Over the last couple of days, you’ve probably noticed a lot more people wearing masks or cloth face coverings in public spaces. Wondering how well these protect from #COVID19 and whether cloth masks make any difference? The big difference they make is for the people around you.

Before I go any further into the science behind the spread of #COVID19, it is critical to say – please do not start buying N95 or surgical masks to wear! Each mask you buy means one fewer for the healthcare workers who most need them.

What the CDC is recommending is that people make their own cloth masks to wear. But, how do those work? Isn’t the virus small enough to fit through the holes in the fabric? Yes, it is. It turns out the mask is more about protecting those around you. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover-faq.html

To understand this, we need to talk about particle sizes. You probably know that the coronavirus is small – after all, you can’t see them. They in fact are very small – each virus has a diameter of 125 nanometers, or nm for short. Here’s a picture of one under a microscope.

How small is 125 nm? Take a look at a piece of your hair – it has a width of about 50-100 microns. 1 micron equals 1000 nanometers. That means that you would have to make a string of 400-800 virus particles to span the minuscule width of one of your hairs. That’s small.

If the virus is that small, how does a mask actually help? That has to do with how the virus spreads. It spreads on the water droplets that you breathe, sneeze, or cough. These droplets are much bigger than the virus – even big enough to see.

How big are they exactly? Scientists have measured that! Their size varies, but is in the neighborhood of a few microns – not too much smaller than the width of your hair.
https://www.ncbi.nlm.nih.gov/pubmed/18158720 

The main route by which the virus spreads through the air is by being carried on these droplets. So, if you can stop the droplets, you can stop the spread. That means that a mask only needs to be made of material that can catch droplets, not the virus particles themselves.

This raises one of the most important things to know about wearing a mask – it doesn’t mean you can’t catch the virus, it just means you’re less likely to spread it to others. It is still incredibly important to distance yourself and wash your hands in order to stay healthy.

There it is. Wearing a cloth mask is something you can do to protect the people around you when you need to be in public spaces. And, by wearing a cloth mask instead of trying to buy a surgical mask, you are also helping to protect the healthcare workers who need those the most!