Can Masks Protect People from The Coronavirus?

Can masks and surgical masks protect against the coronavirus

With the outbreak of the coronavirus in China in early 2020, millions of people have to become experts masks overnight. Yet masks are complicated. Which masks can protect me from viruses? Do surgical masks filter the coronavirus? Do I have to use an N95 mask to protect me from viruses like the coronavirus?

Quora: Can masks protect us from Wuhan coronavirus

Fortunately, scientists have already accumulated hard data on air pollution masks that can answer these questions.

How Big Are Coronavirus Particles?

Scientists have already used electron microscopes to measure how big the corona virus is. Coronavirus virions (or ‘particles’) are spherical particles with diameters of approximately 125 nm (0.125 microns). The smallest particles are 0.06 microns, and the largest are 0.14 microns.

Coronavirus virus particle size

This means coronavirus particles are smaller than PM2.5 particles, but bigger than some dust particles and gases.

Size of coronavirus particle pm2.5 and bacteria

Now that we know how big coronavirus particles are, does a mask filter out these particles? Let’s break this down into two simpler questions.


1. Can air pollution masks capture coronavirus particles?

The skeptic case: 

People might say: The coronavirus (and other viruses for that matter) is tiny – 500 times smaller than the diameter of a human hair. And masks are so thin. How could they possibly get those tiny coronavirus particles?


The scientific test:

Researchers from the University of Edinburgh tested different common masks by running a diesel generator (to mimic car exhaust) and piping the exhaust through different masks. They used a particle counter to see how many particles made it through the mask. Here’s my super scientific rendering of the setup:



One important detail: the particle counter they used measured particles as small as 0.007 microns. That’s over 10 times smaller than the coronavirus particle diameter. We’re talking about truly tiny particles here!

They tested a whole range of masks, and here’s what they found:

N95 mask surgical masks Respro particle capture test data


3M industrial filters were able to capture over 95% of particles down to 0.007 micron. That’s over 10 times smaller than the coronavirus. What might be surprising to some is that the surgical mask was able to capture 80% of the tiny particles.

Conclusion: Masks – including surgical mask and N95 mask – can capture tiny particles over 10 times smaller than the coronavirus.


2. “OK, they can capture particles even smaller than the coronavirus, but when you wear them, all the air just leaks in the side.” 


The skeptic case: 

Mask works in theory, but those tests aren’t on real faces! When you actually wear them, you can’t get a good enough fit, so they’re basically useless.

The scientific test:

To answer this question, you need a really expensive fit-test machine. Fortunately, we were able to get our hands on one machine to test a range of masks.


Pollution masks N95 fit test TSI 3M


The blue tube is sampling air outside the mask, while the white tube is sampling air from inside it (more details on the mask fit-test methods ). 

Smart Air co-founder Anna Guo and Beijing-based Dr. Richard Saint Cyr also did some tests, so I combined all of our data. Here’s how well the masks worked on our faces:


Pollution masks respirator fit test data haze

View the full test data »

Several 3M masks were able to capture over 99% of tiny 0.01 micron particles (10 times smaller than the coronavirus), even while on people’s face. What’s more, surgical ones were surprisingly effective, capturing 63% of the tiny virus-sized particles.

Read more: the health benefits of wearing masks »

Can Masks Protect Us from The Wuhan Coronavirus?

Bottom line: masks can filter out even the smallest particles – those 10 times smaller than viruses. What’s more, they work surprisingly well even while people are wearing them. Surgical ones are cheap and more readily available, and they do surprisingly well at filtering virus-sized particles.


The Sqair air purifier Kickstarter

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How effective 3m 9332 or n95 8210, since the goverment recomend the n95 8210…


Sorry Still a bit lost here, so technically the effectiveness of those cotton Mask with PM 2.5 Filter are similar to surgical mask? or totally useless against viruses?


But I suppose the virus usually doesn’t come alone, but rather with slime/water droplets from coughs or sneezes. How do the masks perform in that case?