Although all laboratory studies show that a mask can protect the user, the performance of masks in the real world depends on a number of variables, including their constant use,
Several laboratory studies have documented that a mask protects the person wearing it, although the level of this protection may vary depending on the type of mask, the material from which it is made, the experimental configuration and how it is worn. measure particle exposure.
It is true that masks work best when everyone wears one. This is because when an infected person wears a mask, a large percentage of their exhaled infectious particles become trapped, stopping the viral spread at the source. And when fewer viral particles float around the room, masks worn by others will likely block those that have escaped.
But there is also a lot of evidence that masks protect the wearer even when other people around them don’t have masks. Protection depends on the quality of the mask and its proper fit. During a hotel outbreak in Switzerland, for example, several employees and a guest tested positive for the test coronavirus they wore only facial shields (no masks); those wearing masks were not infected. And a Tennessee study found that communities with mask warrants had lower hospitalization rates than areas where masks were not needed.
“Healthcare workers, scientists working with nasty pathogens, and workers who may be exposed to airborne particles in the workplace rely on specialized masks like the N95 to protect them, so we know high-altitude masks work. proper efficiency, ”Linsey Marr said. , engineering professor at Virginia Tech and one of the world’s leading experts in viral transmission.
Several laboratory studies have also documented that a mask protects the wearer, although the level of such protection may vary depending on the type of mask, the material from which it is made, the experimental configuration and how it is worn. measured particle exposure. .
But the conclusion of all studies is that a mask reduces the potential exposure of the person wearing it. Here are some of the conclusions.
– A study by the Centers for Disease Control and Prevention found that a standard surgical mask only protected the wearer from 7.5% of the particles generated by a simulated cough. But scoring the loops and getting on the sides of the medical mask reduced exposure by almost 65 percent. Covering the surgical mask with a cloth mask, a technique known as double masking, reduced exposure to simulated cough particles by 83%.
– A Virginia Tech study examined the extent to which homemade masks, surgical masks, and face protectors protected the user based on particle size. Research showed that most masks could block very large particles, such as those from a sneeze. But when the researchers examined smaller aerosol particles that are harder to block, protection ranged from almost zero with a face shield to 30% protection with a surgical mask. (The percentages in the study cannot be directly compared to the CDC study of knots and wraps because the test methods were different.) Based on the results, Marr and colleagues concluded that a mask of two-layer fabric made of flexible fabric and fitted fabric, combined with a filter material (such as a coffee filter or a surgical mask), could offer good protection, reducing 70% of the most penetrating particles and trapping 90 % or more of the larger particles. They also found that the straps or bows created a better fit than the ear loops.
– A Tokyo study tested the extent to which different types of masks protected the wearer from reality coronavirus particles. The study showed that even a simple cotton mask offered some protection (17% to 27%) for the user. Medical masks work best, including a surgical mask (47% to 50% protection), a tight N95 (57% to 86% protection), and a hermetically sealed N95 (79% to 90% protection).
– Although many laboratory studies test mannequin head masks, a 2008 study used real people to measure the extent to which masks could protect the wearer from a respiratory virus. Subjects in the study wore different types of masks equipped with special receptors that could measure the concentration of particles on either side of the masks. In this study, fabric masks reduced exposure by 60%, surgical masks by 76%, and N95 masks by 99%.
Although all laboratory studies show that a mask can protect the user, the performance of masks in the real world depends on a number of variables, including the constant use of people, if a person is in situations of ‘high risk and infection rate in the community. A Danish study of 6,000 participants, half of whom were told to wear masks, showed no benefit from wearing them, but the study has been widely criticized for their poor design.
Laboratory studies have shown that a high-quality medical mask, such as N95, KN95 or KF94, works best. Although vaccination is the best protection against COVID-19[feminine[feminine , vaccinated people are even advised to avoid crowds or large groups indoors when the vaccination status of other people is not known. Given that the delta variant is much more contagious than other variants, Marr also recommended wearing the highest quality mask possible when you can’t keep your distance or be outdoors, or when no one around you is hide.
“If I’m in a situation where I have to rely solely on my mask to protect myself (there may be unvaccinated people, it’s full of people, I don’t know anything about ventilation) I would put the best mask in my closet , which is an N95, “Marr said. “Because the delta has been shown to be transmitted much more easily and because vaccinated people can be transmitted, we need to wear the best possible masks in high-risk situations.”
This article originally appeared in The New York Times.
Tara Parker-Pope c.2021 The New York Times Company