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WHO recognizes was the rubber dissemination is mad the rubber center for new crown virus main infection way Zhongshan University Aerosol Science Research Center: Mouthpiece being closed influence virus anti- efficiency

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WHO recognizes was the rubber dissemination is mad the rubber center for new crown virus main infection way Zhongshan University Aerosol Science Research Center: Mouthpiece being closed influence virus anti- efficiency

14 May, 2021

WHO recognizes was the rubber dissemination is mad the rubber center for new crown virus main infection way Zhongshan University Aerosol Science Research Center: Mouthpiece being closed influence virus anti- efficiency

14 May, 2021

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WHO recognizes was the rubber dissemination is mad the rubber center for new crown virus main infection way Zhongshan University Aerosol Science Research Center: Mouthpiece being closed influence virus anti- efficiency

WHO recently officially recognized the spread of aerosol (also known as aerosols) as the main route of transmission of COVID-19, and the US CDC also followed up and revised the epidemic prevention guidelines. Given the severe local epidemic situation, Director Chia C. Wang of the Aerosol Science Research Center at National Sun Yat-sen University urged the public more vigilant. She emphasized that the latest foreign research found that the tightness of masks greatly affects the efficiency of blocking virus aerosols. For example, when the mask gap increases by 1%, its blocking efficiency for aerosol particles smaller than 2.5 microns will drop by 50%.

Aerosols are tiny droplets or particulate matter suspended in the air. When people talk, sing, cough, or even breathe, they release many aerosols below 5 microns in size. When a COVID-19 infected person performs these exhalation actions, the virus can be released into the environment through the exhalation gel.

Director Professor Chia C. Wang pointed out that as the new crown epidemic continues to rage worldwide, various latest research evidence has been published so far, including field air sampling measurement and analysis, epidemiological statistics, clinical and animal experiments, and aerodynamic simulations. On April 30 this year, the spread of aerosol was officially recognized as the main route of transmission of COVID-19. Since the outbreak of the epidemic, an endless stream of super-spreader incidents has pointed to the main route of aerosol transmission. In New Zealand, investigators found that aerosol transmission was the main cause of cluster infections in epidemic prevention hotels. There have also been many cases in foreign countries where the medical staff still have prevalent infections even when social distancing and wearing masks were observed. The incident was also attributed to the spread of aerosol. Recently, there have been more outbreaks of group infections in China, which has led to a substantial increase in the risk of community transmission.

Director Chia C. Wang of the Aerosol Science Research Center at National Sun Yat-sen University said that when asymptomatic patients do not wear a mask or any protective measures, the aerosol transmission will become the main route of infection. Studies have pointed out that a very high proportion of COVID-19 patients are asymptomatic or have only mild symptoms at the time of diagnosis, and asymptomatic infections cause more than 50% of COVID-19 infections. Faced with a severe domestic epidemic, she especially reminded the public to be vigilant and pay particular attention to the tightness of the mask when wearing it, "must wear well and fully."

"In the past, people mistakenly thought that aerosol transmission would only occur at long distances, but ignored that the concentration of aerosol particles actually increases as the distance from the source of infection is closer, and the probability of infection is higher," said Director Chia C. Wang. Recent foreign studies have pointed out that masks of different materials, such as N95, medical masks, and cotton masks, effectively filter aerosol containing the SARS-CoV-2 virus. The results show that N95 has the highest aerosol filtration efficiency, but masks of other materials also have certain filtration efficiency and protection power. In addition, the research team of the Max Planck Institute in Germany tested the efficiency of filtering aerosols of different particle sizes on the tightness of the mask and found that when the surface gap of the mask increases by 1%, the resulting filtration efficiency is halved for filtering aerosol particles smaller than 2.5 microns. When the mask gap increases to 2%, the efficiency of filtering aerosol particles smaller than 2.5 microns is only 1/7 times that when fully sealed. Director Chia C. Wang reminds the public that in addition to the existing epidemic prevention measures, pay more attention to the tightness of wearing masks, install air filtration and purification devices equipped with high-efficiency filters, install ultraviolet (UV C) into air disinfection devices, and avoid crowds.

【Appendix】

Director Chia C. Wang published an editorial at the beginning of the outbreak in February 2020 to remind the people of Taiwan that the new coronavirus SARS-CoV-2 can spread in the air in the form of extremely fine aerosol particles or droplets. She also published the same message in a special article in the international authoritative journal 'Science' in May of 2020. Unlike droplets with larger particles that are dominated by gravity and quickly sink to the ground within a few seconds, the aerosol can be suspended in the air for several hours or even longer under the influence of air drag. For example, for a droplet with a particle size of 100 microns, it takes only 5 seconds to drop from a height of 1.5 meters (equivalent to the average height of a normal adult human nose) to the ground. Furthermore, for an aerosol with a particle size of only 1 micron, it took 12.2 hours to descend to the ground from the same height. Although the infectivity of the virus will gradually decrease over time, these virus-containing aerosols, if they are breathed into the respiratory tract or lungs by others while maintaining their infectivity, may cause the virus to replicate in the new host lead to the onset of infection.

National Sun Yat-sen University Aerosol Science Research Center is the only research center with aerosol as the theme in Asia. In recent years, the center has been actively engaged in the research of PM2.5 preventive medicine and aerosol biomedicine, exploring the causes and solutions of PM2.5 induced diseases such as respiratory and pulmonary diseases, cardiovascular diseases, and children's brain growth retardation to lay an important foundation for PM2.5 preventive medicine. Moreover, biological aerosols, such as viruses and bacteria, are also one of the key research directions of the Aerosol Science Research Center Sun Yat-sen University, aiming to innovate medical treatment, improve human life quality, and promote health the well-being of the whole people.

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