Important points to consider with disposable masks
, 2 min reading time
, 2 min reading time
Mask-wearing can be effective in the containment of communicable diseases and has thus become a new normal these days around the world as a result of the COVID-19 pandemic. The surge in demand for surgical masks and respirators has led to a global shortage of previously known supply and fear regarding credibility of the unknown. Researchers and industry players have therefore been working hard to address the issue of shortage, as well as to enhance the protection afforded by existing mask models. These efforts include (i) sourcing and engineering alternative materials with sufficient filtering capacity, (ii) engineering the design of masks and respirators for better protection, breathability, and user comfort, (iii) developing and engineering multifunctional masks and materials with hydrophobic, antimicrobial, self-disinfecting, and even sensing properties, and (iv) exploring new technologies for efficient production and customization of masks.
Attempts to procure mask will pivot on the understanding the basics of mask technology. The fundamental questions, to our mind, are as follows: (i) how do masks (and the mask materials) protect us from pathogens; (ii) what are the existing models and materials of mask available in the market; (iii) how do they perform and how is their performance benchmarked against others; (iv) what are their limitations; (v) how can their performance be improved.
3-Ply Surgical Mask
The 3-ply surgical mask is commonly used in the COVID-19 pandemic. The 3-ply surgical mask is made up of 3 different layers of nonwoven fabric with each layer having a specific function. The outermost layer (typically blue but can be a variety of colours) is waterproof to help repel fluids such as mucosalivary droplets. The middle piece is the filter, which prevents particles or pathogens above a certain size from penetrating in either direction. The filter determines the quality of the mask (ASTM Level 1-3) or determines if more layers are required. The innermost layer is made of absorbent materials to trap mucosalivary droplets from the user. This layer also absorbs the moisture from exhaled air, thus improving comfort. Together, these 3 layers effectively protect both the user and the surrounding people by limiting the penetration of particles and pathogens in both directions.
The two most common filters used in the making of nonwoven fabric for surgical mask are spunbond and melt-blown.
The spunbond process combines the spinning and sheet formation process into one continuous, nonwoven manufacturing system. This process is where the polymer is bonded together via heat, chemical, or mechanical means to form the nonwoven fabric.
Although the melt-blown process is very similar to the spunbond, the microfibres produced in melt-blown are much finer and the pore size of the nonwoven fabric can be much smaller. Therefore, due to the finer pore size, melt-blowing is the typical process used to fabricate the middle filtering piece of the 3-ply surgical mask.Face masks provide the user with protection against airborne particles, pathogens, secretions, and body fluids by physically filtering them from breathable air. According to the American Society of Testing and Materials (ASTM) F2100 standard, which specifies the performance requirements for materials used in medical face masks, five performance characteristics have been identified. These are particulate filtration efficiency (PFE), bacterial filtration efficiency (BFE), fluid resistance, differential pressure, and flammability