The World Health Organization (WHO) has changed its advice on face masks, recommending that governments should encourage people to wear fabric masks where social distancing isn't possible and that the over-60s should wear 'medical' masks in specific circumstances.
The WHO has previously resisted advising the use of face masks by the general public because of a lack of evidence for their effectiveness.
It was also concerned their use could lead to a false sense of security, and a lax approach to good hand hygiene and social distancing, which remain the most effective measures to prevent the disease spreading.
Now, it's advising governments to encourage people to use non-medical (ideally triple-layer) fabric masks, 'especially in settings where physical distancing of at least one metre is not possible - such as on public transport, in shops or in other confined or crowded environments'.
It also suggests those over the age of 60 may wish to wear 'medical' masks - the simple surgical-type disposable masks that are worn in some other countries by the general public.
We've spotted an increasing number of high street retailers stocking disposable masks, including Boots, Superdrug and supermarkets such as Tesco and Asda.
Aldi is selling simple reusable fabric masks this week as part of its regular special buy deal (£4.99 for a pack of two cotton masks).
So should you be buying face masks and what type should you buy? We've looked into the WHO guidance to bring you the latest.
But there are some key differences:
The conflicting advice has created further unknowns about the practical implications of mask use for the public.
The WHO defines a medical mask as a surgical or procedure mask that is flat or pleated, affixed to the head with straps that go around the ears or head, or both.
As in the image above, it's the simpler type of disposable medical mask, as opposed to a more tightly fitting medical-grade respirator mask.
These disposable masks can filter large droplets produced by someone coughing or talking loudly near you, but are less able to filter the tiny aerosol particles that also potentially carry the virus, so they aren't generally considered by experts to protect against COVID-19.
We have queried this with the WHO, as its new guidance suggests they should be worn for the benefit of the wearer. Based on their guidance, it seems that WHO currently thinks that larger droplets are a more likely route of infection that aerosol particles, so medical masks would provide some protection for the wearer - but you still should not rely on masks as your main form of protection.
The WHO does caveat that in settings where medical masks are in short supply, medical masks should be reserved for health workers and at-risk individuals.
But some pharmacy and supermarket chains across the UK have now started to stock disposable face masks, even though the UK government still advises that medical masks should not be used by the general public.
Boots has a lengthy explainer on its website, and has interpreted the government advice on face coverings as 'including face masks'. Its selling two different types of disposable mask in packs of 50 (£30, 60p per mask).
Boots says that it has 'worked with the government and Public Health England, as well as our partners in the Care Homes sector, to give them access to stock before we make it available to customers'.
Other chains stocking similar products (at similar prices) include Asda, Co-op Pharmacy, Lloyds Pharmacy, Superdrug and Tesco.
These types of mask don't filter smaller airborne viral particles. All the retailers caveat that the masks are not intended to protect the wearer, but those around them.
Surgical or medical face masks are single-use disposable products, usually sold in boxes of 50 or more.
They tend to be blue, rectangular and pleated, with elastic ear straps. They come in three different levels of filtration:
Respirator masks, including FFP2, FFP3 and N95 masks (picture above) are designed to protect the wearer against the inhalation of both droplets and fine aerosol particles, and should be used by healthcare workers only.
The WHO does not recommend this type of mask for anyone except frontline health workers.
There are environmental and cost considerations around using disposable masks,too, as the need for social distancing and other protective measures to continue for an extended period of time looks increasingly likely.
Larger packs of 50 masks are around £30 at most high street retailers, costing around 60p per mask. In smaller packs they can cost up to £1 per mask.
So using disposable masks could end up costing you £24 to £40 per month, if you were using two per day for commuting to and from work.
They are also single-use and non-recyclable plastic-based products, so widespread use could have a hugely detrimental effect on the environment.
We urge particular caution when buying these products from online marketplaces, as unscrupulous sellers may take advantage of renewed demand to charge extortionate prices or to sell counterfeit products that don't meet required standards.
The UK government instructions for making your own mask include options for single or double-layer cotton masks, and the government has also said that people could just use a bandana or scarf.
The WHO recommends a slightly more complex formulation, based on a review of available evidence. This aims to mimic the surgical mask construction with three layers of different material.
The WHO guidance implies that people may be able to make their own masks, but doesn't give specific instructions on doing so.
It also includes important guidance, which the latest WHO guidance reiterates, on wearing a face mask safely. Failure to do so could increase your risk of infection.
There has so far been little in the way of standardised instructions for maintaining and washing cloth face coverings.
The new WHO guidance says that clothing fabrics used to make masks should be checked for the highest permitted washing temperature and masks should be washed at 60°C with soap or laundry detergent.
Alternatively, you can wash masks with soap/detergent at room temperature water, followed by boiling the mask for one minute.