Face masks during the COVID-19 pandemic: Difference between revisions

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→‎Cloth masks: Rm unsourced, challenged statement. Air pollution is out of scope of this article. The rest is redundant with cited content below.
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Improvised cloth maks seem to be worse than standard commercial disposible masks, but better than nothing. There is, however, little good evidence on them. A single study gives evidence that an improvised mask was better than nothing, but not as good as soft electret-filter surgical mask, for protecting health care workers simulating treating a simulated infected patient, regardless of whether "patient" or carers wore the mask.<ref name=scoping/> Another study had volunteers wear masks they made themselves, to a pattern like that of a standard surgical mask, but with ties rather than earloops,<ref>{{cite journal |last1=Davies |first1=Anna |last2=Thompson |first2=Katy-Anne |last3=Giri |first3=Karthika |last4=Kafatos |first4=George |last5=Walker |first5=Jimmy |last6=Bennett |first6=Allan |title=Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? |journal=Disaster Medicine and Public Health Preparedness |date=22 May 2013 |volume=7 |issue=4 |pages=413–418 |doi=10.1017/dmp.2013.43 |pmid=24229526 |pmc=7108646 |issn=1935-7893}}</ref> from cotton T-shirts, and found that the number of microscopic particles that leaked inside the homemade masks was twice the number that leaked into the commercial masks, and that the homemade mask let three times as many microorganisms expelled by the wearer escape ([[median]] averages). There is limited evidence that cloth masks can significantly reduce [[droplet dispersal]].<ref name=scoping/>
Improvised cloth maks seem to be worse than standard commercial disposible masks, but better than nothing. There is, however, little good evidence on them. A single study gives evidence that an improvised mask was better than nothing, but not as good as soft electret-filter surgical mask, for protecting health care workers simulating treating a simulated infected patient, regardless of whether "patient" or carers wore the mask.<ref name=scoping/> Another study had volunteers wear masks they made themselves, to a pattern like that of a standard surgical mask, but with ties rather than earloops,<ref>{{cite journal |last1=Davies |first1=Anna |last2=Thompson |first2=Katy-Anne |last3=Giri |first3=Karthika |last4=Kafatos |first4=George |last5=Walker |first5=Jimmy |last6=Bennett |first6=Allan |title=Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? |journal=Disaster Medicine and Public Health Preparedness |date=22 May 2013 |volume=7 |issue=4 |pages=413–418 |doi=10.1017/dmp.2013.43 |pmid=24229526 |pmc=7108646 |issn=1935-7893}}</ref> from cotton T-shirts, and found that the number of microscopic particles that leaked inside the homemade masks was twice the number that leaked into the commercial masks, and that the homemade mask let three times as many microorganisms expelled by the wearer escape ([[median]] averages). There is limited evidence that cloth masks can significantly reduce [[droplet dispersal]].<ref name=scoping/>


