Face of the pandemic

We wear them every day, but how much do we know about them? (9 minute read)

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I can still remember the first time I wore a face mask to the supermarket. What stands out in my memory is how self-conscious I felt. I was sure everyone was staring at me. It was towards the end of New Zealand’s first lockdown, and very few people were wearing masks, so it’s quite possible that people were staring. I wasn’t wearing one of the more familiar surgical masks either. I had been experimenting with my sewing machine and pieces of interesting fabric that I had lying around. My mask was red with a pattern of black birds on it.

At the time, there wasn’t much evidence about mask-wearing and Covid-19. But I had read some papers on mask use and influenza. Although none of the research was conclusive, there was some evidence that if someone who was infected wore a mask, they were less likely to pass on the flu virus. More importantly, one of the papers looked at evidence for mask use in reducing the risk of SARS – the close cousin to Covid-19. The paper found that there were several studies suggesting mask use helped to reduce the spread of SARS, even double layered cotton masks. As with the research on influenza, there was nothing conclusive, but there was enough to make me decide that wearing a mask was a responsible thing to do.

The use of face masks to prevent disease transmission dates back to times when people thought diseases were spread by “miasmas” or bad smells. Because the smell itself was thought to be infectious, people developed ways to disguise smells. One such method, used by doctors treating plague victims in the 17th century, was a beaked mask stuffed with herbs.

The modern surgical mask however, has a rather shorter history. It dates back to when people were beginning to understand that exhaled droplets of moisture could spread disease, at the turn of the 20th century. Around this time, doctors in Europe, the USA and China were all coming to the conclusion that covering the mouth and nose could help prevent the spread of disease. During an outbreak of pneumonic plague (an airborne form of plague) in China in 1910 and 1911, Dr Wu Lien Teh advocated the use of face masks to reduce disease transmission. And during the 1918 influenza pandemic masks were used, not just by medical staff, but by the general public.

Early masks were made from gauze, in some cases stuffed with cotton wool. But this changed in the 1960s, as part of a wider shift in the health systems of away from reusable items to disposable ones. Masks changed from being reusable and made from natural fibres to being disposable and made from various forms of plastic, such as polypropylene.

Modern surgical masks had three layers of material. The outer layer – the coloured layer worn on the outside, is a liquid-repellent layer. It’s designed to prevent splashes of liquid and large droplets of moisture passing through the mask. The second layer is the main filter which prevents particles of a certain size from passing through in either direction. The inner layer absorbs moisture, trapping droplets from the wearer’s exhaled breath. Surgical masks must meet certain standards for filtration. These standards are based on how well the masks stop bacteria, specifically a common bug with the name of Staphylococcus aureus, and tiny particles such as very fine dust.

Photo credit: Grandriver/ Getty Images

But the filtration ability of the fabric is only one part of how well a surgical mask works. Also important is how well it fits. If the mask doesn’t fit snugly against the face, unfiltered air can escape around the mask. Even with a well-fitting mask, some air will escape. That’s the big difference between surgical masks and N95 masks – an N95 mask, properly fitted, forms a seal that prevents air from leaking in and out. It means that an N95 mask is far more effective at preventing the movement of droplets and particles in the air. N95 masks are more properly termed “filtering facepiece respirators”, because they filter all air going in and out of the lungs, unlike surgical masks and other types of face mask.

The term N95 doesn’t, strictly speaking, refer to a type of mask or respirator. N95 is a standard for the US National Institute of Occupational Safety and Health, usually abbreviated to NIOSH. To meet N95 standard, a properly fitted mask must filter out 95% of particles great than 0.3 microns (that’s a particle 3/1000th of the width of a human hair). There are a range of different face masks that can achieve this standard, but they must fit closely to the face, have bands which go around the head (not the ears) and they must have the NIOSH approval number on the mask. The KN95 standard is very similar to the N95 standard, however it’s a Chinese rather than US standard. In New Zealand and Australia, the equivalent is P2.

The materials making up N95-type masks filter out particles and droplets in three different ways. Larger particles are most likely to collide with the filter materials and get stuck. Smaller particles are able to pass through the pores, but because the air becomes turbulent as it moves through the filter material, smaller particles still get trapped as they move through, in the same way that twigs and branches get caught up in an eddy on a river. And the filter fabric itself is charged with static electricity, which attracts and traps the smallest particles. The technology and design that goes into these masks is worthy of admiration.

