Only through the combination of mask requirements, good ventilation and a sensible test strategy can it be ensured that the schools can stay open during the Corona winter.

That is the opinion of an interdisciplinary group of professionals.

The 14 air hygienists, aerosol researchers, physicists and ventilation engineers from twelve research institutions in Germany and Austria have sent their position names to the Conference of Ministers of Education and several federal ministries.

Sascha Zoske

Journalist in the Rhein-Main-Zeitung.

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According to the scientists, wearing mouth and nose protection cannot be replaced by ventilation.

The masks should be worn during the entire class - if possible also by teachers who would have to speak loudly, which would release a lot of droplets and aerosols.

Surgical masks are the minimum standard, FFP2 masks are more effective.

The masks should completely cover the mouth and nose and fit tightly.

Better to open windows than set up an air purifier

Regularly opening the windows reduces the risk of aerosols.

The success of the ventilation can be checked by measuring the carbon dioxide concentration;

on average, the value of 1000 ppm should not be exceeded during one lesson.

Exhaust fans are the "standard that has been tried and tested for many years" for fresh air supply and aerosol reduction.

Their effect can be improved by intermittent operation, among other things.

Such fans can be retrofitted quickly and are eligible for funding.

According to the experts, mobile air purifiers can in principle be used.

However, they have the disadvantage that they do not supply fresh air to the room.

They also generate drafts and annoying noises, and the operating costs are high.

They should therefore only be set up where there are no or not enough windows that can be opened.

Link to the statement