With the increased transmissibility of new coronavirus variants being discovered, it has been suggested by some that double-masking could help contain the spread.
The Kent, Brazil and South Africa variants of COVID-19 have been found to be up to 70% more transmissible, and so have the potential to spread more easily than previous iterations of the virus.
As vaccination efforts ramp up, it is important to keep wearing a mask - and make sure that face coverings are working as well as possible.
So what are the scientists saying? Which masks should you be wearing? Can you wear more than two masks? Sky News will answer your questions below.
Should I wear two masks?
The answer appears to be yes.
A report from the Centres for Disease Control and Prevention (CDC) released this week suggested that putting a cloth mask over a medical mask could reduce the wearer's exposure to virus-sized particles by upwards of 90%.
And if two people both double mask, the risk of the virus getting from one to the other was reduced by 96.4%
Dr Anthony Fauci, Joe Biden's chief medical adviser on the pandemic, has also said that the practice of double-masking is "common sense".
The study from the CDC simulated how the virus behind COVID-19 - SARS-CoV-2 - spread in the air.
Dr Julian Tang, consultant virologist at the Leicester Royal Infirmary and honorary associate professor in the department of respiratory sciences, told Sky News that the more masks worn, the greater the protection offered.
He said: "More layers are better than fewer layers."
He added: "Three layers offer even more protection than two if you can tolerate it - but it could make it harder to breathe."
What does the UK government say?
Officials have not commented specifically on double-masking, but the guidance offered by the government describes the best way to wear a face covering.
Among the advice, the guidance states a mask 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
- ideally include at least two layers of fabric (the World Health Organisation recommends three, depending on the fabric used)
- be made of a material that you find to be comfortable and breathable, such as cotton
- unless disposable, it should be able to be washed with other items of laundry according to fabric washing instructions and dried without causing the face covering to be damaged
Should I upgrade my mask?
Any mask is better than no mask - but the CDC study focused on wearing a medical procedure mask covered by a cloth mask.
Some UK voices - including former health secretary Jeremy Hunt - have called for medical quality masks to be made compulsory on public transport and in shops.
Trisha Greenhalgh, a professor of primary care at the University of Oxford, has also said "we need to be wearing medical-grade" following the emergence of new variants of the virus.
France and Germany have already mandated that masks worn in public must be of medical grade.
The report from the CDC found that a medical procedure - or surgical style - mask on its own blocked 42% of simulated virus particles from a cough, and a cloth mask blocked 44.3%. When the two were combined they blocked 92.5% of simulated particles.
The medical procedure mask was defined as the type branded "surgical, laser, isolation, dental, or medical procedure masks". They are not N95 masks (roughly equivalent to UK FFP2 masks).
The cloth masks over the top were just the kind of masks made from natural of synthetic fabrics that are common at this point of the pandemic.
How does it help?
The reason double masking is thought to help is because it helps the fit of the mask around the face.
As Dr Tang points out, most infections from people wearing a mask comes from "around the side of the mask" - the gaps where a seal is not complete.
This works for both those breathing in potential viruses, and also those who may already be infected breathing them out - meaning you are protecting others by double-masking.
What else can I do?
Another way to improve the seal of a surgical mask was to tie a knot in the ear loops near where the straps meet the fabric of the covering.
The CDC found that this method reduced exposure to the virus almost as much as wearing a double mask.
In order to keep your surgical mask clean, Dr Tang suggested spraying it with alcohol cleanser and letting it dry - washing with water can breakdown the protective measures built into the mask.
He also suggested that, for people with facial hair, using products like Vaseline could help create a seal around the side of the mask.
