Wearing two chin straps can double protection against COVID-19, study finds

Using two well-fitting masks can almost double the filtering efficiency of SARS-CoV-2 sized particles, preventing them from reaching the user’s nose and mouth and causing COVID-19, study finds. The research, published in the journal JAMA Internal Medicine, show that The reason for increased protection is not so much the addition of layers of fabric, but the removal of any gaps or areas of improper fit.

“Medical procedure masks are designed to have very good filtration potential depending on their material, but the way they adapt to our faces is not perfect ”, Tenuous Emily Sickbert-Bennett, Associate Professor of Infectious Diseases at the University of North Carolina School of Medicine and lead author of the investigation, in a statement.

Sure the same lines, Disease Control Centers (CDC, for its acronym in English) in February of this year updated its health recommendations regarding the use of chin straps and reported that using properly fitting surgical masks, or putting a fabric mask over a surgical mask, significantly increases protection against the virus, both for the wearer and for third parties.

While masks are known to reduce respiratory droplets and aerosols exhaled by infected users and protect the uninfected user, its effectiveness varies considerably due to air leaks around the edges of the mask. “The proper functioning of a mask depends on two things: filtration and fit”Explain Linsey Marr, Professor of civil and environmental engineering at Virginia Tech, who studies airborne disease transmission but did not participate in the study.

To test the adjusted filtration efficiency (FFE) from a range of masks, UNC researchers worked with the scientific researcher James samet, and his colleagues from EPA Human Studies Center on the campus of UNC-Chapel Hill. There, they filled a 10-by-10-foot stainless steel exposure chamber with tiny aerosols of the salt particles and asked the researchers to don mask suits to test their effectiveness in preventing the particles from entering their room. breathing space.

Each individual mask or combination of layered masks was fitted with a metal sample port, which was connected to a tube in the exposure chamber that measured the concentration of particles entering the breathing space under the mask from the ‘investigator. A second tube measured the ambient concentration of particles in the chamber. By measuring the concentration of particles in the breathing space under the mask versus that of the camera, the researchers determined the FFE.

“Too we put the researchers in the chamber through a series of range of motion activities to simulate the typical movements that a person can do throughout the day: bend your waist, talk and look left to right, top to bottom, ”he says. Phillip clapp, a toxicologist by inhalation of the UNC School of Medicine who tested FFE with masks with Sickbert-Bennett since the start of the pandemic.

According to the researchers, The basic adjusted filtration efficiency of a mask differs from person to person, due to the unique fit of each person’s face and mask. But overall, A non-editable procedure mask is 40-60% effective in preventing COVID-19-sized particles from entering. A cloth mask is about 40% effective.

Their recent findings on the duplication of face masks show that when a cloth mask is placed over a surgical mask, the FFE has improved by approximately 20%. When placed over procedural masks, cloth masks improve the fit by eliminating gaps and keeping the procedural mask closer to the face, constantly covering the nose and mouth. When using a procedural mask over a cloth mask, the FFE improved by 16%.

“Good filtration removes as many particles as possible, and a good fit means there are no leaks on the sides of your mask,” where air – and viruses – can infiltrate. Surgical masks are made of a material that filters well, but they tend to be too loose, so if you add a cloth to the top, you hold the edges together and reduce leakage, ”he said. Marr, adding that even a small hole can reduce the efficiency by 50%.

The specialist pointed out that “the best materials for blocking small particles include non-woven polypropylene, used to make N95 masks and various types of surgical masks, as well as HEPA filters planes. Among fabrics, tight cotton works best. ” “If you wear a cloth mask, choose one that has multiple layers, ideally one with a pocket that you can put good filter material into. Or you can fold the mask by wearing a surgical-type mask with a tight-fitting cloth on top, ”he advised.

The real impact of using the chinstrap to reduce the contagion curve

A scientific study published in the journal PLOS ONE show that There has been a decrease in coronavirus infections in states where the population has adhered to chinstrap use by more than 75% in the United States.

The research, conducted by Charlie fischer and his colleagues from Boston University School of Public Health in Massachusetts, examined publicly available data on chinstrap policies, public reporting habits, and COVID-19 rates for the 50 U.S. states and Washington, DC They took into account a one-month delay between wearing the mask and its subsequent potential impact on COVID-19 rates from May to October 2020. They consider the rates of more than 200 cases per 100,000 inhabitants to be high.

The analysis showed that Of the 15 states that did not require a chin strap to be worn in public, 14 had high rates of COVID-19. Meanwhile, eight states had self-reported compliance rates of 75% or more, and none of those states had high rates of COVID-19. States with the lowest compliance rates were the most likely to have high rates of COVID-19 the following month.

The eight states with at least 75% mask compliance had a median COVID-19 rate of 109 cases per 100,000 residents the following month. In contrast, the median rate of COVID-19 was 239 cases for states with less than 75% compliance.

Consulted by Infobae, Mónica Gandhi, Professor of Medicine and Head of the Division of Global Medicine, Infectious Diseases and HIV at the University of california in San Francisco, USA, positively appreciated the new study in which he did not participate. Gandhi is a prestigious researcher who, since the pandemic, has published other works on the benefits of chinstrap. “This analysis is important because shows that the obligation to wear a mask is useful ”, underlined the American researcher. In addition, he pointed out that The use of the chinstrap in more than 75% of the population led to a drop in case rates in the United States during the increase last summer.

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