How effective are air filters really? And could this mean that the schools could definitely stay open in the autumn? Teachers ‘and parents’ associations urge politicians to take precautions. Scientists from Stuttgart are now stepping on the brakes.
Stuttgart – According to a study by the University of Stuttgart, the effect of mobile air filters in classrooms to protect against the corona virus is limited. In their analysis on behalf of the City of Stuttgart, the experts speak out against purchasing such devices for all schools. The study, which is available to the German Press Agency, states: “Based on the findings from the pilot project, the widespread use of air purification devices is not indicated (indicated).” In individual classrooms that have too small or too few windows, should but the use of mobile devices or the installation of stationary filters are planned.
For the study, the experts from the Institute for Building Energy, Thermotechnology and Energy Storage measured the effect of the filters at ten schools in Stuttgart for six months. They are now warning that the devices are no substitute for burst ventilation during breaks. “When using air purification devices, it should generally be noted that they are not an alternative to a change of outside air, but should only be used as a support for particle and potential virus reduction in the room.” Replace protective measures such as wearing a mask or testing to contain the spread of infection.
Teachers ‘and parents’ associations have long insisted that schools should be equipped with air purification devices. The city of Berlin in particular has a pioneering role here. Because of the risk of the more aggressive delta variant of the corona virus for unvaccinated students, the political debate had recently come to a head – there was also talk of possible new school closings. Bavaria’s Prime Minister Markus Söder (CSU) announced last week that all classrooms and daycare rooms should be equipped with filter systems in autumn.
Baden-Württemberg’s head of government Winfried Kretschmann followed suit, but in a significantly slimmed-down form. The Green politician announced on Monday a funding program of 60 million euros, half of which should be co-financed by the municipalities. The mobile devices cost between 3000 and 4000 euros. Kretschmann said that the filters were only intended as a supplement and should be used primarily in poorly ventilated rooms. In addition, they should primarily be used in grades 1 to 6, because smaller children cannot be vaccinated until further notice. In order to prevent the possible introduction of virus variants through vacation trips, there should be a mask requirement in schools in the first two weeks after the summer vacation.
The study also states that the air purification devices have “the lowest aerosol concentrations when operated with the highest volume flows”. However, the devices are then too loud and the air speeds too high for people in the room to accept them in the long term.
Basically, the scientists recommend making it possible for windows to be opened as wide as possible. “In poorly ventilated rooms, air cleaning devices are a short-term supportive measure. However, the devices are not able to remove CO2 and moisture from the room, which is why they cannot replace ventilation. ”In the medium term, it would therefore be ideal from their point of view to install stationary filter systems that are capable of doing this.
Community assembly president Steffen Jäger sees his skepticism towards mobile devices confirmed by the study. “The study by the University of Stuttgart confirms the prevailing opinion of science that window ventilation is generally preferable to mobile ventilation systems,” said Jäger. “In addition, I think it is an illusion that the school authorities could procure tens of thousands of such devices at short notice. The market will not give that up. ”He demanded a“ realistic, achievable and sensible concept that takes infection protection into account ”from the state. From his point of view, the use of mobile systems is only possible “in individual cases”. (dpa)