Rafal Milach / Magnum

When I first waded into the latest mask conspiracy theory, I was literally wading.

About a month ago, I was in my local pool when I overheard a middle-aged woman in the next lane whisper it to her friend, in the way you vaguely assert something that you’re pretty sure is true but don’t fully understand. “Masks don’t even do anything,” she said. “In fact, they can make you sicker. Because you’re breathing in all the ... stuff ... you breathe out.”

“OK Boomer,” I thought. I dismissed her as a random neighborhood conspiracist and swam my laps.

But then I started to see this false notion appear more frequently on Facebook. It wasn’t the typical argument anti-maskers use, that mask mandates infringe on people’s freedoms. It was that the masks themselves are causing illness. The horror of the idea was apparent even to me: the feds, in their hall-monitor stupidity, forcing you to do something that’s actually bad for you.

Most recently, this surfaced in the form of “copypasta”—a post copied and pasted by many people onto social media, rather than shared as a link—from a purported “OSHA Inspector.” “I have worked in a clean room for 23 years and 10 years on submarines before that,” it reads. The inspector, supposedly from the Occupational Safety and Health Administration, goes on to debunk each type of mask. N95s won’t “filter your air on the way out,” so they don’t reduce the risk of catching COVID-19 from someone who has it. Surgical masks, the post claims, are rendered useless by the moisture from your breath and the “amount of particles” on them. Cloth masks, meanwhile, trap carbon dioxide, risking the health of the wearer. “I know, facts suck,” it concludes. “They throw a wrench into the perfectly (seeming) packaged pill you are willingly swallowing.”

Aside from the fact that few bureaucrats speak this plainly and concisely, there are a number of obvious signs that this information is false. Every kind of face mask has been proved, in study after study, to slow the spread of COVID-19, with N95s being the most effective. To name just one example, two stylists worked at a hair salon in Missouri while infected with the coronavirus, but none of the 139 clients they saw got sick, because everyone wore a mask.

Mainstream experts dismiss the idea that wearing a mask can make you sick, unless you never wash the mask or have a health condition that makes breathing difficult. “The way that masks are being recommended is perfectly safe,” says Angela Rasmussen, a virologist at Columbia University. Cloth masks don’t offer complete protection against the coronavirus, she says, but they reduce the risk enough that they’re worth wearing whenever you’re going to be around people.

Though the latest public posts mentioning the supposed OSHA inspector date from September, the idea that masks make you sicker has been spreading online for months now, even after various fact-checking sites debunked the claim. I emailed Facebook to ask for more information about this type of post, but the company did not respond. One instance of the OSHA post was taken down after my email. But others live on, circulating among mask-haters and affirming what they perceive to be their righteousness. The post is an especially bizarre example of the “infodemic” scientists have been battling alongside the coronavirus pandemic, in which the internet is a giant telephone game reverberating with the weirdest stuff imaginable.

In late July, the “masks make you sick” claim was already circulating in prominent conservative circles. In a video, the conservative activist Charlie Kirk said, “Some doctors think that masks actually make you sicker and have you less likely to be able to get oxygen.” (I reached out to Kirk on Twitter, but he did not respond.) The OSHA connection also came up in an anti-mask video made by a conservative chiropractor with 3,000 Facebook followers.

But the previous month, the OSHA claim had already been widely debunked. Snopes wrote an article on June 18 refuting a near-identical version of the Facebook post that was still bouncing around in September. Not only does the post have its science wrong—people wearing cloth masks are in no danger of breathing in too much carbon dioxide—but it also refers to an OSHA certification that does not exist. “The author of the Facebook post claimed to be ‘OSHA 10&30 certified,’” the Snopes article says. “We reached out to OSHA, and a representative told us that these courses ‘do not include COVID-19 topics,’ nor does OSHA ‘certify’ trainers.”