Cloth masks are commonly made with one layer, two layers, or two layers with a pocket for a removable-filter interlayer <ref name=scoping/> (disposible surgical mask also have three layers, with the filter layer midmost{{cn|date=May 2020}}). The CDC recommends more than one layer.<ref>{{cite web |title=Coronavirus Disease 2019 (COVID-19) |url=https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html |website=Centers for Disease Control and Prevention |language=en-us |date=11 February 2020}}</ref> There is no research on the usefulness of a filter interlayer, {{as of|lc=yes|May 2020}}. There were until recently no non-disposible materials designed for making masks (see end of paragraph). Common household fabrics which could be utilized (turned to a new use) as mask materials have been tested. Cloth materials vary widely in filtration efficiency. Some cotton and polyester household fabrics have been found to compare with disposible surgical masks for dry particle filtering. Cotton T-shirt material, pillowcase material, and 70% cotton/30% polyester [[sweatshirt]] material are among the common materaials that performed well in lab tests, with T-shirts preferred to pillowcases because it was thought that it would probably fit better. Teatowels and vacuum-cleaner bags were effective at filtering, but had a very high air resistance, so were not recommended. Scarves filtered poorly. Surgical sterilisation wrap, a [[polypropylene]] [[non-woven fabric]] made for wrapping sterilized things to keep them sterile, is designed to filter germs from the air. Using surgical sterilisation wrap to make masks, or as a filter interlayer in cloth masks, has been suggested. There are, however, no tests on using surgical sterilisation wrap for masks, {{as of|lc=yes|May 2020}}.<ref name=scoping/> Other suggested materials for filter interlayers include [[air filter]] materials used in ventilation, heating, and air conditioning, some of which are similar to rigid electret masks in the size ranges of particles they filter. Electrostatic cotton and non-woven, meltblown fabric are the conventional materials used in disposible masks, but are not readily available during the COVID-19 epidemic. A new type of filter, a washable electrostatic cotton filter, has been reported since the start of the pandemic; it is said to withstand repeated washing and folding.<ref name=scoping/> It is made of [[electrospun]] [[nanofibers]]; flanking insulating blocks lay these into quasi-aligned nonwoven sheets, which are layered criss-cross to make a meshlike multilayer mask.<ref>{{cite news |title=Washable Face Masks Thanks to Electrospun Nanofibers|url=https://www.medgadget.com/2020/03/washable-face-masks-thanks-to-electrospun-nanofibers.html |work=Medgadget |date=23 March 2020}}</ref><ref>{{cite journal |last1=Hwang |first1=Wontae |last2=Pang |first2=Changhyun |last3=Chae |first3=Heeyeop |title=Fabrication of aligned nanofibers by electric-field-controlled electrospinning: insulating-block method |journal=Nanotechnology |date=28 October 2016 |volume=27 |issue=43 |pages=435301 |doi=10.1088/0957-4484/27/43/435301}}</ref> There is a need for research comparing how well these materials work.<ref name=scoping/>
Cloth masks are commonly made with one layer, two layers, or two layers with a pocket for a removable-filter interlayer <ref name=scoping/> (disposible surgical mask also have three layers, with the filter layer midmost{{cn|date=May 2020}}). The CDC recommends more than one layer.<ref>{{cite web |title=Coronavirus Disease 2019 (COVID-19) |url=https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html |website=Centers for Disease Control and Prevention |language=en-us |date=11 February 2020}}</ref> There is no research on the usefulness of a filter interlayer, {{as of|lc=yes|May 2020}}. There were until recently no non-disposible materials designed for making masks (see end of paragraph). Common household fabrics which could be utilized (turned to a new use) as mask materials have been tested.<ref name="van der Sande Teunis Sabel p=e2618">{{cite journal | last=van der Sande | first=Marianne | last2=Teunis | first2=Peter | last3=Sabel | first3=Rob | editor-last=Pai | editor-first=Madhukar | title=Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population | journal=PLoS ONE | publisher=Public Library of Science (PLoS) | volume=3 | issue=7 | date=2008-07-09 | issn=1932-6203 | doi=10.1371/journal.pone.0002618 | page=e2618}}</ref><ref name="Davies Thompson Giri Kafatos pp. 413–418">{{cite journal | last=Davies | first=Anna | last2=Thompson | first2=Katy-Anne | last3=Giri | first3=Karthika | last4=Kafatos | first4=George | last5=Walker | first5=Jimmy | last6=Bennett | first6=Allan | title=Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? | journal=Disaster Medicine and Public Health Preparedness | publisher=Cambridge University Press (CUP) | volume=7 | issue=4 | date=2013-05-22 | issn=1935-7893 | doi=10.1017/dmp.2013.43 | pages=413–418}}</ref><ref name="Oxford University Press (OUP) p. ">{{cite journal | title=Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles | journal=The Annals of Occupational Hygiene | publisher=Oxford University Press (OUP) | date=2010-06-28 | issn=1475-3162 | doi=10.1093/annhyg/meq044 | page=}}</ref><ref name="Konda Prakash Moss Schmoldt p. ">{{cite journal | last=Konda | first=Abhiteja | last2=Prakash | first2=Abhinav | last3=Moss | first3=Gregory A. | last4=Schmoldt | first4=Michael | last5=Grant | first5=Gregory D. | last6=Guha | first6=Supratik | title=Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks | journal=ACS Nano | publisher=American Chemical Society (ACS) | date=2020-04-24 | issn=1936-0851 | doi=10.1021/acsnano.0c03252 | page=}}</ref> Cloth materials vary widely in filtration efficiency. Some cotton and polyester household fabrics have been found to compare with disposible surgical masks for dry particle filtering. Cotton T-shirt material, pillowcase material, and 70% cotton/30% polyester [[sweatshirt]] material are among the common materaials that performed well in lab tests, with T-shirts preferred to pillowcases because it was thought that it would probably fit better. Teatowels and vacuum-cleaner bags were effective at filtering, but had a very high air resistance, so were not recommended. Scarves filtered poorly. Surgical sterilisation wrap, a [[polypropylene]] [[non-woven fabric]] made for wrapping sterilized things to keep them sterile, is designed to filter germs from the air. Using surgical sterilisation wrap to make masks, or as a filter interlayer in cloth masks, has been suggested. There are, however, no tests on using surgical sterilisation wrap for masks, {{as of|lc=yes|May 2020}}.<ref name=scoping/> Other suggested materials for filter interlayers include [[air filter]] materials used in ventilation, heating, and air conditioning, some of which are similar to rigid electret masks in the size ranges of particles they filter. Electrostatic cotton and non-woven, meltblown fabric are the conventional materials used in disposible masks, but are not readily available during the COVID-19 epidemic. A new type of filter, a washable electrostatic cotton filter, has been reported since the start of the pandemic; it is said to withstand repeated washing and folding.<ref name=scoping/> It is made of [[electrospun]] [[nanofibers]]; flanking insulating blocks lay these into quasi-aligned nonwoven sheets, which are layered criss-cross to make a meshlike multilayer mask.<ref>{{cite news |title=Washable Face Masks Thanks to Electrospun Nanofibers|url=https://www.medgadget.com/2020/03/washable-face-masks-thanks-to-electrospun-nanofibers.html |work=Medgadget |date=23 March 2020}}</ref><ref>{{cite journal |last1=Hwang |first1=Wontae |last2=Pang |first2=Changhyun |last3=Chae |first3=Heeyeop |title=Fabrication of aligned nanofibers by electric-field-controlled electrospinning: insulating-block method |journal=Nanotechnology |date=28 October 2016 |volume=27 |issue=43 |pages=435301 |doi=10.1088/0957-4484/27/43/435301}}</ref> There is a need for research comparing how well these materials work.<ref name=scoping/>


====Sterilizing and re-use====
====Sterilizing and re-use====

Revision as of 08:03, 12 May 2020

Taiwan President Tsai Ing-wen wearing a mask.
Some different types of filtering masks

The wearing of face masks during the COVID-19 pandemic has received varying recommendations from different public health agencies and governments. The topic has been a subject of debate,[1] with various public health agencies and governments disagreeing on a protocol for wearing face masks. As of early May, 88% of the world's population lives in countries that recommend or mandate the usage of masks in public and 75+ countries have mandated the use of masks[2]. Debates have emerged regarding whether masks should be worn even when social distancing at six feet,[3][4][5][6][unreliable source?] whether they should be worn during exercise,[7][8][unreliable source?] worn in the home to reduce viral load,[9][10] and whether there are mitigating factors.[11][9] Additionally, public health agencies of different countries and territories have often changed their recommendations regarding face masks over time.[12] Face masks have been a subject of shortages, and also been made compulsory in some countries.

Types of face masks, from least to most protective, include cloth face masks, medical (non-surgical) masks,[13][14] surgical masks, and filtering facepiece respirators such as N95 masks and FFP masks. Face shields and medical goggles are other types of protective equipment often used together with face masks.

