Definition Of Effective Anti-epidemic Mask

Viruses spread in the air with two methods.

First method: It is a widespread method of transmission that has been confirmed, and it’s transmitted through droplets. The so-called droplet is through airborne and the spread of pollution on the surface where it falls. According to the size of the droplet, we can simply divide it into the following three situations.

  • Larger droplets: refers to particles about 5μm, which can fly about a meter in the air when we talk, sneeze, or cough.
  • Smaller droplets: refers to particles about 1μm~5μm, which are formed after the larger droplets lose their external moisture in a dry environment. These droplets will stay in the air longer, and cause a greater infection risk.
  • Large droplets (over 10μm): The above two types of droplets are both like the large droplets, they will eventually fall on the ground or on objects, contaminating the surface where they fall. At this time, frequent wiping and disinfection are required to achieve the purpose of epidemic prevention.

Second method: It is transmitted through smaller particles (under 1μm) that can float in the air for a long time or relatively long time. The medical profession has not confirmed that this is one of the ways of transmission, but it is worthy of our attention to the possibility of transmission through this method. Generally speaking, the motion of particles over 3μm in the air can be explained by the inertial motion in Newtonian mechanics. That is to say, the motion of the particles can be assumed to be a straight line, and the filtering effect can be assumed to be a sieve type of inertial blocking effect. However, the movement of 1μm~3μm particles is starting to be affected by the Brownian motion by the collision of a few air molecules, and will exhibit random disturbances in the movement, and cause a longer stay in the air.

When the particle diameter is less than 1μm, the benefit of Brownian motion becomes greater and greater, so we can divide this clean aerosol into the following two motion modes:

  • Particle size between 0.3μm~1μm: It belongs to aerosol colloidal particles suspended in the air for a relatively long time.
  • Particle size under 0.3μm: It belongs to aerosol particles that are permanently suspended in the air.

There is no medical evidence that the above two kinds of fine particles suspended in the air can infect the Covid-19 virus. However, under the objective risk that the virus survives longer in the air and the number of asymptomatic infections continues to increase, according to logic to speculate the subsequent development, the potential risk of infection caused by these fine particles is worthy of our attention. Fortunately, the random movement of these particles caused by air collision has greatly increased the probability of these particles being captured by the mask fabric. Therefore, mask designers are allowed to make advance plans based on this phenomenon.

Advance Plan of Mask Design

For a good mask design, the following three situations must be considered in terms of particle filtration.

  • Filtering effect of particles with diameters over 5μm.
  • The combined effect of filtering and blocking particles with a diameter between 1μm and 5μm.
  • The barrier effect of particles with diameter under 1μm.

In the design, to produce sufficient filtering effect, is through the pore size of the fabric on the surface of the mask to make specifications. If you want to effectively filter 5μm particles, the pore of the fabric on the mask surface should be controlled to be smaller than 5μm, there is no need to be too dense to cause air permeability problems and excessive breathing obstruction. For smaller particles (under 1μm), we must consider how to block and adhere these particles that are randomly floating in the air with Brownian motion. There are two basic methods of adhesion, one is through electrostatic adsorption, and the other is through the adsorption capacity of the fiber itself.

Therefore, the ACTife beautify mask uses hydrophobic yarn on the outside, and hydrophilic antibacterial yarn on the inside to completely block the aerosol particles with random movement with the outer layer. If it does enter the inner layer, adsorption will be performed so that the bacteria and the aerosol particles of  the virus will stay on the yarn for a relatively long time for sterilization. At the same time, because the design of the beautify mask also provides an inner pocket that can fit an antibacterial filter for two-stage sterilization, providing wearers engaged in high-risk jobs with more secure.

For the effect of adsorption, weaving and yarn are the best materials seen so far. It can produce a certain thickness to effectively block and adhere these fine particles. At the same time, with such a good effect, we can also maintain the air permeability of the fabric to at least about 5μm, creating the best product that are practical (breathable) and anti-epidemic (while blocking the inertial filtration of particles over 5μm, and the adhering blocking of particles under 5μm).

At the same time, ACTife also planned a design of double-layer antibacterial, and three-layer super-breathable flat masks for disposable masks. It has the same droplet filtration as the beautify mask, and the benefit to block the fine aerosol particles by adhesion, allowing us to achieve the practical purpose of breathability and comfort under the condition of high epidemic prevention.

Understand The Droplets And Droplet Nuclei

When people talk, sneeze, or cough, they generate droplets of large particle size (greater than 5 microns). Generally speaking, the flying distance is about 1 meter (3 feet), when the droplets contain pathogens such as viruses, then close contact can increase the chance of human infection, which is called “droplet infection.” Therefore, for patients with respiratory tract infections, apart from wearing medical masks to avoid symptoms such as coughing from spreading pathogens to others, it is also recommended that patients keep a distance of at least 1 meter when talking with others, in order to reduce the risk of droplets infection. In addition, the large-particle droplets generated when people speak or sneeze will settle on the ground or the surface of objects, so correct hand washing procedures, frequent cleaning and disinfection of various surfaces (such as floors, desktops, equipment, toys, etc.), and proper food coverage can prevent droplet pollution. These are important living habits that people should develop.

As mentioned above, the human body can produce droplets of large particle size, but in fact, it also produces fine droplets. When the droplets containing pathogens are smaller than 5 microns in diameter, there is a risk of airborne infection, The previous content mentioned that large-size droplets containing pathogens, once in a low-humidity indoor environment, the moisture outside the droplets will evaporate to form tiny “droplet nuclei” that can be suspended in that air for a long time. If the pathogen itself can adapt to the environment, that is to say, it can survive safely. At this time, there is a risk of airborne infection. For example, if the human body inhales the air containing 1 to 5 microns of tubercle bacillus droplet nucleus, it may cause tuberculosis.

Up to present, the existing scientific evidence has preliminarily shown that COVID-19 is mainly transmitted by close-range droplets and contact. There is still insufficient evidence to indicate that COVID-19 will cause human infections by air transmission. As for whether COVID-19 will cause airborne infection or not, this is to be proved by more research in the future.

Reference: Chang Gung Medical News

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