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Main measures against the new coronavirus infection (COVID-19) in the United StatesCenters for Disease Control and Prevention (CDC)He announced that “double use of a mask significantly improves protection against viruses.”
Maximizing the fit of cloth face masks and medical procedures to improve performance and reduce transmission and exposure to SARS-CoV-2, 2021 | MMWR
https://www.cdc.gov/mmwr/volumes/70/wr/mm7007e1.htm
CDC Study Supports Duplication of Mask with Exposure to Hazard Particles by 83% | Ars Technica
https://arstechnica.com/science/2021/02/double-masking-more-than-doubled-cough-particle-blocking-in-cdc-study/
An experiment by CDC’s Dr. John Brooks and others is to compare the so-called “double mask,” in which a cloth mask is worn on top of a medical mask, with a normal mask. Dr. Brooks and his colleagues use a mask on a rubber wrist and are droplet particles that may contain the new coronavirus.aerosolI investigated the reducing effect of.
As a result of this experiment, it was found that the aerosol reduction effect was 42% for the medical mask alone, but reached 92.5% for the double mask of the medical mask and the cloth mask.
This difference was thought to be due to the “openness” created by wearing a medical mask. As shown in the image (A) below, a general medical mask has a problem that an opening is created in the side surface of the mask when it is used, and droplets diffuse from this opening. On the other hand, in the case of a double mask as shown in the image (B), this opening is filled, so the diffusion of droplets can be further avoided.
Therefore, Dr. Brooks et al. Also conducted an experiment on a simple method of closing the opening, which consists of tying the mouth strap of a medical mask (hereinafter referred to as knot mask) as shown in the following image.
When we investigate the probability that the non-infected person will receive the aerosol released by the infected person, with one of the two dolls as the “infected person” and the other as the “non-infected person”, only the masked infected person The effect of Aerosol reduction is 82.2% for double masks and 62.9% for knot masks. If only the uninfected person wears a mask, 83% have a double mask and 64.5% a knot mask. When both infected and non-infected people wore masks, the result was 96.4% for double masks and 95.9% for knot masks.
Dr. Brooks et al. They carried out this research only in the laboratory, because they used dolls instead of humans, and there are various types of medical masks, even if it is called a “double mask.” After acknowledging that the effect differs depending on what type of mask is combined, he concludes that “proper use is important to maximize the effect of the mask.”
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in Science, Posted by log1k_iy
You can read the article in English automatically translated here.
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