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Researchers in Finland have released a chilling video that shows how coronavirus droplets can spread in indoor spaces.
Experts from Aalto University worked with the Finnish Meteorological Institute, VTT Technical Research Center of Finland and the University of Helsinki to investigate the airborne transmission and spread of coronavirus in indoor spaces. Aalto University researchers say that, amid the easing of lockdown restrictions in many parts of the world, the video underlines the ongoing risks posed by COVID-19.
The 3D video simulation shows how droplets of different sizes travel in an indoor airflow over a four-minute period. The simulation shows the largest drops sinking to the ground within a few minutes, whereas the smaller drops dry out and remain in the air as aerosol particles. These can travel with the airflow for several minutes or even hours, the researchers explain in the video.
“When a person speaks, cough or sneezes, droplets are generated from their respiratory tract, and these can carry pathogens such as coronaviruses,” the researchers say in a statement accompanying the video.
Researchers involved in the project have published the first pre-print version of their paper on the Arxiv.org repository. The research has also been submitted for peer review.
“Our simulations show that virtually all droplets of less than 50 micrometres – and thus the majority of those produced when coughing – dry up as particles before they reach the floor and then linger around as carried by the indoor airflows,” said Aalto University assistant professor and project coordinator Ville Vuorinen in the statement. “We consider it possible that these particles contain enough virus pathogens to cause infection.”
As part of the same project, the researchers released a video earlier this year that modeled the potential spread of coronavirus in a supermarket.
Experts acknowledge that, while the risk of infection from a single shopping trip is relatively low, the probability of infection accumulates with regular exposure over the course of several weeks.
In the paper, researchers studied infection spikes where a large number of people were infected by a single pre-symptomatic infectious person.
“In the modeling, we examined the effect of the length of time spent in the space, the total number of people and the number of those coughing,” explained Vuorinen. “One person per square meter, as is common in bars, just simply talking, can create a particle cloud sufficient for infecting others nearby.”
In a separate study, scientists recently tracked the “alarming” spread of coronavirus in a South Korean call center.
“A symptomatic person working in an open office can create concentrations in the surrounding space ranging, on average, from 10 to 500 aerosol particles per cubic meter,” Vuorinen added. “If 100 aerosol particles per cubic meter are taken as the risk limit for exposure, people may therefore have exposure in times ranging from a few minutes to as long as several hours.”
As of Wednesday afternoon, over 5.63 million coronavirus cases have been diagnosed worldwide, with at least 1.68 million of them in the U.S., according to data from Johns Hopkins University. The disease has accounted for at least 352,235 deaths around the world, including at least 99,264 in the U.S.
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