Recently, videos showing DIY face masks have been trending on social media. People from all over the world have been making their own masks out of T-shirts, scarves or even just random pieces of cotton. But the question is – can they actually protect you from the coronavirus?

When you wear a mask, you need it to protect you from the virus. You want a filter that prevents you from inhaling harmful airborne particles, such as pathogen-carrying droplets.

But cotton is just not delicate enough to work as a filter. Some say the holes in the fabric are tiny, so the virus won't be able to get through.

Figures talk. Let's see how big the droplets are.

According to a paper published by the U.S. National Library of Medicine, 82 percent of droplets expelled from coughing are in the range of 0.74 to 2.12 micrometers. That's roughly one eightieth the diameter of one strand of your hair.

Here are the efficiencies of four different types of masks, an N95 respirator mask, a medical grade surgical mask, a disposable mask and a cotton mask, respectively.

As mentioned, most of the droplets are in the range of 0.74 to 2.12 micrometers, so let's get that part highlighted.

From the chart, we can clearly see that cotton masks are not very effective, whereas the other kinds can sufficiently protect you from the majority of droplets.

So, no to T-shirts. Droplets can still get through the material. But disposable masks work just fine, so you don't have to get a medical-grade mask.

This is a tough time. Many frontline medical workers are still facing a severe shortage of protective gear; some have been working without proper PPE for days or even months. We do not need to fight with them over medical-grade masks when the disposable kind works just fine.

Read more:

Acute shortage of PPE and ventilators adds woe to COVID-19 battle

But, what if you can't even get a disposable mask? The advice is to stay at home as much as possible and cut off all potential sources of infection. And remember to always wash your hands.

(Video produced by Wang Zeyu; filmed by Fu Gaoliang; edited by Zhao Yuxiang)