Despite 125 years of surgical masking, nobody has ever shown that the practice improves patient outcomes or prevents infections among hospital staff

Wearing diapers on your face serves no demonstrable health purpose in any context.

Community masking is anything but a low-cost, low-risk measure.

The more I read, the more I am convinced that masks owe their mass appeal to their associations with hospitals, and especially their use by surgical teams in operating theatres. Prior to the pandemic, this was the only context in which most ordinary westerners would’ve seen a lot of people wearing masks, and hospitals are associated with the highest hygiene standards. In fact, the evidence that surgical masking does anything is every bit as lacking as the evidence that community masking does anything. To the extent that surgeons know this, they continue to mask because they regard the measure as a traditional procedure important to put patients at ease. There has always been a substantial theatrical element to the use of face masks, in other words – first in hospitals, and more recently among the population at large – but nobody can show that it prevents infection.

This Twitter user has gathered almost all of the available scientific literature on masking into this massive directory of 462 files on archive.org. Of that research, I want to draw your attention in particular to this 2015 review of the literature on surgical masking, and – because it is one of the best individual studies on the question– this 1991 Swedish paper by T.G. Tunevall, who designed his partially randomised trial to investigate an earlier finding that face masks might actually increase the rate of postoperative infections. Across 3,000 operations, Tunevall failed to find any statistically significant difference in patient outcomes, whether surgical teams wore masks or not.

Surgeons began experimenting with masks as the study of bacteria matured at the turn of the twentieth century, and scientists realised that particles expelled from the mouth were full of culturable pathogens. Bacteria in wounds is obviously bad, and masks seem a plausible way of preventing bacterial contamination. As with community masking, the theory is there; it just doesn’t pan out in practice. This shouldn’t be surprising, because almost all proposed medical interventions fail, despite the fact that there’s a theory behind every single one of them.

In 1993, following the Tunevall study, British surgeons were surveyed about masking practices. Ninety-six percent said they personally masked, but of those, a fifth said that tradition was the only reason they bothered. The remaining masking surgeons were equally divided over whether they masked to protect themselves or to protect patients.

As in the pandemic, so in medicine – once masks fail in one direction (source control), it’s simply claimed that they work in the other direction (personal protection). There’s far fewer studies on masks as personal protection, but still no evidence shows that they work here either. The authors of the survey paper note additionally that surgical masks aren’t well designed to protect hospital staff from fluid spatter. And finally, while masking is a general practice of surgical teams regardless of the specific procedure, the authors of the 2015 literature review note that “The incidence of blood/bodily fluid splashes varies substantially between settings … by the role of surgical staff … by surgical specialty as well as by surgical technique.” Surgeons may say they wear masks for personal protection, but their actual masking practices suggest otherwise.

An intriguing feature of the pre-pandemic scientific literature is how frankly it discusses the repeated failure to find that surgical masking does anything on the one hand, while giving masks every fallacious argumentative advantage on the other hand.

From that 2015 literature review again:

Given that there is no evidence that they cause any harm either, proponents would rather err on the side of caution and encourage their continued use, stressing that there is no room for complacency when it comes to ensuring patient safety. This opinion is similarly echoed by the National Institute for Health and Care Excellence guidelines which assert that mask usage contributes towards ‘maintaining theatre discipline’.

Another unavoidable aspect of this debate is that of public perception. In the public psyche, facemasks have become so strongly associated with safe and proper surgical practice that their disposal could cause unnecessary patient distress …

It is clear that more studies are required before any absolute conclusions can be drawn regarding the effectiveness or, indeed, ineffectiveness of surgical masks. The published literature does suggest that it may be reasonable to further examine the need for masks in contemporary surgical practice given the interests of comfort, budget constraints and potential ease of communication, although any such study would undoubtedly have to be large and well controlled to prove causality given the low event frequency of surgical site infections. It is possible, if not probable, that if surgical facemasks were to be introduced today, without the historical impetus currently associated with their use, the experimental evidence would not be sufficiently compelling to incorporate facemasks into surgical practice.

It is important not to construe an absence of evidence for effectiveness with evidence for the absence of effectiveness. While there is a lack of evidence supporting the effectiveness of facemasks, there is similarly a lack of evidence supporting their ineffectiveness. With the information currently available, it would be imprudent to recommend the removal of facemasks from surgery …

Here we have a preview of all the bad arguments that were used to support community masking during the pandemic. We’ve already seen that nobody can work out what it is that masks are supposed to do; if they fail at source and personal protection, then they must be retained because they help with ‘theatre discipline,’ whatever that means. They make people feel better, so not masking would be imprudent; and for this one intervention and this one intervention alone, evidentiary standards are turned on their heads. Suddenly we have to prove that masks don’t work, because otherwise – and I cannot emphasise how much I hate this intelligent-sounding but really quite idiotic maxim – “absence of evidence” is not “evidence for … absence of effectiveness.”

In a rational world, we would discontinue the use of face masks altogether, in every context. Their use persists only because they’re perceived to be a low-cost measure with few downsides, and because they make people with hygiene anxiety feel better. In fact, the past three years have shown that masks are not cheap and that they come with substantial risks. Foremost among them: We now live with the threat of enforced community masking over our heads, like a nerf Sword of Damocles, the next time politicians and public health bureaucrats work themselves up into a furore over a virus.