You can’t keep six feet apart traveling in most vehicles, and even though the Centers for Disease Control and Prevention (CDC) suggests you avoid riding in cars with people who aren’t in your household, that’s not always possible either.

The solution to reducing the risk of COVID-19 transmission in a vehicle, according to a team of researchers from Brown University, is to simply roll down the windows.

According to ABC News, the researchers published a study analyzing air flow patterns in a compact car using computer models to track aerosol transmission. The played out different scenarios, placing passengers in different configurations, blasting the air conditioning system and heater, and found that the best way to increase circulation was to open the windows.

“That’s not surprising because we would expect that the more windows are open, the more circulation of air there is, and the easier it is to flush any contaminants out of the car,” said Kenny Breuer, a researcher in fluid dynamics at Brown University.

But what was surprising is that the team discovered that opening the window opposite you, not closest to you, optimized air flow. They acknowledged that this pattern could change depending on the vehicle.

The CDC suggests that frequently touched surfaces in a car, such as the steering wheel, door frame, and handles be cleaned and disinfected regularly. The agency also recommends using alcohol wipes or hand sanitizer when using pay stations or parking meters.