Types of masks

Small particles zigzag due to Brownian motion, and are easily captured. Large particles get strained out, or have too much inertia to turn, and hit a fiber. Mid-size particles follow flowlines and are more likely to get through the filter; the hardest size to filter is 0.3 microns diameter.[15]

Certified medical masks are disposable (except some faceshields). They are made of non-woven material. They are mostly multi-layer. Filter material may be made of microfibers with an electrostatic charge; that is, the fibers are electrets. An electret filter increases the chances that smaller particles will veer and hit a fiber, rather than going straight through (electrostatic capture).[15][16][17][better source needed][medical citation needed] Generally, washing will destroy the static charge on current electret filters. Washable electret filters are in development, as of May 2020.[18][clarification needed]

Many medical masks are respirators; they are designed to protect the wearer. Surgical masks, on the other hand, are designed to protect the patient from the surgeon's breath.[19][medical citation needed] Some masks have valves,[18] which let exhaled air out unfiltered. This makes them useless for source protection (protecting others against infection by the wearer's breath).[20] It may, however, reduce inwards leakage and thus improve wearer protection.[18]

Face shields

A simple face shield; curved visor, drawstring lanyard, sheet of transparent plastic curved from side to side
A simple 3D-printed face shield. More complex models have helmets.
Person wearing a face shield over a green surgical mask
In medical use, face shields are worn with masks (and, usually, protective clothing, not shown here)

It is not yet known whether face shields are effective at preventing disease transmission. They protect against splash and splatter. Cough simulation experiments show that they protect[18] the wearer[21] against large drops immediately after the cough, but do not keep out smaller aerosols. The longer it was after the simulated cough, the more particles found their way around. Because there is no evidence they prevent the wearer from getting ill, face shields are used with nose-mouth masks, and to protect nose-mouth masks, but use of face shields alone is not recommended.[18]

Cloth masks

Homemade cloth face mask
Sneezing. There is limited evidence that cloth masks can significantly reduce aerosol droplet dispersal.[18]

A cloth face mask is a mask made of a common textile, usually cotton, worn over the mouth and nose. Although they are less effective than medical-grade masks, many health authorities recommend that the general public use them because medical-grade masks are in short supply.[22][23]

They were routinely used by healthcare workers starting from the late 19th century until the mid 20th century. In the 1960s they fell out of use in the developed world in favor of modern surgical masks, but their use has persisted in developing countries.[24][25][26]

There were calls for research into the effectiveness of improvised masks even before the emergence of COVID-19, motivated also by past epidemics and modelling of likely mask shortages. However, little research has been done. There are no studies of the use of cloth masks by the general public, one study on the use of cloth masks in hospitals (by healthcare workers, not patients[citation needed]), and many controlled-setting/lab studies of cloth masks' effects on aerosols as of May 2020.[18]

Cloth masks are low-cost and reusable. They vary widely in effectiveness depending on material, fit/seal, and number of layers, among other factors. Unlike disposable masks, there are no legal standards for cloth masks. Fit is important (as with disposable masks). Measures to improve fit, such as an outer layer made from sheer nylon stockings or sheer tights around the head, reduce leakage.[18]

Improvised cloth maks seem to be worse than standard commercial disposible masks, but better than nothing. There is, however, little good evidence on them. A single study gives evidence that an improvised mask was better than nothing, but not as good as soft electret-filter surgical mask, for protecting health care workers simulating treating a simulated infected patient, regardless of whether "patient" or carers wore the mask.[18] Another study had volunteers wear masks they made themselves, to a pattern like that of a standard surgical mask, but with ties rather than earloops,[27] from cotton T-shirts, and found that the number of microscopic particles that leaked inside the homemade masks was twice the number that leaked into the commercial masks, and that the homemade mask let three times as many microorganisms expelled by the wearer escape (median averages). There is limited evidence that cloth masks can significantly reduce droplet dispersal.[18]

Cloth masks are commonly made with one layer, two layers, or two layers with a pocket for a removable-filter interlayer [18] (disposible surgical mask also have three layers, with the filter layer midmost[citation needed]). The CDC recommends more than one layer.[28] There is no research on the usefulness of a filter interlayer, as of May 2020. There were until recently no non-disposible materials designed for making masks (see end of paragraph). Common household fabrics which could be utilized (turned to a new use) as mask materials have been tested.[29][30][31][32] Cloth materials vary widely in filtration efficiency. Some cotton and polyester household fabrics have been found to compare with disposible surgical masks for dry particle filtering. Cotton T-shirt material, pillowcase material, and 70% cotton/30% polyester sweatshirt material are among the common materaials that performed well in lab tests, with T-shirts preferred to pillowcases because it was thought that it would probably fit better. Teatowels and vacuum-cleaner bags were effective at filtering, but had a very high air resistance, so were not recommended. Scarves filtered poorly. Surgical sterilisation wrap, a polypropylene non-woven fabric made for wrapping sterilized things to keep them sterile, is designed to filter germs from the air. Using surgical sterilisation wrap to make masks, or as a filter interlayer in cloth masks, has been suggested. There are, however, no tests on using surgical sterilisation wrap for masks, as of May 2020.[18] Other suggested materials for filter interlayers include air filter materials used in ventilation, heating, and air conditioning, some of which are similar to rigid electret masks in the size ranges of particles they filter. Electrostatic cotton and non-woven, meltblown fabric are the conventional materials used in disposible masks, but are not readily available during the COVID-19 epidemic. A new type of filter, a washable electrostatic cotton filter, has been reported since the start of the pandemic; it is said to withstand repeated washing and folding.[18] It is made of electrospun nanofibers; flanking insulating blocks lay these into quasi-aligned nonwoven sheets, which are layered criss-cross to make a meshlike multilayer mask.[33][34] There is a need for research comparing how well these materials work.[18]

Sterilizing and re-use

There is no research on sterilizing and reusing cloth masks, as of May 2020.[18] The CDC recommends doffing the mask by handling only the ear loops or ties, placing it directly in a washing machine, and immediately washing your hands in soap and water for at least 20 seconds. They also recommend handwashing before donning the mask and again immediately after any time you touch it.[35]

There is no information on reusing a interlayer filter, and disposing of it after a single use may be desirable.[18]

Surgical masks

A surgical mask

A surgical mask is a loose-fitting, disposable device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. If worn properly, a surgical mask is meant to help block large-particle droplets, splashes, sprays, or splatter that may contain viruses and bacteria, keeping it from reaching the wearer's mouth and nose. Surgical masks may also help reduce exposure of the wearer's saliva and respiratory secretions to others.[36] A surgical mask, by design, does not filter or block very small particles in the air that may be transmitted by coughs, sneezes, or certain medical procedures. Surgical masks also do not provide complete protection from germs and other contaminants because of the loose fit between the surface of the face mask and the face.[36] However, in practice, with respect to some infections like influenza surgical masks appear as effective as respirators (such as N95 or FFP masks).[37] Surgical masks may be labeled as surgical, isolation, dental, or medical procedure masks.[36] Surgical masks are made of a nonwoven fabric created using a melt blowing process.[38][39]

Surgical masks made to different standards in different parts of the world have different ranges of particles which they filter. Similar-looking single-use masks are one-layer and only filter larger particles (e.g. Chinese standard YY/T0969 masks).[40][medical citation needed]

Hard electret-filter respirators: N95 (US)/FFP (EU)/P2 (Australia) etc. standard respirators

An N95 mask
An N95 with an outlet valve is used to clean a space-station toilet. Source control is irrelevant; the astronaut cannot infect the toilet.

