As coronavirus cases rise, the need for social distancing grows ever greater. But for many Arizonans, car commutes are unavoidable.
A new study in the journal Science Advances describes what could be the safest way to rideshare.
Airflow models of a moving four-door Toyota Prius suggest the safest way for two people to share a car is to seat the passenger in the rear spot diagonal from the driver and to roll down all four windows.
The models simulated small, airborne droplets and aerosols, which can remain suspended for extended periods and provide one way for SARS-CoV-2 to spread.
"When you open the windows of your car, you get a lot of natural flows, which can actually help reduce the concentration, or the load, of these airborne particles," said lead author Varghese Mathai of University of Massachusetts, Amherst.
Four open windows created two airflows in the simulated vehicle, one on each side of the cabin. Due to exterior pressure differentials caused by the car's aerodynamics, air flowed from the rear toward the front.
The vehicles' speed did not matter, as long as it traveled at around 20-70 miles per hour.
When only three windows were open, the placement of the closed window matter a great deal. Closing the window beside the non-infected person offered the second safest option overall.
A fully enclosed car posed the greatest risk. In such cases, air conditioning also could affect how droplets were distributed.
Mathai stressed he and his colleagues did not look at other transmission routes, such as contaminated surfaces.
"This was looking at aerosols in airborne mode only, which means you assume these particles are very tiny, that they will move how the air moves," Mathai said.
Mathai chose the vehicle because it's what he drives, and because two people riding in a five-seat car closely reflects the average pattern at play in the U.S. He hopes to study other vehicle types and configurations in the future.
