VERIFY: Do masks with valves work?

The Centers for Disease Control and Prevention recommended the general public wear some kind of face covering or mask several months ago. Since then, more people have searched for and bought a mask.

In some cases, people grab and use whatever they can get including masks that have valves on the outside.


THE QUESTION
Are masks with valves effective in stopping the spread of COVID-19?

THE ANSWER
No. Masks with valves let exhaled particles through without filtration. Some localities have even banned them.


Credit: AP
A British police officer wears a 3M face mask, with few police officers in Britain seen wearing face masks since the outbreak of the coronavirus, outside St Thomas' Hospital, in London, where Prime Minister Boris Johnson remains in intensive care as his coronavirus symptoms persist, Thursday, April 9, 2020. British Prime Minister Boris Johnson remains in intensive care with the coronavirus but is improving and sitting up in bed, a senior government minister said Wednesday, as the U.K. recorded its biggest spike in COVID-19 deaths to date. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Kirsty Wigglesworth)

WHAT WE FOUND
A 3M diagram, explaining how its N95 masks with valves work, shows how exhaled air leaves the mask through the valve. The mask is designed for workers requiring respiratory protection in hot and humid environments.

Both the Food and Drug Administration and the CDC note that while N95 masks with valves offer a certain level of protection to the wearer, they should not be used “when sterile conditions are needed.” The CDC explains that’s because “the exhalation valve allows unfiltered exhaled air to escape into the sterile field.”

The valve doesn’t filter the air you exhale, meaning larger droplets you breathe out can escape the mask through the valve. That defeats the purpose of wearing a mask right now -- to prevent people who have the virus from giving it to others.

The CDC says people can spread the virus before they ever show symptoms, meaning that it’s possible a person who feels healthy can spread the virus through particles that may escape out the valve of a mask with one.

Some localities have included these masks when identifying what you shouldn’t wear. One example is in San Francisco, which said, “holes or one-way valves allow droplets out of the mask, putting others nearby at risk.” The Children’s Hospital of Los Angeles also told people not to wear masks with valves when coming into the hospital because they put others at risk.

The CDC still recommends simple cloth face coverings or masks for the general public.

[Papasquatch]

So if I breathe out with a valve on my mask I breathe out unfiltered air which could be contaminated but they say I protect myself because I breathe in filtered air. Doesn’t that mean everyone could wear Valves as long as they had a mask on because they’re going to be breathing in filtered air. And someone who doesn’t wear a mask at all has assume the risk and that’s fine too

[franciscobongon]

Not all masks with breathing valves allow UNFILTERED air out?! Many re-usable masks with valves have two physical layers before the breathing valve: 1. PM 2.5 insert and a 2. a soft inner cotton lining. This is a sweeping comment that "all valves" are ineffective.

[freedom]

Non valve masks leak all around the outside edges when exhaling instead of just out the valve. If your worried about someone with a valve mask, don’t be so cheap buy your own valve mask.

[mosquitodied]

Because when i design a product, I want the customer to be less safe.

like no shit the customer is gonna be the one protected.

[aryah]

1) no valve sealed
2) valve + sealed
3) no valve; not sealed to face

Video misleading

[totaleisure]

Your report does not include masks with exhalation valves that have filters between the mask and the exhalation valve. The filter usually has 5 layers - 2 of them made of melt-blown material - very similar to N95 masks. N95 masks are made of 5 layers and 2 of them are melt-blown. The advantage of cloth facemasks with a pocket to insert the 5-layer filter is that the user can wash it and reuse several times and change the filter as needed; N95 masks are intended for a single-use. Therefore, the exhalation is filtered and offers much more protection for the person wearing it and the ones around as well. The 3-ply blue facemasks (surgical) have only 3 layers - one melt-blown layer - and offer less protection and don't fit well on the face; with these, you can feel how your exhalation flows around your face, those who wear glasses notice this when their glasses get cloudy with breathing.

[musikSkool]

Correction: Valve masks that filter on inhale are not as effective. Valve masks that filter on exhale but open the valve for easy inhale are perfectly fine.

[justinpesterfield]

Yes this is correct, but my main concern is the usage of this style mask on a 5yr old. Concerned with prolonged use for kids who still have developing lungs. KN95 mask with a valve will reduce the amount of CO2 she would be re-breathing.

[mebeckrich]

All science shows None of them do except P100 respirators

[cooltu]

guys protect ursef wear n95 mask both valve or non practice soc dis u be fine cdc rule by trump

[_multiverse_]

Lol, just don’t wear mask.
Any mask is worse than no mask of it’s just a piece of cloth or if the user doesn’t know how to properly wear one.