Outdoor Airborne Transmission of Coronavirus Among Apartments in High-Density Cities

Frontiers in Built Environment

John D. Spengler¹  Jianxiang Huang²  Anqi Zhang²  Jian Hang³  Phil Jones⁴  Shan Shan Hou⁴ 

[1] Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, United States;Department of Urban Planning and Design, The University of Hong Kong, Hong Kong, China;Key Laboratory of Tropical Atmosphere-Ocean System, Ministry of Education, School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, China;Welsh School of Architecture, Cardiff University, King Edward VII Avenue, Cardiff, United Kingdom;

关键词: Coronavirus;    airborne transmission;    outdoor route;    numerical simulation;    high-density city;   

DOI  :  10.3389/fbuil.2021.666923

来源: Frontiers

【 摘 要 】

The coronaviruses have inflicted health and societal crises in recent decades. Both SARS CoV-1 and 2 are suspected to spread through outdoor routes in high-density cities, infecting residents in apartments on separate floors or in different buildings in many superspreading events, often in the absence of close personal contact. The viability of such mode of transmission is disputed in the research literature, and there is little evidence on the dose–response relationship at the apartment level. This paper describes a study to examine the viability of outdoor airborne transmission between neighboring apartments in high density cities. A first-principles model, airborne transmission via outdoor route (ATOR), was developed to simulate airborne pathogen generation, natural decay, outdoor dispersion, apartment entry, and inhalation exposure of susceptible persons in neighboring apartments. The model was partially evaluated using a smoke tracer experiment in a mock-up high-density city site and cross-checking using the computational fluid dynamics (CFD) models. The ATOR model was used to retrospectively investigate the relationship between viral exposure and disease infection at an apartment level in two superspreading events in Hong Kong: the SARS outbreak in Amoy Gardens and the COVID-19 outbreak in Luk Chuen House. Logistic regression results suggested that the predicted viral exposure was positively correlated with the probability of disease infection at apartment level for both events. Infection risks associated with the outdoor route transmission of SARS can be reduced to <10%, if the quanta emission rate from the primary patient is below 30 q/h. Compared with the indoor route transmission, the outdoor route can better explain patterns of disease infection. A viral plume can spread upward and downward, driven by buoyancy forces, while also dispersing under natural wind. Fan-assistant natural ventilation in residential buildings may increase infection risks. Findings have implication for public health response to current and future pandemics and the ATOR model can serve as planning and design tool to identify the risk of airborne disease transmission in high-density cities.

【 授权许可】

CC BY