To avoid the spread of coronavirus indoors, enclosed spaces should be immediately stoßgelüftet (briefly but completely ventilated) after every cough or sneeze, according to experts from the Federal Environment Agency (Umweltbundesamt).
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The Commission on Indoor Air Quality (Kommission Innenraumlufthygiene) at the Federal Environment Agency also recommends that schools should “use fully opened windows to completely ventilate” classrooms in every break between lessons, and at least after every 45 minutes of teaching.
Keeping windows tilted open over a longer period of time, on the other hand, is not enough to sufficiently ventilate heavily occupied rooms, they said.
Fresh air is necessary regardless of whether other protective measures such as social distancing, hygiene precautions and face coverings are in place, said the Commission in a statement to DPA.
If “individuals show symptoms such as repeated sneezing or coughing”, the affected room should be “immediately ventilated”, the advice states.
This applies not only to classrooms, but also to offices and apartments.
‘Significantly reduce’ the risk
Rooms used for sports should be ventilated significantly more often – the Commission recommends at least five times an hour.
When there are lots of people within a room at the same time, for example at a family gathering, experts recommend that the room be ventilated throughout.
These recommendations should help to “significantly reduce” the risk of becoming infected with COVID-19, according to their statement.
Scientists have discovered that one of the ways that the virus can spread is through so-called aerosol droplets in the air – or tiny particles that are produced when we breathe, cough, speak and sneeze.
Consistent ventilation can significantly reduce the risk of infection, but it cannot eliminate the risk altogether, read the statement.
Social distancing measures in a school in Hessen, Wiesbaden. Photo: Arne Dedert/DPA
Ventilation systems should be set up to ensure that they bring fresh air into a room without recycling any used air – air-circulation systems are therefore not advised.
Experts do not consider portable air purifiers to be a suitable substitute for ventilation either – at best they serve only as a supplement to proper ventilation.
According to their recommendations, so-called “CO2 meters” could offer a rough indication as to whether a room needs to be ventilated.
A CO2 concentration of up to 1000 ppm – ie. parts per million parts – indicates “under normal conditions a hygienically adequate level of air exchange”.
Translated by Eve Bennett