Despite the fact that the industry has recovered from the shock of the first days of the pandemic COVID-19 and now produces enough facial masks of different types, most people in the world due to various reasons use homemade versions. Everyone understands that they are less effective than professional medical model, but the question is: how much exactly? At Duke University (USA) have developed a simple method of testing masks and checked out the most popular models.
The test device consists of a dark chamber, where through the lens served the laser beam. He scatters and covers a vast space inside the chamber, illuminating all the particles that fly in the air. The man in the mask puts a face to the camera and says a few phrases, exhaling into the air. The camera captures the flashes of laser, when droplets of the liquid in the exhale intersect with the beam.
First, the drop of liquid is actively allocated during normal conversation in the mask. Man don’t need no coughing, no sneezing – it can spread the infection through the mask, believing that protection works. But the real surprise to researchers was the fact that a medical mask N95 with valve release much more particles than the mask of rags. The reason is that the valve closes on the inhale, but on exhale, so the carrier of the mask are protected from infection, but he can be a distributor of the virus.
The strange and sad the audit showed masks of fleece and similar common materials. The structure of this tissue breaks large drops of saliva into small, which are much easier to pass through the barriers and spread through the air. This is the paradoxical case when best not to wear a mask than to use a fleece product, although worldly logic seems to say the opposite.
Source — Washington Post