Will my mask protect me if no one else is wearing it? – the health

true that More expensive It works best when everyone in the room wears one. This is because when an infected person wears a mask, a high percentage of exhaled polluting particles are retained, preventing further spread. Widely straight from the source. And when some of the viral particles float around the room, the masks that others wear are more likely to block those that escape.

But there is also plenty of evidence to show that masks protect the wearer even when other people around them are not wearing the mask. The amount of protection depends on the quality of the mask and how well it fits the face. During an outbreak in a hotel in Switzerland, for example, there were several employees and a guest who tested positive for Corona Virus They were using only face shields (no masks); Those who wore masks were not contaminated. A study in Tennessee found that masked communities had lower rates of hospitalization than places that did not require masks.

“Health professionals, scientists who handle harmful pathogens, and workers exposed to airborne particles for their jobs rely on specialized masks such as N95 “For protection, so we know that properly fitted high-efficiency masks work,” said Lynsey Marr, a professor of engineering at Virginia Tech and one of the world’s leading experts on virus transmission.

Several laboratory studies have also documented that the mask protects the wearer, although the level of this protection can vary depending on the type of mask, the material it is made of, its composition and how exposure to particles is measured.

But the central line of all the studies is that the mask reduces potential exposure to the person who wears it. Here are some conclusions.

A study by the Centers for Disease Control and Prevention found that a standard surgical mask protects the wearer only about 7.5% of the particles from a simulated cough. But tying and tucking rubber bands into the sides of a medical mask reduced exposure by about 65 percent. Covering the surgical mask with a tissue mask, a technique known as double masking, reduced exposure to simulated cough particles by 83%.

A Virginia Tech study looked at how household masks, surgical masks, and face shields protect the wearer, based on particle size. Research has shown that most masks can block very large particles, such as those found in sneezing. But when the researchers looked at the smaller, harder-to-block aerosol particles, protection ranged from nearly zero with a face shield to about 30% with a surgical mask. (The study percentages could not be directly compared to the Centers for Disease Control and Prevention’s “knot and stick-sided” study because testing methods were different.) Based on the results, Mar and colleagues concluded that a two-layer cloth mask made of a tough, flexible material could Fabric combined with filter material (such as a coffee filter or surgical mask) provides good protection, reduces 70% of the most penetrating particles and retains 90% or more of larger particles. They also found that seizures were better behind the head than behind the ears.

A study from Tokyo tested how different types of masks protect wearers from particles of the real coronavirus. The study showed that even a simple cotton mask provides some protection (17% to 27%) to the user. Medical masks performed better, including surgical mask (47% to 50% protection), loose-fitting N95 (57% to 86% protection), and airtight N95 (79% to 90% protection).

While many labs test masks using mannequin heads, a 2008 study used real people to measure the ability of masks to protect the wearer from respiratory virus. Study participants used different types of masks made of special receptors that can measure the concentration of molecules on both sides of the mask. In that study, tissue masks reduced exposure by 60%, surgical masks by 76%, and N95 masks by 99%.

While all laboratory studies show that a mask can protect the wearer, the performance of masks in the real world depends on a number of variables, including how often people keep wearing them, whether the person is in high-risk situations, and the rate of contamination from the community. A Danish study of 6,000 participants, half of whom were instructed to wear masks, showed no benefit from wearing masks, but they were widely criticized for their poor design.

Laboratory studies have shown that a high-quality medical mask such as N95, KN95, or KF94 works best. While vaccination is the best protection against COVID-19, even vaccinated people are asked to avoid crowds or large groups indoors because the vaccination status of others is unknown. Knowing that the delta variant is much more contagious than the others, Marr also recommended using the best masks possible when you can’t maintain a distance or outdoors – or when no one around you is wearing a mask.

“If I’m in a situation where I need to rely solely on a protective mask—people who haven’t been vaccinated can be around, it’s crowded, and I don’t know anything about ventilation—I’ll wear the best mask in town because the delta variant has proven that it can be It can transmit more easily and because vaccinated people can transmit, we need to wear the best masks possible in high-risk situations.”/ LÍVIA BUELONI GONAALVES . translation