Video report by ITV News Video Producer Natalia Jorquera
Double masking can significantly improve protection against Covid-19, new data from the US Centers for Disease Control and Prevention (CDC) has found.
Layering a cloth mask over a medical mask, such as a disposable blue surgical mask, can block 92.5% of potentially infectious particles from escaping by creating a tighter fit, researchers have found.
It comes as America's top infectious diseases expert has said double masking is a "common sense approach" to preventing the spread of Covid-19.
Dr Anthony Fauci, chief medical adviser to President Joe Biden, recommended using two masks at a coronavirus response news conference on Wednesday, saying there was "no harm" if people wanted to, for added protection.
What evidence has the CDC found about double-masking?
The CDC tested two simple modifications to improve the performance of commonly used masks in January by using the "double masking" and "knotting" methods.
How have US experts reacted to the CDC recommendation?
Infectious disease expert Amesh Adalja, MD, senior scholar at the Johns Hopkins University Center for Health Security in Maryland, said the effectiveness of wearing two face masks depends on the mask material.
Dr Adalja tells Health: "Where you need to wear two masks depends on the quality of the mask."
"It depends on the fit of the mask and how well it serves as a barrier," he added.
What has the CDC said about double-masking?
The director of the CDC said they continue to "recommend that masks should have two or more layers" to US citizens.
Dr. Rochelle Walensky told a White House briefing on Thursday: "These experimental data reinforce CDC's prior guidance that everyone two years of age or older should wear a mask when in public and around others in the home not living with you."
"We continue to recommend that masks should have two or more layers, completely cover your nose and mouth, and fit snugly against your nose and the sides of your face," she added.
What have UK health experts said?
England's deputy chief medical officer, Professor Jonathan Van-Tam said it's the individuals choice, before adding that he has not seen any evidence of double masking being more efficient
Prof Van Tam told ITV News: "I've seen people doing that on the tube, I think it's a matter of personal preference."
"I don't have any data on that," he added.
Watch our guide on how to make your own DIY face covering:
How do you wear a face mask?
According to the UK’s Health and Safety Executive, a face covering should:
cover your nose and mouth while allowing you to breathe comfortably
fit comfortably but securely against the side of the face
be secured to the head with ties or ear loops
be made of a material that you find to be comfortable and breathable, such as cotton
ideally include at least two layers of fabric (the World Health Organisation recommends three depending on the fabric used)
unless disposable, it should be machine washable