An N95 mask is a particulate-filtering facepiece respirator that meets the N95 air filtration rating of the US National Institute for Occupational Safety and Health, meaning that it filters at least 95 percent of airborne particles, while not resistant to oil like the P95. It is the most common particulate-filtering facepiece respirator.[41] It is an example of a mechanical filter respirator, which provides protection against particulates, but not gases or vapors.[42] Like the middle layer of[citation needed] surgical masks, the N95 mask is made of four layers[18] of melt-blown nonwoven polypropylene fabric.[43][44][unreliable medical source?] The corresponding face mask used in the European Union is the FFP2 respirator.[45][46]

Hard electret-filter masks like N95 and FFP masks must fit the face to provide full protection. Untrained users often get a reasonable fit, but fewer than one in four gets a perfect fit. Fit testing is thus standard. A line of vaseline on the edge of the mask[47] has been shown to reduce edge leakage[18] in lab tests using manikins that simulate breathing.[47]

Sterilizing and re-use

Hard electret-filter masks are designed to be disposable, for 8 hours of continuous or intermittent use. One laboratory found that there was a decrease in fit quality after five consecutive donnings.[18]

Hard electret-filter masks are often reused, especially during pandemics when there are shortages. Infectious particles could survive on the masks for up to 24 hours after the end of use, according to studies using models of SARS-CoV-2;[18] In the COVID-19 epidemic, the US CDC recommended that if masks run short, each health care worker should be issued with five masks, one to be used per day, such that each mask spends at least five days stored in a paper bag between each use. If there are not enough masks to do this, they recommend sterilizing the masks between uses.[48] Some hospitals have been stockpiling used masks as a precaution.[49] The US CDC issued guidelines on stretching N95 supplies, recommending extended use over re-use. They highlighted the risk of infection from touching the contaminated outer surface of the mask, which even professionals frequently unintentionally do, and recommended washing hands every time before touching the mask. To reduce mask surface contamination, they recommended face shields, and asking patients to wear masks too ("source masking").[50]

Apart from time, other methods of disinfection have been tested. Physical damage to the masks has been observed when microwaving them, microwaving them in a steam bag, letting them sit in moist heat, and hitting them with excessively high doses of ultraviolet germicidal irradiation (UVGI). Chlorine-based methods, such as chlorine bleach, may cause residual smell, offgassing of chlorine when the mask becomes moist, and in one study, physical breakdown of the nosepads, causing increased leakage.[18] Fit and comfort do not seem to be harmed by UVGI, moist heat incubation, and microwave-generated steam.[18]

Some methods may not visibly damage the mask, but they ruin the mask's ability to filter. This has been seen in attempts to sterilize by soaking in soap and water, heating dry to 160°C, and treating with 70% isopropyl alcohol, and hydrogen peroxide gas plasma[18] (made under a vacuum with radio waves[51]). The static electrical charge on the microfibers (which attracts or repels particles passing through the mask, making them more likely to move sideways and hit and stick to a fiber[citation needed]) is destroyed by some cleaning methods. UVGI (ultraviolet light), boiling water vapour, and dry oven heating do not seem to reduce the filter efficiency, and these methods successfully decontaminate masks.[18]

UVGI (an ultraviolet method), ethylene oxide, dry oven heating and (highly toxic[citation needed]) vaporized hydrogen peroxide are currently the most-favoured methods in use in hospitals, but none have been properly tested.[18] Where enough masks are available, cycling them and reusing a mask only after letting it sit unused for 5 days is preferred.[48]

Elastomeric respirators

Elastomeric full-face masks

Elastomeric respirators were used as a substitute for N95 masks in the COVID-19 pandemic. Elastomeric respirators are reusable, but contain disposible components, such as filters which must be replaced when soiled, contaminated, or clogged. These components may be hard to find in a pandemic; the filters may thus be sterilized, in a way that does not harm the filter, and re-used. In medical use, they must be cleaned and disinfected, as some germs can survive on them for weeks. Full-face versions seal better and protect the eyes. If they have exhalation valves, then they are counterrecommended in settings where the unfiltered exhaled air might infect others (for instance, surgery). Fitting and inspection is essential to effectiveness.[20]

Powered air-purifying respirators (PAPRs)

A PAPR in a level-3 biosafety lab. Note waist pack and hose to blow air into headpiece.

PAPRs are expensive masks with a battery-powered blower that blows air through a filter to the wearer. Because they create positive pressure, they need not be tightly-fitted.[52] They do not filter exhaust from the wearer.[citation needed] They are not generally designed for healthcare use, as of 2017.[19]

Recommendations

Health organizations have recommended that people cover their mouth and nose with a bent elbow or a tissue when coughing or sneezing, and dispose of any tissue immediately.[53][54] Surgical masks are recommended for those who may be infected,[55][56][57] as wearing a mask can limit the volume and travel distance of expiratory droplets dispersed when talking, sneezing, and coughing.[58]

Masks have also been recommended for use by those who are taking care of someone who may have the disease.[57] The WHO has recommended the wearing of masks by healthy people only if they are at high risk, such as those who are caring for a person with COVID-19, though they also acknowledge that wearing masks may help people avoid touching their face.[57] Several countries have started to encourage the use of face masks by members of the public.[59]

As of May 2020, 88% of the world's population lived in countries where their government and leading disease experts recommended the use of masks in public places to limit the spread of COVID-19.[2]

World Health Organization recommendations

World Health Organization advice to the public in the context of COVID-19 endorsed the use of masks only under the following conditions:[60]

  • If you are healthy, you only need to wear a mask if you are taking care of a person with suspected 2019-nCoV infection.
  • Wear a mask if you are coughing or sneezing.
  • Masks are effective only when used in combination with frequent hand-cleaning with alcohol-based hand sanitizer or soap and water.
  • If you wear a mask, then you must know how to use it and dispose of it properly.

