The Covid-19 has halted the world. Other than causing deaths of millions and draining the economy, the pandemic also changed the way our daily life activities go. From being able to enjoy the outside and see the world, we had to stop and stay in our spaces inside our homes.
After more than a year since the Covid-19 health crisis started, we are now accustomed to the fact that we have to wear face masks in order to be protected against the infectious pathogen. However, even after all this time, there are still debates on what face mask one should wear in order to be provided with adequate protection and comfort both at the same time. While one would argue that it should be surgical masks, another would disagree because he thinks it should be home-made or cloth masks.
So to put an end to this debate, here is the difference on the effectiveness of surgical masks and home-made or cloth face masks.
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A surgical mask is a loose-fitting, disposable device that produces a physical barrier between the mouth and nose of the wearer and possible pathogens in the direct environment. Surgical masks are heavily regulated by organizations such as the American Society for Testing and Materials (ASTM). If worn properly, surgical masks can help in blocking almost all large-particle droplets, splashes, sprays, or splatter that may contain contaminants, keeping them from entering the wearer's nose and mouth. Also, surgical masks are effective barriers for retaining large droplets released from the wearer's mouth and nose.
Surgical masks are produced using a variety of materials with different thicknesses and different abilities in protecting you against contact with respiratory droplets. Most surgical masks are manufactured through the combination of three various layers of nonwoven fabric with each layer having a vital function. The outermost layer is the waterproof layer which helps in keeping out fluids including mucosalivary and respiratory droplets. The middle layer is the filter. The middle layer has the ability to block particles or pathogens above a specific size from penetrating in both directions. The innermost layer is the absorbent layer. Absorbent materials are utilized in order to confine mucosalivary droplets from the user. The innermost layer also improves comfort through absorbing the moisture from exhaled air.
When combined together, these three layers effectively protect both the user and the surrounding people by reducing the penetration of particles and pathogens in either direction. The comfort, breathability, and filtering capacity of surgical masks are greatly dependent on the properties of these materials that were utilized in manufacturing the mask. It must be noted that due to the materials used, surgical masks are not intended to be reused and should only be utilized once. With that, if your surgical mask is soiled or damaged, or if breathing through the surgical mask becomes hard, you should remove the face mask, discard it safely, and replace it with a new one.
Unlike Home-made or cloth masks, surgical masks undergo the scrutiny and testing of the ASTM. The ASTM is responsible for setting the standards for surgical masks. The ASTM F2100, the current standard for surgical masks, reviews 5 basic criteria. These include:
- Bacterial Filtration Efficiency (BFE) - the ability to filter bacteria;
- Particulate Filtration Efficiency (PFE) - the ability to filter sub-micron particles
- Fluid Resistance - the ability of the surgical mask to prevent fluid penetration from the mask to the wearer;
- Delta P (Pressure Differential) - the measurement of how comfortable, light, and breathable a mask feels;
- Flame Spread - the ability to withstand exposure from flame.
In addition to these criteria set by the ASTM, skin sensitivity and cytotoxic testing for surgical masks should also be done by the ISO (International Organization for Standardization). This is important for it makes sure optimal comfort is achieved and the risk of adverse reaction from surgical mask materials and surgical mask usage is greatly minimized. If the surgical masks passed these quality checks, certification will be provided by the ISO.
The filtering capacity, which depends significantly on the materials and engineering design utilized for making the mask, dictates the level of protection that the surgical mask can offer against pollutants and pathogens. With that, surgical masks are greatly effective in filtering out viruses such as SARS-CoV-2 that has a size of approximately 60 to 140 nm. Unlike those masks made of materials with larger pore sizes such as those made from cotton and synthetic fabric, surgical masks are tested and proven to have filtering capacity for matter smaller than that of viruses and other microorganisms. The effectiveness of surgical masks can be categorized as ASTM level 1, 2, or 3. Level 1 Surgical masks are ideal for scenarios where low amounts of fluid, spray and aerosol are produced. Level 2 Surgical masks are for procedures where moderate amounts are produced and Level 3 Surgical masks are ideal for surgery.
