Mask-wearing is now mandatory indoors and outdoors in Italy, which begs the question: should the UK follow suit?

A recent document shared by the Scientific Advisory Group for Emergencies (SAGE), which advises the government on pandemic measures, suggested making mask-wearing mandatory outdoors would have a “very low” impact on transmission of the virus in the community. 

It pointed out there are “low transmission rates outdoors and [the] most risky contacts are made indoors”.

That said, scientists acknowledged that implementing such a measure “may have a small impact for those people who have to come into close contact with others”. But on the whole, it’s not enough to warrant a change in Covid-19 rules.

Dr David Strain, a clinical academic at the University of Exeter Medical School, believes we should be wearing masks outdoors. He says we know with influenza (flu), the virus is more stable in cold, dry conditions, and low humidity means it can hang in the air for longer than normal. It’s therefore a possibility that Covid-19 might follow suit. 

Some studies have found the virus that causes Covid-19 can remain infectious in the air for more than three hours. Ventilation is key to dispersing airborne droplets, which is why outdoor transmission is thought to be less of a risk.

Recent recommendations from the British Medical Association (BMA), however, called for mandatory mask-wearing in all outdoor settings where two-metre social distancing is not possible. 

“The bottom line is that the current plan of the rule of six and mask-wearing indoors in some places isn’t working,” says Dr Strain. “So it’s [about] trying to do absolutely anything that prevents us from ending up in another lockdown with school closures and the devastating consequences of that.”

Dr Strain doesn’t think people should wear face masks in their own gardens or to walk the dog, but rather, in places where we interact socially with others – outside a pub or walking between shops, for example. 

There are two main benefits, he says. The first is we’re keeping our droplets to ourselves when we do interact with others, so we’re not endangering them. The second is that putting our mask on and off repeatedly when we’re going into shops, or in and out of beer gardens, could risk us moving virus from our masks onto our hands, and then onto surfaces which other people might touch.

Obviously there are caveats to outdoor mask-wearing, as rainy, damp weather can compromise their effectiveness.

Julii Brainard, a researcher at Norwich Medical School, University of East Anglia, suggests there isn’t any “emerging and robust evidence” that wearing face covers outdoors would make a noticeable difference to transmission of the virus. That said, she recognises the benefits of it. 

“It could be that making face cover-wearing more conventional everywhere will ensure people don’t forget to mask up when they pop indoors and remind us all to be constantly careful,” she says. 

People who want to wear masks when outdoors should continue to do so if it makes them feel comfortable, but it’s highly unlikely we’ll see a shift in government guidance on the issue – as SAGE said: “It is critical that recommendations are seen to be based on the science and proportionate otherwise the legitimacy of mask-wearing overall will be compromised.

“Given that the evidence suggests outdoor spread to be very limited, this may be seen as an excessive measure.”

Professor Melinda Mills, director of the Leverhulme Centre for Demographic Science, at the University of Oxford and author of a Royal Society report on face coverings for the general public, says mandatory mask-wearing in closed and crowded places, and close contact settings, are more essential than ever as we head into winter.