Using computer simulations, scientists analyzed the airflow patterns in the car’s passenger compartment, shedding light on potential ways to reduce the risk of Covid-19 transmission when traveling with others.
The study, published in the journal Science Advances, assessed airflow inside a compact car with various combinations of opening and closing windows.
According to scientists, including scientists at Brown University in the US, the simulations showed that opening windows creates airflow patterns that dramatically reduce the concentration of aerosol particles in the air exchanged between the driver and the individual passenger.
However, they said blowing up the car’s ventilation system didn’t circulate the air almost as well as having a few open windows.
“Driving with the windows up and the air conditioning or heating on is by far the worst-case scenario, according to our computer simulations,” said Asimanshu Das, research co-author at Brown University.
“The best scenario we found was to open all four windows, but even opening one or two windows was far better than closing all of them,” said Das.
While there is no way to completely eliminate the risk, and current guidelines recommend postponing travel, the researchers said the purpose of the study was simply to assess how changes in airflow in a car can worsen or reduce the risk of Covid-19 transmission.
In the research, computer models simulated a car loosely based on a Toyota Prius, in which there are two people – the driver and the passenger sitting in the back seat on the opposite side of the driver.
The researchers said they chose this seating arrangement because it maximized the physical distance between two people.
Since the novel coronavirus is believed to spread via small aerosol particles that can remain in the air for long periods, scientists simulated the airflow around and inside a car traveling at 50 miles per hour.
One reason opening windows is better at conveying aerosols is because it increases the number of air changes per hour (ACH) inside the car, which reduces the overall concentration of aerosols, the study noted.
Scientists showed that different combinations of open windows created different air currents inside the car, which could increase or decrease exposure to other aerosols.
As the passengers in the simulation sat on opposite sides of the cabin, they said that very few particles were transferred between them.
The research showed that the rider was at a slightly higher risk than the passenger because the average airflow in the car goes from rear to front, but he added that both passengers experienced significantly less particle flow.
When some – but not all – windows were disabled, the study produced counterintuitive results.
Citing the example of one such case, the researchers found that opening windows next to each resident increased the risk of exposure compared to lowering the window in front of each resident.
“When the windows facing the passengers are open, there is a jet that enters the car behind the driver, sweeps the passenger compartment, and then exits through the passenger-side front window,” said Kenny Breuer, an engineering professor at Brown University and senior research author.
“This pattern helps to reduce cross-contamination between driver and passenger,” said Breuer.
The researchers said airflow regulation would not replace both occupants wearing masks inside the car, adding that the findings were limited to potential exposure to persistent aerosols that could contain pathogens.
Citing another study limitation, the researchers concluded that neither larger airway droplets nor the risk of actual infection with the virus were modeled.
However, they found that the findings provide valuable new information about the air circulation patterns in a car’s passenger compartment.
This story was published by a wire agency with no text modification. Only the header has been changed.