“Kras-test” between the different fabrics used in face masks

A research team put under the microscope a number of fabrics (and more) used to make face masks – from a simple T-shirt and socks to jeans and vacuum cleaner bags – to find out which ones are most effective at trapping Researchers from the University of Cambridge and the University of Northwestern have studied the effectiveness of different materials in filtering particles with a diameter of 0.02 to 0.1 microns – this is the case with microscopic particles that may contain viruses such as the new coronavirus. for the particle size of most viruses – when they “travel” at high speeds, such as when a person coughs. The scientists also studied the effectiveness of the N95 mask as well as the surgical mask in filtering hazardous particles. High-speed filtering analysis Previous studies had examined the effectiveness of only a small range of fabrics, even in conditions where the wearer was wearing them. normally resulting in the microparticles being released at a slower rate. Now the analysis of more types of fabrics and the conditions under which microparticles “travel” at high speeds provides a better picture of the effectiveness of fabric masks. New findings published in the BMJ Open show that most fabrics that commonly used to make non-medical masks are effective in filtering out very small particles. N95 masks prove to be extremely effective, although HEPA filter vacuum cleaner bags seem to outperform N95 in some cases. Effective handmade masks As for handmade masks, those with multiple layers of fabric appear to be multi-layered. effective, while those that carry extra hard material inside (such as that used on shirt collars) are even more effective. It should be noted, however, that adding such a material to the mask makes breathing more difficult compared to a N95 mask. The researchers also studied the performance of different fabrics when they wet and when they have gone through a wash-and-dry cycle. They concluded that the fabrics were effective when wet and that they did not lose their effectiveness after a wash cycle. However, previous studies have shown that repeated washing wears out fabrics, which is why researchers warn that cloth masks can not be reused indefinitely. The experiment Cambridge and her colleagues built a special machine in the center of which they placed the fabric sample. One end of the machine created and released aerosols that passed through the fabric at a speed similar to that of aerosols released when a person coughs. The researchers measured the levels of aerosols before they passed through the fabric and after passing through it. An important parameter was that it did not obstruct breathing. . “A mask that blocks microparticles very well but blocks breathing is not an effective mask,” O’Kelly said. “Denim fabric, for example, was effective in filtering out particles, but it did not allow the person to breathe well, so it is probably not a good idea to make a mask out of an old pair of jeans. N95 masks allow the person to breathe more smoothly compared to any combination of fabrics that offers similar levels of filtration. The vacuum cleaner bags The study even examined the use of a vacuum cleaner bag with a HEPA filter to create a face mask against SARS-CoV-2. According to the researchers, at the beginning of the pandemic, due to the great shortage of N95 masks, some manufacturers began experimenting with this material for use in masks. As it turned out, both disposable and reusable vacuum cleaner bags were effective in blocking microsomes. . However, the scientists who conducted the study warn that disposable bags should not be used to make face masks as when cut the material wears out and may contain materials that should not be inhaled. “It’s a matter of balance – we want the materials used to be effective in filtering the particles, but we also need these materials not to put users at risk of inhaling threads or fluff, which can be harmful,” O’Kelly said. The limitations The researchers report that their study is associated with limitations: the main one is that the role played by the mask in the filtering of the part of the face of each user was not examined. In another study, O’Kelly explores how mask application can be improved in hospitals. make a mask at home and look for the right fabric. “We have shown that fabric masks can be surprisingly effective in filtering out particles that may contain viruses, even when released at high speeds.” Follow it on Google News and be the first to know all the news See all the latest News from Greece and the World, at

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