— World Health Organization

US Centers for Disease Control and Prevention

Guidance from the US Centers for Disease Control and Prevention on using and making cloth masks during the COVID-19 pandemic[61]

The United States Centers for Disease Control and Prevention (CDC) recommended in April 2020 that the general public wear cloth face coverings in public settings where other social distancing measures are difficult to maintain, such as grocery stores and pharmacies, especially in areas of significant community-based transmission, due to the significance of asymptomatic and pre-symptomatic disease transmission.[61][62]

In March 2020, the CDC recommended that if neither respirators nor surgical masks are available, as a last resort, it may be necessary for healthcare workers to use masks that have never been evaluated or approved by NIOSH or homemade masks, though caution should be exercised when considering this option.[63]

In March and April 2020, the CDC faced backlash over their earlier statements advising that most healthy people did not need to wear a mask. The earlier recommendations had been made to try to conserve supplies for medical professionals,[dubious ][medical citation needed] but damaged the agency's credibility.[64][65][66]

In January 2020, the was no evidence on whether masks were useful for people who were not sick in a community setting.[67]

China and Asia

China has specifically recommended the use of disposable non-surgical medical masks by healthy members of the public,[13][68] particularly when coming into close contact (1 metre (3 ft) or less) with other people.[69] Hong Kong recommends wearing a surgical mask when taking public transport or in crowded places.[70][71] Thailand's health officials are encouraging people to make cloth face masks at home and wash them daily.[72] The Taiwanese, South Korean, and Japanese governments have also recommended the use of face masks in public.

When asked about the mistakes that other countries were making in the pandemic in March, the Chinese Center for Disease Control and Prevention director-general George Fu Gao said:

"The big mistake in the U.S. and Europe, in my opinion, is that people aren't wearing masks. This virus is transmitted by droplets and close contact. Droplets play a very important role − you've got to wear a mask, because when you speak, there are always droplets coming out of your mouth. Many people have asymptomatic or presymptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others."[73]

Rationale for wearing masks

Queue to buy face masks in Hong Kong, 30 January 2020. Everyone in the line is already wearing a disposable medical mask.
Shadowgraphs. Left, videos of the outer airflow during a sneeze, comparing different methods of covering one's mouth and nose (and none).[74] Right, conversation. Convection also shown.

Among the reasons cited by Chinese health officials for the wearing of masks, even by healthy individuals, are the following:

  1. Asymptomatic transmission. Many people can be infected without symptoms or only with mild symptoms.[75]
  2. Impossibility of appropriate social distancing in many public places at all times.[75]
  3. Cost-benefit mismatch. If only the infected individuals wear a mask, they would possibly have a negative incentive to do so. An infected individual might get nothing positive, but only bear the costs such as inconvenience, purchasing expenses, and even prejudice.[75]
  4. There is no shortage of masks in China, which has been producing 100 million masks per day since early March.[75]

Leading microbiologist Yuen Kwok-yung from the University of Hong Kong cites a large viral load in sputum and saliva of an infected person and asymptomatic cases as the reasons why even healthy individuals should wear a mask.[76][77]

According to Stephen Griffin, a virologist at the University of Leeds, "Wearing a mask can reduce the propensity [of] people to touch their faces, which is a major source of infection without proper hand hygiene."[78] The precautionary principle has also been cited by the British Medical Journal as a reason some may encourage universal face mask wearing.[79]

Asian health officials and experts have been promoting universal masking. For instance, Linfa Wang (a leading infectious disease expert who heads a joint Duke University and National University of Singapore research team) stated that masking is about "preventing the spread of disease rather than preventing getting the disease," remarking that the point is to cover the faces of people who are infected but do not know it, so it is imperative for everyone to wear one in public.[80]

Recent studies have suggested that the required six feet of social distancing is insufficient and based on debunked studies from the 1930s or error.[81][82][1] Researchers and science writers have suggested that masks be worn even when social distancing at six feet,[3][4][5][6] should be worn during exercise,[7][8] and might be worn in the home to reduce viral load.[10][9]

Shortages of face masks

Early epidemic in China

People in Wuhan lining up in front of a drug store to buy surgical masks.
A notice at a supermarket in Beijing, which says each person can only buy one pack of surgical masks and one bottle of 84 disinfectant liquid a day.
Chinese electronics manufacturers, such as BYD Electronic, began to produce surgical masks after the outbreak.

As the epidemic accelerated, the mainland market in China saw a shortage of face masks due to increased public demand.[83] In Shanghai, customers had to queue for nearly an hour to buy a pack of face masks; stocks were sold out in another in half an hour.[84] Hoarding and price gouging drove up prices, so the market regulator said it would crack down on such acts.[85][86] In January 2020, price controls were imposed on all face masks on Taobao and Tmall.[87] Other Chinese e-commerce platforms – JD.com,[88] Suning.com,[89] Pinduoduo[90] – did likewise; third-party vendors would be subject to price caps, with violators subject to sanctions.

By March China had quadrupled its production capacity (100 million masks per day).[75]

National stocks and shortages

In 2006, 156 million masks were added to the US Strategic National Stockpile in anticipation of a flu pandemic.[91] After they were used against the 2009 flu pandemic, neither the Obama administration nor the Trump administration renewed the stocks.[91] By 1 April, the US's Strategic National Stockpile was nearly emptied.[92][clarification needed]

In France, 2009 H1N1-related spending rose to €382 million, mainly on supplies and vaccines, which was later criticised.[93][94] It was decided in 2011 to not replenish its stocks and rely more on supply from China and just-in-time logistics.[93] In 2010, its stock included 1 billion surgical masks and 600 million FFP2 masks; in early 2020 it was 150 millions and zero, respectively.[93] While stocks were progressively reduced, a 2013 rationale stated the aim to reduce costs of acquisition and storage, now distributing this effort to all private enterprises as an optional best practice to ensure their workers' protection.[93] This was especially relevant to FFP2 masks, more costly to acquire and store.[93][95] As the COVID-19 pandemic in France took an increasing toll on medical supplies, masks and PPE supplies ran low, causing national outrage. France needs 40 millions masks per week, according to French president Emmanuel Macron.[96] France instructed its few remaining mask-producing factories to work 24/7 shifts, and to ramp up national production to 40 million masks per month.[96] French lawmakers opened an inquiry on the past management of these strategic stocks.[97] The mask shortage has been called a "scandal d'État" (State scandal).[98]

