New corona study: Without a mask, even three meters is not enough

Next March, the World Health Organization (WHO) will have declared the COVID-19 disease a pandemic for the second time. Since then, the masks have also been our daily companions: While these were hardly present in public at the beginning of the corona outbreak to protect against self and third-party infections, they have been an integral part of public space since summer 2020 at the latest.

The question of how effectively the mask requirement helps against the coronavirus was particularly discussed at the beginning. Even the renowned Charité virologist Christian Drosten saw in April 2020 little valid data per mask, but then quickly changed his attitude. One new study by the Max Planck Institute for Dynamics and Self-Organization in Göttingen has now checked how helpful masks are in particularly critical everyday situations, for example in – again very crowded – local public transport. The researchers around institute director Eberhard Bodenschatz concentrated on the solutions commonly used today, i.e. FFP2 and surgical mask.

In the flow laboratory it was shown that maskless people can become infected after less than five minutes, even if they are three meters away from an infected person in the air they breathe. This is especially true for a high viral load. Virus-rich particles had previously fallen to the ground. “Nevertheless, in our study, we found an enormous risk of infection even at a distance of three meters if you meet infected people with a high viral load, as occurs with the predominant delta variant of the SARS-CoV-2 virus, for a few minutes and does not wear a mask, “says Bodenschatz.

On the other hand, if both infected and healthy people wear well-fitting FFP2 masks or surgical masks, the risk of infection is significantly reduced – especially with FFP2. There, the maximum risk of infection after 20 minutes is barely more than a per mille, even at the shortest possible distance. With a mask, however, it depends a lot on how it fits. The edges and thus the cheek and nose area are problematic here. Accordingly, it would make sense for people to seek advice on how masks can be adapted – this is common with masks for occupational safety. “A mask can be perfectly adapted to the shape of the face if you bend its metal bracket into a rounded W before putting it on,” says Bodenschatz.

But despite the fact that masks are not infrequently worn incorrectly: They still reduce the risk of infection, “because the air that flows out of the mask at the edges is diluted so that you do not get all of the unfiltered air you breathe,” according to the researchers.

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