While surgical and N95 masts must meet certain standards, there are no such rules for cloth masks, and that’s where there is a problem. There’s a wide variation in how well cloth masks work, depending on what they are made from and how well they fit. In general, however, they are less effective than surgical masks and N95 masks, and are generally considered to be something that should only be used when surgical or N95 masks aren’t available.

On the other hand, that doesn’t mean N95-type mask are perfect. Some of these masks contain a valve which allows exhaled breath to escape more easily. When the masks are being worn as protection for the person wearing the mask, that’s not a problem, but it does mean that if the wearer is infected with a respiratory virus like Covid-19, the mask probably isn’t so effective at preventing disease spread. There have been problems with counterfeit N95 masks as well.

Not an N-95 mask: photo credit Pikusisi-studio/ Getty Images

But how useful are masks, of any kind, in preventing the spread of Covid-19?

That question was the subject of much debate early in the pandemic, but the evidence has been building that they do help to reduce Covid-19 transmission and mortality when commonly worn by the public. This conclusion is based both on experimental studies, and comparisons of areas where mask wearing is mandatory and where it is not. Masks provide both source control – that is reducing spread from people who are infected – and protection from infection for the wearer. How much they help is debatable, though, because you can’t directly apply the results of testing masks experimentally or having them worn by experienced health workers to their use by the general public.

Masks are not without their drawbacks and detractors. A common criticism early in the pandemic was that people would have a false sense of security from mask-wearing and stop other protective behaviours. However, the opposite effect has been shown – in general, people who wear masks are also more likely to take other precautions. There were supply issues with masks too, especially earlier in the pandemic, which meant that the public was often discouraged from using surgical or N95 masks so healthcare workers didn’t run out. There have been claims circulating that masks affect people’s breathing (often coming from those who also deny the severity of Covid-19 and claim that vaccines are harmful), but these claims are not supported by evidence.

But there’s one concern that bothers me a lot, and that is that masks contribute to the problem of plastic waste. By one estimate, the world is throwing away three million masks every minute. They are referred to as disposable, but that’s a misleading term for something that cannot be easily recycled or biodegraded. Masks do eventually disintegrate, but then they contribute to the problem of microplastics. Mostly, microplastics end up in the ocean. But there is evidence that some end up in the nasal passages of people wearing masks as well. What harm microplastics might do is still uncertain, but they are a reminder that no action we take is without consequence.

So where does this leave us when it comes to mask-wearing? There’s a good case to support widespread mask-wearing when Covid-19 is a risk, and it’s a precaution that I’m happy to take. And I have to acknowledge that my home-made cloth masks are not particularly effective. On the other hand, I mostly work from home, which means I seldom need to wear a mask for any length of time.

In the end, I’ve compromised. My cloth masks fit me well and have a pocket which can hold an extra filter. I wasn’t using the filter pocket, but I’ve concluded that I need to. I’ve just started using the fabric from a surgical mask as the filter. The cloth masks go through the washing machine and surgical masks can be washed in warm water (but without detergent). I’ve also found no strong evidence that I can’t safely reuse the surgical mask material without washing if I’m not wearing it for long and it isn’t actually dirty. Viruses like Covid-19 don’t survive for long on surfaces, with most of the virus surviving less than a day, even without UV light. If exposed to UV light, they degrade faster.

In doing the research for this article, I’ve convinced myself that I should probably buy some N95-type masks – if I can get hold of some that don’t look as if they’re fake. If I were working in a job which put me constantly in contact with the public, I think I’d wear one. But since I work from home, my mask-wearing is limited to short periods, such as a trip to the supermarket. My need for N95 masks is not great. I’ll be saving them for high risk situations, such as taking a plane flight.

Ultimately, there is no single answer on what to do about masks. I encourage everyone to consider their own circumstances when making decisions on what type of mask to wear. Are you in a group that’s at higher risk from Covid-19, or are you in regular contact with people who are? How much time do you spend in close contact with people? And how much harm to the environment are you willing to accept? Until someone comes up with a better way to dispose of the so-called disposable masks, that’s something we all need to consider.

The Turnstone comes out once a week. Every two weeks, I publish an original article, like this one. On one of the alternate weeks I send out “Talking about vaccines” - resources to help you have better conversations about vaccines. On the other week I share something about climate change, called “Talking about climate change”. The focus is conversations we can have and actions to take on climate change.

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