A short review on the development of novel face masks during COVID-19 pandemic

COVID-19 pandemic has emerged as a challenging situation for the entire world. This paper has covered outbreak of SARS and MERS coronavirus in the past, their effect on communities and preventive guideline by WHO, CDC and governments agencies. This paper also includes comparison of SARS CoV-2 which is driving current pandemic with SARS CoV and MERS CoV. The effect of COVID-19 pandemics across the globe are also highlighted in this paper. A review on various preventive measures and their impact on controlling a pandemics has been discussed. During a pandemic, face masks plays a key role in controlling the spread of virus from one person to another. The effect of wearing mask on the decrease in number of cases during the pandemic has been quantified. A comparative study of effectiveness of different masks has also been covered in this paper. Various novel face masks that have emerged during the COVID-19 pandemic has also been discussed in the current manuscript.


Introduction
Global outbreak of disease such as Viral hemorrhagic fevers, Zika virus epidemic, small pox, influenza including swine flu, Asian flu, Hong Kong Flu, Spanish flu etc. has been encountered by the humankind in the past. Currently world is facing COVID-19 pandemic, which is due to the spread of a coronavirus called SARS CoV-2. Coronaviruses are a family of RNA viruses which is responsible for causing diseases in mammals and birds. These viruses have been transferred from animals to human, and have caused respiratory diseases ranging from mild diseases like common cold to severe diseases like SARS, MERS and COVID-19. Coronavirus is of spherical structure with diameter around 125 micron. It has an envelope of diameter around 85 micron which is surrounded by 20 micron long spikes. [1]. Coronavirus have around 74 spikes on the surface of its envelope. [2].
Presently eight categories of coronaviruses have been found which can cause illness to human i.e. HCoV-NL63, HCoV-229E, HCoV-OC43, HCoV-HKU1, SARS-CoV, MERS-CoV, SADS-CoV and SARS CoV-2. Bat is the natural host for all the coronaviruses except HCoV-OC43 and HCoV-HKU1 which was first found in rats [3]. Generally the coronaviruses are responsible for causing mild diseases such as cold, diarrhoea etc. but SARS CoV, MERS CoV and SARS CoV-2 was found responsible for severe fatal respiratory related diseases.  Mask use various air filtration mechanism such as straining, inertial impaction, interception, diffusion and electrostatic attraction. Straining, inertial impaction, and interception are the dominant collection mechanisms for particles greater than 0.2 microns whereas diffusion is dominant for particles less than 0.2 microns. Straining occurs when the gap between the media members is kept smaller than the diameter of the particulate, therefore these particles can be captured outside the mask as shown in Fig 1(a). Inertial Impaction uses a rapid change in air direction and the principles of inertia to separate the particulate from the air stream. Particles at a certain velocity tend to remain at velocity and travel in a continuous direction as shown in Fig 1(b). This principle is normally applied when there is a high concentration of coarse particulate. Figure 1(c) shows the phenomenon of interception in which the particulate make physical contact and remain attached to the media fiber. The particulate which is intercepted is smaller and its inertia is not strong enough to cause the particle to continue in a straight line.
It, therefore, follows the air stream until it comes into contact with a fiber. The phenomenon of diffusion is shown in Fig. 1(d) in which the gas molecules collide with the smallest particles, especially those below 100 micron in diameter, which are thereby impeded and delayed in their path through the filter, increasing the probability of capturing of that particle. Electrostatic attraction, also called electrostatic precipitation involves using certain resins, waxes, and plastics as coatings on the filter material to attract particles with an electrostatic charge that holds them on the filter surface as shown in Fig 1(e). In most of the masks a layer of electret is kept to filter the substrate by electrostatic attraction. This technique is used for the removal of very fine particulates such as dust and smoke. [4] (a)  The face masks can be broadly divided into three different categories: (i) cloth face masks, (ii) surgical mask and (iii) N95 mask.
i. Cloth mask: Cloth mask can be made at home with the use of available cloth material.
These mask are helpful restricting an infected person to transmit their viruses during talking, coughing or sneezing to another person or nearby objects. However possesses very low effectiveness in restricting the virus to reach wearer nose or mouth. Still wearing a cloth face mask is a far better choice than not using any mask. Due to sudden increase in the demand of N95 respirator, CDC has recommended the use of cloth face mask by people in public areas, so that N95 masks can be preserved for healthcare professionals.
ii. Surgical Mask: These masks are also known as medical mask or procedure mask. It is  Although these masks are better than a cloth mask but still very less effective in preventing the wearer from getting infected because of its inability to filter small particles and lose fitting causing leakage from sides. Its main purpose is to restrict the spread of large virus loaded droplets coming out from the mouth of an infected wearer during cough or sneeze. A surgical mask with an electret layer also have the ability to capture small particles by electrostatic attraction and thus is more effective than the one without electret layer. iii

Effect of coronaviruses (SARS-CoV, MERS-CoV and SARS-CoV-2) across the globe:
Coronaviruses are a family of RNA viruses which is responsible for causing diseases in humans related to respiratory system. [3]. Although there are various coronavirus have been found in the past but three coronavirus namely SARS-CoV, MERS-CoV and SARS-CoV-2 caused serious impact on society. The details about these viruses are shown in Table 1.  [9], [10], [11] *Data as on 23 rd May 2020

