CSIC researchers design a system to determine the filtering capacity of mask materials

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Researchers from the Spanish National Research Council (CSIC) have written a report that compiles the available scientific information on how the SARS-CoV-2 virus, which causes the disease COVID-19, is emitted and transmitted through the air, and on what requirements It must have a mask or half mask to be effective. The researchers present an unapproved system that can be useful both for the administration that makes the decisions on what type of masks to be tested and for the laboratories that carry out the standardized test.

The report has been written by María Cruz Minguillón, researcher of the Group of Environmental Geochemistry and Atmospheric Research (EGAR), of the Institute of Environmental Diagnosis and Water Studies (IDAEA-CSIC), with the collaboration of other researchers from the team such as Xavier Querol, Andrés Alastuey, Natalia Moreno, Cristina Reche, Carla Ribalta, Mar Viana, Teresa Moreno, director of the IDAEA-CSIC, Jesús de la Rosa, from the University of Huelva and José Luis Jiménez, from the University of Colorado-Boulder.

The document indicates that SARS-CoV-2, about 100 nanometers in size, travels through the air as part of particles of various sizes, such as droplets and aerosols, which also contain salts and proteins present in the mucosa of the human respiratory system. Various studies show that these particles that are emitted when breathing, vocalizing, coughing, sneezing and breathing are initially similar, “says María Cruz Minguillón, from IDAEA-CSIC. “But when they are emitted into the air, they become smaller when the water they contain evaporates. Coarse particles tend to deposit quickly, but finer particles remain in suspension for hours or even days. SARS-Cov-2 can remain active in airborne suspension for more than three hours, “adds the researcher.

The concentration of viruses in the environment varies depending on the location. A study conducted in Japan, based on contact monitoring, has concluded that contagion is 19 times more likely in indoor than outdoor spaces.

Feasible alternatives in an emergency situation

The effectiveness of protection devices depends on three factors: the filtration efficiency of the material; adjusting the device to the face; and the purpose of filtration, either to filter the emission of particles from a sick person, or to filter particles from the ambient air inhaled by a healthy person.

In the current emergency situation, there is approved protection material in Europe that complies with the regulation for surgical masks, regulated by the EN 14683: 2019 standard, and personal protective equipment (half masks FFP2, FFP3), regulated by the EN standard. 149: 2001, referring to standard EN 13274-7:2019 to evaluate the filtering capacity of the material with which they are produced.

Given the inability to manufacture enough approved material, IDAEA-CSIC researchers have designed a non-approved system to determine the filtration capacity of materials that may be candidates for the manufacture of filter masks or half-masks.

The report attempts to compile relevant information to assess what requirements a mask must have to be effective for both commercial and craft devices. This system is not intended to be an alternative to certification protocols or a replica of standard systems, but has been designed based on scientific and technical knowledge on particulate filtration and SARS-CoV-2 and considering the feasibility of means available. It could be useful for both administration and laboratories.

Complete and detailed information is available on the website of IDAEA, CSIC and the Ministry of Science and Innovation.

This article was first published on 18 April by CSIC.

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