"When you compare the videos side by side, the difference is striking," Staymates said. Using an imaging system that "causes differences in air density to show up on camera as patterns of shadow and light," the videos demonstrate how large quantities of unfiltered air exit vented masks.
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The hole in the material may allow your respiratory droplets to escape."Īs it turns out, that's putting it lightly. To illustrate just how flawed these masks are, Matthew Staymates, a research engineer with the National Institute of Standards and Technology (NIST), created a series of videos comparing vented and non-vented masks. The agency explains that "this type of mask may not prevent you from spreading COVID-19 to others. The Centers for Disease Control and Prevention (CDC) has issued a similar warning, and has included vented masks on their own list of masks to avoid. While vented masks may help keep particles away from the wearer, "masks with vents or exhalation valves allow unfiltered exhaled air to escape," they explain. The one mask type explicitly branded as "unacceptable" on the Mayo Clinic's list? Any mask with vents.
Among their list of " acceptable masks" are homemade masks that cover the nose and mouth and surgical or procedural masks. But as the Mayo Clinic warns, not all masks are created equal, and some can be downright dangerous. In a policy posted on its website, the Mayo Clinic has outlined which mask types are welcome on clinic grounds, and which are banned. Along with social distancing and frequent hand washing, mask wearing is one of our best defenses against COVID-19.