A new study points out that the use of a used mask may be less effective in protecting against coronavirus than not using it. According to dailymail The researchers looked at three levels of surgical masks, which are often used by health and nursing staff.
During the investigation they concluded that unused masks can filter almost three-quarters of the tiny particles that remain in the air and are responsible for contamination.
However, when used more than once, they filter only a quarter of the small droplets. This is because the masks are deformed with each use. The team of researchers from Lowell University of Massachusetts and California Baptist University point out that the findings at their disposal provide information on the shape of the mask should be taken into account both when considering their protection and when designing new masks.
It is noted that the three-level masks are one of the most recommended for health and nursing staff. Their inner layer is made of absorbent material, their middle layers act as a filter and their outlet is made of non-absorbent material. For the study, published in the journal Physics of Fluids, The team of researchers developed a computer model of a person wearing a surgical mask with folds.
They then examined their behavior aerosols, tiny droplets of liquids and airborne particles. This model tracked where aerosols landed on the mask and face, and whether they reached the nose or lungs. So it seemed that when people wear masks, the way the air flows around their face changes. At the same time, the researchers found that air does not enter through the nose and mouth at specific points, but through the entire surface of the mask at low speeds.
Immediately after, they examined the filtration performance of the three-level masks. During the test they found that the new masks can filter the 65% of the particles. However when used they can only filter the 25%. AThis means that a mask, when new, offers good protection, but its wear can often be worse than not wearing a mask at all.
Researchers believe this is because aspects of the surgical mask affect airflow patterns, and when used over and over again, they change shape and thus reduce their effectiveness. It is noted that this research team hopes through a future research to study how different mask shapes affect our protection.
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