Influence of current pandemic COVID-19 across the globe:
Present pandemic COVID-19 is due to the spread of SARS CoV-2. This virus can be transferred from one person to other through respiratory droplet and contact routes [12].
Transmission of infected droplets can occur when a person is in close contact (less than 1 m) with an infected person during coughing or sneezing. These droplets can enter into the body of a healthy person though mouth nose and eyes. Transmission may also occur through indirect contact with surfaces in the immediate environment or with objects used on the infected person [13]. The life span of SARS CoV-2 at different surface is given in Polypropylene Plastic 3 Days Table 2    The total time to end a pandemic does increase by taking precaution measures but the reduction in total number of cases are far important than decreasing the time duration of the pandemic.
A systematic review of physical intervention to reduce the spread of respiratory viruses (  Table 3: Main finding of systematic review of physical intervention to reduce the spread of respiratory viruses [17].

Effectiveness of face mask during a pandemic
The influenza-like illness (ILI). Compared to masks, N95 respirators conferred superior protection against CRI, but not ILI. [18] Researchers have quantified the influence of wearing N95 facemasks in reducing the spread of influenza H1N1. The result obtained from the simulation are shown in 2.7% Table 4: Reduction in percentage of population infected in case of wearing N95 mask during pandemic influenza. [19] The effect of wearing surgical mask to reduce spread of influenza H1N1 was also quantified and compared with N95 mask. The result shows that if we consider the effectiveness of surgical mask in reducing susceptibility and infectivity is 5% and 50% of the total population wear it, then the percentage of infected population decreases from 74% to 68% as shown in Table 5. It can also be concluded that N95 masks are far more effective than surgical masks in controlling pandemic influenza. [20] Surgical of the population could reduce economic losses by $478 billion, $570billion and $573billion respectively. [21] The guidelines of WHO and CDC on wearing face masks during various outbreak of virus is shown in Fig 5(a) [22], [23], [24] Proceedings of International Conference on Advances in the Field of Health, Safety, Fire, Environment & Allied Sciences (HSFEA 2020).

Novel face mask design emerged during COVID-19 pandemic:
During COVID-19 pandemic colleges, universities and research labs from all over the world have focused their attention on advancement of convention face mask. During this period many novel face mask were designed by various organizations. Due to the lack of availability of face masks, reusable silicon face masks and washable cloth face mask were manufactured by various industries [25]. Japan based Mitsufuji Corporation has manufactured reusable mask ( Fig 6) that can be washed more than 50 times and used repeatedly to help alleviate the nationwide shortage of sanitary masks [26]. LIGC Applications has developed the Guardian G-Volt face mask (Fig 7) with a graphene filtration system with integrated electrical charge technology to repel viruses. These masks can be sterilized and safely re-used.
[27].  Microbiologist from University of Massachusetts Amherst invented a reusable facemask made out of copper, a material known to kill bacteria and inactivate respiratory viruses including the coronavirus [28]. An ear guard was developed to take the pressure off health care workers' ears from wearing masks all day [29]. Stanford University bioengineering associate professor Manu Prakash has modify full-face snorkel masks into reusable PPE for health care workers shown in Fig 8 [30]. Hyo-Jick Choi, a biomedical engineer and assistant professor at the University of Alberta has developed special salt-coated filters that can deactivate a pathogen like the coronavirus in few minutes [31]. Dr. Ashish Karn, faculty from University of Petroleum and Energy Studies have designed a COmfortably Vented, Indigenously Designed (COVID) Fabric Helmet (Fig 9) to curb infection spread in Education, Healthcare and other community settings [32]. The fabric helmet is integrated with many innovative design features to make it better fitted, comfortable, cheap, more protective and well ventilated.  Efforts have been made toward designing customized face mask for all age groups because of the reason that an adult face mask is not effective for children due to poor fit. Mobile applications have been launched to get the 3D map of the face, in order to manufacture well fitted face mask for each face. During the pandemic, various DIY tutorials were made to easily make face masks using stuff which is readily available at home like paper towel, plastic bottle, cotton clothes etc. Researchers from the University of Cambridge and the University of Queensland have collaborated to create a special origami design for a face shield called the "HappyShield" [33]. As the mask became a part of daily wardrobe during the pandemic, various fashionable design for mask were also observed.

Conclusions
This statistical data presented in this paper clearly shows that an outbreak of a pandemic is an alarming situation for the globe. SARS CoV, MERS CoV and SARS CoV-2 can cause severe respiratory related disease to human. SARS CoV-2 has infected around 5.6 million persons across the world and is responsible for more than 348 thousand death. Preventive measures can significantly decrease the transmission of virus from one human to another and is very effective in controlling the outbreak of a pandemic. Maintaining social distance, proper usage of mask and hand hygiene reduces the risk of spreading of infection in community. N95 face masks can remove 95% the contamination of size more than 3 micron and are most effective in preventive transmission of virus. Surgical masks on the other hand are ineffective in preventing the wearer due to lose fit which cause leakage from the sided, these masks are also incapable of filtering small droplets. Cloth masks although cannot provide higher degree of safety to the wearer but is effective in restricting transmission of virus from wearer to others. Due to lack of N95 masks, during the outbreak of disease, cloth masks can be used in community settings in order to preserve N95 masks for healthcare workers. During the pandemic, various novel design of face masks were developed. Some of the design emerged during COVID-19 pandemic are