COVID-19 Day 25: A Mask from the Past

Promoting mask-wearing during the 1918 Spanish Flu Pandemic • US Library of Congress


A little over 100 years before COVID-19, the world faced an even deadlier pandemic, the infamous 1918 Spanish Flu. Between 20–40 million died worldwide, including about 675,000 Americans. Like today, institutions and health agencies struggled to find the most effective means of combating the unseen germ.

Cloth face masks were one of the strategies used in various cities, some going so far as making the public wear them by law. Unfortunately health authorities cited many inconsistencies in how they were worn, the materials used, and how disciplined the population was in wearing them. Written reports complained of scofflaws, putting away their masks when law-enforcement was not present. Because of these difficulties, the benefits of widespread mask-wearing was inconclusive.

After the pandemic abated in 1920, a laboratory experiment lead by Dr. Kellog at the California State Board of Health, set about to determine the effectiveness of cloth masks. Their conclusion: “Masks have not been proved efficient enough to warrant compulsory application for the checking of epidemics…”

In the hundred years since this experiment, there have been numerous studies proving the effectiveness of modern masks to trap virus particles and protect the wearer from infection. I found it odd, therefore that this study would indicate otherwise. Deep diving this experiment I noted some issues with applying their findings to today’s pandemic.

The Kellog study tested the effectiveness of gauze masks, which were the medical standard back in 1918. Specifically they tested different layers of fabric, and different weaves of cotton gauze from coarse, medium and “buttercloth” which what we call today “buttermuslin”; a cheesecloth like fabric used to in dairy making. They found that additional layers of cotton gauze made more effective filters. But at 9 layers, there was too much breathing resistance to be worn. It’s unreasonable and inaccurate to use this experiment as a proxy for all cloth masks, as the authors of a CIDRAP article imply.

Cloth masks are obviously imperfect in both intrinsic filtering effectiveness and in how people misuse them. In light of today’s pandemic, we’re trying a multitude of tactics including masks, such as social distancing, hand-washing, sneezing into elbows, etc., all in an effort to reduce the risk to spreading infection. No one single tactic can reduce all risk to 0.

Even Kellog’s study demonstrated that the thinnest gauze was more effective than no mask at all. This is the key point that they seem to disregard in recommending against the general use of masks. If we learn anything from history, it should be this: Don’t let the perfect become the enemy of the good [enough].



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