The new study found that by wearing masks and maintaining social distancing prevent new crown virus ( COVID-19 ) the effect of the past that is not so good. During the ongoing global epidemic of new coronary pneumonia ( Wuhan pneumonia , COVID-19 ), wearing masks and maintaining social distance are common prevention methods. But a new study found that although these two measures are effective, they are not enough. The understanding of droplet transmission is based on research decades ago. The scientific basis for wearing masks and maintaining social distancing to prevent droplet transmission is based on research decades ago. Recently, research teams from the Vienna University of Technology, the University of Florida , the Sorbonne University and the Massachusetts Institute of Technology have jointly developed a new droplet propagation model using fluid dynamics.
“Our understanding of droplet propagation is derived from measurements in the 1930s and 1940s ,” said Alfredo Soldati , a professor at the Institute of Fluid Mechanics and Heat Transfer at the Vienna University of Technology . “At that time, the measurement method was not as good as it is today, especially the test for small droplets, which may not be as accurate and reliable.” The past measurement method believed that when an infected person sprays droplets, the large droplets will fall to the ground due to gravity. The droplets spray straight ahead, but they evaporate quickly.
“This depiction is too simple,” Soldati said. Virus droplets entering the air will spread farther and stay longer. In fact, the situation after spraying droplets into the air is quite complicated. Soldati pointed out that although the water in the droplets has evaporated, there are still aerosol particles in the air, which may contain viruses. This allows the virus to spread several meters and stay in the air for a long time. Generally speaking, the average diameter of small droplets is 10 microns, and it takes about 15 minutes to fall to the ground. Therefore, even if you observe social distancing, you may be exposed to the virus, such as taking an elevator that an infected person has just taken. Environments with high humidity are more risky, such as conference rooms with poor ventilation.
The Vienna University of Technology stated that although wearing a mask can block large droplets and maintain social distancing is also useful, it should not give a false sense of security . Because even if you wear a mask, the distance and time that the sprayed virus travels in the air is longer than expected. The new model developed will be able to calculate the concentration of virus droplets at different times and distances.