COVID-19 has completely changed the journey as we know it, with a massively reduced number of people taking flights and public transport – but our cars have been a mystery. How safe are we in our vehicles? What is the risk?
A study published by Science Advances in early January has begun to answer some of our most pressing questions about COVID-19 transmission in our vehicles. Four researchers from the University of Massachusetts, Amherst and Brown university used calculation fluid dynamics to evaluate the risk of the virus in the cab and has also suggested ways to reduce the risk.
If you are familiar with the design process of a race car or a plane, then you have probably encountered computational fluid dynamics before. Essentially, these computer simulations model how gases and liquids move over and through different surfaces. In this particular case, our researchers used CFDs to model the way air moves inside a car.
The simulated vehicle used in the study was loosely based on a Toyota Prius driving 50 mph with two passengers: a driver in the front left of the car and a passenger in the back right. Interesting, the air flow outside the moving car creates a pressure gradient inside the car that causes air to circulate from the back of the car to the front. Then they started modeling the internal airflow with different combinations of windows that were open or closed. It is important to note here that regardless of the combination, the air conditioning was on.
The results are not likely to be surprising. When all four windows were closed, the car was poorly ventilated, so eight to ten percent of the aerosols – which COVID-19 runs on – exhaled from one person in the car to the other. When everyone the windows were open, the car was at best ventilated, with only 0.2 to two percent aerosols switching between passengers.
Of course, open windows are not always practical when driving. To the north you freeze in the winter. Down in the south, some are melting with a delicate constitution in the summer. Heavy rain will make things twice as miserable. So having both the driver and the passenger rolled down the windows was found to be better than keeping everything tight. The diagonal configuration allows air to flow in and then straight out again. It may not be comfortable, but it can save lives.
A later study, which has not yet been published, showed that it was also a good idea to break windows halfway, but just rolling them a quarter of the way down was significantly more dangerous, The New York Times reports. For larger cars such as minibuses or for cars that transport more people, the recommendation is to keep everything open.
Opening windows has been recommended since the virus started. The increased ventilation means that virus particles can be whipped away instead of being recycled. And we also know that the less space we share, the more likely we are to replace aerosol particles. This study initially used only science to give us the ideal strategy for, for example, rideshares or short trips outside your bubble.
Of course, there are still dangers, even when you open the windows. In fact, you drive with open windows increases air pollution in the car by 80 percent, which thus increases the probability of dying as a result of air pollution.
The very best option is, of course, to be at home unless absolutely necessary, and when traveling, to do so in low hours.