Is wearing a mask outdoors really useful? The scientific consensus which is gradually emerging leans more towards the “no” in most cases. For a very simple reason: the wind, even light, disperses very quickly droplets and aerosols which carry the virus. Moreover, no open-label cluster has been identified to date. But the absence of proof never constitutes proof of the absence, one might rightly argue.
A recent Japanese study of 100 positive cases estimated that the risk of contracting the virus is 18.7 times lower when outdoors than indoors. If the precision of this figure is puzzling, this work says two things: that this risk is (very) low, but also that it is not completely zero. No one can rule out the hypothesis that it is possible to be infected on the terrace of a café, in the queue of a museum, in a crowded market or a bustling city center. Provided obviously that