‘Opening the window against corona’


Good ventilation helps to reduce the aerosols in the air. We don’t know if you get corona from these small droplets, but it should still be advice from the RIVM. Professor Daniel Bonn argued this in EenVandaag on Sunday 28 June. The WHO now also seems to be advocating for better airing.

When someone talks, sneezes, or coughs, millions of aerosols are released, droplets smaller than 10 micrometers. In a poorly ventilated area such as an elevator, they can still hang in the air 10-15 minutes later. In theory, you could still become infected with the coronavirus, says physicist Daniël Bonn in a broadcast of EenVandaag. A danger that needs more attention. “I would rather not take an elevator in a hospital that has also had corona patients.”

Contamination uncertain

It is not certain whether people do indeed become infected with the coronavirus if they inhale those aerosols or small droplets. Not even if there are virus particles in those aerosols. It is so little that contagiousness is by no means certain. Reason for the RIVM not to advise any measures on this. It may only be different for singing and sports, which is still being investigated.

The larger drops are proven to be contagious. These fall down pretty quickly. The 1.5-meter distance has been introduced to ensure that we do not cough or breathe larger drops of coronavirus to each other. That indeed appears to be effective.

Take the stairs

Bonn is researching the smaller droplets in the air and ventilation systems. There are now many questions about air treatment. Which system protects well against contamination by corona? What can you pay attention to, as a consumer? We don’t know everything yet, so there is still work to be done.

What is certain is that the aerosols can remain in the air for a long time and that ventilating helps to reduce them. Bonn: “If you open a window, the number of drops is halved after 30 seconds. Much faster than in a poorly ventilated room.” His advice: let’s ventilate well just to be sure. Take the stairs instead of the elevator. When visiting a cafe, preferably sit outside on the terrace. Open doors and windows so that any virus particles are diluted as quickly as possible.


The WHO may also open the windows. 200 experts had called on the World Health Organization to do so in a letter. Good ventilation is important because the coronavirus can linger on tiny droplets in the air, according to experts. But is that enough virus to make you sick? The WHO is not yet convinced of the evidence that this is the case, but it now recognizes that there is some evidence for it. It is, therefore, possible that advice will be given to ventilate well.

Anyway – the big drops are definitely contagious, everyone agrees on that. Keeping a distance, therefore, remains the best advice against airborne contamination.

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