Story at a glance

  • “Masks with exhalation valves or vents should NOT be worn to help prevent the person wearing the mask from spreading COVID-19 to others,” the CDC said.
  • Masks with valves have since been prohibited by several U.S. airlines.
  • The CDC recommends the use of cloth masks or facial coverings when it isn’t possible to stay at least 6 feet away from others in public spaces.

The Centers for Disease Control and Prevention (CDC) is warning that masks with valves do not stop the spread of the novel coronavirus and should not be used.

“Masks with exhalation valves or vents should NOT be worn to help prevent the person wearing the mask from spreading COVID-19 to others,” the CDC said in updated mask guidance on its website this month.


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Masks are meant to act as a simple barrier to keep potentially infectious respiratory droplets from being released into the air when a person exhales to slow the spread of COVID-19.

The CDC said masks with valves, which are often worn by construction workers who want to avoid inhaling dust, allow for air to be exhaled through the material.

“The purpose of masks is to keep respiratory droplets from reaching others to aid with source control,” the CDC said. “However, masks with one-way valves or vents allow air to be exhaled through a hole in the material, which can result in expelled respiratory droplets that can reach others.  This type of mask does not prevent the person wearing the mask from transmitting COVID-19 to others.”

Masks with valves have been prohibited by several U.S. airlines.

A recent study also found that people should avoid using neck gaiters to slow the spread of COVID-19 as they may actually be worse than wearing no mask at all.

Public health experts have largely agreed that widespread mask-wearing can reduce the spread of the coronavirus that has infected more than 20 million people worldwide this year.

The CDC recommends the use of cloth masks or facial coverings when it isn’t possible to stay at least 6 feet away from others in public spaces.

According to the Association of American Medical Colleges, cloth face masks should have a minimum of two layers, but three layers is recommended whenever possible. Face coverings should cover both nose and mouth and should be fitted properly to limit gaps around the nose and chin.

Research has shown face coverings that have two layers are significantly more effective at reducing droplets released by coughing and sneezing compared to a single-layer mask.

Published on Aug 13, 2020