In the study of Corona Infection, scientists are increasingly called aerosols under the magnifying glass. Thus, a mixture of solid or liquid suspended particles is referred to – like particles of Sars-CoV-2 – in the air.
“We are pretty sure that aerosols are one of the ways that Covid-19 spread,” said the former President of the International society for aerosols in medicine, Gerhard Scheuch, in Gemünden (Wohra), the German press Agency. Lubrication infections about played less of a role.
There are many questions that are still open, so Scheuch – for example, how the Virus is ride while you Speak, or what role temperature plays. “There’s a lot of research work needs to be done,” he said. “But it is being researched more and more in that direction.” Long is not clear, therefore, how infectious the dried aerosols.
Transfer to the air is unlikely
According to the Robert Koch Institute (RKI), the Transmission of the novel Virus, mainly through droplets produced during coughing and Sneezing, and when Compared with the mucous membranes are included.
Aerosols are defined as droplet nuclei smaller than five microns – but could also contribute, “even if a final evaluation at the present time is difficult.”
There are already studies that deal with the dissemination of droplets and aerosols in the air. However, the to part different results come.
So a Team of Christian Kähler by the Institute of fluid mechanics and aerodynamics at the Universität der Bundeswehr in Munich with a singer, has made experiments, and comes to the conclusion that the air while Singing only added to 0.5 meters in front of the mouth in the movement – regardless how loud the sound was.
As a tip-it-yourself test, the researchers advise, to stand in front of a burning candle, and to look to flicker when the flame starts, if you approach it when you Speak.
The scientists Talib Dbouk and Dimitris Drikakis, in turn, have calculated how far the saliva drops spread with a slight cough: without Wind is not more than two meters, but in the case of winds from four to 15 kilometres per hour, also six meters.
Although the concentration and size of drops to take, but perhaps a distance of two meters is not enough. Researchers from the Washington analyzed the infection within a Choir, and suspected that the Transfer was due to a distance of two meters.
However, Kähler makes it clear that, in addition to the distance, whether each of the hygiene rules were complied with, or, for example, shaken hands, and chairs were crazy.
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Danger from poor ventilation
Other aspects that can have an influence on the routes of infection are about the height of the room and the ventilation. So Kähler advises, for example, it should be increased “on the one hand, the air exchange rate in times of a pandemic, significantly, on the other hand, should be in an ideal room ventilation, the air from below through the floor and flat on the ceiling are filtered off with suction”.
In the Chinese city of Wuhan researcher for a study looking for in hospitals after the Sars-CoV-2-the genetic material in aerosols. The amount was about rooms in ventilated patients is very low, in toilet areas, however, higher. The fresh air was not detectable, except in two areas, which are prone to Overcrowding.
Also, Kähler says in Free, there was a risk hardly. You breathe out about a pint of air, which is quickly diluted. Dangerous it will be if it comes about because of a brass band in the Background, closer and louder speaks. But then that is again a question of distance.
Aerosols can be hours infectious
As long as there is a potential threat, researchers have examined already: another Team from the USA has been measured with laser light, the life time of small droplets in the air produced when Speaking. Thus, they disappear in a closed environment with a stationary air after eight to 14 minutes.
In conclusion, it is said, “that there is a significant probability that to Speak normally created in limited environments, Transmission of viruses in the air”. According to Scheuch, the leading company for Bio-Inhalation, could keep aerosols in closed spaces, even over hours, and can be infectious.
A push of breath containing 1000 particles. “Outside, the dilution is strong, inside it accumulates.
Masks protect other people
Remedy of the mouth-nose is to create protection. However, you have to know that the so-called Community-masks, particles may not be able to stop with a diameter of up to two micro-meters almost at all, what has shown Kählers Team is impressive, with video recordings.
Nevertheless, the simple masks had a significant effect, says the Professor: “they offer resistance to flow. Rather than particles the far outside of the blow, keep you close to the head.”
Tickler goes even one step further: Because the Coronavirus is only around 0.1 to 0.14 microns in size, not enough time, the so-called FFP-masks. “Which are for larger bacteria. Such small particles are difficult to filter.” Particulate filters were a better fit. But this is yet to be explored.
Sources
- Robert-Koch-Institute: SARS-CoV-2 plug-in a letter to the Coronavirus-disease-2019 (COVID-19) Stand: 29.5.2020, last accessed on 03.06.2020 https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Steckbrief.html#doc13776792bodyText1
- Dbouka T, Drikakisb D (2020): On coughing and airborne droplet transmission to humans, Physics of Fluids 32, 053310 (2020); https://doi.org/10.1063/5.0011960
- Hamner L, Dubbel P, Capron I, et al. High SARS-CoV-2 Attack Rate Following Exposure at a Choir Practice — Skagit County, Washington, March 2020. MMWR Morb Mortal Wkly Rep 2020;69:606-610. DOI: http://dx.doi.org/10.15585/mmwr.mm6919e6external icon.
- Valentyn Stadnytskyi, Christina E. Bax, Adriaan Bax, Philip Anfinrud: The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission, Proceedings of the National Academy of Sciences, Jun 2020, 117 (22) 11875-11877; DOI: 10.1073/pnas.2006874117
- Liu, Y., Ning, Z., Chen, Y. et al. Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospital. Nature (2020). https://doi.org/10.1038/s41586-020-2271-3
- Christian J. Kähler, Rainer Hain: Music-making during the pandemic – what the science advises?, last https://www.unibw.de/lrt7/musizieren_waehrend_der_pandemie.pdf archived from the original on 03.06.2020
- Christian J. Kähler, Rainer Hain: flow analysenzur SARS-CoV-2 protective mask debate, last accessed on 03.06.2020 https://www.unibw.de/lrt7/bericht_atemschutzmaske_unibw_lrt7_06_04_2020.pdf
Deutsche Presse-Agentur (dpa)
*The contribution of “Transfer & contagion: What is the role of aerosols in the Corona-infection play?” is published by FitForFun. Contact with the executives here.