What’s the most effective face mask for preventing COVID-19 transmission?
Face coverings have become a standard feature of pandemic life, but which mask is best for everyday use, and how should you take care of it?
27 January 2021 – by Linda Geddes
*Updated on 9 February 2021
From washable cloth masks to medical grade respirators, consumers are spoilt for choice when it comes to face coverings. Retailers are also cashing in on the demand, turning protective face coverings into the latest fashion accessories.
Increasingly though, governments are issuing stricter guidance on which masks people should be wearing for everyday activities. French and German health officials have advised people to wear surgical masks rather than cloth face coverings, while in Bavaria and Austria, it is now compulsory to wear a medical grade FFP2 mask (standing for filtering face piece) on public transport and in shops.
Masks are designed to provide an additional layer of protection in situations where you can’t physically distance and in rooms with poor or unknown ventilation.
Whichever mask you choose, it will be more effective in protecting you from COVID-19 when combined with other measures. To stay safe, it is also important to keep your distance from other people, avoid crowds, keep rooms well-ventilated, regularly clean your hands and cough into a bent elbow or tissue.
Types of face covering
Cloth masks: These usually consist of several layers of fabric, and attach to the face using ear loops or head ties. They are primarily designed to minimise the transmission of virus particles contained within larger respiratory droplets produced when we speak, cough or sneeze, but provide little protection for the wearer themselves. This makes physical distancing and ventilation particularly important when wearing one.
Fabric masks should ideally have three layers, including a middle layer, which can be a disposable filter. The inner layer should be made from a fabric which easily absorbs moisture from the breath, like cotton. The middle layer should ideally be made from “spunbound” polypropylene – a man-made material with a random arrangement of fibres, like spaghetti on a plate – while the outermost layer should be made from a fabric that repels droplets and moisture, e.g., polyester, or a polyester and cotton blend.
When choosing a fabric mask, avoid those with only a single layer of fabric, and look for one with a bendable strip of metal or plastic that can be moulded over the bridge of the nose, for a better fit. A recent investigation by the British consumer magazine, Which?, found a huge variation in the ability of fabric masks to filter particles, with the best filtering out 99% of bacteria-sized particles – as good as surgical masks – and the worst managing just 7%. Three-layer masks, particularly those which included a disposable filter insert, tended to be the most effective. The type of fabric also mattered: the worst-performing masks consisted of a single layer of mostly polyester. Ideally, Which? suggested to look for a mix of different fabrics such as cotton, polypropylene and different types of polyester.
Also, since fabric masks are primarily designed to protect other people, steer clear of other people wearing a flimsy-looking mask or no mask at all.
Surgical masks: Like cloth masks, these are relatively loose-fitting face coverings, which attach around the ears with elastic, and are designed to protect other people against any large respiratory droplets that the wearer emits. However, because they are worn by health workers and constitute a form of Personal Protective Equipment (PPE), their production is regulated and the level of protection they provide is more consistent than fabric masks. This is the reason the French health ministry gave for recommending them.
Surgical masks are often light blue in colour, and made of a combination of paper and plastics. They are disposable, so potentially more harmful for the environment.
Respirators: These are designed to protect healthcare workers from droplets in the air. They fit snugly against the face, meaning both inhaled and exhaled air is filtered through. This also means they need to be carefully fitted to ensure the mask creates a full seal – otherwise unfiltered air will come through the gaps between mask and face. Some respirators have one-way valves that make them easier to breathe through, but these should be avoided as they do not protect the wearer from spreading the virus.
Respirators have different names depending on where they’re manufactured and the degree to which they filter air. For instance, a N95 mask is manufactured in the US and is designed to filter out at least 95% of very small (0.3 micron) particles, including bacteria and viruses. FFP2 face masks are the European equivalent, and meet World Health Organization (WHO) guidelines for protection against COVID-19 – they filter at least 94% of particles and are designed to be used for a maximum of eight hours. FFP3 masks filter at least 99% of particles, and typically have a valve because the filtration material is much thicker.
Although it may be tempting to purchase medical masks to protect yourself, doing so risks diverting supplies away from medical staff who are in greater need. These masks are also designed to be thrown away after each use, which has environmental consequences, and re-wearing them may expose you to any virus on their surface, so this should be avoided.
The WHO currently recommends that FFP2 or N95 masks be worn by medical staff who are performing aerosol generating procedures, such as inserting a breathing tube or performing cardiopulmonary resuscitation. At other times, healthcare workers are advised to wear surgical masks.
Surgical masks should also be worn by anyone who is feeling unwell, including people with mild symptoms such as muscle aches, slight cough, sore throat or fatigue; those awaiting COVID-19 test results or who have tested positive; and anyone caring for a person with suspected or confirmed COVID-19. They are also recommended for people aged 60 or over as well as those with underlying medical conditions where distancing of at least one metre cannot be achieved.
Fabric masks are appropriate for most younger people, including those working as cashiers and in other service roles, the WHO says.
When should I wear a mask?
Masks are designed to provide an additional layer of protection in situations where you can’t physically distance and in rooms with poor or unknown ventilation. This includes if a visitor comes into your home who is not part of your household and in outdoor situations where you cannot maintain a physical distance from others, such as crowded streets or bus stops – particularly if there’s a wall or other obstacles preventing air from circulating freely.
Should I double-mask?
As the new variants spread potentially even faster than the original virus, some health experts are advising people to wear two masks – a cloth mask with a surgical mask on top, which could block virus particles and aerosols by up to 75%. This would be an increase on, for example, a cloth mask that might only offer 50% protection. Double-masking wouldn’t be necessary all the time, only in situations where you might be indoors, around a lot of people and where physical distancing isn’t always possible – such as in a shop or market place. For taking a walk outside, however, a single mask would be fine.
How to look after your mask
Fabric masks should ideally be washed after each time you wear them. A hot wash at 60 degrees Celsius or more is best, and masks can go in with your normal laundry. Handwashing in cold or lukewarm water is inadequate, studies suggest. Frequent washing is particularly important if you’re coming into contact with vulnerable individuals.
Reusing dirty masks presents a risk to both yourself and others. If you have been in the same environment as an infected individual, there may be virus particles on the outside of your mask, which you may get onto your hands, or potentially breathe in. And, if you leave a dirty mask lying around and someone else picks it up, they could get your germs on their hands.
Disposable masks should also be thrown away after use and sealed in bags if they’ve been worn by someone with COVID-19, or their carer.
Also be aware that masks become less effective if they are damp, including if they are worn outdoors in cold weather, when condensation can quickly accumulate on the inside.
For more tips on wearing and caring for your mask, see the WHO’s website.