Introduction: face masks: a barrier to COVID-19
This chapter provides an insight on the use of face masks during a pandemic and how face masks can help curb the spread of various air or aerosol-borne infectious diseases.
Face masks, although a personal protective equipment (PPE) by function, have been shown to be one of the effective measures to help in stopping the spread of the pandemic when the majority of the population adopts it early on. This chapter will discuss the various face masks available to the general public and their efficacy along with the key issues and concerns regarding face masks.
Airborne transmissions can transmit small particulates through the air over time and distance. Airborne transmissions are usually distinct from transmission by respiratory droplets. Respiratory droplets are droplet particles greater than 5-10 μm in diameter whereas droplets less than 5 μm are referred to as droplet nuclei. Development of effective control measures against aerosol or airborne transmission of infections with various outbreaks like Severe Acute Respiratory Syndrome (SARS), human avian influenza A (H5N1), pandemic influenza A (H1N1/2009), and ongoing COVID-19 have become important. 
Transmission of infectious agents may occur via short-range, large-droplet aerosols and long-range, smaller, airborne droplet nuclei as shown in Figure 1. 
Figure 1. Illustration of different transmission routes of airborne and aerosol infections (Credit: Elsevier COVID-19 resource centre. 
From the experience gained in response to SARS in Southeast Asia, wearing face masks can help prevent spreading or breathing in infectious droplets to a certain degree and should be applied together with other risk control measures, such as hand hygiene, social distancing, ventilation control, and vaccination, to make a significant contribution to the prevention of COVID-19 .
Purpose of face masks
In general, face masks serve several purposes; they help reduce the amount of, as well as slowing down the speed of, droplet or aerosol breathe out or sneeze from an infected person to the environment, or reduce the amount of virus-contaminated air breathing in by an uninfected person. Face masks can also reduce the possibility of people touching their mouth and nose with contaminated hands or other objects.
Figure 2 shows the probability of a person being affected by aerosol or airborne virus in different scenarios. The probability greatly reduces when both individuals wear face masks. Face masks are mainly used to contain the spread of the virus from the wearer to others. One common misunderstanding is to assume face masks are mainly used to protect the wearers against contacting the virus. Depending on the application and type of masks, most face masks available in the market are designed to protect others against infection from the wearer.
Figure 2. Transmission risk related to wearing masks
Adopting a face mask
Wearing face masks had been less perceptive in the western countries at the onset of the COVID-19 pandemic. Research works have shown that adopting face masks at an early stage in the outbreak can significantly reduce the number of infections sooner . Previous studies have shown that face masks can control respiratory virus transmission in households [4a, 4b]. Masking has been one of the main barriers and has become mandatory for the public for the duration of the pandemic in most of the Eastern countries at the onset of the COVID-19 pandemic.
Face masks in public
US Centre for Disease Control and Prevention (CDC) has subsequently recommended the use of face masks in public settings when social distancing of 6 feet is not possible. CDC agrees that masks can help stop the spread of COVID-19 to others .
Relative risk (RR) reductions for infections
Systematic reviews of the use of face masks also suggest relative risk (RR) reductions for infections ranging from 60-80%, depending on the type of masks used. Despite the high range, possible RR reduction must be considered. In Norway, for example, it was estimated that 200 000 people would need to wear face masks to prevent one new infection per week. They assumed a 40% RR reduction with the use of surgical masks .
Different types of masks and their uses
There are different types of face masks available in the market. These include a basic cloth face mask, surgical face mask, copper mask, N95 respirator, etc. Each has its own specific applications and offers a different degree of protection against COVID-19 transmission. Various tests have been performed for different types of face masks based on their use.
Key issues and concerns
As vaccine is being rolled out, people are still advised to cover their nose and mouth while roaming around in public. As donning of face masks has proven to be important to help curb COVID-19, other barriers like social distancing, personal hygiene can also help in creating a combined effective method to reduce the spread and chances of getting infected as can be shown in Figure 6
Figure 6. The Swiss cheese model showing various layers to prevent infectious diseases and control transmission risks
Correct methods on how to use masks and strict control by the governments not only on wearing masks but also on how they should be worn and handled can further reduce the spread of COVID-19. The Public must be trained about the correct way of putting on, wearing, removing, and disposing of face masks for face masks to be effective .
The COVID-19 aerosol, mainly appearing in the submicron region (d p between 0.25 and 1.0 μm) and super micron region (d p > 2.5 μm), can be effectively filtered out from the inhaled air by either surgical masks or N95 masks. A recent COVID-19 dynamic modelling study also suggested that broad adoption of even relatively ineffective non-medical grade “social” masks may meaningfully reduce the community transmission and decrease peak hospitalizations and deaths during the current COVID-19 pandemic .
A study conducted on the effectiveness of homemade masks as an alternative to commercial masks concluded that surgical masks are more effective in preventing microorganisms than homemade masks. Nevertheless, in short of supply scenarios, homemade cloth masks are better than no protection and 100% cotton is the best material to use while making them. The use of double-layer cotton masks reduces the emission of larger particles [14,16].
