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Omicron Waves, what's the problem of normal medical masks?

Updated: Feb 27


Living with the overwhelming COVID-19 pandemic for more than two years, it is known that wearing masks is a vital protection against being infected. Are surgical masks good enough? How about the N95 masks that medical professional wear like we see on TV? How are they different from the surgical masks? What else are so called “N95 equivalent” in the market? How do I choose the proper mask to protect myself better?



As regulated by global standards, the “N95 masks”, as well as the other equivalent standards of masks which are recommended by WHO against Covid-19 should be regarded as “(Particle) Respirators” in precise way. According to its function and intention of use, it can be defined as “fluid-resistance” or “non-fluid resistance” types. N95 masks’ function and effectiveness far outweigh that of the common medical/surgical masks.


After taking two shots of vaccination, these high ranks still preferred wearing N95s. It seems to tell the public that Omicron is extremely infective and those common masks are not good enough. “It is for your best to wear N95 in a crowded environment.”, says Leana Wen, Doctor in AD and Medicine Analyst for CNN. “In general, the Americans are not used to wearing masks. To prevent a wild spread of Omicron, it needs everyone to wear N95s.”


Common Surgical Masks: Not Protective Enough


Nowadays, the common surgical masks seem to be inadequate in providing protection. Wearing them in even higher risk areas, such as medical facilities, is putting the doctors and nurses in exposure to virus and bacteria.


Unable to effectively filter and protect against tiny droplets and viruses

The medical staff is often exposed to body fluids and secretions on the job and are at great risk of contracting diseases. Small droplet particles (<Mu, meter) are caused by many medical treatments, and COVID-19 has been confirmed to be transmitted through virus-containing droplets, one of the many ways.


For traditional medical/surgical masks, the test objects of filtration capacity are bacteria (Bacterial Filtration Rate BFE) and solid particles (Particle Initial Filtration Rate PFE). The test objects are usually bacteria with a diameter of 0.3 μm and above (American ASTM and European EN) and 0.1-5.0μm aerosol latex ball (American ASTM), even in the common American ASTM F2100 standard requirement of the highest Level 3 and the European EN 14683 standard Type II and Type IIR requirements are BFE/PFE above 98% (standards vary with product grades level down and further decrease).


On the other hand, although medical masks have detailed requirements for liquid barrier / fluid resistance, the test method is "synthetic blood penetration barrier test", which reflects that the mask material will not be affected by liquid under a certain liquid (droplet and liquid column) pressure. Penetration performance is an effective test method (also applied to the test of fluid resistance respirators), but these standards do not effectively measure the filtration performance of smaller diameter viruses and tiny droplets, and do not evaluate medical performance or effectiveness of using a face mask in preventing the infiltration of tiny harmful particles and droplets. Similarly, the filtration rate and liquid barrier tests of medical masks do not cover the design of the mask and the exact fit of the mask on the user's face, etc., and are only suitable for relatively low-risk protection and self-protection of patients and ordinary citizens.


In the case of an epidemic, medical staff must respond to a variety of droplets at any time, such as endotracheal intubation and extubation, sputum aspiration, bronchoscopy, induced sputum, or nasal swabs, nasal washing, throat swab or nasopharyngeal swab, etc. Even dentists are faced with the droplets of patients when filling and cleaning teeth.


Compared with bacteria and solid particles, droplets (as liquid particles) are more penetrating to general mask materials and clothing. Therefore, medical staff in high-risk environments must wear respirators of the same level or higher than N95. In particular, Surgical N95 and similar products with fluid resistance ability can effectively protect themselves and avoid infection.

Does not fit the face effectively, leaving a gap that is not sealed

Traditional surgical masks are mostly flat designs (thus also known as 2D or flat masks, although not all flat masks are surgical masks). Their main function is to prevent common droplet infection, and their edges are not sealed. That part of design greatly reduces the effect of filtering bacteria, particles, and droplets.


The surface of the soft folded and unfolded mask is easy to collapse and deform, directly contacting the mouth and nose, increasing the risk of infection. The area of ​​the mask that is unfolded up and down may not effectively cover the nose to the chin. The folds on the bridge of the nose, the wing of the nose, and the side of the face that do not fit are also compromised.


Further, it is easy to form the entrance and exit of air and harmful substances, resulting in leakage. Plus the exhaled or inhaled air flow is not filtered.


In order to achieve greater protection, WHO requires the use of respirators designed in a shape that will not collapse, such as a cup or duckbill structure, rather than the folded structure of a flat mask. For example, an N95 mask adopts a three-dimensional design, and the edge is close fit to the face. With the fit test, users can find a more suitable type and size of respirator to ensure that air does not enter through the gap, and every breath of air will be filtered by the mask and filter layer, which can greatly block bacteria and viruses in the air.


Reference

  1. World Health organization. (2020, November 13). Technical specifications of personal protective equipment for covid-19. World Health Organization. Retrieved February 3, 2022, from https://www.who.int/publications/i/item/WHO-2019-nCoV-PPE_specifications-2020.1


Update : 20220210-Eng


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