Airborne coronavirus particles in a car can build up to concerning levels in just a quarter of an hour if the windows are not opened, a study has found.
They can linger for almost four hours but opening all the windows is the most effective way to ensure adequate ventilation and reduce risk of transmission if either the passenger or driver is infected.
However, if this is not possible in the frigid and damp winter months, opening just two windows can significantly reduce risk.
The best arrangement, according to computer simulations, is for the passenger to sit diagonally behind the driver and open the rear driver’s side window as well as the one on the front passenger’s side.
Opening all the windows dramatically increases ventilation and reduces the risk of infection if one of either driver or passenger is infected (stock)
Medical officials warn against getting into a car with someone who is not from your household, but if you have to, precautions are encouraged.
Many rideshare and taxi companies now mandate masks, restrict passenger numbers per trip and have installed barriers between the front and the back.
But ventilation to reduce the number of circulating infectious particles produced by a Covid-19 sufferer is a powerful weapon in lowering transmission risk.
Dr Varghese Mathai, a physicist from the University of Massachusetts Amherst, led an investigation into how effective opening certain windows in a car can be.
All possible combinations of open windows was tested, and the intuitive opening of the window next to the passenger and driver was not the most effective. ‘The simulations showed an air current that acts like a barrier between the driver and the passenger,’ says Dr Mathai
The experiment was based on a typical rideshare trip with one driver and one passenger sitting at opposite ends of the cabin of a Toyota Prius at 50mph. If all windows can not be opened, the best two to open are the rear driver’s side and the front passenger’s side
The simulations were based on a left-hand drive car, such as those on the roads in the US and most of Europe.
However, the findings also apply for cars driven on the left-side of the road, like the UK, as they work as a mirror image.
All possible combinations of open windows was tested, and the intuitive opening of the window next to the passenger and driver was not the most effective.
‘The simulations showed an air current that acts like a barrier between the driver and the passenger,’ says Dr Mathai.
‘While these measures are no substitute for wearing a face mask while inside a car, they can help reduce the pathogen load inside the very confined space of a car cabin.’
The experiment was based on a typical rideshare trip with one driver and one passenger sitting at opposite ends of the cabin of a Toyota Prius at 50mph.
The findings are published in Science Advances.