The Centers for Disease Control and Prevention of the United States (CDC) recommended this Wednesday to improve the fit of the masks so that they filter better and further reduce the risk of contagion. To do this, they suggest systems such as the use of knots or even a cloth mask over the surgical one. The alternative is to use a single high protection mask, type N95, but the objective is the same: to make sure that there are no lateral gaps. This CDC recommendation is an interesting measure when it comes to improving the capabilities of certain masks that do not have the levels of protection demanded by some risk situations.
After the initial uncertainty at the beginning of the pandemic and the absence of masks on the market, the recommendation was to prevent contagion by maintaining a prudential safety distance to prevent transmission. A few weeks later, the need to wear masks to prevent transmission in risky places was confirmed. To the extent that the regulations required the obligation to wear a mask in any public place, the use of a mask became widespread. This was also possible as they became more accessible.
SARS-CoV-2 is a respiratory transmitted virus. This evidence, however, involves a debate as to the vehicle through which the virus enters our body, saliva droplets or aerosols. The particles that we emit when we speak, cough and even breathe, are the vehicles that the virus uses to transmit itself from person to person. The size of these particles and the amount of virus present in them are two determining factors in infection.
Given the different risk situations in which a mask must be used, the variety of masks available and their level of protection must also be taken into account. The main types of masks used by the population are of four types: cloth, hygienic, surgical and high protection or FFP2 (in some places N95, with an equivalent effectiveness).
Fabric masks can have a wide variety of properties, depending on the characteristics of the materials used in their manufacture, but in many cases they are not approved in terms of their level of filtration. It is possible that some of them retain the virus very effectively and, even, some made with materials that contain compounds with silver or copper can have viricidal properties.
Limited efficacy
In the case of hygienic masks, their effectiveness is limited and their use is not recommended to prevent the transmission of the virus.
Surgical masks have characteristics that due to their ease of use and level of containment have made them the most popular masks. Its structure contains in most cases three layers in which the exterior has hydrophobic properties and the interior, which is in contact with our skin, mouth and nose, the ability to absorb moisture.
These masks can have pore sizes between 2 and 10 microns and can contain around 80% of the particles that can remain in the air. In addition to its pore size, the electrical charge of the material helps attract airborne micro-organism particles.
Finally, the approved FFP2 masks have the capacity to filter more than 92% of the particles that are in the air. These, in addition to the properties mentioned for surgical ones, contain at least six layers of insulation and the pore size of the mesh of these is less than 0.5 microns.
To all the characteristics previously exposed, we must add the fact that the daily and continuous use of masks is associated with their deterioration and accumulation of matter in the pores of the fabric, the difficulty of breathing with them after a few hours and the loss of its effectiveness.
Beware of the accumulation of microorganisms
Together with these characteristics, its continued reuse can lead to the accumulation of microorganisms in it and the risk that such accumulation entails on the skin and respiratory system of some people, which is why its replacement is recommended.
In this context, and with the idea of increasing its protective capacity, the use of a double mask may be an interesting option in some situations, but it must be qualified.
Not all people have the same risk from the virus and not all situations they face involve the same level of risk. Also, wearing multiple masks can make it extra difficult for some people to breathe. The use of two could be recommended in high-risk situations in which, for example, an FFP2 mask is not available, or in personal situations in which a person has difficulty guaranteeing that the mask perfectly closes the possible spaces. remaining free if it is not adjusted properly.
In this sense, it would be convenient to specify the recommendations regarding the situations in which the use of a double mask is suggested. These should be those in which the use of FFP2 masks is recommended but there is no access to them.
Estanislao Nistal Villán, Virologist and Professor of Microbiology at the Faculty of Pharmacy, CEU San Pablo University
This article was originally published on The Conversation. Read the original.
