Do N95 masks really blow coronavirus into the air? What to know about the viral post

Maybe you’ve seen it — a post on Facebook challenging the effectiveness of masks to combat coronavirus, according to the Raleigh News & Observer.

It’s said to have been written by someone “OSHA 10&30 certified” and claims that N95, surgical and cloth masks are not only ineffective at protecting against coronavirus, but are potentially harmful.

Some versions of the post include an image of a car with writing on the window that suggests masks cause brain damage, headaches and high blood pressure.

A video posted by The Healthy American in June made similar claims, including that “OSHA says masks don’t work” and that masks violate the administration’s oxygen level requirements.

So are their claims true? Let’s take them one-by-one.


First, it’s important to note that being “OSHA 10&30 certified” does not mean someone is affiliated with the Occupational Safety and Health Administration, USA Today reported.

The term refers to a person who took the administration’s 10-hour and 30-hour training on health and safety hazards, according to the outlet.

It does not include training on topics pertaining to COVID-19.


Here’s what the Facebook post — which has since been flagged for sharing partly false information — claims:

“N95 masks: are designed for CONTAMINATED environments. That means when you exhale through N95 the design is that you are exhaling into contamination. The exhale from N95 masks are vented to breathe straight out without filtration. They don’t filter the air on the way out. They don’t need to,” adding that an “N95 blows the virus into the air from a contaminated person.”

So is it true? Kind of.

Experts say it depends on what N95 mask you have.

In May, the San Francisco Department of Public Health shared an image of two different kinds of N95 masks: one with a valve on the front, and one without a valve designed for medical use.

The health department said that masks with valves on the front “are not safe and may actually propel your germs further.”


“By now hopefully you all know CLOTH masks do not filter anything,” the Facebook post says.

In reality, it depends.

OSHA’s guidelines state that cloth face coverings are effective at trapping the wearer’s germs to protect others.

The administration said they are ineffective at protecting the wearer from the germs of others, echoing widely shared information from the Centers for Disease Control and Prevention.

While cloth masks won’t filter what’s coming in, research suggests that they’re still effective at slowing the spread of the virus.

Recently, researchers from Cambridge and Greenwich universities in the United Kingdom found that if people wear masks all the time in public, not just when they show symptoms, it is twice as effective in reducing the number of people infected.

“Even homemade masks with limited effectiveness can dramatically reduce transmission rates if worn by enough people, regardless of whether they show symptoms.”

OSHA also recommends face coverings for employees, refuting the claims in The Health American’s video that OSHA says “masks don’t work.”

In a statement to PolitiFact, OSHA said it “generally recommends that employers encourage workers to wear face coverings at work. Face coverings are intended to prevent wearers who have COVID-19 without knowing it from spreading potentially infectious respiratory droplets to others.

“OSHA has not suggested they are ineffective for that purpose.”


Here’s what the Facebook post claims:

“Cloth masks trap this carbon dioxide!!!! It actually creates a health risk!!!!!”

According to Healthfeed, cloth masks and mask filters are porous enough to allow oxygen and carbon dioxide molecules to flow through the mask while still stopping larger droplets.

“The oxygen [percentage] inside the mask should be the same as outside the mask,” Dr. Marissa Baker, director of the University of Washington’s Industrial Hygiene program, told Agence France-Presse.

Similarly, The Healthy American’s video says that wearing a mask creates an “oxygen-deficient environment,” which OSHA describes as “any atmosphere that contains less than 19.5 percent oxygen.”

The video shows a man wearing a mask who slides a gas monitor — which is said to measure oxygen — inside. The monitor reads 19.3% oxygen.

But that’s just how breathing works, according to LeadStories.

“This is the stuff of simple seventh-grade science class: The lungs take up oxygen from the inhaled air and they send back out breaths containing more carbon dioxide,” the outlet reported.

In a statement to PolitiFact, OSHA said it has not made a determination as to whether masks affect the wearer’s oxygen levels, according to the outlet.


The Facebook post claims that surgical masks are made for sterile environments and that “If you come in contact with COVID and your mask traps it, you become a walking virus dispenser. Every time you put your mask on you are breathing the germs from EVERYWHERE you went. They should be changed or thrown out every 20-30 minutes in a non sterile environment.”

Baker told Agence France-Presse that the claim is misleading.

While surgical masks are not intended to be worn more than once, Baker said “once an operation starts the environment is no longer sterile — there could be blood, other bodily fluids, etc. And the physician wearing the mask is breathing, coughing, sneezing into the mask. That is what a surgical mask is meant to protect against — large droplets (the size of droplets that may contain coronavirus),” she told the news outlet.

Further, OSHA’s guidelines indicate that surgical masks are used to “protect workers against splashes and sprays (i.e., droplets) containing potentially infectious materials.”

OSHA also says that surgical masks are effective in trapping the wearer’s respiratory droplets and should be used by people who are sick to prevent transmission of respiratory infections spread by droplets.

The administration does warn that surgical masks are not useful in protecting the wearer against airborne particles due to their loose fit. When it comes to disposal, OSHA doesn’t say they should be changed every half-hour or so, but should be tossed “after use.”

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