A multivariate risk assessment of the airborne transmission of SARS-Cov-2 in different scenarios in Bangladesh: Identifying potential danger zones and proposing solutions

Abstract

Bangladesh is a developing country with one of the world’s densest populations, and thus, is very vulnerable to the impacts of the COVID-19 pandemic. Bangladesh has found it challenging to contain the transmission of SARS-CoV-2, leading to a high number of COVID-19 cases. The dominant avenue of SARS-CoV-2 transmission is through airborne droplets. We have attempted to compare the probability of SARS-CoV-2 transmission in different scenarios and situations, with a view to proposing mitigations to reduce this risk in the context of the country. A multivariate approach was taken, whereby a number of physical and environmental parameters were considered. Based on the Wells-Riley model, we have integrated several different equations into the original, developing a modified model that takes into account the factors of distancing, ventilation and the decay of airborne particles. The modified model was run on a number of different scenarios and situations. From the results, a distance risk matrix was developed, which indicates the relative risk of transmission someone faces at a distance from an infectious person compared to the risk being at some other distance. Additionally, it was found that environments with strong sunlight exposure and high temperature and humidity have greatly reduced transmission risk, as the airborne deactivation of virus particles is accelerated. Proper ventilation in indoor situations also greatly reduces this risk. The results of the study are used to suggest a number of mitigation methods that can be adapted as policy or guidelines.