Coronavirus: a video shows how the virus can spread in the air of a supermarket: Femme Actuelle Le MAG

Covid-19 is mainly spread through nasal secretions, postlets and droplets, through close contact with an infected patient, such as in a home or health care setting. But the virus can also be transmitted through contaminated surfaces or objects. Hence the need to apply barrier gestures: social distance from a minimum of one meter, regular hand washing, sneezing or coughing in your elbow and using a tissue only once.

Transmission of the virus could also occur through air exhaled by individuals. According to some scientists, invisible saliva projections can play an important role in the dissemination of Covid-19. But what happens when an infected person coughs or sneezes in a crowded closed space? How and for how long does the virus spread through the air? A team of Finnish scientists investigated the question and answered it on video.

Coronavirus: particles can stay in the air for a while and contaminate others

Scientists at four Finnish research organizations studied the airborne propagation of microscopic particles expelled when an infected person coughs, sneezes or chats. These airborne particles, known as "aerosols", can carry pathogens such as Covid-19. To do this, the researchers carried out independent 3D modeling. They depicted a scenario in which a person coughs in an aisle between two shelves of a supermarket, taking ventilation into account.

In the situation studied, the particles emitted by this individual form an aerosol cloud, which then propagates in the other rays before being diluted in the air. This can take up to several minutes. "A person infected with the coronavirus can cough and move away, but then leaves behind very small particles of aerosol carrying the virus. These particles could then be found in the respiratory tracts of other people nearby", explains Professor Ville Vuorinen of Aalto University.

"For a dry cough, which is a typical symptom of the current coronavirus, the particle size is generally less than 15 micrometers", they detail. The researchers say that particles of this size cannot end up on the ground, but rather move in the air currents or remain floating in the same place.

Coronavirus: the importance of barrier gestures

"The preliminary modeling results underscore the importance of our recommendations. The Finnish Institute of Health and Welfare recommends staying at home if you are not feeling well and keeping a physical distance from everything the world. The instructions also include coughing in your sleeve or in a handkerchief and ensuring good hand hygiene. ", says Jussi Sane, a specialist at the Finnish Institute of Health and Welfare.

In the press release from Aalto University, the researchers state that "Thanks to this modeling and this video, we know that the spread of a virus can slow down or even be completely stopped when mobility decreases at the 'nodal points', that is to say in the places where many people congregate such as shops, restaurants and public transportation ". Conclusion: Avoiding busy indoor spaces reduces the risk of infection through droplets when in the vicinity of other people, which is the main cause of contamination.

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