Wednesday, March 04, 2020

To mask or not to mask?

Let's just clarify the usefulness of surgical masks in the coming Covid-19 epidemic.

Surgeons have worn masks since 1897 in order to avoid spraying contaminated droplets from their own airways into the open wound in front of them. The mask works by physically reducing the column of air coming from mouth and nose. The same effect will operate with someone infected with the coronavirus; they will not spray everyone in front of them so much. On the other hand, they may contaminate someone standing close behind them with their deflected exhalations, but overall, masks are useful in reducing spread from an infected person. Remember, people can be shedding viruses for up to 14 days before they begin to get symptoms, so the safe assumption is that everyone is spreading viruses.

So it is polite and thoughtful to wear a mask if there is a virus running in the population, for the sake of others. Especially if you actually have a cold or cough (although you should really try not to go out with a cold or cough).

Do masks prevent you from getting infected? A bit. They will save you if an infected droplet from sneeze, cough or speech lands on your mask, but they will not filter your air of all viruses, because most of the air will get through the gaps around your nose. They do however prevent you from touching your mouth or nose with your contaminated hands, which is an important route of entry.

One point is that if we all go and panic buy surgical masks, there can be shortages for health care staff, which is obviously not good. In fact, any piece of cloth applied to your face, from a designer cotton mask right down to a scarf, will reduce spread a bit. Remember to wash it frequently thought.

So there we go. Wear a mask, when the time comes. It's the polite and social thing to do.

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