infection transmission, and sustainability engineering. His team investigates ventilation requirements for mitigating SARS-CoV-2 transmission and exploring resilient city design strategies and technologies. Their work prior to and during the pandemic contributes to redefine the transmission mechanisms of respiratory infection. Professor Li serves as a member of the WHO Infection Prevention and Control Guidance Development Group (IPC GDG) for COVID-19 and is the founding Editor-in-Chief of Indoor Environments, the official journal of the International Society of Indoor Air Quality and Climate (ISIAQ). He is a Fellow of the Hong Kong Academy of Engineering, currently serving as its Honorary Secretary, and has received numerous accolades, including the Pettenkofer Award, the Guanghua Engineering Science and Technology Prize in China, the Medal of Honour from the HKSAR Government, the Louise and Bill Holladay Distinguished Fellow Award, the Rydberg Gold Medal, and an honorary doctorate from Aalborg University.