Risk of SARS‐CoV‐2 in a car cabin assessed through 3D CFD simulations

Abstract

In this study, the risk of infection from SARS‐CoV‐2 Delta variant of passengers sharing a car cabin with an infected subject for a 30‐min journey is estimated through an integrated approach combining a recently developed predictive emission‐to‐risk approach and a validated CFD numerical model numerically solved using the open‐source OpenFOAM software. Different scenarios were investigated to evaluate the effect of the infected subject position within the car cabin, the airflow rate of the HVAC system, the HVAC ventilation mode, and the expiratory activity (breathing vs. speaking). The numerical simulations here performed reveal that the risk of infection is strongly influenced by several key parameters: As an example, under the same ventilation mode and emitting scenario, the risk of infection ranges from zero to roughly 50% as a function of the HVAC flow rate. The results obtained also demonstrate that (i) simplified zero‐dimensional approaches limit proper evaluation of the risk in such confined spaces, conversely, (ii) CFD approaches are needed to investigate the complex fluid dynamics in similar indoor environments, and, thus, (iii) the risk of infection in indoor environments characterized by fixed seats can be in principle controlled by properly designing the flow patterns of the environment.

Increasing ventilation reduces SARS-CoV-2 airborne transmission in schools: A retrospective cohort study in Italy's Marche region

“…The novel aspect of the approach is the a priori evaluation of the viral emission of the infected subject on the basis of the viral load, the expiratory flow rate (influenced by the activity level), and the particle volume concentration expelled by the infectious person (affected by the expiratory activity, i.e., speaking, breathing, etc.). Major details of this predictive approach are reported in our previous papers and are not repeated here for the sake of brevity (32,33,(35)(36)(37). Figure 2 shows the comparison between the RRs observed in the investigated classrooms and those estimated through the theoretical predictive approach for a specific scenario as a function of the ventilation rate per person.…”

Fate of Exhaled Droplets From Breathing and Coughing in Supermarket Checkouts and Passenger Cars

“…Similarly, identifying high-risk areas in a grocery store based on infected individuals along a defined route and emitting viral aerosols in the range of 0.3 to 3 μm 27 also did not incorporate size distributions of exhaled droplets as well as the evaporation of droplets after emission. Simulations in passenger car cabins estimate the risk of infection from SARS-CoV-2 Delta variant during breathing and speaking in the presence of different ventilation modes 28 used particle sizes between 2.4 and 90 μm with an assumption that the droplets evaporate as soon as they are emitted. However, in the simulations presented here trajectories of exhaled droplets differ from those of residual droplet nuclei as a result of size-dependent competing forces.…”

A CFD-based framework to assess airborne infection risk in buildings

“…Of the many studies using CFD to investigate airborne infection risk, many have focussed on healthcare settings [ [32] , [33] , [34] , [35] , [36] ], and other settings [ [37] , [38] , [39] , [40] ]. Good practice guidance to set up CFD simulations applicable to industrial practices to inform design against airborne infection risk is of utmost importance and currently considered a ‘work in progress’.…”