A version of this article first appeared in Emily Oster’s newsletter, ParentData.
The approval of vaccines for 5- to 11-year-old kids last week left a lot of parents very relieved (including this one; both kids had a first dose on Thursday). It’s also brought more attention to the ongoing conversation about when it makes sense to dial down some of the other COVID mitigation strategies—notably, masks. In recent weeks, a number of articles (here, here, here) have been written about the need to articulate “off-ramps” for masking in schools. These pieces recognize that while in-school masking provides some protection, with lower case rates and vaccines for kids and adults widely available, there will be a time to remove this layer. It goes without saying that the discussion is very fraught and generates a lot of anger.
A number of pieces have also been written about the evidence of the protective value of masks in schools. Not everyone agrees on that topic. But today I want to look at what we know about the other side of the coin, which is actually the question I get most frequently from parents: Are there any downsides to mask wearing for kids in school or child care?
This is important to consider, since it influences how we think about changes in masking policy. Here’s a simple thought experiment. Say that, instead of face masks, you protected against COVID-19 by wearing a friendship bracelet. As unobtrusive as that is, some people would still object to forcing children to wear one, claiming it infringed on freedom of expression, but most people would be willing to continue the practice as long as we believed it had some protective effect. On the other hand, imagine that the protection required kids to wear a blindfold at school. Again, some people would argue for continuing this indefinitely, at least until we reached “zero-COVID,” but most people would say that we’d need to be convinced of significant value to continue it.
All this is to say that as we contemplate off-ramps, or a move to mask-optional approaches in schools, the question of whether there are downsides to masks and, if so, how large they are matters. We will—and should—think about it differently depending on whether masks are more like friendship bracelets or blindfolds.
Interruption to say: By and large, kids have adapted extremely well to masks. They are able to wear them, and they don’t complain (much). Which is all great! But it doesn’t necessarily mean there are not some possible downsides.
When people discuss possible concerns with masks for kids, there are a few key issues that are raised:
● Interference with breathing/respiratory health
● Interference with social development (ability to read emotions and interact with friends)
● Interference with intellectual development (learning to speak, learning to read, learning in general)
● Concerns about students with disabilities
Answering most of these questions precisely is extremely difficult or impossible. But by triangulating across different pieces of data, we can start to get a picture.
In June, JAMA Pediatrics published a study in which the authors suggested that face masks cause children to inhale dangerous levels of carbon dioxide. This was based on laboratory measurements, and it really scared parents. Without going into details, the most important thing you should know is that the study was retracted. The calculations ignored some basic understanding of how breathing works. In fact, at least one other study (not retracted!) evaluated respiratory function in infants and young children while wearing masks and did not find any evidence of impacts.
There’s other work focused on whether face masking would impact respiratory function, even during exercise, that does not suggest negative effects. The bottom line is that while you can certainly find anecdotal evidence of people claiming their child cannot breathe wearing a mask, this isn’t a claim that is well supported in the data.
Social and intellectual development
I’m going to lump these together, because the type of evidence we bring to bear on them is roughly the same.
Stepping back: The concerns here stem from the observation that seeing the bottom half of the face is important for reading emotions, learning to speak, and learning to read. The theory behind this is compelling.
In the study of socioemotional development, the idea of facial expressions conveying emotions goes back to Charles Darwin (in one of his lesser-known books, The Expression of the Emotions in Man and Animals). As adults, it should be obvious from our own experience that we use facial expressions to understand the emotions of others.
This is a skill that develops over childhood (see, for example, this paper on how kids get better at reading emotions from faces between the ages of 3 and 11). Kids differ in the speed at which they develop this ability; there is literature on how children’s reading of facial expressions correlates with their social skills. This starts early: Infants respond to faces, rapidly learning to distinguish between happy, sad, and other emotions, and can distinguish their mom’s face from others within a short period.
There is also a potential role for facial expressions in language development. Watching how mouths move is part of learning to speak (see, for instance, this paper). And when kids need help with speech issues, being able to observe the movement of their mouth [and the mouths of others in pronouncing letters is crucial
A final argument relates to hearing. There is direct evidence that masks make it difficult to hear the speaker, and that this may be exacerbated for kids in loud classrooms. It stands to some logic that if you are trying to teach a young child to read—or, really, do anything—it is valuable for them to be able to hear you. And social interactions are better if kids can hear each other and be heard by teachers.
Putting all this together, it is reasonable to think that some aspects of learning or social skills may be impacted by masks, and indeed others have argued this. But this isn’t quite the same as direct evidence that masking is detrimental, and it doesn’t tell us about magnitudes. Maybe seeing half a face is almost as good as a whole face. The impacts of hearing on learning may be small.
Large-scale evidence on the particular question of masking in schools and development is lacking and is unlikely to ever appear. One could imagine exploiting differences across schools in mask policies to look at differences in learning outcomes, but you would rapidly realize in doing so that too many other things vary across these schools. There will never be anything convincingly causal.
What we can see is a bit of lab-based evidence on masking directly, especially on emotion-reading. There is, for example, this paper showing that children performed worse on a face-perception test when masks were involved versus without. There’s also this paper—co-authored by a researcher and a 9-year-old—which showed that children had trouble reading emotions from masked faces. Or this one, which showed that masks reduced kids’ ability to read emotions from pictures (though notably, not more than sunglasses).
This type of in-lab analysis for studying language development or learning evolution is less feasible, and there is therefore little we can say directly.
In the end, what we arrive at is a lot of theoretical reasons to think that masking could be somewhat detrimental to social learning and intellectual progress, with the evidence for the former being somewhat stronger. But it is nearly impossible to be precise about magnitudes.
Students with disabilities
For students with disabilities—especially students with autism, for whom reading emotions is already more challenging, or those who are deaf—masks may be a particular barrier. There is some direct evidence among children with hearing impairment of masks impacting their word understanding.
A challenge is that these students are also, in some cases, at higher risk for COVID-19. There is a balance, then, between risk and benefit.
It remains extremely difficult to make any concrete statement about possible risks or downsides of masks in kids. Perhaps the strongest evidence is on effects on emotion-reading, but even there we have to ask: How much does it matter in practice? If kids are unmasked at home and when out at recess, is it a big deal to wear a mask while learning to subtract?
We expect variation in impacts across children. Those who are slightly hearing-impaired, or have more trouble paying attention, may be more affected by the muffled nature of voices through masks. Those kids who struggle more to read emotions may benefit more from getting “whole-face” information and may struggle more with masks, too.
None of this is intended to scare parents. Kids are resilient, kind of amazingly so. If your child is in school with a mask, you shouldn’t panic—and far, far better to be in person at school with masks than at home without.
So this isn’t a moment to be scared about yet another thing. But what seems quite clear to me in reflecting on this is that masks are not a friendship bracelet. The effects may be small, or mixed across kids, but in the absence of a disease risk, we would not have children mask at school or child care. And these effects are likely larger for younger kids. Which means that there are strong reasons to consider when we will feel the COVID risks are such that we can remove masks, probably even before the youngest kids are vaccine-eligible. Which, basically, means we need to design off-ramps.