Fact Check FFP2 masks outdoors - useful or nonsense?

Berlin · Some wear a mask outdoors as a precaution against the corona virus. What is mandatory in stores and public transport, is conspicuous in parks and in the forest. Where does this still make sense?

 Experts consider a brief encounter with people in the open air without a mask to be harmless. Photo: Kira Hofmann/dpa-central image/dpa

Experts consider a brief encounter with people in the open air without a mask to be harmless. Photo: Kira Hofmann/dpa-central image/dpa

Foto: dpa/Kira Hofmann

When the sun shines and the temperatures climb, it drives people out of the house. Some wear their FFP2 masks to protect against the corona virus outdoors, even when they are out and about on wide-open streets or in parks.

Yet in most cases it is not even prescribed there. Does it still make sense?

OPINION: If you really want to protect yourself from corona, you must wear an FFP2 mask outdoors.

EVALUATION: Not proven.

FACTS: Nationwide, either plain OP or particle-filtering FFP2 masks must be worn on public transportation and in stores. The former primarily protect the person in front of them, while the latter additionally protect the wearers themselves.

Experts have long agreed that the risk of corona infection is much higher indoors than outdoors. Nevertheless, some people still put on their FFP2 masks over their nose and mouth.

The reason for this is probably the concern of getting caught in a so-called aerosol cloud. This is formed by exhaling in front of the mouth and can contain coronaviruses in infected persons. When people talk to each other, these aerosols are virtually blown into the face of the person they are talking to. While the viruses can collect in unventilated rooms, the exhaled air is quickly diluted and carried away outdoors, according to the Society for Aerosol Research (GAeF) in Cologne.

Gerhard Scheuch, former president of the International Society for Aerosols in Medicine, considers a brief encounter with people in the fresh air to be harmless. The amount of viruses that one might pick up in passing is not sufficient for an infection, the advisor to the European Medicines Agency EMA recently told Deutschlandfunk Kultur. "Jogging, running, hiking, walking, I consider that absolutely harmless.“

The GAeF also gives the all-clear in its position paper: "Outdoors, there are virtually no infections caused by aerosol particles." However, caution should be exercised in groups where minimum distances are not maintained and/or masks are not worn - for example, during prolonged conversations.

So far, the Robert Koch Institute (RKI) considers people who stand together with an infected person for longer than 15 minutes and at a distance of less than 1.5 meters, even outdoors without any protection, as contact persons with a "higher risk of infection."

On the other hand, wearing a mouth-to-nose covering for too long may well be counterproductive: because the moist exhaled air reduces the effectiveness of FFP2 masks. The GAeF warns that over time the material loses its electrical charge. The German Federal Institute for Drugs and Medical Devices (BfArM) writes: "A soaked/wet mask should be removed and changed.“

According to the Fraunhofer Institute for Industrial Mathematics in Kaiserslautern, there is also a risk of a so-called infection bridge between the wearer and the environment: if the material is moist, droplets could also be thrown from the outer surface of the mask into the environment, for example by coughing or sneezing, even with FFP models.

In principle, FFP2 masks are not intended for reuse from the manufacturer's point of view. However, according to experts at Münster University of Applied Sciences, who have been studying these models for months, masks that have been soaked by breathing air can be reprocessed up to five times - by air-drying them for at least a week.

Original text: Sebastian Fischer. Translation: Mareike Graepel

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