I’ve seen people driving around wearing masks, even when they’re the only person in a vehicle. What are the risks of getting the coronavirus while driving? Is it safe to drive with the windows down?
Chances are, the only way you could catch COVID-19 on the road is if somebody in your car already has it.
“I’d only wear a mask in the car if there’s someone else in the car who might be infected,” says David Evans, a virologist and professor of medical microbiology and immunology at the University of Alberta. “You can open a window in the car. It’s a beautiful day today in Edmonton, sunny and three degrees Celsius and so I drove to work with the top down on my convertible, no mask.”
Last week, Dr. Theresa Tam, Canada’s Chief Public Health Officer, said that wearing masks in public to prevent the spread of the coronavirus might not be a bad idea.
While you might consider a mask at the grocery store, where it can be tough to keep two metres from other people, public officials haven’t said to wear masks while driving.
That makes sense, Evans says, because the virus that causes COVID-19 isn’t believed to spread easily in the air, especially outside.
“This idea that the external environment is contaminated with enough virus to cause infections isn’t credible,” Evans says. “We’ve been doing some back-of-the-envelope calculations, and I figure it’ll still be an experimental challenge for us to detect infectious virus spread out onto surfaces by a sick patient around a hospital room.”
Coronavirus not in the air?
There has been public confusion over whether or not the coronavirus is airborne.
“Very few viruses are spread as airborne particles,” Evans says. “Measles is an exception, but even that capacity is limited to indoor rooms. It doesn’t spread outdoors because outside it gets diluted and inactivated below the point it can cause infections.”
The coronavirus isn’t believed to be airborne, but it can spread by droplets from someone who is infected.
So, if someone with COVID-19 coughs up mucous or is “speaking moistly” near you, you could breathe in the droplets containing the virus. That’s why we’ve been told to keep at least two metres from each other.
Or, if someone with COVID-19 coughs or sneezes on their hands and then touches something, such as a door handle or gas pump nozzle, they could leave particles of the virus, called virions.
If you get enough virions on your hands and then touch your mucous membranes, including your mouth, nose and eyes, you could get infected.
That’s why surfaces should be disinfected and why you should be washing your hands before you touch your face.
After a few hours, the virions die off. It’s likely that you need direct contact with a lot of coronavirus virions to get infected, Evans says.
“They’re not really good at causing infections so you need a big wallop,” Evans says. “Admittedly I don’t know what that number is for COVID-19, but it’s likely hundreds or even thousands of particles given the behaviour of other viruses,” Evans says.
In drive-through COVID-19 testing centres in South Korea, drivers were reportedly told to hit the recirculation button on their car’s air conditioning so the pathogens stayed in the car.
But as long as you’re not close enough to someone to inhale droplets from their breathing, sneezing or coughing, the chances of catching COVID-19 outside are slim, Evans says.
Catching it from an open window while driving is even more unlikely.
“If someone breaths out some infectious droplets outside, these will rapidly settle to the ground, dry out and stick to the surface they’ve landed on, and the virus in them will begin to inactivate,” Evans says. “That’ll be faster in the sunshine, as UV [ultraviolet light] inactivates viruses.”
No time for joyrides?
So far, most provinces have told people to stay home, or within walking distance from home, as much as possible right now. In several provinces, parking lots have been closed at parks and hiking trails.
That advice, to make essential trips only, is mainly to reduce crowds everywhere.
In Nova Scotia, for instance, health officials are telling people to stay off the roads to avoid crashes that the health-care system can’t handle right now.
But police forces say they generally haven’t been ticketing people for unnecessary trips – or for not social distancing in vehicles.
Is social distancing possible in a vehicle? Not really, Evans says. That means you should only share a car with people you live with.
“Of course a group or couple already sharing an interior space are at no more or less risk in a car than at home,” Evans says.
If you need to take someone with you on an essential trip – for instance, if you’re taking a parent to a doctor – err on the side of caution.
“The best advice would be to have everyone wear masks, and if someone is in a high-risk category, see if they can get an N95 mask rather than a homemade one,” Evans says. “Limit the numbers to driver and passenger and don’t travel if someone has COVID-19 symptoms.”
Editor’s note: Update: Since this story was written in April, there has been debate whether the virus that causes COVID-19 is airborne – spread in the air in aerosols, much smaller respiratory droplets, over distances greater than two metres. In a scientific brief on July 9, the World Health Organization (WHO) called for more research, but it said evidence shows, so far, that the virus spreads in the air mainly through close contact with infected people. We will update this story as more information becomes available.
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