A comprehensive analysis of the effect of ventilation and climatic conditions on covid-19 transmission through respiratory droplet transport via both airborne and fomite mode inside an elevator

TL;DR

This study uses numerical simulations to analyze how ventilation and climate conditions affect COVID-19 droplet dispersion and infection risk inside elevators, revealing that certain ventilation speeds and dry, hot conditions influence transmission risk.

Contribution

It provides a detailed numerical analysis of droplet transport in elevator environments considering various climatic and ventilation scenarios, highlighting optimal ventilation speeds to reduce infection risk.

Findings

Hot, dry, quiescent conditions pose the highest infection risk.

Increasing fan speed initially increases risk, but risk decreases significantly at 1100 RPM.

Ventilation at 1100 RPM reduces infection risk by 67% in hot, dry climates.

Abstract

The risks of disease transmission due to these droplets are significantly high in confined public spaces like elevators. A numerical analysis using OpenFOAM has been performed in this work to investigate the droplet dispersion routes in an enclosed environment resembling an elevator. The effect of two scenarios on droplet dispersal, namely the quiescent and the fan-driven ventilation, both subjected to various climatic conditions (of temperature and humidity) ranging from cold humid (15 degree C, 70 percent relative humidity) to hot dry (30 degree C, 30 percent relative humidity and 30 degree C, 50 percent relative humidity) and hot humid (30 degree C, 70 percent relative humidity) have been studied. A risk factor derived from a dose response model based on the time averaged pathogen quantity present around the passengers mouth is used to quantify the risk of infection through airborne mode. It is found that the hot, dry quiescent scenario poses the greatest threat of infection (spatio averaged risk factor 42 percent), whereas the cold humid condition poses the least risk of infection (spatio averaged risk factor 30 percent. The implementation of Fan ventilation at low RPM increases the risk as compared to a quiescent scenario, however with the increase in speed the risk decreases significantly. The Fan ventilation scenario with 1100 RPM (having a spatio averaged risk factor of 10 percent) decreases the risk of infection by 67 percent in a hot, dry climatic condition as compared to a quiescent scenario. However, there is no significant reduction in risk beyond a certain Fan speed, 1100 RPM. The deposition potential of aerosolized droplets in various parts of the respiratory tract namely the Extrathoracic and the Alveolar and Bronchial regions has been analyzed thoroughly because of the concomitant repercussions of infection in various depths of the respiratory region.