The World Health Organization (WHO) recommended that in places with widespread transmission of coronaviruses, all people who cannot maintain a distance of two meters with others, such as in public transport, shops or crowded indoor spaces, use masks or any face cover.
In an update of its advice on this protective element, the organization believes that as countries lift confinement measures and restrictions on movement, people need to use them to curb spread.
Until now, the WHO only recommended - according to its guide of April 6 - the use of masks for people who come into contact with potentially contaminated people, or those showing symptoms; as well as for healthcare personnel.
WHO now states that masks were part of an effective strategy to suppress the virus and could lead people to a false sense of security. It said they were not a substitute for physical distancing or hand hygiene.
Do fabric face masks work?
There is new scientific evidence (from research at Stanford University and Colorado University) about face masks, the various materials they can be made from, and the level of protection they provide.
Ideally, the fabrics should be combined and the mask should have three layers, using the most absorbent material (e.g. cotton) closest to the mouth, which will cause the drops to stay there if you cough or sneeze.
In many countries, the most commonly used masks are cotton masks made by hand, either because surgical masks are in short supply and are reserved for medical personnel or because they are cheaper.
Face masks have to fit tightly around the face, covering the nose and mouth. Studies show that household materials that best remove particles of the typical size of viruses and bacteria include vacuum cleaner bags, heavyweight cotton or multiple layers of material. Materials typically ised for scarves are less effective, but still captured some particles.