• The CDC is now recommending that everyone wear a face mask when they’re outside of the home in order to help get the spread of the COVID-19 coronavirus under control — that is, if they’re unable to stick to the social distancing guidelines of staying six feet away from other people in public.
  • A video published in the New England Journal of Medicine shows why face masks are so important. For one thing, they protect other people from all the particles we don’t realize we emit from our mouth when talking.
  • Visit BGR’s homepage for more stories.

Everyone who works at Walmart or Sam’s Club now has to wear a face mask during their shift, an update to a policy that previously said the masks were optional. But this doesn’t just extend to the workers on the floor — the same now also holds true for anyone who works in Walmart’s distribution and fulfillment centers, as well as in its corporate offices.

This shift in recent days by the largest brick-and-mortar retailer in the world comes after a similar recommendation from the US Centers for Disease Control and Prevention, which now says that “cloth face coverings” are recommended for everyone outside of their home when “other social distancing measures are difficult to maintain.” Anecdotally, I’ve been out of the house some in recent days, and face mask usage still doesn’t seem to be terribly widespread (there are plenty of reasons for that, of course, such as the shifting and confusing guidance from health officials at first, in the early days of the coronavirus crisis). But if you want to see a pretty basic, straightforward visualization of why it’s important for everyone to wear face masks right now, this video from the New England Journal of Medicine should make things pretty clear.

The video below use lasers to illuminate the degree to which we all expel particles (okay, spit) when we talk. Even when we don’t think we do. And not only that, but you do it more the louder you talk. Click play on the video below, though, and watch what happens when you wear a mask:

“The act of speaking generates oral fluid droplets that vary widely in size, and these droplets can harbor infectious virus particles,” the piece in the journal reads. “Whereas large droplets fall quickly to the ground, small droplets can dehydrate and linger as ‘droplet nuclei’ in the air, where they behave like an aerosol and thereby expand the spatial extent of emitted infectious particles.”

Interestingly, the piece goes on to point out that it found the number of particles emitted during speech seems to increase whenever you speak louder. While the journal explains that one study has found droplets to be somewhat smaller than those we emit when we cough or sneeze, their number is at least comparable whether the person is just speaking or coughing. As the video above shows, though, this is what’s so nuanced about wearing a mask, and why it can be a little counterintuitive to wear one.

The average person might think, “I’m not sick, so why do I have to wear one?” My mask is not meant to protect me, though — it’s for you. And the mask you wear, likewise, protects me from all those particles emitted during speech that could very well include the coronavirus.

Andy is a reporter in Memphis who also contributes to outlets like Fast Company and The Guardian. When he’s not writing about technology, he can be found hunched protectively over his burgeoning collection of vinyl, as well as nursing his Whovianism and bingeing on a variety of TV shows you probably don’t like.