COVID-19 Day 69: Why Cloth Masks Work Better Than You Think


This graphics is used by some to claim that cloth masks are ineffective in stopping the spread of COVID-19 or most viruses. Similar memes claim that even N95 masks can’t filter out particles smaller than 0.3 microns in size and coronavirus are 0.1 microns in size. Both claims are wrong because they fail to understand some key concepts in how viruses are spread, and how small particles actually behave in filters.

If you see one of these memes you can simply cut and paste the following in reply:

That’s funny. But I really need to debunk it so you aren’t passing along false information.

It’s true that COVID-19 virus particles are about 0.1 microns in size, smaller than the 0.3 chemical particulates used to measure N95 effectiveness.

But viruses aren’t leaving your body as individual particles. They are trapped inside respiratory fluid droplets that are 0.6-1.0 microns in size. These droplets are large enough to get caught and absorbed in cloth fibers, trapping the viral particles on those fibers. Which is why you need to change and wash those masks often.

Furthermore, at sizes below 0.1 micron, objects are effected by static electrical attraction and Brownian motion, making them more likely to get caught by fibers, rather than pass around them. Here’s an article explaining that:

Finally, no mask is perfect, nor protective measure is absolute. Cloth masks are only about 50%-80% as effective as surgical masks.
These are measures we can take to lower the chances of getting infected and lower the chances of infecting others unintentionally. You can take your own chances for yourself as you see fit. But you should do your best improve the odds for your friends and neighbors.

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