Researchers decode how airflow inside a car can affect COVID-19 transmission risk – Edexlive

Using computer simulations, scientists analyzed airflow patterns inside a car’s cabin, shedding light on potential ways to reduce the risk of COVID-19 transmission by sharing journeys with others. The study, published in the journal Science Advances, evaluated the airflow inside a compact car with various combinations of open or closed windows.

According to researchers, including those from Brown University in the United States, simulations showed that opening windows created airflow patterns that dramatically reduced the concentration of airborne aerosol particles exchanged between a driver and an individual. passenger. However, they said blowing up the car’s ventilation system didn’t circulate the air as well as some open windows.

“Driving around with the windows up and the air conditioning or heating is definitely the worst case scenario, according to our computer simulations,” said Asimanshu Das, co-lead author of the Brown University research. “The best scenario we found was having all four windows open, but even having one or two open was much better than having all of them closed,” Das said.

While it is not possible to completely eliminate the risk and current guidelines recommend postponing travel, the scientists said the goal of the study was simply to assess how changes in airflow inside a car can worsen or reduce the risk of transmitting COVID-19. In the research, the computer models simulated a car, loosely based on a Toyota Prius, with two people inside: a driver and a passenger sitting in the back seat opposite the driver.

Scientists said they chose this seating arrangement as it maximizes the physical distance between the two people. Because the novel coronavirus is thought to spread via tiny aerosol particles that can remain in the air for long periods of time, the researchers simulated the flow of air around and inside a car moving at 50 miles. then.

Part of the reason opening the windows is better in terms of aerosol transmission is because it increases the number of air changes per hour (ACH) inside the car which reduces the overall aerosol concentration, the study notes. Scientists showed that different combinations of open windows created different air currents inside the car that could increase or decrease exposure to the remaining aerosols.

Since the occupants in the simulations were seated on opposite sides of the cabin, they said very few particles were transferred between the two. According to the research, the driver was slightly more at risk than the passenger as the average airflow in the car goes from rear to front, but added that both occupants experience significantly less particle transfer.

When some, but not all, windows were closed, the study produced counterintuitive results. Citing an example of one such case, the scientists said opening the windows next to each occupant carried a higher risk of exposure than lowering the window in front of each occupant. “When the windows in front of the occupants are open, you get a stream that enters the car behind the driver, goes through the cabin behind the passenger and then exits the front passenger side window,” said Kenny Breuer, an engineering professor at Brown. University and senior author of the research.

“This model helps reduce cross-contamination between driver and passenger,” Breuer said. Scientists said airflow adjustments do not replace the use of masks by both occupants inside a car, adding that the results are limited to potential exposure to persistent aerosols that may contain pathogens. . Citing another limitation of the study, the scientists said it did not model larger respiratory droplets or the risk of actually being infected with the virus. However, they said the findings provide valuable new insights into air circulation patterns within a car’s cabin.