Home-Made or Cloth Masks
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Unlike surgical masks that undergo standard checks to provide maximum protection against airborne pathogens, home-made masks do not undergo the scrutiny of internationally recognized quality assurance bodies. Hence, cloth masks are the most permeable and offer the least protection. A home-made mask acts as a reusable barrier to protect the wearer from inhaling droplets released by others. It is intended to trap respiratory droplets that are released when the wearer talks, coughs or sneezes. Cloth masks are commonly retained long term and reused a number of times, with a variety of cleaning methods and widely different intervals of cleaning.
There are many materials to utilize in order to make home-made masks. These include cotton and silk, among others. The most effective home-made masks are those that have multiple layers of tightly woven fabric like cotton. A home-made mask with several layers is better in preventing the respiratory droplets from getting through your mask or escaping from it. Other people also make cloth masks that have filter slots so that it can have an additional protective layer.
Furthermore, home-made masks are made of flexible material. Hence, they can tightly cling on to your face which removes gaps, such as those in the side of your face, which reduces the risk of pathogens possibly entering these spaces.
Cloth masks are frequently utilized in resource-poor settings because of the reduced cost of a reusable option. Several types of cloth masks, including those made of cotton, gauze and other fibres, have been tested in many in vitro studies in the past. Findings show lower filtration capacity compared with disposable surgical masks. However, it must be noted that studies also showed that the protection offered by home-made or cloth masks increases with the fineness of the cloth and the number of layers, indicating potential to develop a more effective cloth mask, for example, with finer weave, more layers and a better fit.
The Verdict
Findings of studies showed that all types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear or type of activity. Many studies conclude that any type of general mask, whether surgical or home-made cloth masks, is likely to decrease viral exposure and infection risk on a population level, despite imperfect fit and imperfect adherence. This is because it is always better to have some form of protection than have nothing at all.
However, multiple evidence show that the filtration, effectiveness, fit, and performance of home-made masks are significantly inferior to those of surgical masks and respirators. With that, the scientific body does not recommend home-made or cloth masks for use in healthcare settings, whose workers should as a priority be given proper respiratory protection through surgical masks or N95 respirators. Therefore, cloth mask use in the community is only advisable in certain situations such as when surgical masks are unavailable. If the supply of surgical masks are low, one can improve the protection provided by home-made masks through selecting appropriate material, adding a number of layers, and utilizing those with a design that offers better filtration and fit.
References:
- Howard, J. (2021, January 26). An evidence review of face masks against COVID-19. PNAS. https://www.pnas.org/content/118/4/e2014564118
- Chughtai AA, Seale H, Macintyre CR. Effectiveness of Cloth Masks for Protection Against Severe Acute Respiratory Syndrome Coronavirus 2. Emerg Infect Dis. 2020;26(10):e200948. doi:10.3201/eid2610.200948
- Seongman Bae, Min-Chul Kim, Ji Yeun Kim, et al. Effectiveness of Surgical and Cotton Masks in Blocking SARS-CoV 2: A Controlled Comparison in 4 Patients. 2020. Ann Intern Med. 173; W22-W23. Doi: 10.7325/M20-1342.
- U.S. Food And Drug Administration. 2021. N95 Respirators, Surgical Masks, and Face Masks. Retrieved from: https://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-surgical-masks-and-face-masks. Retrieved on 26 April 2021.
- Popular Mechanics. 2021. Cloth Masks, Surgical Masks, or Double Masks: Which Are Safest?. Retrieved from: https://www.popularmechanics.com/science/health/a35290705/which-face-mask-is-best-for-covid-protection/. Retrieved on 26 April 2021.
- Johns Hopkins Medicine. 2021. Coronavirus Face Masks & Protection FAQs. Retrieved from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/coronavirus/coronavirus-face-masks-what-you-need-to-know. Retrieved on 26 April 2021.