In late-March/early-April 2020, as Western countries were in turn dependent on China for supplies of masks and other equipment, China was seen as making soft-power play to influence world opinion.[99][14] However, a batch of masks purchased by the Netherlands was reportedly rejected as being sub-standard. The Dutch health ministry issued a recall of 600,000 face masks from a Chinese supplier on 21 March which did not fit properly and whose filters did not work as intended despite them having a quality certificate.[99][14] The Chinese Ministry of Foreign Affairs responded that the customer should "double-check the instructions to make sure that you ordered, paid for and distributed the right ones. Do not use non-surgical masks for surgical purposes".[14] Eight million of 11 million masks delivered to Canada in May also failed to meet standards.[100][101]

N95 and FFP masks

A woman in Ukraine wearing an FFP mask after masking in public places was made mandatory.

N95 and FFP masks were in short supply and high demand during the COVID-19 pandemic.[102][93] Production of N95 masks was limited due to constraints on the supply of nonwoven polypropylene fabric (which is used as the primary filter), as well as the cessation of exports from China.[43][103] China controls 50 percent of global production of masks, and facing its own coronavirus epidemic, dedicated all its production for domestic use, only allowing exports through government-allocated humanitarian assistance.[43]

In March 2020, US President Donald Trump applied the Defense Production Act against the American company 3M, which allows the Federal Emergency Management Agency to obtain N95 respirators from 3M.[104][105] White House trade adviser Peter Navarro stated that there were concerns that 3M products were not making their way to the US.[104] 3M replied that it has not changed the prices it charges, and was unable to control the prices its dealers or retailers charge.[104]

In early April 2020, Berlin politician Andreas Geisel alleged that a shipment of 200,000 N95 masks that it had ordered from American producer 3M's China facility were intercepted in Bangkok and diverted to the United States. Berlin police president Barbara Slowik stated that she believed "this is related to the US government's export ban."[106] 3M said they had no knowledge of the shipment, stating "We know nothing of an order from the Berlin police for 3M masks that come from China," and the US government denied that any confiscation had taken place and said that they use appropriate channels for all their purchases.[106][107] Berlin police later confirmed that the shipment was not seized by US authorities, but was said to have simply been bought at a better price, widely believed to be from a German dealer or China. This revelation outraged the Berlin opposition, whose CDU parliamentary group leader Burkard Dregger accused Geisel of "deliberately misleading Berliners" in order "to cover up its own inability to obtain protective equipment". FDP interior expert Marcel Luthe said "Big names in international politics like Berlin's senator Geisel are blaming others and telling US piracy to serve anti-American clichés."[108] Politico Europe reported that "the Berliners are taking a page straight out of the Trump playbook and not letting facts get in the way of a good story."[109] The Guardian also reported that "There is no solid proof Trump [nor any other American official] approved the [German] heist".[110]

Jared Moskowitz, head of the Florida Division of Emergency Management, accused 3M of selling N95 masks directly to foreign countries for cash, instead of the US. Moskowitz stated that 3M agreed to authorized distributors and brokers to represent they were selling the masks to Florida, but instead his team for the last several weeks "get to warehouses that are completely empty." He then said the 3M-authorized US distributors later told him the masks Florida contracted for never showed up because the company instead prioritized orders that came in later, for higher prices, from foreign countries (including Germany, Russia, and France). As a result, Moskowitz highlighted the issue on Twitter, saying he decided to “troll” 3M.[111][112][113] Forbes reported that "roughly 280 million masks from warehouses around the US had been purchased by foreign buyers [on March 30, 2020] and were earmarked to leave the country, according to the broker — and that was in one day", causing massive critical shortages of masks in the US.[114][115]

As more and more countries restricted the export of N95 masks, Novo Textiles in British Columbia had plans to become the number-one manufacturer in Canada.[116] AMD Medicom in Quebec also plans to become the second Canadian manufacturer of N95 masks, with a contract to supply the Government of Canada.[117]

The mask industry

Manufacturing

The government of Taiwan instituted a mask rationing system. With population of 24 million, Taiwan has been producing more than 10 million masks per day since March.
The U.S. National Guard sews facemasks

As of 2019, mainland China manufactured half the world output of masks.[118] As Covid-19 spread, enterprises in several countries quickly started or increased the production of face masks.[119] Cottage industries and volunteer groups also emerged, manufacturing cloth masks for localised use. They used various patterns, including some with a bend-to-fit nosepiece inserts. Individual hospitals developed and requested a library of specific patterns.[120][121][122][123]


Distribution

Some clinical stockpiles have proved inadequate in scale, and markets have expanded as non-medical consumers started obeying mandated mask-wearing or determined that masks might help or encourage them. Worldwide demand for face masks has resulted in masks shipping around the globe as a result of commercial transactions or of donations.[124]

Culture

Attitudes

In East Asian societies, a primary reason for mask-wearing is to protect others from oneself.[125][126] It is seen as a collective responsibility to reduce the transmission of the virus.[127] The broad assumption behind the act is that anyone, including seemingly healthy people, can be a carrier of the coronavirus.[126] A face mask is thus seen as a symbol of solidarity.[127] Elsewhere, the need for mask-wearing is often seen in an individual's perspective where masks only serve to protect oneself.[125]

Cultural norms and social pressure may also impede mask-wearing in public.[128] According to the Hong Kong doctor and infectious disease expert Joseph Tsang, the promotion of universal masking may resolve perceptions against mask-wearing, because mask-wearing is intimidating if few people wear masks due to cultural barriers, but if all people wear masks it shows a message that people are in this together.[80]

In the western world, the public usage of masks still often carries a large stigma,[125][127][129] as it is seen as a sign of sickness.[129] This stigmatization is a large obstacle to overcome, because people may feel too ashamed to wear a mask in public and therefore opt to not wear one.[130] Secondly, it is heavily racialized as an Asian phenomenon.[127] This has been reinforced in a lot of media discourses, where unrelated stories about the pandemic are often accompanied by imagery of Asian people in masks.[131] The focus on race has brought hostility towards Asians who are confronted with the choice to mask as precaution while they face discrimination for it.[132] However, there is also a divide within the western world, as seen in the Czech Republic and Slovakia where mass mobilization has occurred to reinforce the solidarity in mask-wearing since March 2020.[125]

