With crucial protective gear in short supply, federal authorities are saying health workers can wear lower-grade surgical masks while treating Covid-19 patients – but growing evidence suggests the practice is putting workers in jeopardy.
The Centers for Disease Control and Prevention (CDC) recently said surgical masks are “an acceptable alternative” to highly protective N95 respirators unless workers are performing intubations or other procedures on patients with Covid-19 that could unleash high volumes of virus particles.
But scholars, not-for-profit leaders and former regulators in the specialized field of occupational safety say relying on surgical masks – which are considerably less protective than N95 respirators – is almost certainly fueling illness among frontline health workers, who probably make up about 11% of all known Covid-19 cases.
“There’s no doubt in my mind that that’s one of the reasons that so many healthcare workers are getting sick and many are dying,” said Jonathan Rosen, a health and safety expert who advises unions, states and the federal government. As of 23 April, more than 21,800 healthcare workers had contracted the coronavirus and 71 have died, according to a House education and labor committee staffer briefed by the CDC.
The allowance for surgical masks made more sense when scientists initially thought the virus was spread by large droplets. But a growing body of research shows that it is spread by minuscule viral particles that can linger in the air as long as 16 hours.
A properly fitted N95 respirator will block 95% of tiny air particles – down to 0.3 micron in diameter, which are the hardest to catch – from reaching the wearer’s face. But surgical masks, designed to protect patients from a surgeon’s respiratory droplets, aren’t effective at blocking particles smaller than 100 microns, according to the mask maker 3M. A Covid-19 particle is smaller than 0.1 micron, according to South Korean researchers, and can pass through a surgical mask.
White House tells aides to wear masks The White House has sent a memo to staff directing more aides to wear masks when in the West Wing or avoid President Trump's office altogether if possible.
The memo was obtained by US media moments before Trump is due to deliver remarks from the White House on the role of testing in the effort to reopen the country's economy.
It also comes as three high-ranking members of the White House coronavirus taskforce - including top disease expert Anthony Fauci - are in self-isolation after two White House staff members tested positive.
According to US media, the latest White House memo on masks is unlikely to apply to Trump, who has so far not worn one during the pandemic.
Here's a visual guide to what the government's new Covid alert levels mean, which Boris Johnson has just been discussing.
The claim: Face masks drastically reduce oxygen intake, cause carbon dioxide toxicity As states are reopening, health guidelines recommend that people maintain social distancing, practice hand-washing and wear face masks.
The use of face masks is encouraged by the Centers for Disease Control and Prevention and members of the White House's coronavirus task force to prevent further spread of the coronavirus, especially in places where it is hard to social distance.
Wearing face masks has become controversial — even political in some cases — resulting in misinformation about their effectiveness.
One Facebook post claims that wearing a mask for prolonged periods of time can drastically reduce the wearer's oxygen levels and result in carbon dioxide toxicity. (The poster said she did not know the origin of the image she shared and did not check to see whether the information was correct.)
Another viral meme featuring three people wearing masks while walking on a beach says face mask wearing "reduces oxygen up to 60%" and "increases risk of CO2 poisoning."
Face masks 101 According to the FDA, there are two main types of masks, N95 respirators and surgical masks. Both are tested for fluid resistance and filtration efficiency.
N95 masks are more tightly fitted, making them more likely to inhibit the breathing of the wearer if worn for a prolonged period of time. Surgical masks, which are disposable, and other types of cloth face masks are looser fitting, making it highly unlikely that wearers would see significant depletions in their oxygen intake. Non-N95 masks also are porous, allowing air to flow in and out and permitting normal respiratory functions, while limiting the release of respiratory droplets.
It is common for surgeons and other scientists or health care workers to wear face masks, particularly N95 respirators, for prolonged periods of time.
Neither the CDC nor the World Health Organization has issued warnings suggesting the use of surgical face masks would result in dangerous oxygen level depletion within the general public.
The CDC has requested the general public reserve N95 respirator masks for health care workers, but members of the public and other industries do still have access to them.
Despite the N95 mask's proven filtration effectiveness, research has found that the masks can inhibit the wearer's breathing if worn for extended periods of time, particularly in cases where the person has an existing respiratory illness.
The CDC does advise that cloth face coverings should not be placed on children younger than 2, those who have trouble breathing or anyone who is unconscious, incapacitated or unable to remove the mask without help.
Will face masks cause hypoxia? A reduced oxygen intake level may lead to hypoxemia, a condition where there is low arterial oxygen supply, or hypoxia, a condition where the supply of oxygen in tissue is insufficient.
One Facebook post claimed "wearing a mask for an 8 hour shift can reduce your oxygen intake level to a 93 if you have healthy lungs ... it is not healthy to have your oxygen level at that." The post did not specify which type of mask it was referencing.
A healthy oxygen intake level, or the amount of oxygen circulating in your blood, ranges from 95-100%, with anything below 90% considered low, according to Mayo Clinic.
Will a mask give the wearer hypoxia? Simply, no.
"This misinformation may arise from the feeling of lack of air due to mechanical obstruction depending on the type of mouthpiece we are using. But the feeling of obstruction is because we are not used to using the mouth mask. But as such it will not cause us any kind of hypoxia," Dr. Daniel Pahua Díaz, an academic from the Department of Public Health at the National Autonomous University of Mexico medical school, told Animal Político earlier in May.
