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Tag: High-quality masks

  • Wildfire Masking Is Just Different

    Wildfire Masking Is Just Different

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    Late last night, New Yorkers were served a public-health recommendation with a huge helping of déjà vu: “If you are an older adult or have heart or breathing problems and need to be outside,” city officials said in a statement, “wear a high-quality mask (e.g. N95 or KN95).”

    It was, in one sense, very familiar advice—and also very much not. This time, the threat isn’t viral, or infectious at all. Instead, masks are being urged as a precaution against the thick, choking plumes of smoke from Canada, where wildfires have been igniting for weeks. The latest swaths of the United States to come into the crosshairs are the Midwest, Ohio Valley, Northeast, and Mid-Atlantic.

    The situation is, in a word, bad. Yesterday, New Haven, Connecticut, logged its worst air-quality reading on record; in parts of New York and Pennsylvania, some towns have been shrouded in pollutants at levels the Environmental Protection Agency deems “hazardous”—the more severe designation on its list. It is, to put it lightly, an absolutely terrible time to go outside. And for those who “have to go outdoors,” says Linsey Marr, an environmental engineer at Virginia Tech, “I’d strongly recommend wearing a mask.”

    The masking advice might understandably spark some whiplash. For the majority of Americans, face coverings are still most saliently a COVID thing—a protective covering meant to be worn when engaging in risky gatherings indoors. Now, though, we’re having to flip the masking script: Right now, it’s outdoor air that we most want to guard our airways against. In more ways than one, the best masking practices in this moment will require snubbing some of our basest COVID-fighting instincts.

    The COVID masking mindset can, to be fair, still be helpful to game out the risks at play. Viral outbreaks and wildfires both introduce dangerous particles into the eyes and the airway; both can be blocked with the right barriers. The difference is the source: Pathogens travel primarily aboard people, making crowds and crummy indoor airflow some of the biggest risks; fires and their smoky, ashy by-products, meanwhile, can get stoked and moved about by the very outdoor winds we welcome during viral outbreaks. Conflagrations clog the air with all sorts of pollutants—among them, carbon monoxide, which can poison people by starving them of oxygen, and a class of chemicals called polycyclic aromatic hydrocarbons that’s been linked to increased cancer risk. But the primary perils are the fine-particulate-matter components of soot, ash, and dust, fine enough to be borne over great distances until they reach an unsuspecting face.

    Once breathed in, these particles, which the EPA tracks by a metric known as PM2.5, can deposit deep in the airway and possibly even infiltrate the blood. The flecks irritate the moist membranes that line the nose, mouth, lungs, and eyes; they spark bouts of inflammation, triggering itching and irritation. Chronic exposure to them has been linked to heart and lung issues, and the risks are especially high for individuals with chronic medical conditions—burdens that concentrate among people of color and the poor—as well as for older adults and children.

    But N95s and many other high-quality masks have their roots in environmental health; they were designed specifically to filter out microscopic particulate matter that travels through the air. And they’re astoundingly good at their job. Jose-Luis Jimenez, an aerosol scientist at the University of Colorado at Boulder, recently put their performance to the test with an N95 strapped to his own face. Using an industry-standard test, he measured the particulate matter outside the mask, then checked how much made it through the device and into the space around his nose and mouth. Percentage-wise, he told me, “it removes 99.99 … I didn’t measure how many nines; it was working so well.” On broader scales, too, the protective math plays out: Well-fitting masks can curb smoke-related hospitalizations; studies back up their importance as a firefighting mainstay.

    The key, Jimenez told me, is choosing the right mask and getting it flush against your face. Experts in the field even get professionally fit-tested to avoid contamination infiltrating through any gaps. Surgical masks, cloth masks, or any other loose accessories that aren’t specifically designed to filter out tiny particles just won’t do the trick, though they’re still better than not covering up at all. (If that sounds familiar, it should; viral or smoky, “masks don’t care what the particle is,” Marr told me. “They care about the size.”)

    N95 masks aren’t perfect protectives either. They don’t shield the eyes, and they aren’t great at staving off carbon monoxide and the other gaseous pollutants that wildfires emit. (That’s for a reason: Allowing gas through masks is how we continue to breathe while wearing them.) But gases are volatile and quickly dissipate; for Americans hundreds or even thousands of miles from the source of the smoke, “it’s going to be the particulate matter that is most concerning to us,” Marr told me. Even in the parts of New York and Pennsylvania where PM2.5 has rocketed up to dangerous levels, the carbon-monoxide stats have remained low.

