Very high protection against corona infection confirmed

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FFP2 masks offer extremely high protection against corona infection. However, it depends on the correct way of wearing them, as researchers from the Max Planck Institute for Dynamics and Self-Organization in Göttingen report according to a study.

If an infected and an uninfected person meet in an indoor space at a short distance, the risk of infection is a good one per mille (0.1 percent) even after 20 minutes. The prerequisite is the correct fit of the FFP2 or KN95 mask, writes the team around Institute Director Eberhard Bodenschatz in the “Proceedings” of the U.S. National Academy of Sciences (“PNAS”).

With poorly fitting FFP2 masks, on the other hand, the risk of infection in the same scenario is around four percent, the team calculates. For optimal protection, the nose clip must be shaped into a “rounded W” so that it presses laterally on the nostrils. In the case of surgical masks, a good fit is still sufficient to reduce the risk of infection to a maximum of ten percent.

The researchers calculated the risk of infection by combining diverse factors such as particle sizes, physics on exhalation, diverse mask types and risk of inhaling coronaviruses. “In daily life, the actual probability of infection is certainly ten to a hundred times smaller,” Bodenschatz is quoted as saying in a news release from the institute. That’s because the breathing air that flows out of the mask at the edges is diluted, he said.

However, the researchers had wanted to calculate the risk as conservatively as possible. “If even the greatest theoretical risk is small under these conditions, you are on the completely safe side under real conditions,” Bodenschatz says.

This contrasts with the result for encounters between two people not wearing masks: in this case, if an uninfected person stood in the breathing air of an infected person for a few minutes at a distance of three meters, he or she would be very likely to become infected, the researchers say. Bodenschatz emphasizes, “Our results show once again that mask-wearing in schools and also in general is a good idea.”