It may seem obvious, but research from the US confirms that opening the windows of your car can significantly reduce the risk of covid-19 contamination. According to the Brown University study, published in Science Advances, effectiveness varies in relation to the number of windows open and the speed of the car.
Based on a host of simulations, the study of air flow patterns within a car's cabin shows that opening windows can play an important role in minimizing the circulation of potentially dangerous particles, like those that can spread covid-19, among different vehicle occupants.
With all the windows open, the study shows two distinct air flows in the vehicle cabin, notably separating the left and right sides and maximizing the number of air changes per hour (ACH) inside the car. In fact, so long as it's not too bothersome for the vehicle occupants, opening all the windows is by far the best solution for reducing the risk of contamination.
Among the scenarios tested, keeping all windows closed and using the air conditioning system to provide air flow was by far the most risky. Between the two, opening the two front windows or the two rear windows gave mixed results.
Note that the speed of the car can also affect air flow through the vehicle. The slower the speed of the car, the lower the ACH. That means that particles remain a little longer in the air inside the cabin. As the speed increases, the air changes more quickly.
Car users should consider wearing a mask and disinfecting the steering wheel, gear stick and front door handles with alcohol-based solution before any journey, especially with passengers onboard.