    Considering how dicey the discourse over masking has gotten, masking advice won’t necessarily be embraced by all. Less than a month after the official end of the United States’ COVID public-health emergency, people are fatigued by face coverings and other mitigations. And we’re fast entering the stretch of the year when having synthetic polymer fabrics strapped across your face can get downright miserable, especially in the humidity of northeastern heat. But when it comes to avoiding the harms of wildfire smoke, experts generally consider masks a second-line defense. The first priority is trying to minimize any exposure at all—which, for now, means staying indoors with the doors and windows tightly shut, especially for people at highest risk. Paula Olsiewski, an environmental-health researcher at the Johns Hopkins Center for Health Security, also recommends running whatever air filters might be available; air conditioners, portable air cleaners, and DIY air filters all help.

    It’s also a good time, experts told me, to be mindful of the differences between filtration and ventilation, or increasing flow to turn over stale air. Both are crucial, sustainable interventions against respiratory viruses. But in the context of wildfires, excellent ventilation could actually increase harm, Jimenez told me, by allowing in excess smoke. For right now, stale indoor air—a classic COVID foe—is a smoke-avoider’s ally. The masks come in for anyone who must go outside in a part of the country where the air quality is bad—say, above an index of 150 or so.

    The move might feel especially counterintuitive for people who have long since stopped masking against COVID—or even ones who still do, simply because the rules don’t mesh. Through the flip-flopping guidance of mask everywhere to mask until you’re vaccinated to actually, mask after you’re vaccinated too to mask only indoors, Americans never hit much of a stable rhythm with the practice. The inertia may be especially powerful on the East Coast, which has largely been spared from the scourge of wildfires that’s constantly plaguing the West. (That puts the U.S. well behind other countries, especially in East Asia, where masking against viruses and pollutants indoors and out has long been commonplace; even in California, N95 and HEPA shortages aren’t anything new.)

    That said, our COVID-centric view on masking was always going to get a wake-up call. Wildfires—and viral outbreaks, for that matter—are expected to become more common going forward, even in regions that haven’t historically experienced them. And for all their weariness with COVID, Americans now have far more awareness of and, in many cases, access to masks than they did just a few years ago. The wildfires aren’t good news, but maybe a mask-friendly response to them can be. Smoke does, from a public-health perspective, have one thing going for it, Olsiewski told me: It is visible and ominous in ways that a microscopic virus is not. “People can see that their air is not clean,” she told me. It’ll take more than ash and haze to break through the divisiveness around masks. But a threat this obvious might at least forge a tiny crack.

    This story is part of the Atlantic Planet series supported by the HHMI Department of Science Education.

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    Katherine J. Wu

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  • Somehow, the Science on Masks Still Isn’t Settled

    Somehow, the Science on Masks Still Isn’t Settled

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    For many Americans, wearing a mask has become a relic. But fighting about masks, it seems, has not.

    Masking has widely been seen as one of the best COVID precautions that people can take. Still, it has sparked ceaseless arguments: over mandates, what types of masks we should wear, and even how to wear them. A new review and meta-analysis of masking studies suggests that the detractors may have a point. The paper—a rigorous assessment of 78 studies—was published by Cochrane, an independent policy institution that has become well known for its reviews. The review’s authors found “little to no” evidence that masking at the population level reduced COVID infections, concluding that there is “uncertainty about the effects of face masks.” That result held when the researchers compared surgical masks with N95 masks, and when they compared surgical masks with nothing.

    On Twitter, longtime critics of masking and mandates held this up as the proof they’d long waited for. The Washington Free Beacon, a conservative outlet, quoted a researcher who has called the analysis the “scientific nail in the coffin for mask mandates.” The vaccine skeptic Robert Malone used it to refute what he called “self-appointed ‘experts’” on masking. Some researchers weighed in with more nuanced interpretations, pointing out limitations in the review’s methods that made it difficult to draw firm conclusions. Even the CDC director, Rochelle Walensky, pushed back against the paper in a congressional testimony this week, citing its small sample size of COVID-specific studies. The argument is heated and technical, and probably won’t be resolved anytime soon. But the fact that the fight is ongoing makes clear that there still isn’t a firm answer to among the most crucial of pandemic questions: Just how effective are masks at stopping COVID?

    An important feature of Cochrane reviews is that they look only at “randomized controlled trials,” considered the gold standard for certain types of research because they compare the impact of one intervention with another while tightly controlling for biases and confounding variables. The trials considered in the review compared groups of people who masked with those who didn’t in an effort to estimate how effective masking is at blunting the spread of COVID in a general population. The population-level detail is important: It indicates uncertainty about whether requiring everyone to wear a mask makes a difference in viral spread. This is different from the impact of individual masking, which has been better researched. Doctors, after all, routinely mask when they’re around sick patients and do not seem to be infected more often than anyone else. “We have fairly decent evidence that masks can protect the wearer,” Jennifer Nuzzo, an epidemiologist at Brown University, told me. “Where I think it sort of falls apart is relating that to the population level.”

