Open the window, even in winter

Keeping your distance, frequently washing your hands, wearing a mouth mask - these corona measures have been in place since the spring of 2020. But at the start of the special school year 2020-21, the VITO experts on indoor air quality insisted on adding the following advice: ventilate the classroom. And, by extension, all rooms where several people come together for a long time, even if those present can respect the safety distance and/or if partitions, e.g. made of Plexiglas, have been installed. Research had shown in the meantime that the coronavirus is also spread through the air, in microscopic aerosols, in which it can survive for up to 16 hours. Someone with corona is most contagious in the initial phase of the infection, when he or she does not even show any symptoms yet, and can emit up to one million virus particles per minute. Good ventilation can reduce the concentration of these particles in the air. 

Ventilation and airing of an enclosed space is also very important for other harmful substances in the air. In new buildings, an adapted ventilation system is present, but not in older buildings. Especially where there is good insulation, polluted air accumulates. In buildings without a mechanical ventilation system, one must therefore ventilate manually, in other words, open the window. Ideally, fresh air is supplied constantly, for example via a tipping window, and the windows are opened wide in between lessons or meetings. Even in winter. 

A good indicator of the quality of indoor air is the CO2 content. We breathe this gas out and it is not harmful in itself. But if there is too much of it in a room, the people present will become sleepy and perform less. Moreover, CO2 is linked to the presence of other pollutants. Measuring the CO2 content in a room therefore provides a good indication of how "fresh" and thus healthy the air is. 

The VITO research into factors that influence indoor air quality is of international top level. Hence, it is not surprising that VITO experts are part of the task force of the Agency for Care & Health and the Departments of Environment and of Education for the development of guidelines, instruments and advice to limit the coronary risk. Our experts have also given training to e.g. school prevention advisors on the best ways to ventilate. By informing the general public about this important measure through the press, VITO has also contributed to containing the corona crisis. 

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