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Wearing a face mask with a valve? It might be time to find something else, some experts say

The masks protect no one. "They need to be banned,” said a prominent Brigham and Women’s Hospital doctor.

The CDC says, “respirators with exhalation valves should not be used in situations where a sterile field must be maintained ...because the exhalation valve allows unfiltered exhaled air to escape into the sterile field.”
The CDC says, “respirators with exhalation valves should not be used in situations where a sterile field must be maintained ...because the exhalation valve allows unfiltered exhaled air to escape into the sterile field.”Justin Chin/Bloomberg/FIle

Masks and other face coverings have become as necessary as your smartphone or wallet when leaving the house amid the coronavirus pandemic.

But as people begin to ease back into public life, experts are warning that certain types of masks could actually be putting others at risk — and users should think twice before slipping them on.

In recent weeks, masks with small plastic valves embedded in the front have become the target of some health officials, who claim that while they may stop particles from reaching the wearer, they do little in the way of blocking what comes out of their noses and mouths.

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“The valves actually make things a lot more comfortable because they make the mask a lot more breathable,” said Dr. Ali Raj, executive vice chairman of the department of medicine at Mass. General Hospital. “But they don’t do anything in terms of filtering out anything the wearer is exhaling.”

Because people can be carriers of COVID-19 but never exhibit any of the telltale signs or symptoms, Raj said, they could be unintentionally expelling the virus through the mask’s one-way air hole and potentially infecting those around them.

“When you’ve got people coming out and businesses opening back up, you might as well have people not wearing masks at all if they’ve got a one-way valve,” he said, “because they’re just breathing everything right out into the air without any filtration.”

The most common type of masks with a vent are N95 masks, which can often be found in hardware stores. Raj, an associate professor at Harvard Medical School, said this can be confusing for consumers, since they tend to associate N95 masks with the medical professionals on the front lines of COVID-19.

But, he said, doctors and nurses at Mass. General and Brigham and Women’s Hospital aren’t donning the protective gear with valves when handling patients during the coronavirus pandemic, and instead use a more standard N95 mask without them.

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In a section on the Centers for Disease Control and Prevention’s website about personal protective equipment, officials say that an N95 respirator with an exhalation valve “does provide the same level of protection to the wearer as one that does not have a valve.”

However, the CDC says, “respirators with exhalation valves should not be used in situations where a sterile field must be maintained ... because the exhalation valve allows unfiltered exhaled air to escape into the sterile field.”

Raj said the valved masks are more widely used in industrial settings, or when doing things like woodworking or mowing the lawn. He said at Mass. General, health care workers will actually take a mask with a vent away from a patient when they come into the emergency department, and give them a different one instead.

“We essentially tell them they are not protecting any of us from what they are breathing out,” he said.

The warning from health experts doesn’t just apply to N95 masks with one-way vents. According to Dr. Atul Gawande, a surgeon at Brigham and Women’s Hospital and professor at Harvard Medical School, certain cloth masks being sold online that feature circular plastic vents on the front also can be a problem.

On Sunday night, Gawande tweeted that he has been targeted by online advertisements for such “evil” valved masks, coverings he said provide "'breathability’ when you exhale by releasing your breath and its contagion-carrying respiratory droplets.”

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“The masks protects [sic] no one,” said Gawande, who was not immediately available for comment. “They need to be banned.”

Earlier this month, Governor Charlie Baker issued an order that everyone wear a face covering both inside and outside when in public if they can’t properly distance themselves from others.

A representative of the state Department of Public Health did not immediately return a request for comment about whether or not people should use masks with vents or valves on them when venturing outside of their homes.

But in San Francisco, these types of masks don’t comply with an order to wear face coverings when in certain public settings, according to a COVID-19 related FAQ on the city’s website.

“A face covering can be made of cloth, fabric, or other soft or permeable material, but it should not have holes,” the website says. “Holes or one-way valves allow droplets out of the mask, putting others nearby at risk.”

According to healthline.com, the San Francisco Department of Public Health shared a strong warning against using N95 masks with valves earlier this month, after “still seeing a lot of these masks out there” despite regulations.

“It’s confusing, because they are called N95,” health officials wrote. “But the ones with the **valves** or openings on the front are NOT safe, and may actually propel your germs further!!”

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Not all experts have drawn such a hard line about the use of the masks, however.

Dr. Joshua Barocas, an infectious disease physician at Boston Medical Center and assistant professor of medicine at the Boston University School of Medicine, said when it comes to wearing masks in general, including ones with valves, he takes “a little bit more of a harm-reductionist view.”

“My recommendation would be to wear a surgical mask or a cloth mask,” he said. “That said, if [a one-way valve mask is] all you can get your hands on and all you’re comfortable wearing, I would rather you wear something rather than nothing.”

Barocas said anything short of wearing full-on protective gear while in public, at this point, essentially puts other people at risk.

But, for obvious reasons, “that’s not feasible,” he said.


Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.