Are homemade face masks safe? They need two or three more layers to be more effective in protecting a person from the coronavirus, says a new study.
An observational study published in the medical journal Thorax suggests the importance of two layers for a cloth face covering.
“A cloth face covering with at least two layers is preferable to a single-layer one,” Prateek Bahl of the School of Mechanical and Manufacturing Engineering at UNSW, a lead author of the study, wrote in the findings. “Guidelines on home-made cloth masks should stipulate multiple layers.”
The team at the University of New South Wales in Australia assessed the effectiveness of single- and double-layer cloth face coverings at preventing the transmission of respiratory droplets that takes place when an infected person coughs, speaks, or sneezes. The results were compared with that of a three-ply surgical face mask.
The study involved the use of LED lighting and a high-speed camera to document the dispersal of airborne droplets coming from a healthy person without respiratory infection. The video for speaking was captured at 850 frames per second, while coughing and sneezing was filmed at 1,000 frames per second due to the higher expulsion speeds, they noted.
Observations showed that a three-ply surgical face mask was considered the most effective at minimizing airborne droplet dispersal. The single-layer covering lessened the droplet spread from speaking, but the double-layer covering was better in minimizing droplets from sneezing and coughing.
The team stressed that a single-layer face covering is better than no face covering at all. Moreover, several other factors shape the effectiveness of homemade cloth masks, such as type of material, the arrangement of different layers, the number of layers, and frequency of washing.
For the single-layer face covering, there is a folded piece of cotton T-shirt and hair ties. The double-layer covering was done using a sewing method. Tissue paper was used to simulate the mucus membrane of the nasal cavity and produce a sneeze.
CDC recommendation
The Centers for Disease Control and Prevention or CDC urges public to wear masks to get coronavirus pandemic in the US under control.
Dr. Robert Redfield, director of the CDC, believes the spread of the virus can be under control in one to two months if every American wore a mask.
“The time is now,” he said during an interview with the Journal of the American Medical Association’s Dr. Howard Bauchner. “I think if we could get everybody to wear a mask right now I think in four, six, eight weeks we could bring this epidemic under control.”
Along with the World Health Organization (WHO), CDC calls on everyone to wear masks as a way to curb the spread of the virus. Data compiled by Johns Hopkins University showed that Covid-19 infected more than 13 million people across the world and killed at least 574,600 as of Tuesday.
“I think we’re being very clear now,” Redfield stressed. “Now’s the time to wear a mask.”
Scientists explain that respiratory droplets, through one’s coughing or sneezing, can spread the virus. Studies emphasize the role of masks in hindering the spread of coronavirus infection.
