Coronavirus aerosols: Infectious Mini-droplets in the air
More and more research work suggest that aerosols play in the air a greater role in the spread of the novel Coronavirus SARS-CoV-2, as was previously thought. An expert on aerosols, summarizes the current state of knowledge.
Large droplets generated during coughing, Sneezing, Talking and Breathing, to sink quickly to the ground. However, corona virus can also stay in Mini-droplets longer in the air. These so-called aerosols, is increasingly a focus of research.
Aerosols win in the research, the importance of
In the study of Corona infection because scientists are increasingly called aerosols under the magnifying glass. Thus, a mixture of solid or liquid suspended will be able to contain be referred in the air, the particles of Sars-CoV-2.
Lubrication infections seem to play no special role
“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), compared to the German press Agency (dpa). 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. WDa needs to be done a lot of research work,“ he said. “But it is being researched more and more in that direction.” Long is not clear, therefore, how infectious the dried aerosols.
Assessment is currently difficult to
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.”
Self-test with a candle
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.
Like the Wind, aerosols spread
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 winds of 4 and 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.
Height and ventilation of rooms appear to play a role
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 fresh air, aerosols are diluted quickly
In the Chinese city of Wuhan, Researchers have searched for a study 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.
How long aerosols remain in the air?
As long as there is a potential threat, researchers have examined the end 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.”
What protection face masks make?
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. (vb; Source: Marco Krefting, dpa)
Also read: Coronavirus infection risk in indoor spaces 19 times higher than outside.
Authors and source of information
This Text meets the requirements of the medical literature, medical guidelines, as well as current studies and was examined by doctors and Medical scientists.