14 July 2020 14: 20
Updated at 15h19
Mask mandatory: is the glass half-empty or half-full?
BLOG / Next timing, the physicist of the University of Montreal Normand Mousseau could hardly have hoped for better — or worse, depending on your point of view. His open letter in which he denounces the obligation to wear a mask in enclosed public places of Montreal (“Mask mandatory, science-optional”) was published in The Press, just 48 hours before the government announced that the same measure will apply to all of Quebec, from Saturday next.
Essentially, it criticizes the scientific basis on which the directors Plant has supported his decision, bases which seem to be clearly inadequate to impose the mask at all : “the scientific evidence demonstrating the usefulness of wearing a mask generalized to prevent the spread of a virus are very low, particularly in a context where this virus is not very widespread (we’re talking about, in Quebec, for example, of less than 100 new cases per day, for a population of over 8 million people) and that measures of distancing physics are in place,” he wrote.
In a debate like the one on the port of the mask where a lot of people are very on edge, either because they fear the COVID-19, like the plague, either because they don’t care, or even dispute his existence, and categorically refuse the wearing of the mask, the letter from Mr. Mousseau has caused the turmoil that could be expected. Some readers have also helped me asked what I thought of it. So, as we’ll all have to wear masks in a few days, see what it is.
First, is it true that the scientific evidence of the effectiveness of the port widespread of the mask are at this point “weak” ? We can easily find studies that find in favor of the port of the mask, it must be said — the Fédération des médecins spécialistes du Québec pointed out on Twitter in a reply to Mr. Mousseau. For example, there are studies of physics like this on the dispersion of droplets in the air, with and without a mask. And if the COVID-19 is spread in infected droplets that are projected into the air by coughing, sneezing or even just speaking, it is entirely logical to think that a mask that prevents their dispersion will slow significantly the spread of the disease.
However, between “logical implication” and “proven”, there is a good margin of science, and it is not always easy to overcome. In a review of the scientific literature published last month in The Lancet, researchers have found a whole series of work suggesting that, yes, there is reason to think that the wearing of the mask seems to indeed prevent the spread of the COVID-19. But for all sorts of reasons, they indicate that the level of certainty to this conclusion is “down” :