Should I use a splint or double masking to block the coronavirus?

Wearing a face mask to slow the spread of Covid-19 has become standard practice.

But some people still wear masks incorrectly or use one that doesn’t fit properly on their face, allowing aerosols that carry the coronavirus particles to escape.

One solution to this problem is “double masking” – wearing two masks at the same time. Another is to use an “ adjuster ” or splint to secure a mask more tightly to your face. Both approaches aim to prevent air from escaping around the edge of a mask and to force tiny droplets to be blocked by the material, which serves as a filter.

What is the scientific proof that double-masking and mask orthotics prevent air leakage? What is the best approach? And how do they compare to N95 respirators which filter 95% of airborne particles?

Double masking

In February 2021, the Centers for Disease Control updated their guidelines for effective masks, which now include the recommendation that people “ add layers of material to a mask. ” The agency suggests either using a fabric mask with several layers of fabric, or wearing a disposable mask under the fabric mask.

Asked about double-masking on Jan. 25, Chief Medical Advisor to the President and Director of the National Institute of Allergy and Infectious Diseases, Anthony Fauci, said it was “common sense that it would be more effective “. Common sense is not a science, however.

To date, only one study has tested the effectiveness of double-masking. Led by CDC epidemiologist John Brooks, the experiment measured the amount of particles that reached a dummy head from a simulated cough, which showed that a double-mask suit blocked over 85% of the particles. , compared to 56% and 51% respectively for the surgical mask (“medical procedure”) and fabric mask alone.

The study was published in the CDC’s own digest, Morbidity and Mortality Weekly Report, which is not evaluated by external researchers. Thus, if the results appear conclusive, the research would have had greater credibility if it had been submitted to an independent journal and / or to a pre-print server such as medRxiv.

Brace Mask

Several studies support the hypothesis that modifications such as braces / adjusters improve filtering efficiency.

An article, published in JAMA Internal Medicine and led by biologist Phillip Clapp, measured the effectiveness of improvised face masks and coverings. He showed that the modifications increased the filtration of surgical masks from 39% to 80%.

Another recent study (unpublished but in medRxiv) used salt to mimic aerosol transmission in a classroom and equations to estimate the risk of infection for teachers and students. Led by mechanical engineer David Rothamer, the study found that most masks fit poorly and allow more than 50% leakage, but braces can lower a mask’s filtration efficiency to its level. expected performance.

Consumers can buy a special mask splint, but it’s relatively expensive: for example, Fix the Mask sells a two-pack of silicone splints (designed by a former Apple engineer) for $ 30. The company offers a downloadable template for making a DIY splint from a sheet of rubber … if you have such material around your house.

But you can make a brace on a budget, from three rubber bands and a paper clip, as the doctors led by Daniel Runde demonstrated in Journal of the American College of Emergency Physicians Open now. The study concluded that the ‘eight-eight double mask’ ‘does not create an N95 equivalent in terms of filtration’ but ‘would provide better protection against airborne viruses when worn with a surgical mask. basic”.

What is better?

In terms of effectiveness in blocking aerosols, there is much more evidence in favor of mask orthotics. This doesn’t mean double-masking doesn’t work, but the approach needs more study to support the claim that it helps with fit and filtration.

There are, however, other factors to consider besides effectiveness. Using two masks is a waste, for example, wrapping rubber bands around your head is like fixing an inherently broken device instead of replacing it with a working device – in this case, a mask that fits properly in the first place.

Another factor is compliance. Some people refuse to cover their faces – if you can’t get these people to adhere to the basic guidelines for wearing a mask, good luck getting them to wear two. Even with the emergence of new variants of Covid, it can be difficult to convince people to take action: in a 1984 poll of Americans, while 61% support double-masking, only 40% do, even if they think it’s a good idea.

Telling the general public that they need better masks may alienate some people as long as they don’t bother to wear anything, which is worse for public health.

As epidemiologist Saskia Popescu puts it, “Focus on finding a quality mask that meets the target, rather than trying to layer masks and create discomfort, difficulty breathing … or a frustration that could lead to no mask at all.