It’s not clear how OSHA got roped into this. Part of the Department of Labor, the agency primarily concerns itself with safe working conditions, rather than pandemic responses. People who don’t want to do something, like wear masks, will often glom onto quasi-scientific rationalizations, says Matt Motta, a political scientist at Oklahoma State University who studies online misinformation.

Outside of Facebook, a June 18 article on a site called GreenMedInfo claims that “OSHA says masks don’t work—and violate OSHA oxygen levels.” The article consists mainly of a video by Peggy Hall, the founder of an anti-mask site called thehealthyamerican.org, explaining how “the U.S. Department of Labor Occupational and Safety and Health Administration’s guidelines clearly show cloth and surgical masks don’t work to reduce transmission of COVID-19, and how they deplete the body of oxygen, causing adverse health effects.” (In response to a request for comment, an OSHA spokesperson told me that this is not true, and that masks do not compromise oxygen levels or cause carbon dioxide buildup.)

The video is no longer available, and when I emailed Hall, she said it had been taken down. “My now-banned videos simply explained that OSHA, the FDA and the CDC all have no evidence of masks preventing the spread of this virus,” Hall wrote. (They do.) “Since they are making the claim, the burden of proof is on those agencies to show that the masks DON’T make anyone sick.” This is, of course, a completely different statement than the one made in the article. And indeed, a few days later, the fact-checking site PolitiFact debunked Hall’s article, too.

Before that, anti-mask articles and advocates would occasionally claim that masks made people sick, but they rarely invoked OSHA. A Chattanooga, Tennessee, news station in early June claimed, “Wearing a fabric mask for long periods of time—or for several days at a time—can allow bacteria to build up and actually make you sick,” but didn’t cite any research or experts to back the claim. In May, a group of filmmakers released a video titled Plandemic, which traveled widely on social media. It featured the discredited researcher Judy Mikovits saying, among other things, that masks can make people sick. Plandemic was viewed millions of times before Facebook and YouTube removed it. (Mikovits did not respond to a request for comment.)

These videos and articles all came months after government officials had begun encouraging—and then mandating—that people wear masks in public. But crucial to understanding the spread of this particular piece of misinformation is that, for many weeks early in the pandemic, everyday people were told not to wear masks. Back then, prominent experts claimed masks were needed for health-care workers and were borderline ineffective for the general public. Versions of this advice also suggested that masks could raise the risk of illness. On March 12, Jenny Harries, England’s deputy chief medical officer, claimed that masks could “actually trap the virus.” Therefore, she said, “for the average member of the public walking down a street, it is not a good idea.” (Harries did not respond to a request for comment.)

In fact, the earliest instance of a “masks make you sicker” claim I could find was in a February 27 news article published on a Utah radio station’s website. (Its author did not return a request for comment.) Though the article has since been updated, the original contains the subhead “Wearing a face mask incorrectly might put you at greater risk of getting sick.” The article then quotes a doctor named David Eisenman as saying, “I think people see a mask and they see an illusion of protection.” Though Eisenman’s quote does not quite support the subheading on the article, I reached out to him to see whether he still stands by his interview.

In short, he does not. “These things come back and haunt you,” Eisenman, a professor-in-residence at UCLA, told me. “Science recommendations have evolved. Now I would say that the evidence is very much in favor of masks as an important protector in the spread of COVID-19.”

Eisenman says the article was widely read. People occasionally tweet at him asking how he can be recommending masks now when he didn’t six months ago. He explains that the science changed, and so did his advice, but according to him, “it doesn’t seem to satisfy anybody.”

The “masks make you sicker” idea underscores how online misinformation is like an ocean liner: Once it’s headed in one direction, it’s difficult to turn around. The advice on masks changed seven months ago, but some people have stuck with what experts were saying in the confusing early days. One doctor’s criticisms of masks—which he now recants—live on in Twitter threads. And as people find new ways to share incorrect information, through posts, photos, and videos, social-media platforms are struggling to catch and remove all the hokum. Before long, the conspiracy theories break free of Facebook and infect reality.

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