Evaluation of COVID-19 infection risk of public transport in developing country

Research conducted in collaboration with Udayraj Thorat, Amirul Khan, Zia Wadud & Rory Hetherington.

In developing countries, where healthcare infrastructure may be limited and densely populated urban areas are prevalent, the transmission of COVID-19 poses unique challenges. A dominant mode of transmission for the virus is through the dispersion of virus-laden aerosols in the air. As these countries begin to ease their lockdown measures and people resume traveling, there is an urgent need to evaluate the risk of COVID-19 transmission associated with different forms of public transportation, considering the specific circumstances and conditions of these regions. In this work, two popular modes of transport in developing countries are compared: buses and motorbike taxis.

To achieve this, a CAD model for the bus and the motorbike taxi were created, and numerical simulations were performed using Ansys FLUENT at three different velocities (1, 5 and 15 m/s). The complex air flow was modelled by using a steady RANS approach, and a transport equation was used to estimate the aerosol concentration field around the passengers.

Given that mechanical ventilation systems are often lacking in buses in developing countries, ventilation primarily relies on natural means, such as opening windows and doors. Here, different risk mitigating strategies for the bus case were considered, where the ventilation rate was increased by using different combinations of open windows and doors. The simulation results were subsequently compared to determine the most effective and safest option to reduce aerosol concentrations and minimize the risk of COVID-19 transmission within these modes of transportation.

By conducting this research, insights can be gained into the specific challenges posed by COVID-19 in developing countries and provide valuable information for policymakers, transportation authorities, and public health agencies to implement appropriate measures to safeguard public health during travel.

We found that opening all windows in the bus could significantly help in reducing the risk of infection when compared to a case where only windows close to the driver were opened. On top of this, the risk for the passenger on the motorbike taxi was found to be superior than the bus case that was studied, but that risk mitigation was easier to implement on the motorbike taxi.