What is a mask valve, and why are cities banning them?
Some masks and respirators have a little plastic piece embedded in the fabric. It’s a one-way valve. That means it closes when you breathe in, so pathogens can’t get in through it. But when you breathe out, this valve opens, creating a doorway for your exhalation to leave the mask.
Valves don’t make sense for infection control
Valves defeat that second purpose. A valved mask is letting your breath out unfiltered; the valve acts as a little escape hatch for any virus-laden droplets you’re breathing out. Some municipalities that require masks have specified that masks with valves do not count. You also won’t typically see valved masks in healthcare settings for the same reason.
- Experts are warning the public against wearing certain types of N95 face masks with front valves.
- They say the masks protect the people wearing them but do not stop virus droplets from escaping and infecting others.
- The masks are designed for construction workers to use to keep out dust and other particles.
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