San Antonio Express-News (Sunday)
In moving vehicles, a way to drive the coronavirus away
Over the past year, as health authorities have tried to curb the COVID-19 pandemic, researchers have trained their scientific attention on a variety of potentially risky environments: places where large groups of people gather.
They have paid less attention to another everyday environment: the car. Cars come with risks of their own; they are small, tightly sealed spaces that make social distancing impossible and trap the tiny, airborne particles, or aerosols, that can transmit the coronavirus.
In a new study, Varghese Mathai, a physicist at the University of Massachusetts, Amherst, and three colleagues at Brown University — Asimanshu Das, Jeffrey Bailey and Kenneth Breuer — used computer simulations to map how virus-laden airborne particles might flow through the inside of a car. Their results, published in Science Advances, suggest that opening windows can create air currents that could help keep both riders and drivers safe from infectious diseases like COVID-19.
The team simulated a car loosely based on a Toyota Prius driving at 50 mph with two occupants: a driver in the front left seat and a single passenger in the back right, a seating arrangement common in taxis that maximizes social distancing.
They found the ventilation rate was lowest when all four windows were closed. In this scenario, roughly 8 percent to 10 percent of aerosols exhaled by one of the car’s occupants could reach the other person. When all the windows were completely open, ventilation rates soared, and the influx of fresh air flushed many of the airborne particles out of the car; just 0.2 percent to 2 percent of the simulated aerosols traveled between driver and passenger.
They found that while having the driver and the passenger each roll down their own windows was better than keeping all the windows closed, a better strategy was to open the windows opposite each occupant.