Double-masking is only slightly better at stopping the spread of coronavirus than wearing one face covering, a study has suggested.
Japanese researchers said wearing one surgical mask that is fitted correctly could stop up to 85 per cent of viral particles from passing through.
Doubling up on surgical masks offers no benefit because air resistance builds up and causes leakage around the edges of the mask, they claimed.
The study found there was some benefit in wearing a tight-fitting reusable mask on top of a surgical one, but it was marginal, offering up to 89 per cent protection.
The experts, who used a super-computer simulation to test different face covering combinations, said ‘the performance of double masking simply does not add up’.
Their findings contradict recent recommendations from health experts in the UK and US, who have claimed it’s ‘common sense’ two masks are better than one.
Wearing two masks at once – known as double-masking – was made popular in the US where President Joe Biden and Dr Anthony Fauci regularly use the technique.
The US-based Centres of Disease Control and Prevention (CDC) recommends Americans wear two face coverings to have the best chance of not catching Covid.
Public Health England officials have claimed the ‘more layers you have, the better’, however the current guidance is to wear one.
Double-masking could provide better protection against Covid-19
Dr Anthony Fauci, a top infectious diseases expert in the US, has claimed it is common sense to wear two masks to stop the spread of the virus. He is pictured in January at a press conference in the White House
Researchers from Riken and Kobe University in Japan used the Fugaku supercomputer – considered the most powerful computer in the world – to model the effect of double-masking.
The team previously used the computer to model how humidity can affect Covid’s spread and the infection risks in trains, work spaces, and other environments.
Professional grade N95 masks were found to be the best in protecting against infection, followed by surgical masks, cloth masks and finally reusable plastic types, the study showed.
Several prominent scientists have thrown their weight behind double-masking including Dr Anthony Fauci, the US’s top infectious diseases expert.
He said it was ‘common sense’ they would be more effective, adding it was ‘likely’ to offer better protection against mutant strains which could be better able to evade immunity from vaccines and past infections.
Dr Benjamin Killingley, a scientist advising the UK Government in the pandemic, has also said wearing two masks was ‘common sense’.
Public Health England’s Dr Susan Hopkins told a Downing Street press conference this week the ‘more layers you have the better’.
The comments have likely caused Britons to question the effectiveness of their current face masks.
However, millions of people may unknowingly be wearing double or triple layer masks already.
Many commercially available cloth masks are at least double or triple layered, while disposable surgical masks are usually made of three layers of non-woven fabric.
The Government also has advice on its website on how to create your own double layered face masks from scratch with two pieces of cloth.
Separate modelling by the Fugaku computer in September showed plastic face shields allowed nearly 100 per cent of tiny airborne droplets released by Covid-infected patients to escape through visors.
And half of larger droplets measuring 50 micrometres in size — given off by coughs and sneezes — found their way into the air, posing a risk to others. One micrometre is one millionth of a metre.
The World Health Organization (WHO) says face shields can help prevent the virus from spreading.
But the agency says they only work in combination with other safety measures such as wearing a mask, social distancing, and frequent hand-washing.
Face shields do not completely cover the entirety of the face, leaving room for droplets expelled by the mouth and nose to escape.
Face visors are also worn by doctors, nurses and other hospital workers on the Covid-19 frontline, but with the addition of a fitted surgical face mask.
It comes after research published last summer suggested home-made face coverings need to be at least two layers and preferably three to curb the spread of Covid-19.
The study, published in the journal Thorax in July, saw experts from the University of New South Wales in Sydney, Australia, test 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.
The researchers concluded that while a single-layer face covering is better than none at all, a double-layer was ‘significantly better at reducing the droplet spread caused by coughing and sneezing’.
They added: ‘A surgical mask was the best among all the tested scenarios in preventing droplet spread from any respiratory emission.’
Another popular technique, particularly in America, is to wear a respirator mask – such as an N95 mask – and a cloth mask at the same time.
N95 respirator mask are designed to have a close fit and filter airborne particles, with an electrostatic charge that can trap matter.
President Biden has often been seen using a N95 mask and a paper or cloth covering on top.
However, the US President explained during the election campaign that he struggles to get a medical grade N95 mask to fit comfortably.
Therefore he wears a paper one over the top to keep it in place.