Given the emergency situation caused by SARS-VOC-2, there is currently a shortage of both surgical masks and anti-particle grade P1, P2, N95, and P3. In this report we present the results of preliminary analyzes of textile materials, evaluating their effectiveness as filters for transporting particles of the coronavirus. These measurements have been made, using the experimental design proposed by CSIC-IDAEA, in the GFAT laboratories at IISTA.
Given the inability to manufacture enough approved material, and in the absence of the ability to carry out all standardized tests on alternative material, IDAEA-CSIC designed a system to determine the filtration capacity of materials that can serve as a guideline in the current emergency situation . It should be noted that this system is not intended to be an alternative to certification protocols or a replica of standard systems, but it has been designed based on scientific and technical knowledge on particle filtration and the SARS-CoV-2 and considering the feasibility with the means available.
The University of Granada has the necessary instrumentation to replicate the system designed by IDAEA-CSIC , which is based on the generation of aerosols, selection of particles of a certain size (mainly 300 nm), and determination of the concentration of particles generated before and after passing through the material to be tested. The system used by the University of Granada consists of an aerosol generator (Aerosol Generator, TSI), an aerosol size classifier (SMPS, Electrostatic Classifier Model 3082, TSI) and two optical particle counters (CPC 3775 and 3776, TSI ). At the Interuniversity Research Institute of the Earth System in Andalusia (IISTA-CEAMA), the test of different materials has been carried out using sodium chloride at 0.5 M. The system selects sodium chloride particles of a certain size (300, 100 and 500 nm in this work) and then the concentration of particles is measured in both particle counters: one with the filter before entry and the other without a filter. Each of the meters measures at a flow of 1.5 lpm (liters per minute) and both devices have been compared before the measurements. Furthermore, the SMPS equipment has been previously calibrated by latex testing at 203 nm. The filter holder accommodates a 25.9 mm diameter filter and is clamped with an O-ring. It is important to emphasize that the flow is fixed at 1.5 lpm, which allows comparing between measurements, but does not give information about the breathability (or breathability) of the filter in question. On the other hand, we want to emphasize that a sample is chosen from each material, so the results may not be representative of each material studied. For example, a specific type of kitchen cloth was studied, and we cannot assure that the filtering efficiency does not vary between brands. Again, this study tries to give a brief orientation of filtering efficiencies, in the context of sanitary emergency.
 Minguillón et al. Emission and exposure to SARS-CoV-2 and filtration options, Institute of Environmental Diagnosis and Water Studies (IDAEA), CSIC, Report v3, April 15, 2020.
The full report is accessible through the following download link: