By Charlotte Webster-
Researchers at the University of New South Wales insists that three layers of masks are necessary for home made masks, designed to prevent spreading the coronavirus.
The researchers from Australia looked at the effectiveness of single and double-layer cloth face coverings at reducing the spread of respiratory droplets that pass when an infected person speaks, coughs or sneezes. They then compared those results with that of a three-ply surgical face mask.
The researchers used LED lighting and a high-speed camera to film the dispersal of airborne droplets produced by a healthy person with no respiratory infection. The video for speaking was captured at 850 frames per second, while coughing and sneezing was captured at 1,000 frames per second due to the higher expulsion speeds, they said.
A three-ply surgical face mask was concluded to be the most effective at reducing airborne droplet dispersal, the researchers found after reviewing the footage. The single-layer covering reduced the droplet spread from speaking, though the double-layer covering was better in reducing droplets from coughing and sneezing, according to the researchers.
“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.”
Researchers said a single-layer face covering is better than no face covering at all. Additionally, several other factors determine the efficacy of cloth masks such as type of material, the number of layers, the arrangement of different layers and frequency of washing, they said.
The single-layer face covering was made from a folded piece of cotton T-shirt and hair ties. The double-layer covering was made using the sewing method as shown by the Centers for Disease Control and Prevention. The researchers used tissue paper to simulate the mucus membrane of the nasal cavity and induce a sneeze, according to the study.
The study comes as the the Uk government made it mandatory for customers in all shops in Britain to wear masks or risk facing fines of £100.Only gyms, hairdresser salons and barbers and cinemas are exempt from the rules.
The United States has the worst outbreak in the world with 4 million cases and at least 143,820 deaths, according to data compiled by Johns Hopkins University.
President Donald Trump’s response to the pandemic has also come under increasing scrutiny. In recent weeks, Trump has downplayed the threat of the virus, tying the surge in new cases to an increase in testing. However, public health officials and infectious disease experts dispute those claims, saying the rate of cases that test positive in the U.S., hospitalizations and deaths remain high in some states.
Trump endorsed masks for the first time this week after resisting them for months. The CDC began recommending face masks for the general public in April.
Earlier in the day, Adm. Brett Giroir, an assistant secretary for health at the Department of Health and Human Services, told reporters that 90% of the public or more need to wear face coverings in order to curb the spread of the virus.
“If we close the indoor bars, reduce the occupancy of restaurants, have face coverings and hygiene, this is essentially equivalent to shutting down the entire economy, which means shutting down elective surgeries and everything else that goes with that,” he said.
n the study, published Thursday in the journal Thorax, researchers pitted three kinds of facial coverings against one another: a single-layer “no sew” mask, a two-layer variety made to specifications from the U.S.
Centers for Disease Control and Prevention (CDC), and a three-layer surgical mask. Using LED lights, a high-speed camera and a healthy volunteer willing to have their nose repeatedly ticked with a tissue, each variety of facial covering was tested to see which best contained droplets generated from speaking, coughing and sneezing, with the idea that better containment suggests better efficacy in terms of curbing transmission.
“The COVID-19 pandemic and the need for community face masks has raised questions about whether you can just throw a scarf over your face, or whether you should use a better designed cloth mask,” says Raina MacIntyre, a professor of global biosecurity at the University of New South Wales Sydney, and one of the study’s authors.
The result? The surgical mask did the best job overall, but the two-layer CDC mask was still “significantly better” at containing droplets than the single-layer covering. However, the researchers added, “even a single-layer face covering is better than no face covering.