A City, If You Can Keep It: Masks — What are they good for?

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A Winters Express op-ed column

Masks … do they work? If you ask some people, you’ll get an unequivocal “no” and a look as if you’re stupid. If you ask others, you’ll get an unequivocal “yes” and be accused of being anti-science for even broaching the question. Both are correct, and both are wrong. The real answer is, it depends. Peak effectiveness of masks lies in encounters between people closer than six feet that last between 15 and 50 minutes. I will call this the zone of real-world benefit. Encounters below the zone don’t give you a viral load, and encounters above the zone you get a viral load regardless. Let’s start with some basic things we can hopefully all agree on: 1. Masks are a tool, tools must be used properly and in the right situation to be effective. You wouldn’t frame a house with a wrench. 2. Knowing the limitations of your tool is important – No face covering, be it made of cloth, a surgical mask, or an N95 mask, is 100 percent effective. 3. Masks, as used in the past year, do not provide protection to the wearer, but are supposed to cut down on the ability of infected persons to transmit the virus. So, the important question is how effective is a non-sealed mask at reducing the spread of the virus? To answer this, I engaged some Google-fu. The Journal of the American Medical Association has an article reporting results of 11 studies on the effects of wearing masks as they relate to the spread of COVID. Results are mixed and not presented with any standard metric. We have per-capita reduction in new cases, percent change in new daily cases, percent change in diagnosis, and change to the risk of infection. All related, all similar, none can be directly compared or combined for a larger sample size. There were articles last year measuring how well cloth masks reduced airflow but I prefer to use practical examples rather than theoretical effectiveness. This creates an average that accounts for the wide range of masks, proper and improper wear of them, and measures how things are in the real world not how they could be in a lab. The USS Theodore Roosevelt in Guam reported that mask wearing reduced risk of infection by 70 percent with a confidence interval of 95 percent. If mask wearing on the Teddy Roosevelt reduced spread by 70 percent, we can say that masks, as worn by people, provide up to 70 percent protection FROM the wearer. Dividing the 15-minute exposure time to infection by the 30 percent remaining risk, we get 50 minutes. At 50 minutes of close contact with masks, your risk of infection is equal to 15 minutes of close contact without masks. Masks work. However, if it takes 15 minutes of close contact to become infected for the average encounter (i.e. no one is spitting or sneezing directly into your mouth or face), then a mask is essentially a placebo for interactions shorter than 15 minutes. Masks are pointless. Supposedly, the Delta variant requires five minutes of exposure in close contact. If we apply that information to the math above, we get a zone of real-world benefit of 5 – 16:40. So do masks work? Yes and no. It depends on the situation. Use the right tool for the right situation. Masks probably didn’t have much impact on the alpha variant spread because most interactions are brief and do not fall between 15-50 minutes. How often are you within six feet of someone for no less than 15 minutes but no more than 50? That would explain why nearly all the spread was from private gatherings and there was no dramatic change in the new daily cases graph after mask guidance was issued. Maybe some of you should apologize to their neighbors they accused of being anti science last year because it seems they were right. By the same math, mask may be more effective against the delta variant precisely because more encounters are brief and fall within the delta variant mask zone of real-world benefit. Evidence of this may already be on the Yolo County COVID Dashboard, where the daily new cases from the latest “spike” seems to have peaked already. We should have a better picture in a week. Maybe those who thought mask wearing was ineffective last year should re-evaluate their position given a changed operational environment. So what can we take from this? Masks in a store (particularly while in the checkout line) are probably more effective than last year. Masks on kids in school, probably don’t do anything. Masks while driving alone in a car are still pointless. Regardless of your feelings on masks, you can take comfort in the fact that the New York Times reported earlier this year that “there is not a single documented COVID infection anywhere in the world from casual outdoor interactions, such as walking past someone on a street or eating at a nearby table.” This would seem to be anecdotally supported by the lack of local infections attributed to our parks and restaurants, outdoors or indoors. I will caveat this all by saying these timelines are a rule of thumb and should only be applied to unvaccinated people. As of yet, there is no documented evidence that a vaccinated person with a breakthrough case has actually infected anyone, merely hedged vague speculation about “rare instances” and detected viral amounts. Be nicer to your neighbors, people. When you think no one is looking, many of you are pretty nasty about folks who don’t agree with you. We all still have to live with each other once normal returns.

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