Health experts have issued a warning for those who are making their own face coverings during the coronavirus pandemic.
Scots have been adjusting to wearing face coverings after it became law to wear one in shops and on public transport earlier this month.
A study conducted by experts in Australia has found that surgical masks are the best to curb the spread of Covid-19, reports Bristol Live.
However, the World Health Organisation (WHO) has urged people to make their own face coverings in order to reserve the surgical ones for those working on the frontline.
The UK Government has issued advice on how to make your own one - all you need is fabric, elastic, needle and thread and a pair of scissors.
Researchers at the University of New South Wales in Sydney have urged people to use at least two layers to maximise protection.
They found that one layer of cotton t-shirt material is fairly effective as a barrier against droplets expelled during speech, but two are “significantly better at reducing the droplet spread caused by coughing and sneezing”.
Three layers are considered to be even better.
For the new study, published in the journal Thorax, experts from the university in Australia tested three types of masks.
Their one-layer face covering was made using a cotton t-shirt material, the two-layer covering was prepared by sewing two strips together, and the third was a surgical mask.
A tailored LED lighting system and a high-speed camera were used to capture the light scattered by droplets and aerosols expelled during speaking, coughing and sneezing while wearing the different types of mask.
The volunteer who took part was healthy with no respiratory infection. Tissue paper was put up the nose to stimulate sneezing.
The researchers concluded: “From the captured video it can be observed that, for speaking, a single-layer cloth face covering reduced the droplet spread but a double-layer covering performed better.
“Even a single-layer face covering is better than no face covering.
“However, a double-layer cloth face covering was significantly better at reducing the droplet spread caused by coughing and sneezing.
“A surgical mask was the best among all the tested scenarios in preventing droplet spread from any respiratory emission.
“These visualisations show the value of using face masks and the difference between types of masks.”
The home-made masks in the study were made with 175 g/m² cotton fabric, with a thread count of 170 per inch.
The researchers said other factors contribute to the effectiveness of cloth face masks, such as design and fit, as well as the frequency of washing.
But they added: “In case of shortages of surgical masks, a cloth face covering with at least two layers is preferable to a single-layer one.
“Guidelines on home-made cloth masks should stipulate multiple layers.”
The team pointed to another study which showed a 12-layer cotton mask is as effective as a surgical mask, but a single-layer cloth mask does not protect against coronaviruses.
They said: “There is a need for more evidence to inform safer cloth mask design, and countries should ensure adequate manufacturing or procurement of surgical masks.”
