Covid, are outdoor masks really useful?

THE mask. One of the most powerful symbols of this pandemic, no longer a simple measure of public hygiene, but a fundamental accessory of the pandemic bon ton. Hated by those who would like to reopen, loved by those who consider closures and cautions wiser. Custom phenomena aside, on closer inspection the debate on the real usefulness of masks has never ended even among the experts: there are those who consider useless, worse harmful, the obligation to wear them outdoors, where the risk of contagion in the case of airborne viruses it is by definition very limited; and those who consider it an important measure, if not to limit the infections directly, at least to educate the population to take the necessary care.