Experts: Homemade masks can be effective, but also provide a false sense of security
They are the three “F’s” of face coverings: fit, fibers and (air) flow.
According to medical and environmental professionals, these are the primary factors that determine how effective a homemade mask is at limiting the transmission of the novel coronavirus.
The first wave of the virus throughout the state has infected more than 24,000 and led to about 1,800 deaths. It put stress on health care facilities and workers and precipitated stringent social distancing measures aimed at hindering the disease. And it has prompted Connecticut Gov. Ned Lamont to require everyone in public to wear some sort of face covering when keeping a safe distance of 6 feet apart is not possible.
While most of the public does not have access to N95 or surgical masks, a question for many has become: What is the most effective face covering?
And not all homemade masks are created equal.
“The best homemade mask is one that can fit tightly over your nose
and mouth, has densely woven fibers in multiple layers, and that still allows you to breathe easily,” said Summer Johnson McGee, dean of the School of Health Sciences at the University of New Haven. “The more tightly woven the fabric in your face covering, the better it will be at preventing particles from getting through.”
Knit fabrics, like scarves, have a loose weave and are not impermeable. Similarly, cotton masks, like bandanas, or bed sheets (depending on their thread count) might be too thin, unless they’re folded. On the other hand, while folding fabrics can strengthen the fibers of a mask, it also may reduce airflow.
Johnson McGee pointed to a recent commercial study that showed that, in addition to high-thread count bed sheets, denim, canvas and shop towels are among the most effective cloth materials for making masks.
But still, they are far from perfect.
“Those materials do not keep the tiny viral particles from entering your breathing zone from behind the mask,” said Diane Lauricella, a Norwalk-based independent environmental consultant and a former health and safety officer for the Department of Energy and Environmental Protection.
These homemade designs can also be bolstered, though, by adding additional low-cost, household screens, Lauricella said. Coffee filters, dress-maker facing, vacuum bags and feminine products can all be cut and fastened into a mask to provide additional protection. But these items may only slightly improve an imperfect mask. Lauricella said its incumbent on the government to advise people of the limitations of homemade masks.
“If someone is wearing one of the loose, cotton face masks, they may think, ‘I’m invincible,’ without having the knowledge that this face mask is going to slow, but not prevent, transmission,” Lauricella said.
According to Jacqueline Vernarelli, a nutritional epidemiologist at Sacred Heart University, the usefulness of a homemade mask depends less on the material of the covering and more on how its worn.
“We know that asymptomatic individuals can unknowingly spread the illness, so telling everyone to wear a mask prevents accidental spread,” Vernarelli said. “Wearing any face covering, whether a bandana, a construction mask, a surgical mask, or even a neck buff, is better than nothing, provided it covers the nose and mouth.”
Eduardo Meza, president of Norwalk-based Earth Environmental Consultants, said he hoped to clear up a misconception about masks: Because a homemade mask is not made to seal to a wearer’s face, it is not a reliable means of protecting the person from coming into contact with viral particles.
“A mask will not necessarily protect you against a contamination,” Maza said. “But the mask is effective, not because it protects you, because the saliva from your mouth and your nose is not coming out. The mask is not to protect you, it’s to protect your neighbor.”
Others stressed that there is still too much unknown about homemade masks and their reliability.
“The short answer is, there’s not good data to answer the question,” said Dr. Patrick William Kelley, a distinguished fellow of Nursing and Health Studies at Fairfield University. “The data they do present is nothing that instills a tremendous amount of confidence in me. Clearly, these masks can provide some protection, but it is humblingly less than what you would find with a mask manufactured by a company specializing in medical masks.”
Before coming to Fairfield, Kelley worked for 13 years at the National Academy of Science, which recently published a study comparing the effectiveness of different types of masks.
According to the study, Kelley said, N95 masks provided 25 times the protection of surgical masks and 50 times the protection of cloth masks. The study also found that cloth masks reduced admitted particles by one-fifth, surgical masks reduced it by half and N95 reduced particles by two-thirds. Citing this data, Kelley said those wearing homemade masks should not feel overly comfortable when out in public.
Steve Schrag, a health and safety coordinator for the Service Employees International Union (SEIU), was even more skeptical. According to Schrag, there is not enough research available to substantiate claims made that homemade masks can help stem the transmission of the virus. He believes it’s caused some people to have a false sense of safety.
“I think they’re absolutely perfect for Halloween,” Schrag said. “Other than that, they don’t have much use.”