    The research on individual masking generally shows what we have come to expect: High-quality masks provide a physical barrier between the wearer and infectious particles, if worn correctly. For instance, in one study, N95 masks were shown to block 57 to 90 percent of particles, depending on how well they fit; cloth and surgical masks are less effective. The caveat is that much of that support came from laboratory research and observational studies, which don’t account for the messiness of real life.

    That the Cochrane review reasonably challenges the effectiveness of population-level masking doesn’t mean the findings of previous studies in support of masking are moot. A common theme among criticisms of the review is that it considered only a small number of studies by virtue of Cochrane’s standards; there just aren’t that many randomized controlled trials on COVID and masks. In fact, most of those included in the review are about the impact of masking on other respiratory illnesses, namely the flu. Although some similarities between the viruses are likely, Nuzzo explained on Twitter, COVID-specific trials would be ideal.

    The handful of trials in the review that focus on COVID don’t show strong support for masking. One, from Bangladesh, which looked at both cloth and surgical masks, found a 9 percent decrease in symptomatic cases in masked versus unmasked groups (and a reanalysis of that study found signs of bias in the way the data were collected and interpreted); another, from Denmark, suggested that surgical masks offered no statistically significant protection at all.

    Criticisms of the review posit that it might have come to a different conclusion if more and better-quality studies had been available. The paper’s authors acknowledge that the trials they considered were prone to bias and didn’t control for inconsistent adherence to the interventions. “The low to moderate certainty of evidence means our confidence in the effect estimate is limited, and that the true effect may be different from the observed estimate of the effect,” they concluded. If high-quality masks worn properly work well at an individual level, after all, then it stands to reason that  high-quality masks worn properly by many people in any situation should indeed provide some level of protection.

    Tom Jefferson, the review’s lead author, did not respond to a request for comment. But in a recent interview about the controversy, he stood by the practical implications of the new study. “There’s still no evidence that masks are effective during a pandemic,” he said.

    Squaring all of this uncertainty with the support for masking and mandates early in the pandemic is difficult. Evidence for it was scarce in the early days of the pandemic, Nuzzo acknowledged, but health officials had to act. Transmission was high, and the costs of masking were seen as low; it was not immediately clear how inconvenient and unmanageable masks could be, especially in settings such as schools. Mask mandates have largely expired in most places, but it doesn’t hurt most people to err on the side of caution. Nuzzo still wears a mask in high-risk environments. “Will that prevent me from ever getting COVID? No,” she said, but it reduces her risk—and that’s good enough.

    What is most frustrating about this masking uncertainty is that the pandemic has presented many opportunities for the U.S. to gather stronger data on the effects of population-level masking, but those studies have not happened. Masking policies were made on sound but limited data, and when decisions are made that way, “you need to continually assess whether those assumptions are correct,” Nuzzo said—much like how NASA collects huge amounts of data to prepare for all the things that could go wrong with a shuttle launch. Unfortunately, she said, “we don’t have Houston for the pandemic.”

    Obtaining stronger data is still possible, though it won’t be easy. A major challenge of studying the effect of population-level masking in the real world is that people aren’t good at wearing masks, which of course is a problem with the effectiveness of masks too. It would be straightforward enough if you could guarantee that participants wore their masks perfectly and consistently throughout the study period. But in the real world, masks fit poorly and slip off noses, and people are generally eager to take them off whenever possible.

    Ideally, the research needed to gather strong data—about masks, and other lingering pandemic questions—would be conducted through the government. The U.K., for example, has funded large randomized controlled trials of COVID drugs such as molnupiravir. So far, that doesn’t seem to have happened in the U.S.  None of the new studies on masking included in the Cochrane review were funded by the U.S. government. “The fact that we never as a country really set up studies to answer the most pressing questions is a failure,” said Nuzzo. What the CDC could do is organize and fund a research network to study COVID, much like the centers of excellence the agency has for fields such as food safety and tuberculosis.

    The window of opportunity hasn’t closed yet. The Cochrane review, for all of its controversy, is a reminder that more research on masking is needed, if only to address whether pro-mask policies warrant the rage they incite. You would think that the policy makers who encouraged masking would have made finding that support a priority. “If you’re going to burn your political capital, it’d be nice to have the evidence to say that it’s necessary,” Nuzzo said.

    At this point, even the strongest possible evidence is unlikely to change some people’s behavior, considering how politicized the mask debate has become. But as a country, the lack of conclusive evidence leaves us ill-prepared for the next viral outbreak—COVID or otherwise. The risk is still low, but bird flu is showing troubling signs that it could make the jump from animals to humans. If it does, should officials be telling everyone to mask up? That America has never amassed good evidence to show the effect of population-level masking for COVID, Nuzzo said, has been a missed opportunity. The best time to learn more about masking is before we are asked to do it again.

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    Yasmin Tayag

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