Face masks become a more regular site on our streets, in our supermarkets and on public transport.
People have turned to them as one of the ways to help protect themselves during the coronavirus pandemic, and they’ve become so popular it’s very hard to buy any.
But when should you wear one? And who should wear one?
Mayor of London Sadiq Khan believes the public should be wearing facemasks when they leave the house., however the UK's chief medical officer Chris Whitty has said evidence of their effectiveness is minimal.
The World Health Organisation (WHO) has issued advice on who should use them, and when.
Its advice covers who should wear them, when they should be worn, and how to wear them - in order to avoid masks causing infections of their own.
The UK government’s social distancing guidelines do not advise people to wear masks either.
Who should wear a face mask and where?
The WHO advises people to wear masks if they are showing symptoms such as coughing, sneezing, a fever or difficulty breathing.
It says anyone not displaying symptoms does not need to wear them as “there is no evidence that they protect people who are not sick”.
As well as those who are sick, the WHO says medical masks "should only be used by healthcare workers and caretakers", meaning healthy people should wear a mask if taking care of someone suspected of being infected with Covid-19.
They should also be worn in combination with constant hand-washing, with the WHO suggesting that a mask alone can give a “false feeling of protection”.
The WHO also gives guidance for how to use masks and how to dispose of them.
How to wear a face mask
Anyone using a mask must clean their hands with alcohol-based hand gel or soap and water before putting it on.
The mask must cover the nose and mouth with no gaps between skin and mask.
Once on, it must not be touched. If anyone touches their masks with their hands while wearing it, they must wash their hands with hand sanitizer or soap and water.
If the mask becomes damp it must be replaced immediately. Single-use masks must not be re-used.
When taking a mask off, remove it from behind with the straps - don’t touch the front of the mask - and put it into a closed bin immediately before washing hands.
