There’s something in the air: small particles can spread the Coronavirus. Peppy and well-visible when Sneezing or coughing, but also rather timid, and to the human eye, barely visible in the simple Speak.
U.S. researchers have shown that recently by laser light in an impressive way: While a man “stay healthy” (“Stay healthy”) says, glitter, green speckles against a black Background.
The speaker wears a mask, is seen no more.
The debate influenced the virus distribution
As the debate is damp, hanging out, among other things, of the volume, and the Loud, explains environmental medicine Claudia Traidl-Hoffmann from the Helmholtz Zentrum München and the Institute for environmental medicine at the Technical University of Munich.
The “th” from the English, as in “thunderstorm” (a Storm) or sibilants were wonderful for demonstrations.
In other words: “When a Infected person is standing in front of me and the thunderstorm says that there is a great risk to infect me.”
Like other seasonal Corona-, influenza or Rhino virus is also transmitted Sars-CoV-2 classic way, by droplet infection. That’s why it’s called: keep your distance. And: Mouth-Nose Protection.
Covid-19: How far the droplets fly?
But how far these droplets fly? How big is the risk of infection? And it makes a difference whether the people are in a closed room or in the fresh air and the pace at which they are are on the go?
So new, the novel Coronavirus is so fresh, and partly relied on small samples of studies and models that have been published in the past few days are related. “At the present time, the are often still speculation”, stressed Traidl-Hoffmann.
A study from China suggests, however, that the Corona-concentration inside buildings is usually higher than in public places.
Minimum distance of 1.5 metres to the small
Researchers from the Netherlands and Belgium have recently published calculations from the wind tunnel, according to the recommended 1.5-Meter distance at a faster continued sufficient movement to escape all of the droplets.
Who goes about five miles an hour in a row, should be true, therefore, five meters distance, Jogger with speed of 14.4 even around ten meters. Scientists at the Finnish Aalto University, in turn, visualized cloud of the spread of a Breath when someone coughs, for example, between super-market shelves unprotected.
However, such models are often quite theoretical in nature.
The creators of the spaces such that the back and side wind would have to be taken into account. And environmental medicine Traidl-Hoffmann advises to think before all-too-hasty reactions, which can be derived by the Individual from it.
Also, Bernhard Weigand, one of the researchers at the Institute for thermodynamics of the air and space at the University of Stuttgart, among other things, to the drop dynamics, says: “Directly behind a runner or cyclist, the flow breaks off, since particles in the air. But if you don’t drive straight Tour de France, don’t come so close.”
In addition, models are not taken into account often the behavior of drops, as the Professor makes it clear. “Very small droplets will evaporate in a fraction of a second. Great to fall very quickly and do not follow the air stream.”
A warm, windy summer could reduce Corona
With a view to possible infections 30 to 40 microns large droplets were not interesting – that’s about half as thick as a human hair. At a temperature of 20 degrees 20 to 30 seconds survived. Models, emanating from a distribution over several minutes, far be a reality.
For the evaporation, the decisive factor is the humidity in addition to temperature. The higher this is, the worse the evaporation of drops. In General the faster the evaporation, the lower the risk of infection to say: The hotter and drier.
Drafts blow in turn, the drops and boosts the evaporation.
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“The droplets dose makes the poison”
It is crucial also to where the drops of velvet virus to arrive, and how infectious you are, so Traidl-Hoffmann. On the nasal mucosa, it schnäuze you quickly. “If you inhale, you directly deep into the lungs, they are the greatest harm.”
The Professor seeks a well-known wisdom of the pharmacy: The dose makes the poison.
In a cubic meter of air could be located, for example, 1600 Pollen, you get to feel this Allergy. “How high is the concentration of virus particles in a Corona-patients around, it is so far unclear,” says the environmental physician.
It is established that the Sars-CoV-2 Virus is 160 nanometers in size – in smaller particles in the air 100 virus would be found so maybe. “How many of these virus particles are necessary to infect, is unclear and also quite crucial from the recipient and his receptivity-dependent.”
New study: The particle size of the Virus
With the help of a cascade impactor Traidl-Hoffmann and her Team now want to investigate which particle size in the air the Virus is spread.
In the device and sieves with different pore sizes are placed, the so-called bio-aerosols according to size filters. So, the scientists want to find out how high the virus concentration in the air, when an Infected person is, for example, quietly in bed, or if he is intubated.
Just medical staff be infected, because it was exposed to the virus, especially so Traidl-Hoffmann. However, this research project is still at the beginning.
Sources
- Y. Liu, Z. Ning, Y. Chen, M. Guo, Y. Liu (2020): Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospital, archived from the original on 06.05.2020: https://www.nature.com/articles/s41586-020-2271-3
- Aalto University (2020): Researchers modelling the spread of the coronavirus emphasise the importance of avoiding busy indoor spaces, retrieved on 06.05.2020: https://www.aalto.fi/en/news/researchers-modelling-the-spread-of-the-coronavirus-emphasise-the-importance-of-avoiding-busy
- B. Block, F. Malizia, T. van Druenen, T. Marchal (2020): Towards aerodynamically equivalent COVID-19 1.5 m social distancing for walking and running , archived from the original on 06.05.2020 http://www.urbanphysics.net/COVID19_Aero_Paper.pdf
- P. Anfinrud, V. Stadnytskyi, C. E., Bax, A. Bax (2020): Visualizing Speech-Generated Oral Fluid Droplets with Laser Light Scattering, retrieved on 06.05.2020: https://www.nejm.org/doi/full/10.1056/NEJMc2007800
Deutsche Presse-Agentur (dpa)
*The article “Coronavirus: How the droplet infection is spread?” is published by FitForFun. Contact with the executives here.