On social media, there has been an effort with the #masks4all campaign to encourage people to use masks.[133] Mask-wearing has been called a prosocial behavior in which one protects others within their community.[134][135]

In the US, mask-wearing was politicized and is seen as a political statement by some people. Democrats were more likely than Republicans to say that they are wearing a mask when leaving home, 76% to 59% according to one poll.[136]

Fashion

Face masks have had an impact on fashion, with the masks themselves becoming a fashion statements, haute couture brands having pivoted to address both public health and aesthetic needs.[137][138][139][140]

Mask use and policies by country and territory

Beijing Subway advises passengers to wear masks when taking trains
  • Argentina Argentina: After appearance of three asymptomatic cases, the capital Buenos Aires introduced compulsory masking since 14 April. Wearing a mask was made obligatory for everyone on public transit and everyone who contacts with the public in their position. Violators can face a fine. Authorities also prohibited the sale of N95 face masks to non-medical workers, suggesting the general public to use home-made masks instead.[141]
  • Austria Austria: Everyone entering a supermarket, a grocery store, or a drug store or using public transportation must wear a face mask, mandatory since 14 April.[142][143][144]
  • The Bahamas Bahamas: On 19 April, the prime minister announced that wearing a mask or covering one's face with clothing is mandatory in public. Employers must provide their employees who are serving the general public with masks.[145]
  • Bahrain Bahrain: The Kingdom made wearing face masks in public areas compulsory for citizens and residents as well as shop workers.[146]
  • Benin Benin: From 8 April, Benin's authorities began enforcing the mandatory wearing of face masks to halt the coronavirus.[147]
  • Bosnia and Herzegovina Bosnia and Herzegovina: Wearing a face mask is compulsory.[148][149]
  • Bulgaria Bulgaria: Bulgaria's government passed an order imposing an obligation to wear face masks on 30 March. The order was cancelled the next day and changed into a recommendation, due to legal complaints.[150]
  • Cambodia Cambodia: Many Cambodians started wearing face masks soon after the outbreak began in Wuhan. Businesses started to require customers to wear masks.[151]
  • Cameroon Cameroon: On 6 April, mayor of Douala announced that wearing a mask will be mandatory to slow the spread of coronavirus.[152]
  • Canada Canada: Since 6 April, health officials recommend wearing non-medical masks in situations where physical distancing from others is difficult (like buying groceries, or public transit).[153]
  • Chile Chile: From 8 April, Chilean Health Minister announced wearing a mask is mandatory in public transit.[154]
  • China China: Healthy individuals are advised to wear disposable medical masks in public places.[13][69] Some local governments require wearing masks when going outside. Shanghai makes wearing masks mandatory in public places.[155]
  • Colombia Colombia: In response to the most recent recommendations of the WHO, Colombia changed its policy on the use of masks and made it mandatory throughout the country for the use of public transport during the coronavirus emergency.[156]
  • Cuba Cuba: On 11 March, the government urged citizens to make their own masks, while the textile industry was drafted to fabricate them. People were advised to carry several cloth masks with them, depending on how many hours they plan to spend in public areas.[157] Later, wearing a mask was made mandatory.[158]
  • Czech Republic Czech Republic: Forbidden to go out in public without wearing a mask, or covering one's nose and mouth.[159]
  • Dominican Republic: Since 16 April, the use of face mask is mandatory in all public spaces and in the workplace.[160]
  • Democratic Republic of the Congo DR Congo: Since 20 April, wearing masks in the capital of Kinshasa is mandatory.[161]
  • Ecuador Ecuador: On 8 April, the Emergency Operations Committee (COE) decided to make face masks obligatory in public spaces.[162]
  • Ethiopia Ethiopia: The Council of Ministers approved a regulation that outlaws handshakes, and obligates the use of face masks in public places.[163]
  • France France: On 3 March, the government issued a degree announcing requisition of stocks of FFP2 and anti-splash masks until 31 May 2020.[164]
  • Gabon Gabon: On 10 April, the Gabonese government announced individuals in all parts of the country are required to wear masks in public to limit the spread of COVID-19.[165]
  • Germany Germany: On 31 March, city-county Jena, Thuringia, was the first large German city to introduce an obligation to wear masks, or makeshift masks including scarves, in supermarkets, public transport, and buildings with public traffic, from 6 April, very successfully. On 2 April, the Robert Koch Institute, the federal epidemic authority, changed its previous recommendation that only people with symptoms should wear masks to also include people without symptoms.[166][167] County Nordhausen, Thuringia, followed the example of Jena, since 13 April, several other cities later. German chancellor Merkel and state governors first gave "strong advice" to wear face masks in public from 20 April, Saxony made it mandatory from that day, Saxony-Anhalt followed from 23 April and (the rest of) Thurinigia from 24 April, finally the governors agreed to make it mandatory, so most other states followed from 27 April, except Schleswig-Holstein, from 29 April, and Berlin, where shops were excluded first, they were included from 29 April.[168]
  • Guinea Guinea: Guinean President Alpha Conde decided to make wearing masks compulsory.[169]
  • Honduras Honduras: From 7 April, Honduras President announced all citizens will now be required to cover their mouths when they are outside.[170]
  • Hong Kong Hong Kong: Members of the public are recommended to wear a surgical mask when taking public transport or staying in crowded places.[70]
  • India India: From 9 April, masking is compulsory in the state of Odisha. When leaving their home, people must cover their mouth and nose with masks or multilayered cloth (like handkerchief, dupatta, towel, etc.).[171]
  • Indonesia Indonesia: Citizens were ordered to wear face masks when they leave the house.[172]
  • Israel Israel: All residents are asked to wear face masks when in public.[173]
  • Italy Italy: Regions of Lombardy and Tuscany made wearing a face mask compulsory before going out in early April.[174]
  • Ivory Coast Ivory Coast: From April, 26 masks have become compulsory to enter shopping malls or supermarkets in the Southern suburb of Abidjan, Marcory.[175]
  • Japan Japan: Masks have been widely used by healthy individuals despite absence of official advice to do so.[176] On 1 March, prime minister Shinzo Abe enacted a policy in Hokkaido instructing manufacturers to sell face masks directly to the government, which would then deliver them to residents.[177]
