sewing a mask

What you should know about DIY masks and ventilators

Here's what scientists and healthcare workers say about making homemade protective gear and medical supplies amid the coronavirus pandemic.

Tailor Elase Wong making masks out of patterned material at a shop in Hong Kong on February 20, 2020. Faced with shortages in the midst of a virus outbreak, Hong Kong residents have started making their own face masks, from professional factories to seamstresses churning out coverings on sewing machines.

Photograph by Isaac Lawrence, AFP via Getty Images

In five minutes, Brianna Slatnick can teach hospital staff how to make an air-filtering faceguard akin to the N95 respirators that are widely recommended to mitigate the spread of the coronavirus. Made with simple parts that cost less than $3 combined and are common in hospitals, the version she and colleagues created does not look factory-made, but they say it works.

A viral video of the technique, developed at Boston Children’s Hospital, shows Slatnick, a surgical innovation fellow and general surgery resident, as she fits together an anesthesia mask with a basic filter, attaches elastic straps, and pulls the contraption to her face. The invention has not been approved by the National Institute for Occupational Safety and Health (NIOSH), the federal agency charged with workplace safety oversight, and Boston Children’s is not using the device near patients yet because it still has standard supplies on hand.

As the global spread of COVID-19 accelerates, this sort of do-it-yourself response to the shortage of personal protective equipment (PPE) is becoming increasingly common, with medical researchers, businesses, and citizen-scientists designing their own face masks, respirators, and ventilators.

“The CDC is announcing additional steps Americans can take to defend against the transmission of the virus,” President Donald Trump said at a White House press briefing on April 3, citing recent research on asymptomatic cases. “In light of these studies, the CDC is advising the use of non-medical, cloth-face covering as an additional, voluntary public health measure.”

But are homemade devices safe? So far, the evidence is scant and mixed, and while a few ideas show promise, there is some concern that stopgap measures could make things worse. A study published April 2 in The Lancet found that the coronavirus could survive on cloth for at least a day and on surgical masks for up to seven days. And on April 7, The World Health Organization said there is currently no evidence that wearing any kind of mask can prevent healthy people in their communities from getting a respiratory infection, including COVID-19.

“The last thing you want is for healthcare workers to have a false sense of protection and [inadvertently] perform a risky procedure on a patient,” says Christopher Friese, professor of nursing and public health at the University of Michigan, Ann Arbor.

Here’s what we know about the most widely proposed DIY gear, and how healthcare experts are embracing the trend in a time of dire need.

Making masks

The internet is bursting with instructions for DIY surgical masks and articles peppered with arguments over the best patterns and materials to use, but the medical opinion on homemade masks is mixed.

In a 2013 study, researchers in the U.K. tested a variety of everyday materials as filters for surgical masks, including cotton T-shirts, dishtowels, pillowcases, and vacuum cleaner bags. While the makeshift masks were better than nothing at all, none of the materials worked as well as a commercial surgical mask, which filtered out three times as many particles in a test chamber and blocked twice as many droplets in a cough test. (Respiratory droplets are the primary way diseases like COVID-19 spread.)

However, the homemade versions did prevent some microbes from getting through, suggesting the makeshift masks were better than nothing at all, says study co-author Anna Davies, a research facilitator at the University of Cambridge (U.K,) and a former public health microbiologist.

A separate study, from 2015, casts additional doubt on homemade masks. In a randomized trial in Vietnam, healthcare workers who wore cloth masks acquired more respiratory infections and influenza-like illnesses than their colleagues who wore surgical masks. Lab tests showed that 97 percent of particles got through the cloth masks, compared to 44 percent with surgical masks. One caveat: This study did not compare wearing cloth masks to no masks at all, so the additional infections could have been due to continuously re-using the cloth masks.

Yet even if the cloth masks aren’t perfect, they could theoretically slow the spread of a disease by helping keep the virus from escaping people’s noses and mouths, Davies says. A small study published April 2 in Nature Medicine shows surgical masks worn by sick individuals can block the spread of coronavirus, whether it be via respiratory droplets or airborne particles.

Regardless, Davies wrote in a recent summary of her team’s findings that social distancing, hand-washing, and the avoidance of face touching are by far the most effective ways to protect society, adding that masks should be a last resort that is meant to prevent “an unavoidable risk of exposure.” (Here’s how long coronavirus lasts on surfaces and in the air.)

Replicating respirators

Recommended by the U.S. Centers for Disease Control and Prevention, N95 respirators (which filter at least 95 percent of airborne particles), are considered the best line of facial protection for healthcare workers treating patients with COVID-19. One problem: they should be discarded after a single use. So some people are trying to find ways to clean their respirators.

At Duke University, researchers have developed a decontamination procedure with hydrogen peroxide. The University of Nebraska created a similar protocol using ultraviolet light. But not all researchers are focused on cleansing; some are driven to invention.

In March, a group of more than a dozen surgeons, medical students and residents, respiratory therapists, and others participated in a COVID-19 hackathon at Boston Children’s Hospital. After discussing ideas by video conference, they met in a large room—perfect for social distancing—and worked for 10 hours with scissors, rubber glue, silicone caulking, elastic, coffee filters, anesthesia face masks, and medical filters to create a novel ventilator for a novel pandemic.

By the end of the day, they had a working prototype for the DIY respirator that features in the team’s video, which Slatnick narrates. (And they have already made a second version.) Preliminary tests of 11 healthy people who followed directions to make their own respirators indicate that users had stable oxygen levels, heart rates, and respiration after wearing the mask for 20 minutes.

Engineering challenges remain; the respirator must be durable, fit well, and filter out particles. Still, the Boston Children’s design appears to be gaining momentum. “We have received photos from all around the world of people utilizing the device,” Slatnick says. “There is a severe shortage of PPE in many institutions, and the fact that physicians are reaching out to us to consider using a device that is not NIOSH approved speaks to the fact that they’re very worried.”

Inventing novel ventilators

A shortage of ventilators is raising concerns about the ability of U.S. hospitals to treat surges of COVID-19 patients. According to one estimate, the U.S. has roughly 160,000 ventilators—not nearly enough to cover the projected need, as also predicted by past studies that identified critical weaknesses in medical supply chains. An experimental technique to use one ventilator on multiple patients received attention—and much criticism from medical specialists—when some New York City hospitals recently adopted the risky practice.

Ventilators are in high demand, and University of Florida mechanical engineer and anesthesiology professor Samsun Lampotang is responding with PVC pipe, a sprinkler valve used to water lawns, and computer boards. Based on open-source blueprints and built with the help of his research group—which had previously engineered traditional ventilators—Lampotang’s makeshift ventilator is nearing completion.

His goal is to design a reliable DIY ventilator that can be assembled with basic hardware and software in less than five hours and for as little as $250. This would be significantly quicker and cheaper than what it will take for non-healthcare companies such as General Motors to ramp up production on traditional ventilators, as directed by the White House.

Once the device is built, it must be tested with artificial lungs nonstop for three weeks—the maximum amount of time a patient might need it—before the team deems it ready for human use. Early reports are promising, Lampotang says, and he is already fielding numerous requests from doctors.

But what happens if the design is still undergoing testing when hospitals in places such as New York run out of ventilators—do they use Lampotang’s version anyway? “Here’s where the ethical dilemma is,” he says. “Unfortunately, we are running out of time.”

Editor’s note: This story was updated to add the White House announcement about cloth face coverings and the World Health Organization's new advice on face masks. The story was originally published on April 3.

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