With the new school year in progress, certain decisions are being made in terms of the COVID pandemic. Read more to see where Germany stands regarding air filters in schools.

The KMK rejects the widespread use of air filters in schools, although two studies have come to the conclusion This would largely eliminate the danger of corona from aerosols in classrooms. Experts estimate 3,000 euros for an effective device – too much, as NRW Education Minister Yvonne Gebauer (FDP) admitted this week with remarkable openness. Hessen’s Minister of Education Alexander Lorz shifts the responsibility onto the school boards.


Alexander Lorz (CDU), Minister of Education and Cultural Affairs of the state of Hessen sees the regular airing of classrooms during the cold season as a very effective method against the spread of the coronavirus.

Experts like the Team of HealthMask judged it anyway rather critically if children sat in stuffy, overheated rooms, he said in Wiesbaden with a view of the school start after the autumn vacations on Monday. According to hygienists, ventilation is the best way to prevent infections. With the recommended airing every 20 minutes, the room temperature would only drop by two to three degrees for a short time. The child and youth medical profession would say quite clearly that this is harmless. “You can withstand that – and as soon as the windows are closed again, the temperature will also rise rapidly again,” Lorz explained.


On behalf of the KMK, the German Federal Environmental Agency this week issued recommendations for ventilation in winter that require open windows in class every 20 minutes.

Lorz: On-air filters in classrooms, there is “no conclusive opinion” in science


According to Lorz, there is still no conclusive opinion in science on the question of whether special ventilation equipment should be used for classrooms. First studies would give indications that certain techniques could be helpful under certain circumstances, so Lorz. “But experts also say that this cannot replace ventilation, but only supplement it,” the minister emphasized.

Correct is: There are two studies, both of which independently conclude that the use of air filters in classrooms is highly recommended. Atmosphere researchers at the Goethe University in Frankfurt had determined that air purifiers of filter class HEPA (H13) can reduce the aerosol concentration in a classroom by 90 percent in half an hour.

Previously, scientists from the Institute of Fluid Mechanics and Aerodynamics at the University of the Federal Armed Forces in Munich had examined a room air cleaner whose filter combination separates even very small aerosol particles from the room air by 99.995 percent. In an 80 square meter room, the aerosol concentration could be halved in six minutes. Because the aerosols are filtered out, the devices do not become virus spinners, the researchers stated. They expressly recommend room air cleaners of filter class HEPA (H14) for schools – and they expressly warn that ventilation alone does not reliably reduce the potential pollution load. “The possibility of reducing the viral load in the room by regular free ventilation is overestimated,” the study says.

KMK misrepresented the results of a hearing on air filters in schools


The Standing Conference of the Ministers of Education and Cultural Affairs in Germany had invited the head of the Munich study, Prof. Dr. Christian J. Kähler, to its expert hearing on September 23. However, his findings presented there were ignored, even though he was the only one in the group who had conducted research on classroom ventilation. In a press release issued by the KMK after the meeting, it was stated with regard to the air filters – recognizably wrong: “The scientists agreed that the use of such devices was basically not necessary. Kähler contradicted: “I do not share the opinion stated in the press release.

Nevertheless, the ministers of education and cultural affairs are sticking to this. NRW Education Minister Yvonne Gebauer told WDR this week that equipping all schools with air filters was too expensive. Experts estimate that the purchase of the equipment would cost around 100 euros per pupil. By way of comparison, the state paid 300 euros per child for the “Corona Bonus”, which was paid out to families in Germany.

“The discussion has now been going on for about four to five weeks. Since then, we have been inundated with offers from corresponding companies,” says Lorz now (it is true that the study by the University of the Bundeswehr was already published at the beginning of August – more than two months ago). This, he says, needs to be looked at very closely. “We need valid findings in order to then be able to make sensible investments if necessary”. But the Minister of Education already knows: “In the end, not every classroom needs a ventilation unit, but primarily the classrooms in which shock and cross-ventilation do not work well. The acquisition is then a matter for the school authorities. Whether and in what form the state government will support them in this matter has not yet been conclusively determined.


Bavaria has already set up an investment program of 50 million euros to promote the purchase of air filters in schools and daycare centers. Lorz’s party friend, Christian Baldauf, the top candidate for the CDU in Rhineland-Palatinate, accuses the state government there – and thus also the Minister of Education and KMK President Stefanie Hubig (SPD) – of having long since been able to make appropriate preparations for school operations in autumn and winter. “Ventilation alone is not enough everywhere,” said Baldauf. He called for “planning security to be created for the schools and for the suitability of possible devices to be tested immediately.

It is true: Prof. Christian Drosten, the chief virologist at Berlin’s Charité hospital, had already warned in May of the danger of infection via corona-contaminated aerosols in classrooms.

Is Germany doing the right thing with these decisions and should the other EU members follow its example or not? What is your take on this? Feel free to leave your comment below.