This viral video shows how masks help stop the spread of coronavirus

Here's what a cough actually looks like with and without a mask.


Officials say wearing a mask is the easiest and one of the best ways to slow the spread of the novel coronavirus as we wait for a vaccine.

If you or someone you know are looking for an explainer on how masks work, try this YouTube video from "It’s Okay to Be Smart."

Viruses can be difficult to understand because they’re invisible to the naked eye, traveling inside water droplets on unseen air currents. With a technique called schlieren imaging, though, we can see these air currents, and that’s what It’s Okay to Be Smart uses to demonstrate how masks work.

The science behind schlieren imaging is a little complicated, involving a spherical mirror bending light in subtly different ways to reveal differences in density that would otherwise be invisible. It’s important to note that this doesn’t let us see viruses — they’re too small for that — but it does let us see how air flows when we exhale.

Using a combination of slow motion and schlieren imaging, the video reveals what a cough looks like with and without a mask. The differences are striking. The unmasked cough creates a massive plume of potentially virus-laden air, traveling much farther than you’d expect — about 2 meters, which is why social distancing means staying outside that zone.

A mask does two things: First, it captures much of the droplets expelled when you cough, sneeze or breathe. Second, any that aren’t captured have their momentum blunted, keeping them from traveling very far. That means there is less of a chance of infection for people around you.