How opening windows and other measures decrease virus concentration in a moving car

Abstract

PurposeDue to the ongoing Covid-19 pandemic, ventilation in a small cabin where social distancing cannot be guaranteed is extremely important. This study aims to find out the best configuration of open and closed windows in a moving car at varying speeds to improve the ventilation efficiency. The effectiveness of other mitigation measures including face masks, taxi screens and air conditioning (AC) systems are also evaluated.Design/methodology/approachEach window is given three opening levels: fully open, half open and fully closed. For a car with four windows, this yields 81 different configurations. The location of virus source is also considered, either emitting from the driver or from the rear seat passenger. Then three different travelling speeds, 5 m/s, 10 m/s and 15 m/s, are examined for the window opening/closing configurations that provide the best ventilation effect. A study into the effectiveness of face masks is realised by adjusting virus injection amounts; and the simulation of taxi screens and AC system simply requires a small modification to the car model.FindingsThe numerical studies identify the top window opening/closing configurations that provide the most efficient ventilation at different moving speeds, along with a comprehensive ranking list. The results show that fully opening all windows is not always the best choice. Simulations evaluating other mitigation measures confirm good effect of face masks and poor performance of taxi screens and AC systems.Originality/valueThis work is the first large-scale numerical simulation and parametric study about different window opening/closing configurations of a moving car. The results provide useful guides for travellers in shared cars to mitigate Covid-19 transmission risks. The findings are helpful to both individuals' health and society's recovery in the Covid-19 era and they also provide useful information to protect people from other respiratory infectious diseases such as influenza.