Will face masks cause carbon dioxide toxicity? Carbon dioxide toxicity, or hypercapnia, is a condition that results from too much carbon dioxide in the bloodstream, which can be caused by rebreathing exhaled carbon dioxide.
The same Facebook post claimed face masks "block your exhaling of carbon dioxide and then you breathe it back in … it destroys lung tissue." The viral meme suggests wearing a mask can increase a wearer's chance of carbon dioxide poisoning.
As noted, surgical masks are porous, allowing for normal respiratory function. Other cloth face masks typically are even more porous.
It's important to note that the majority of the time, with health care workers as an exception, the general public is not wearing face masks for prolonged periods of time, meaning a dangerous build-up of CO2 is unlikely.
Additionally, the CDC told Reuters, "The CO2 will slowly build up in the mask over time. However, the level of CO2 likely to build up in the mask is mostly tolerable to people exposed to it ... It is unlikely that wearing a mask will cause hypercapnia."
Poynter notes that the rumor of mask wearing causing hypoxia has circulated the globe for a month or more, and has been fact-checked by several organizations.
The CDC told Snopes that N95 respirators could cause the buildup of carbon dioxide over time, which can also be mitigated by feeding in oxygen or simply taking a break and removing the mask. But the same effects are not likely in people wearing cloth face masks, especially for the brief amount of time they are in public.
Our rating: Partly false The claims in the post have been rated PARTLY FALSE, based on our research.
There is no evidence to support that the general public — which doesn't typically wear masks for prolonged periods of time — will experience significant reductions in oxygen intake level, resulting in hypoxemia. While CO2 can build up in face masks, it is unlikely that wearing a mask will cause hypercapnia, according to the CDC
It is true that those who are most at risk of negative effects from face masks have been advised by the CDC to avoid the face coverings and reach out to their health care providers for additional guidance.
It's understandable if some people remain skeptical, since, at the beginning of the pandemic, public health officials in the U.S. said the general public didn't need masks. But that changed as it became clear that infected people can spread the coronavirus before they even show symptoms of COVID-19 or even if they never show symptoms.
Researchers emphasize there are two main reasons to wear masks. There's some evidence of protection for the wearer, but the stronger evidence is that masks protect others from catching an infection from the person wearing the mask. And infected people can spread the virus just by talking.
"If you're talking, when things are coming out of your mouth, they're coming out fast," says Linsey Marr, a researcher at Virginia Tech who studies the airborne transmission of viruses. "They're going to slam into the cloth mask. I think even a low-quality mask can block a lot of those droplets."
Marr points to a study published in Nature Medicine1 in April that looked at people infected with the flu and seasonal coronaviruses. It found that even loose-fitting surgical masks blocked almost all the contagious droplets the wearers breathed out and even also some infectious aerosols — tiny particles that can linger in the air.
Other recent studies offer indirect evidence for universal mask use, even if worn by people who are feeling healthy. One study, published in late May in BMJ Global Health2, looked at people in households in Beijing where one person was confirmed to have COVID-19. At the time, explains study co-author Raina MacIntyre, research was already showing that the majority of transmission of the virus was happening inside households, and China already had a culture of mask wearing. The study found that in households where everyone was wearing a face mask indoors as a precaution before they knew anyone who lived there was sick, the risk of transmission was cut by 79%.
"The more people that were wearing a mask, the more protective it was," says MacIntyre, head of the biosecurity program at the Kirby Institute at the University of New South Wales in Australia. In other words, when everyone wore a mask, it protected the whole household.
Another study, published in late May in the journal Cell3, suggests that the coronavirus may first establish itself in the nasal cavity, before sometimes moving down to the lungs to cause more serious damage. If that's the case, the authors conclude, the findings "argue for the widespread use of masks" to prevent the virus from exiting an infected nose or entering an uninfected one.
And a modeling study, published this month in Proceedings of the Royal Society A, concluded that if the majority of a population wore face masks in public — even just homemade ones — that this could dramatically reduce transmission of the virus and help prevent future waves of the pandemic. (Remember, we're still in the first wave in the U.S.)
And a modeling study4, published this month in Proceedings of the Royal Society A, concluded that if the majority of a population wore face masks in public — even just homemade ones — that this could dramatically reduce transmission of the virus and help prevent future waves of the pandemic. (Remember, we're still in the first wave in the U.S.)
Surgical masks are designed to protect people from the wearer. Because they fit loosely, the wearer can still breathe in unfiltered air from the sides. Even so, surgical masks provide some benefit to the wearer as well: Laboratory testing has found that surgical masks block out 75% of respiratory-droplet-size particles.
As for cloth masks, the protection depends on what they're made out of and how well they fit. But with the right combination of materials, you can create a cloth mask that offers protection to the wearer in the 30% to 50% range or more, says May Chu, an epidemiologist at the Colorado School of Public Health who co-authored a paper published on June 2 in Nano Letters on the filtration efficiency of household mask materials. That's far from full protection, but combined with social distancing and hand-washing, she says, it's certainly better than nothing.