Since January 20, 2020, masks have become a scarce resource.
It seems that wearing a mask is certainly a good way. The multilayer structure of the mask can effectively block large particles, and those nano-sized particles will be adsorbed on the internal fibers due to electrostatic effects.
So if we take the diameter of the particles as the abscissa and the filtering efficiency as the ordinate, the filtering effect of these masks is actually a U-shaped curve.
It can be seen that the most difficult to filter is actually particles with a diameter of about 0.3 microns. This is why most masks use the 0.3 micron sodium chloride filtration capacity as a test indicator, and it is N95 that can filter more than 95% in the test.
N95's filtering effect is of course the best, but even the worst gauze masks can achieve close to 80% protection for particles above 10 microns, which is about one-tenth of our hair diameter.
How big is the size of the droplet core?
According to this 2007 paper, 82% of the droplet nuclei produced by cough are concentrated at 0.74-2.12 microns.
Looking at it this way, most ordinary nuclear medical masks are sufficient for droplet droplets. In a randomized trial involving more than 2,800 flu medical staff in the United States, the infection rate of influenza wearing N95 masks and medical masks was not even significant. difference.
Therefore, don't worry about the complicated mask types, brands and national standards. Rather than wearing N95, more importantly: did you wash your hands?
Wash your hands because your hands are likely to have a coronavirus alive.
Take the SARS virus as an example. In this study of the Academy of Military Medical Sciences, they can survive for at least 2 days on glass, plastic, and metal. They stay in various places with droplets, and your hands are likely to Will touch.
Then when you rub your eyes and pick up booger, the virus will contact the mucous membrane cells and complete the infection.
So, wash your hands. Wash a little longer.
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