To answer that question, we need to understand why we wear masks and why they are useful for COVID-19.

Whether it is the N95, N90, or the KN series, or the KF series, these masks can effectively prevent the virus from invading our respiratory tract. N95 means that the filtration efficiency of particles up to 0.3 microns is 95 percent, while N90 is 90 percent. In fact, it is not us who need N95 or N90, but medical workers at the front line of epidemic prevention. For us who just go out to take out the garbage, disposable medical masks are enough.

The type of mask we wear is primarily based on our exposure risk. In treating new crown pneumonia patients for doctors and nurses, the high risk population were necessary to wear medical N95 or N95, and whether, take out the rubbish, express, get take-out and even commuting to work, these all belong to low risk of exposure, we don’t want the white and the front angels for valuable resources protection, ok?

So do air purifiers work?


If you admit that masks work, it’s hard to deny that air purifiers work, too. Because the principle of the two is basically the same, and the filtration efficiency of the air purifier is better.

The core filter screen of air purifiers on the market is basically HEPA, which is no less than 99.97% for particles of 0.3 microns, while the N95 is 95%. So masks can filter out the virus, and air purifiers are better.

But that’s not very precise,

Because they are not actually filtering the virus, but the carrier carrying the virus.

Yes, in order for a virus to spread, it usually has to use a vector.

If you look at the confirmed modes of transmission of COVID-19, which are droplet and contact transmission, there is one that has been announced and later withdrawn, called aerosol transmission.

Whether it is droplet transmission, contact transmission or aerosol transmission, the virus root is the same, that is, the patient when talking, coughing, sneezing produced droplets.

The green droplets are the “droplets” that have been popularized over and over again, while the red ones are the “droplet nuclei,” or aerosols. Aerosol viruses are like small droplets, floating in the air as particles, and the size of the particles determines how far the virus spreads, with smaller particles spreading farther.

When a normal person sneezes, hundreds of millions of viruses are ejected by the strong pressure of the respiratory tract. Droplets larger than 10 microns soon fall within a distance of 1-3 meters, while droplet nuclei can float in the air within 9-10 meters.

Fear not, both droplets and droplet nuclei are within range of masks and air purifiers.

The diameter of the droplet is generally more than 10 microns and will settle to the ground, while the diameter of the droplet core, which stays in the air for a longer time, is generally around 0.5 to 5 microns. In other words, both droplet and droplet core can be effectively filtered by masks and air purifiers that can effectively filter particles of 0.3 microns.

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