Regular and correct ventilation is important during the coronavirus pandemic. While this isn't a problem when it's hot outside, on cold days it's important to ensure that rooms do not get too cold when ventilating or opening windows regularly.

CO2 measuring devices can help, explains the Central Association of German Electrical and Information Technology Trades. The systems are recommended for rooms where many people are present, such as classrooms, offices, restaurants or shops.

With displays in yellow and red, the measuring devices warn if there is a high level of carbon dioxide in the air. This is exhaled air, which can contain potentially pathogenic aerosols.

The devices can be used to determine when it's time to ventilate. For complete exchange of air in the room, the window should be opened wide for several minutes. Regular airing is more effective and energy-efficient than tilted windows.

If ventilating rooms intensively on a regular basis is not possible, the association recommends installing a ventilation system with a special air filter in addition to the CO2 sensors. As soon as the CO2 measuring devices detect that the carbon dioxide in the air is rising above a critical value, they switch on the ventilation system. This extracts used air from the room, while letting fresh air in at the same time.

 - dpa