Researchers at Florida Atlantic University have experimented with different materials and styles of nonmedical masks, and found that a well-fitted sewn-in mask made of two layers of padded fabric was most effective in stopping the spread of cough drops and emulated sneezes.
The researchers said they chose to try out these styles of facial coverage because they are available to the general public and do not deviate from the supply of medical-grade masks and respirators for healthcare workers.
“While there are some previous studies on the effectiveness of medical grade equipment, we don’t have a lot of information on fabric-based coatings that are most accessible to us at the moment,” said Siddhartha Verma, assistant professor in the engineering department. oceanic and mechanical from Florida Atlantic University and author of the study.
“We hope that the visualizations presented in the document help convey the rationale for the recommendations for social distancing and the use of face masks.”
The study published in the journal Physics of Fluids on Tuesday.
Emulating coughs and sneezes
In the experiment, a mannequin’s head was padded to emulate a person’s nasal passages and mounted at a height of 5 ‘8 “to approximate the height of an adult male. The researchers” delivered “the sneeze or cough with a manual pump and a smoke generator
They then used a laser to detect drops as they coughed and sneezed from the mannequin’s head and mapped the paths of the drops and examined how different designs and materials alter that path.
The main challenge for the researchers was how to faithfully simulate a cough and a sneeze.
“The setup we’ve used (is) a simplified cough, which is actually complex and dynamic,” Verma said in a statement.
They found that the drops from a simulated bare cough could travel more than 8 feet; with a scarf they traveled 3 feet, with a folded cotton scarf, they traveled 1 foot, 3 inches; and with the cone-style mask, the drops traveled approximately 8 inches. With the quilted cloth mask sewn, they traveled 2.5 inches.
“We found that, while unobstructed turbulent jets were observed to travel up to 12 feet, a large majority of the ejected droplets fell to the ground at this point,” said Manhar Dhanak, a professor in the department of oceanic and mechanical engineering at Florida Atlantic University . and co-author of the study.
“It is important to note that both the number and concentration of the drops will decrease with increasing distance, which is the fundamental reason behind social distancing.”
A higher thread count alone was not more effective, the researchers said. In his experiment, the handkerchief had the highest count and was the least effective.
They said that their experiment could help healthcare professionals, medical researchers, and manufacturers evaluate the effectiveness of face masks.