DUH?!?:

A meta-analysis, published in The Lancet at the beginning of June, looked at 172 studies that investigated how COVID-19, SARS, and MERS spread. The study found that mask wearing was strongly correlated with reduced risk of viral transmission and that "face mask use could result in a large reduction in risk of infection with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar [coverings]."

In a more recent study published last week in the journal Physics of Fluids, researchers at Florida Atlantic University used a visualization technique to demonstrate how a variety of masks helped stop the spread of these aerosol droplets. The team looked at three types of masks: A single-layer bandana-style covering, a homemade mask that had two layers of cotton, and a non-sterile cone-style mask. They chose these three on purpose, says study co-author Siddhartha Verma, a professor in the department of Ocean and Mechanical Engineering at Florida Atlantic University because they were the three that seem to be most often used by the general public. The researchers also looked at how far aerosols spread with no mask on at all.

In a lab, the team put masks on mannequins and used a mixture of water and glycerin to create a fog that emulated how droplets would travel by talking, coughing, and sneezing. The researchers found that without a mask, droplets traveled more than 8 feet. With a bandana, they reached an average of 3 feet and 7 inches, versus 1 foot and 3 inches with a two-layered cotton homemade mask, and about 8 inches with a cone-style mask.

What amazed Verma the most about the study was just how widespread droplets traveled without a mask on. "Seeing it with my own eyes was a bit surprising." Equally interesting, he says, was how much slower the spread was when the masks fit better on the mannequin's face. Based on these findings, as well as prior studies, he suggests this tip when choosing an effective mask: Hold the mask up to a light--the less you can see through it, the more effective it is.

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