  • Kenya Kenya: Wearing a face mask is compulsory. The government has Kenyans to strictly observe social distancing, which has been proved to one of the most efficient ways of preventing infection risks.[178]
  • Liberia Liberia: From 21 April, it is now compulsory to wear a face mask or covering in public.[179]
  • Lithuania Lithuania: Wearing a face mask or any other means of covering one's nose and mouth in public places is compulsory since 10 April 2020.
  • Luxembourg Luxembourg: From 20 April, wearing a mask is mandatory in places where it is not possible to keep enough distance to others such as supermarkets or on public transport.[180]
  • Malaysia Malaysia: Masks have been widely used by healthy individuals despite absence of official advice to do so.[181] On 17 March, Malaysia banned exports of medical and surgical masks, to meet local demand.[182] In April, the government was set to distribute 24.62 million masks, four for each household, while advising people to only use them if they have symptoms.[172]
  • Mexico Mexico: From 17 April, all Mexico City Metro passengers must wear masks while inside stations and on trains, Mayor Claudia Sheinbaum announced on 15 April.[183]
  • Mongolia Mongolia: Wearing a mask is now mandatory while riding public transportation in Ulaanbaatar. Public officials and news broadcasters had even adopted to wearing masks through press conferences and news broadcasts.[184]
  • Morocco Morocco: Wearing a face mask is compulsory.[185]
  • Mozambique Mozambique: The Mozambican government announced on 8 April that wearing face masks is now compulsory on all forms of passenger transport, and wherever groups of people are gathered.[186]
  • North Macedonia North Macedonia: As of 22 April, citizens of Kumanovo, Tetovo, and Prilep must wear protective masks and gloves outside their homes, at public places, outdoor and indoor areas, markets, and shops announced the government.[187]
  • Pakistan Pakistan: The Balochistan government on 18 April told citizens to wear face masks when going outside. According to provincial government spokesperson Liaquat Shahwani, citizens have been urged to wear masks or to cover their faces with any cloth in the wake of the COVID-19 outbreak.[188]
  • Panama Panama: Panama has made it obligatory to wear a face mask whenever going outside, while also recommending the manufacture of a homemade cloth face mask to those who cannot purchase face masks.[189]
  • Peru Peru: From 7 April, the Peruvian government started distributing free masks after decreeing their mandatory use in the streets to chase away the new coronavirus, said President Martin Vizcarra.[190]
  • Philippines Philippines: From 2 April, the government required all those living in areas under enhanced community quarantine to wear face masks.[191]
  • Poland Poland: Since 16 April, covering lips and nose is compulsory before leaving one's house (e.g., by a disposable mask, cloth mask, or scarf).[192]
  • Russia Russia: Khabarovsk has made the wearing of face masks obligatory to fight the spike in respiratory diseases and prevent the spread of the coronavirus.[193]
  • Rwanda Rwanda: On 20 April, Cabinet Minister of Health Daniel Ngamije said the latest guidelines require everyone to wear a mask in public, and at home during the lockdown and thereafter.[161]
  • Scotland Scotland: On 28 April, the First Minister for Scotland Nicola Sturgeon advised the voluntary use of cloth face masks in enclosed spaces such as shops and public transport (but not generally in public), while noting their limitation.[194]
  • Singapore Singapore: Masks have been widely used by healthy individuals despite initial absence of official advice to do so.[195] General mask-wearing was no longer discouraged from 3 April,[196] and made mandatory outside of one's residence from 14 April.[197]
  • Spain Spain: Wearing masks has been required since 4 May while on public transportation, which includes taxis, trains and buses. The government is providing masks to the majority of people riding public transportation, regardless of if they have a mask on.[198][199]
  • Slovakia Slovakia: Forbidden to go out in public without wearing a mask or covering one's nose and mouth.[159][148]
  • Slovenia Slovenia: From 29 March, wearing a face mask, even one made at home, or equivalents such as scarves that cover the mouth and nose is mandatory along with protective gloves; the decree stipulates that masks and gloves need to be worn in indoor public spaces.[200]
  • South Africa South Africa: On 10 April, Minister of Health recommended that the general public use cloth face masks when going out in public (in addition to hand-washing and social distancing).[201] After 1 May, covering one's nose and mouth will be mandatory in public (with a cloth mask, scarf, T-shirt, etc.).[202]
  • South Korea South Korea: Masks have been widely used by healthy individuals despite absence of official advice to do so.[203] The government implemented a policy of centralized procurement and rationing of face masks, purchasing 80 percent of national production since early March.[204]
  • Taiwan Taiwan: On 21 January, the government announced a temporary ban on the export of face masks.[205] On 6 February, the government instituted a mask rationing system.[206] Taiwan has been producing ten million masks per day since mid-March.[207] On 1 April, passengers on trains and intercity buses were required to wear face masks,[208] unmasked riders facing a fine.[209]
  • Turkey Turkey: Residents will be required to wear masks at markets, as Turkish president announced.[210]
  • Ukraine Ukraine: Since 6 April, wearing a face mask is required by the government in public places. In Kyiv, public places were clarified to include parks and streets.[211]
  • United States United States: On 6 April, the CDC recommended the wearing of non-medical cloth face coverings when in public places.[212][213] Since 17 April, residents of New York, must wear masks in public; New Jersey and Maryland issued similar requirements for their residents.[214]
  • Uzbekistan Uzbekistan: Officials made protective masks mandatory in all major cities in order to prevent the spread of coronavirus. Officials on 22 March said citizens not wearing masks in public in major cities would be fined $22 for the first offense and $67 for repeat offenses.[215]
  • Venezuela Venezuela: The government ordered the country’s citizens to wear face masks in public in response to the arrival of the novel coronavirus.[216]
  • Vietnam Vietnam: Since 16 March, everyone must wear a face mask when going to public places (such as grocery stores, transportation hubs, and public transport).[217]
  • Zambia Zambia: The government made it mandatory to wear face masks to minimise the spread in the country.[218]

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