A new dramatic visualization shows exactly why it is a good idea to use a mask to prevent the spread of the new coronavirus.
Without a mask, the drops produced during the cough can travel up to 12 feet (3.7 meters), the visualization revealed, but with a mask, this distance is reduced to just a few inches in the best cases.
The simulation, which was described today (June 30) in the magazine Fluid PhysicsIt also reveals that some cloth masks work better than others to stop the spread of potentially infectious droplets.
“The images used in our study can help convey to the general public the reasons behind social distancing guidelines and recommendations for wearing face masks,” said study lead author Siddhartha Verma, an assistant professor at the College of Engineering and Computer Science from Florida Atlantic University, he said in a statement.
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To simulate a cough, the researchers connected a mannequin’s head to a fog machine (which creates a water vapor and glycerin), and used a pump to blow the steam out of the mannequin’s mouth. They then visualized the vapor droplets using a “laser foil” created by passing a green laser pointer through a cylindrical rod. In this configuration, the simulated cough appears as a bright green vapor that flows from the manikin’s mouth.
The researchers then placed various types of non-medical masks on the mannequin’s head to assess their effectiveness in blocking these “coughs.” These included a homemade face mask sewn with two layers of cotton fabric used for quilting (70 threads per inch), a single-layer scarf, a slightly folded cotton scarf, and a non-sterile cone-shaped mask sold in pharmacies.
They discovered that, without a mask covering, the simulated cough traveled up to 12 feet in 50 seconds.
The homemade stitched cotton mask, with its multiple layers and snug fit, reduced the spread of droplets to the maximum, although there was a leak at the top of the mask between the nose and the fabric material. When the mannequin wore this mask, the drops traveled only about 2.5 inches (1 centimeter) forward from the face. The cone-style mask also worked well, with drops traveling just 8 inches (20 cm) from the face.
However, the single-layer scarf (made of a stretchy jersey material) and the folded scarf were less effective. The droplets filtered through the mask material and traveled more than 3.5 feet (1 m) with the handkerchief and more than one foot (0.3 m) with the handkerchief.
Still, “although the nonmedical masks tested in this study experienced varying degrees of flow leakage, they are likely to be effective in preventing larger respiratory droplets from dispersing,” the authors wrote in their article.
“Promote widespread awareness of effective preventive measures [for COVID-19] it is crucial at this time as we are seeing significant spikes in cases of COVID-19 infections in many states, especially Florida, “Verma said.
Originally published in Living science.