Airflows inside passenger cars and implications for airborne disease transmission

Transmission of highly infectious respiratory diseases, including SARS-CoV-2, is facilitated by the transport of exhaled droplets and aerosols that can remain suspended in air for extended periods of time. A passenger car cabin represents one such situation with an elevated risk of pathogen transmission. Here, we present results from numerical simulations to assess how the in-cabin microclimate of a car can potentially spread pathogenic species between occupants for a variety of open and closed window configurations. We estimate relative concentrations and residence times of a noninteracting, passive scalar-a proxy for infectious particles-being advected and diffused by turbulent airflows inside the cabin. An airflow pattern that travels across the cabin, farthest from the occupants, can potentially reduce the transmission risk. Our findings reveal the complex fluid dynamics during everyday commutes and nonintuitive ways in which open windows can either increase or suppress airborne transmission.

Automated summary

This study uses numerical simulations to evaluate the potential spread of pathogenic species between car occupants and finds that airflow patterns across the cabin may reduce transmission risk. The research also reveals the complexity of fluid dynamics during everyday commutes and how open windows can affect airborne transmission in nonintuitive ways.