“Why do we have more cases than anyone if everyone wears a mask?” That is the question that focuses a large part of the debates on coronavirus and that a group of researchers from the Polytechnic University of Catalonia has tried to answer to explain the figures of the second wave of COVID-19 that is hitting the country. The bottom line: it is often not used properly.

He study, carried out by the Department of Physics of Computational Biology and Systems (BIOCOMSC) of the UPC, has analyzed the use of the mask of 3,100 residents of Barcelona and has concluded that conspicuous by its absence in terraces and parks by spending time with family and friends.

To reach this result, this work, led by biophysicist Daniel López Codina, has studied the use of the mask in the street, supermarkets, parks and terraces between September 2 and 9 in five districts of the city of Barcelona. This approach has allowed researchers to analyze the behavior of citizens in open and closed places in the presence of acquaintances and strangers.

Field work has concluded that just 2% of citizens use it in the terrace of bars and restaurants when they are in the presence of family and friends. Of the 913 people analyzed in this environment, only 17 were wearing it. Apparently, the population chooses to directly remove the mask all the time they are at the table, instead of doing it only at the time of consumption.

And the percentage of those who use it in meetings in parks where more than two people congregate to chat is not much higher, since stays at 8%, despite being, in principle, mandatory.

The situation is very different in supermarkets, in a closed space with unknown people, where the use of the mask goes up to 94%, ahead of street use, which remains at 71%.