What actually happens when we breathe or cough? Scientists from the Department of Applied Physics at the Bauhaus University in Weimar have made visible what in reality remains hidden from the human eye – the process of air distribution during human breathing.

The experiment clearly shows how the smallest streams of air from the mouth spread in space and how pathogenic viruses can be transmitted due to this. Once again, it turns out why we should observe the “cough etiquette” developed by the World Health Organization (WHO) to protect against the coronavirus.

What happens to the air during breathing

The video of scientists shows the silhouette of a person who initially just breathes normally. In the next step, the subject coughs without protective measures, then into the arm, into the crook of the arm, and into the two most common types of masks: dust-proof (but we call them medical) and surgical respirator.

Spoiler: even with normal breathing, a large number of invisible drops of liquid can be released into space. The frames show the intensity with which exhaled fluid particles can fly forward. If the minimum distance of 1.5 meters is not respected, the particles can be inhaled by other people. Therefore, be sure to maintain a “social” distance – at least 1.5 meters.

What happens when you cough?

The man coughs in the room. A whole stream of exhaled air flows into the room along with many small drops of liquid. The particles propagate many meters in front of the subject.

1. A person coughs into an open hand.

There is a twist. Air with invisible drops now spreads in all directions. If another subject were standing in front of the man now, he would take a breath full of air and droplets from the coughing participant in the experiment.

2. The person coughs into the elbow.

The droplets are unable to spread. Only a few particles can fly forward or sideways due to the high pressure. However: the overwhelming mass of particles ends up in the cubit. It is this “cough etiquette” that is recommended by experts and scientists around the world.

3. A person coughs in a medical mask.

If the wearer coughs while wearing a dust mask, which can be bought in general stores and pharmacies, the exhaled air flies forward just as it would without protective measures. If another person were standing nearby, the mask would not give anything at all in terms of protection. In the end, of course, some (few) drops of liquid stop – but not all.

4. A person coughs into a medical surgical respirator.

Here the situation is changing. Exhaled air is severely restricted and liquid droplets remain in the mask. If some of them do fly forward, they disappear into thin air after only a few inches. But even at the same time, respirator masks do not provide 100% protection against such a “drop” infection as coronavirus.

What should be the conclusion?

The conclusion of scientists: when coughing, the mouth should be covered, but not necessarily with a mask. “The best thing to do is to use the bend of your hand, as well as keep your hands clean and not transfer possible viruses or other pathogens through physical contact or surfaces.”

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