If you’ve been wondering how masks work against airborne infections like COVID-19, take a look at the Schlieren imaging above. It was filmed in slow-motion by fluid dynamicist and mechanical engineer Matthew Staymates, who set up this optical technique to see how our hot breath meets the colder air around us. He then filmed the results at 250fps, both with and without a mask.
And though we can’t see viruses with this technique, we can see the air currents that can potentially carry microscopic moisture droplets full of Coronavirus. This, Dr. Joe Hanson explains in this video from It’s Okay to Be Smart, is one of the reasons why masks work:
“Viruses are carried on that breath just like a river carries a fish.” Without the mask, that river is strong and travels much farther. Masks slow that river down, localizing it into swirls and eddies.
Cloth and surgical masks don’t limit oxygen intake in ways that could be harmful; fibers in these masks aren’t dense enough. Viruses carried within moisture droplets, however, can get caught in the mask before that moisture evaporates and releases them into a harder-to-stop size.
Another example from this video includes a test by Dr. Richard Davis, who “sneezed, sang, talked and coughed toward an agar culture plate with or without a mask. Bacteria colonies show where droplets landed. A mask blocks virtually all of them.”
And though bacteria are not viruses, the masks block the respiratory droplets that carry both.
What does a mask do? Blocks respiratory droplets coming from your mouth and throat.
Two simple demos:
First, I sneezed, sang, talked & coughed toward an agar culture plate with or without a mask. Bacteria colonies show where droplets landed. A mask blocks virtually all of them. pic.twitter.com/ETUD9DFmgU
— Rich Davis, PhD, D(ABMM), MLS 🦠🔬🧫 (@richdavisphd) June 26, 2020
Hanson also addresses some of the misconceptions around wearing masks (and umbrellas), and how, those perceptions can change over time.
Note: There are two versions of this video. The unlisted one above is a kid-friendly, slightly edited version. Thanks, Joe!
And as always,watch more It’s Okay to Be Smart.