The British public has been advised to wear "face coverings" as part of the Government's Covid-19 recovery strategy.
Here are your questions about the use of coverings and masks answered.
– What has the Government said?
People should wear face coverings when they are in "an enclosed space where social distancing isn't possible and where you will come into contact with people you do not normally meet", for instance in some shops or on public transport.
– Why is it recommending face coverings?
The Government document states that, while wearing a face covering does not protect the wearer, it may protect others if people are infected but have not yet developed symptoms.
– Who should wear one?
Experts have previously suggested that, in order for the use of masks to be an effective tool in reducing infections, around nine in 10 people need to wear them.
Some groups – such as people with breathing problems or young children – may struggle to wear face coverings.
The Government document states that face coverings should not be used by children under the age of two, people with respiratory conditions or those who may find it difficult to manage them correctly – such as primary school age children unassisted.
– Will pupils need to wear face coverings at school?
No. Further advice on protective measures in schools will be published in "coming weeks", officials said.
– What about at work?
The Government FAQ on face coverings at work states: "Face coverings are not compulsory. However, if you can, people are advised to wear face coverings in enclosed public spaces where social distancing is not possible or where you are more likely to come into contact with people you do not normally meet."
A Department of Health and Social Care press release on the issue adds: "They do not need to be worn outdoors, while exercising, in schools, in workplaces such as offices, and retail or by those who may find them difficult to wear."
– If I develop Covid-19 symptoms can I still go out if I wear a mask or covering?
No. The document states: "If you have symptoms of Covid-19 (cough and/or high temperature) you and your household should isolate at home: wearing a face covering does not change this."
– What sort of face coverings should I use?
Scarves, cotton home-made coverings that cover nose and mouth and other bought masks that are not ones used by the health service are fine.
Officials said that people can make coverings at home, but added that "the key thing is it should cover your mouth and nose".
People have been advised not to use surgical masks or respirators as these should be reserved for health and care workers and for people in industrial settings such as those exposed to dust.
The World Health Organisation has said it is imperative that medical masks are prioritised for health and care workers.
But it has also suggested that people in the community who have Covid-19, or are caring for someone with it, should also wear medical masks.
– What about health workers?
Concerns have previously been raised about the prospect of dwindling supplies for health workers following an instruction for the general public to wear masks.
But health and care workers are required to wear specific types of surgical masks or respirators depending on the type of care they are giving a patient.
The government document suggests that surgical masks and respirators must be reserved for those who need them to protect against risks in their workplace.
Last month, Scotland issued guidance on the use of face coverings in public, urging people to use coverings in enclosed spaces where the two-metre social distancing rule is hard to maintain – in food shops or on public transport for example.
– What is the science?
Officials have said that the science behind the use of face masks and face coverings is "not straightforward".
It appears that one of the main routes of the spread of the novel coronavirus is through droplets – usually through coughs and sneezes, but these can also spread through talking.
The Scientific Advisory Group for Emergencies (Sage) thinks the evidence of masks preventing the spread of infection from one person to another is "marginal but positive".
Studies into coughs and flu have previously shown that a medical mask can help prevent the spread of infectious droplets from an infected person to someone else.
They might also prevent potential contamination of the wider environment by these droplets.
But the World Health Organisation has stressed that there is no evidence that wearing a mask – whether medical or other types – by healthy persons in the wider community can prevent them from infection with respiratory viruses, including Covid-19.
– Will it be enforced?
Officials have said that the new guidance will not be enforced by law.
– Can I make a face mask at home?
Yes. The Government website has suggestions on how masks can be made with an old T-shirt or material sewn together.
– Are there any downsides to using face coverings?
Concerns have been raised that masks could give a false sense of security and mean that people are less stringent with other preventative measures such as social distancing and hand hygiene.
Problems could also arise without the proper use of a mask – including possible self-contamination if people touch and re-use a contaminated mask.
Depending on the type of mask used, some people may incur breathing difficulties.
– What about public transport?
Transport for London has urged people to wear face coverings while travelling on its network.
And the Government document specifically mentions public transport as a place where face coverings should be used.
– What have experts said?
Trish Greenhalgh, professor of primary care at the University of Oxford, told the PA news agency: "I'm delighted that the Government has changed its position on face coverings for the lay public. The science on this is clear: Covid-19 is most commonly transmitted by droplets emitted when we cough, sneeze, shout, sing and even just breathe in close proximity to others.
"Cloth face coverings are highly effective at blocking droplets coming out of the mouth and nose. They're not perfect, but if you can stop 90% or 95% of the droplets this will cause a very dramatic reduction in the number of people who catch the virus.
"Face coverings, which can be made out of a double layer of cloth, are a crucially important measure for bringing the country out of lockdown, since in reality few of us can get properly back to work without getting within two metres of other people (either while travelling to work or in offices and factories).
"We can't stay behind our front doors forever, and nobody wants a second wave of Covid-19, so covering our faces will become the new normal in public places, workplaces and on public transport.
"We'd all prefer not to have to wear these but if most people do wear them, we'll flatten the curve a lot more quickly, reduce pressure on the NHS, and help the economy recover.
"Remember, cloth masks are for source control: my mask protects you and your mask protects me."
Face coverings for the lay public is now UK government policy, though I wish they'd asked me to help draft this paragraph. I'd have been more emphatic and succinct. pic.twitter.com/r1U7MJe9qU
— Trisha Greenhalgh 😷 (@trishgreenhalgh) May 11, 2020
Babak Javid, professor at the Tsinghua University School of Medicine in Beijing and a consultant in infectious diseases at Cambridge University Hospitals, told PA: "For transmission blocking, face coverings would need to be used by at least 50% and ideally more than 70% of the population to have an appreciable impact on transmission.
"Although face coverings are all likely to have some impact, some coverings – for example, well-designed cloth masks made with appropriate materials, are likely to be more effective than wrapping a scarf around one's mouth."
– Will the Government supply coverings?
No. Officials said that people can use items already found in their homes which can be turned into face coverings – such as old t shirts.
– What have officials said?
Prime Minister Boris Johnson told the House of Commons: "With more activity outside our homes we'd now advise people to wear a cloth face covering in enclosed spaces where social distancing is not always possible and you're more likely to come into contact with people you don't normally meet.
"Face coverings can help to protect each other and reduce the spread of the disease, particularly if you have coronavirus-like symptoms.
"But this does not mean wearing medical face masks... which must be reserved for people who need them."
England's chief medical officer Professor Chris Whitty said face coverings are not a replacement for social distancing and regular handwashing – which remain the most important actions.