Exposure risk analysis of COVID-19 for a ride-sharing motorbike taxi.

R Hetherington,A Khan,D Roy,A B M Toufique Hasan,M Salehin,Z Wadud

doi:10.1063/5.0069454

Abstract

A dominant mode of transmission for the respiratory disease COVID-19 is via airborne virus-carrying aerosols. As national lockdowns are lifted and people begin to travel once again, an assessment of the risk associated with different forms of public transportation is required. This paper assesses the risk of transmission in the context of a ride-sharing motorbike taxi—a popular choice of paratransit in South and South-East Asia and Sub-Saharan Africa. Fluid dynamics plays a significant role in understanding the fate of droplets ejected from a susceptible individual during a respiratory event, such as coughing. Numerical simulations are employed here using an Eulerian–Lagrangian approach for particles and the Reynolds-averaged Navier–Stokes method for the background air flow. The driver is assumed to be exhaling virus laden droplets, which are transported toward the passenger by the background flow. A single cough is simulated for particle sizes 1, 10, , with motorbike speeds . It has been shown that small and large particles pose different types of risk. Depending on the motorbike speed, large particles may deposit onto the passenger, while smaller particles travel between the riders and may be inhaled by the passenger. To reduce risk of transmission to the passenger, a shield is placed between the riders. The shield not only acts as a barrier to block particles, but also alters the flow field around the riders, pushing particles away from the passenger. The findings of this paper therefore support the addition of a shield potentially making the journey safer.

Highlights

In March of 2020, the World Health Organization (WHO) declared the spread of SARS-CoV-2 to be a global pandemic
A single cough is modeled from the driver, which is transported back toward the passenger by the surrounding air flow
A complex turbulent flow is generated by the motorbike and riders, which heavily influences the transport of particles

Summary

Introduction

In March of 2020, the World Health Organization (WHO) declared the spread of SARS-CoV-2 to be a global pandemic. National lockdowns have been implemented globally to reduce the spread of the COVID-19 virus. Virus laden fluid droplets are generated in the respiratory tract during respiratory events, such as breathing, talking, coughing, and sneezing. Once expelled from an infected host, droplets typically take three routes to a susceptible individual: (i) contact with surfaces onto which droplets have been deposited, (ii) ballistic projection of large droplets directly onto a susceptible individual, and (iii) inhalation of small virus laden droplets, otherwise referred to as aerosols. The definition of an aerosol follows that of Fennelly:2 “a suspension of fine solid particles or liquid droplets in air with a small diameter typically less than

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Results

Conclusion