Let’s face it — you’re not going to any marvellous parties as long as social distancing is in force, so why not cut up your mothballed Vera Wangs to make face masks?
Scientists have claimed that homemade masks made from cotton combined with natural silk or chiffon provide the best protection against coronavirus.
Chiffon — used to fashion stunning couture — can sift out 99 per cent of droplets from coughs and sneezes when placed between two layers of cotton.
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Scientists have claimed that homemade masks made from cotton combined with natural silk or chiffon provide the best protection against coronavirus. Chiffon — used to fashion stunning couture — can sift out 99 per cent of droplets from coughs and sneezes when placed between two layers of cotton (stock image)
‘One layer of a tightly woven cotton sheet combined with two layers of polyester-spandex chiffon—a sheer fabric often used in evening gowns—filtered out the most aerosol particles,’ said paper author Supratik Guha of the University of Chicago.
Researchers found that they are virtually as good as the visors used by doctors and nurses in hospitals — which are in extremely short supply.
The British public have been told to wear face masks at work and on public transport after scientists told the government that they may help slow coronavirus’ spread.
Substituting the chiffon with natural silk or flannel, or simply using a cotton quilt with cotton-polyester batting, produced similar results.
‘Tightly woven fabrics, such as cotton, can act as a mechanical barrier to particles,’ said Professor Guha.
‘Fabrics that hold a static charge, like certain types of chiffon and natural silk, serve as an electrostatic barrier.’
This explains why they work so well in combination, the team report,
But even the tiniest gap between the face reduced their efficiency by half or more — emphasising the importance of a properly fitted mask, Professor Guha warned.
Virus particles are tiny, ranging from 0.1–0.3 micron — invisible to the naked eye — but surgical masks are designed to prevent them flowing in and out of the mouth.
However, such protective wear is in short supply — and being reserved for health care workers treating patients with COVID-19.
Made correctly, a homemade mask can reduce transmission from the wearer to others — and vice versa — by impeding the droplets and spray produced when we breathe, cough or sneeze.
Virus particles are tiny, ranging from 0.1–0.3 micron — invisible to the naked eye — but surgical masks are designed to prevent them flowing in and out of the mouth. However, such protective wear is in short supply — and being reserved for health care workers, pictured
The US Centers for Disease Control and Prevention has recommended that people wear face masks when out in public.
‘Because hospital masks are scarce and should be reserved for health care workers, many people are making their own coverings,’ said Professor Guha.
‘A combination of cotton with natural silk or chiffon can effectively filter out aerosol particles — if the fit is good.’
COVID-19 spreads mainly through the respiratory droplets that are released when an infected person coughs, sneezes, speaks or breathes.
These droplets form in a wide range of sizes, but the tiniest ones — called aerosols — can easily slip through the openings between certain cloth fibres.
This has led some people to question whether masks can actually help to prevent diseases from spreading — yet a growing body of evidence suggests that they can.
‘Tightly woven fabrics, such as cotton, can act as a mechanical barrier to particles,’ said Professor Guha. ‘Fabrics that hold a static charge, like certain types of chiffon and natural silk, serve as an electrostatic barrier.’ This explains why they work so well in combination
Chiffon filtered out 80–99 per cent of the droplets, depending on their size — with a performance ‘close to that’ of a hospital mask, Professor Guha said (stock image)
Professor Guha and colleagues analysed the ability of common fabrics, alone or in combination, to filter out aerosols similar in size to respiratory droplets.
They used an aerosol mixing chamber to produce particles ranging from 10 nanometres to 6 μm microns in diameter.
A fan blew the aerosol across various cloth samples at a flow rate corresponding to a person’s respiration at rest.
The team then measured the number and size of particles in the air before and after passing through the fabric.
The chiffon filtered out 80–99 per cent of the droplets, depending on their size — with a performance ‘close to that’ of a personal protective equipment hospital mask, Professor Guha said.
Masks should completely cover the nose and mouth. When measuring for a pattern, it needs to extend from the top of the nose — as close as possible to the eyes without obstructing sight — to under the chin.
Masks should cover the face side-to-side and well past the opening of the mouth. All edges should be checked for gaps.
These can be closed up by pinching the fabric together and stitching, taping or stapling to create a pleat or dart.
Masks should stay securely in position and fit comfortably with ties or elastic ear loops. If the mask is too tight or loose, the wearer may continuously adjust the mask, forgetting the admonition — ‘Don’t touch your face!’
The ties and loops should also be the mechanism for taking off the mask, as the front of the mask might be contaminated.
‘Our studies also imply that gaps, as caused by an improper fit of the mask, can result in over a 60 per cent decrease in the filtration efficiency,’ said Professor Guha.
‘In summary, we find the use of cloth masks can potentially provide significant protection against the transmission of particles in the aerosol size range.’
The full findings of the study were published in the journal ACS Nano.