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Revision as of 13:29, July 28, 2020

During the COVID-19 pandemic, the use of face masks is one of the public and personal health control measures employed against the spread of SARS-CoV-2. The use of masks has received varying recommendations from different public health agencies and governments. The World Health Organization and other public health organisations agree that masks can limit the spread of respiratory viral diseases such as COVID-19. However, the topic has been a subject of debate, with some public health agencies and governments initially disagreeing on a protocol for wearing face masks.

Template:As of, 88% of the world's population lives in countries that recommend or mandate the use of masks in public; more than 75 countries have mandated the use of masks. Debates have emerged regarding whether masks should be worn even when social distancing at 1 metre, and whether they should be worn during exercise. Additionally, public health agencies of some countries and territories have changed their recommendations regarding face masks over time. Face masks have been a subject of shortages, and not all have been certified. Moreover, substandard masks were reported on the market with significantly reduced performance.

There are different types of face masks including:

Face shields, medical goggles, and other types of personal protective equipment are sometimes used together with face masks.

Mask

Cloth masks

Main article: Cloth face mask

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.

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), and many controlled-setting/lab studies of cloth masks' effects on aerosols Template:As of.

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.

Improvised cloth masks seem to be worse than standard commercial disposable 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. 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, 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.

Cloth masks are commonly made with one layer, two layers, or two layers with a pocket for a removable-filter interlayer (disposable surgical masks also have three layers, with the filter layer midmost). The CDC recommends more than one layer. There is no research on the usefulness of a filter interlayer, Template:As of. There were until recently no non-disposable materials designed for making masks (see end of paragraph). Common household fabrics which could be used (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 disposable surgical masks for dry particle filtering. Cotton T-shirt material, pillowcase material, and 70% cotton/30% polyester sweatshirt material are among the common materials 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.

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. 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. There is a need for research comparing how well these materials work.

Decontamination and re-use

There is no research on decontaminating and reusing cloth masks, Template:As of. The CDC recommends doffing the mask by handling only the ear loops or ties, placing it directly in a washing machine, and immediately washing one's hands in soap and water for at least 20 seconds. They also recommend washing one's hands before donning the mask and again immediately after one touches it.

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

Surgical masks

Main article: 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.

Certified medical masks 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).Template:Better sourceTemplate:Medcn Typically, efficiency of the filtering materials decreases when washed or used multiple times.

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. However, in practice, with respect to some infections like influenza, surgical masks appear as effective as respirators (such as N95 or FFP masks). Surgical masks may be labeled as surgical, isolation, dental, or medical procedure masks. Surgical masks are made of a nonwoven fabric created using a melt blowing process.

Surgical masks made to different standards in different parts of the world have different ranges of particles which they filter. For example, the People's Republic of China regulates two types of such masks: single-use medical masks (Chinese standard YY/T 0969) and surgical masks (YY 0469). The latter ones are required to filter bacteria-sized particles (BFE ≥ 95%) and some virus-sized particles (PFE ≥ 30%), while the former ones are required to only filter bacteria-sized particles.

Disposable filtering respirators

Main article: Mechanical filter respirator

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. It is an example of a mechanical filter respirator, which provides protection against particulates, but not gases or vapors. Like the middle layer of surgical masks, the N95 mask is made of four layers of melt-blown nonwoven polypropylene fabric.Template:Medrs

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 has been shown to reduce edge leakage  in lab tests using manikins that simulate breathing.

History

On the 25 March 2020, just before the closure of Bizlink Singapore, you must wear your mask with trainers such as Mr Ron will be on hand to guide people to do so. However, this policy was only communicated to people who are boarding the Bizlink Shuttle Bus and around Bizlink, and must be placed on at all times. Once Timothy Mok does that, other people will also do that too. It was not guided through other policy channels.

However, the wearing of masks was later made mandatory for all individuals leaving their house from 14 April 2020. This was being implemented in various places:

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