While utilizing cloth masks, care must be taken while removing and cleaning the masks as cloth masks can be prone to shedding fibres and in turn lodge deposited micro-organisms . Few tips for cloth masks are shown in Figure 7.
Figure 7: Good practices while using facemasks 
Facemasks have always been a debatable topic as to its efficiency in controlling the pandemic. One should understand that wearing facemask only does not completely stop the virus, but at least acts as a layer of protection as mentioned earlier. Majority of the countries have adopted to implement mandatory face masking in public and on the other hand, there are countries which still haven’t. Countries with minority of residents wearing masks quickly contained outbreaks, but others had high death tolls. Places such as Denmark, Finland and Norway initially had their covid outbreaks controlled, but Sweden suffered high death toll rate at a later stage. As acknowledged by WHO, a reduction in infection rate by 85% was observed when masked.
All in all, a momentum has been observed in wearing facemasks as countries try and reopen their economics with covid still at bay. Facemasks have become a social behaviour, more or less like a car seatbelt. It will only prevent you from getting into a serious accident. Governments should proactively advise their population to wear facemasks as a layer of protection to effectively battle novel coronavirus and its emerging strains .
Precautions in wearing face masks
While wearing a face mask is essential, wearing them with proper precautions is also important. The effectiveness of face masks can be reduced if not wearing properly causing leakage or exposure of nose/ mouth to environment. This can be due to:
- Improper fitting
- Improper wearing
- Wearing old and worn out mask
- Wrong size
- Using or improper handling of contaminated mask
- Defective masks
- Bad behaviour when wearing mask (e.g., touch nose with hand)
The following precautions should be observed while wearing a face mask
- Hands should be properly cleaned with soap and water or hand sanitizer before touching the mask.
- Mask should be checked for any tears or holes before being used.
- The coloured side of the mask is usually in the front and away from the face while the white side faces towards the face.
- Hands should be thoroughly cleaned before and after the process of removing the mask. Touching the front face of the mask should be avoided.
- Mask should be properly discarded in the trash.
Environmental Concern on waste
Used Masks and Environment Issues
While the use of face masks as a first line of defence has been recognized, it is estimated that 129 billion masks are used and disposed of every month. That translates into 3 million face masks used per minute.
A separate study reports that 3.4 billion face masks or face shields are discarded every day. Asia is projected to throw away 1.8 billion face masks daily, the highest quantity of any continent globally. China alone, with the world’s largest population (1.4 billion) discards nearly 702 million face masks daily.
Face masks are made from multiple plastic fibers, primarily polypropylene, that will remain in the environment for decades, possibly centuries, fragmenting into smaller and smaller microplastics and nano plastics. A single face mask can release as many as 173,000 microfibers per day into the seas, according to a study in Environmental Advances.
Currently, most municipal systems do not allow for recycling of used masks. Masks can contain a mix of paper and polymers, including polypropylene and polyester, that can’t be separated into pure streams of single materials easily for recycling. They are also so small they get caught in recycling machinery, causing mechanical breakdowns.
The issue of used masks has arrived at a complicated time in the global effort to curb plastic waste. The amount of plastic waste accumulating in the oceans is originally forecast to triple in the next 20 years with no real solution on the horizon. This estimation was without the surge of plastic due to used masks. If every corporate pledge to use more recycled plastics were kept, the shift would reduce that projected tripling by just 7 percent (Parker 2021).
Can Reusable Masks Help
Even with reusable masks, their specific design and how you choose to clean them makes a difference. The University College London team examined the manufacture, use and disposal of masks that were disposable, reusable, and reusable with disposable filters, to calculate their overall environmental impact. They found machine washing reusable masks with no filters had the lowest impact over a year duration.
Hand washing masks increased the environmental impact due to machine washing uses electricity, but manual washing uses more water and detergent for each mask. Disposable filters also increase the environmental impact because the small filters are often made from plastic similar to the disposable masks, with a filter discarded periodically or after every use.
Perhaps surprisingly, the working paper estimates that hand washing reusable masks with disposable filters had the highest environmental impact overall – higher even than using fully disposable masks (Ketchell 2020).
What should be done
With all the above in mind, one should consider the following steps to reduce the impact of wearing a face mask:
- Use reusable masks without any disposable filters. Machine wash them regularly following the instructions for the fabric (assuming could achieve the desirable filtration one desired)
- Try to carry a spare so if something goes wrong with the one you’re wearing you don’t need to use or buy a disposable mask.
- If you do need to use a disposable mask, take it home (maybe in a bag if you have to take it off) and then put it straight into a bin with a lid. If this isn’t possible, place it in a proper public bin.
- Don’t put disposable masks in the recycling. They can get caught in specialist recycling equipment and be a potential biohazard to waste workers.
Section 5 References
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