Scientists have investigated the importance of ventilation in preventing the spread of the coronavirus. Their research shows that good ventilation, both mechanical and natural, is crucial to reduce the risk of contamination.
At the moment, there are still a lot of questions about how we can best prevent the new coronavirus from spreading. However, this information is crucial to prevent a further major outbreak in the future.
It is especially important to know which situations are the most risky to transfer the virus to someone else. Is 1.5 meters away enough? How much more risky is meeting someone inside in the same room compared to meeting outside?
Small moisture droplets
Physicists Daniel Bonn, Stefan Kooij and Cees van Rijn of the Institute of Physics of the University of Amsterdam, together with medical researchers Aernout Somsen (Cardiology Centers Netherlands) and Reinout Bem (Amsterdam UMC), have used laser light techniques to see how long small droplets of water in a space in the air. The results of their study were published on the authoritative website The Lancet.
They used healthy subjects in their study and asked them to speak out loud and cough. Then they looked at the released droplets with laser light. Both during speaking and coughing, they noticed that large amounts of small droplets, between 1 and 10 micrometers, were released. Coughing also releases larger drops of one millimeter in diameter. However, due to their weight, they fall to the ground within a second and therefore do not pose a danger of infecting anyone.
The smaller droplets can remain in the air for several minutes before falling to the ground. The study found that after someone has coughed in an area that is not ventilated, it takes about five minutes for the number of small droplets in the air to halve. These droplets thus pose a risk to the transmission of the coronavirus.
The experiment was then repeated in areas that are better ventilated. A mechanical ventilation system ensured that half of the droplets disappeared from the air after two and a half minutes. Natural ventilation, such as opening windows and a door, gives even better results. The droplets were found to be halved in the air after thirty seconds, ten times faster than without ventilation.
The results of the research are very important in order to be able to take measures in the future to prevent the spread of the coronavirus. For example, keeping a distance of one and a half meters in closed spaces such as public transport appears to be insufficient to prevent new infections. There too, one must look to ensure more ventilation. That is why the Dutch railway company NS is already looking at how it can apply the guidelines of the scientists in its trains.
The researchers recommend that authorities also pay attention to good ventilation in residential care centers. In this way, a new outbreak could also be avoided there.