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It has become an indisputable fact that the new coronavirus can be transmitted through droplets and aerosols. Recently, the global cluster of epidemics broke out in many places, showing the characteristics of many points, wide areas, and frequent occurrences. Therefore, epidemic prevention and control and elimination work still face very serious challenges.
In daily life, behaviors such as speaking, coughing, and sneezing are accompanied by the generation of droplets and aerosols. The droplets of infected people contain pathogens, and people who are not sick are also likely to be infected by inhaling droplets and aerosols containing pathogens.
In a report by the Nordic Energy and Environmental Research Center, the distance of droplet transmission during coughing was studied, and it was found that taking the vertical height of the human body as an example of 1.63m, in the state of no wind (wind speed of 0km/h), coughing The resulting droplets quickly settled to the ground, with a horizontal spread of no more than 1 meter.
Figure 1 Droplet transmission distance (wind speed is 0 km/h)
At the same height, when the wind speed is 4km/h (about 1 m/s), the droplets can travel 6 meters horizontally in only 5 seconds.
Figure 2 Droplet transmission distance (wind speed is 4 km/h)
Similarly, when the wind speed is 15km/h (about 4 meters/second), the droplets can travel 6 meters horizontally in only 1.6 seconds.
Figure 3 Droplet transmission distance (wind speed is 16 km/h)
These droplets spread quickly and widely in the air. After the virus in the droplets loses moisture, they will form an aerosol state and be suspended in the air, making them more infectious. Based on this, in order to prevent the spread of aerosols from person to person, it is not only necessary to isolate and block from the source, but also to find suitable disinfectants to inactivate viruses in the air, so as to obtain safer and more reliable airborne viruses. control effect.
Recently, the research team of Professor Yu Miyaoka of Tokyo University of Agriculture and Technology in Japan built a special airtight device (Figure 4) to simulate the propagation environment of aerosols in the air, and used different concentrations of slightly acidic hypochlorous acid water for atomization in the device. In the process of killing, the virus particles moving at high speed in the air are captured in real time, and then the inactivation effect of slightly acidic hypochlorous acid water on viruses is analyzed.
Figure 4 In vitro simulation device for aerosol disinfection
Among the experimental devices used in this study, (1) is a virus aerosol atomization device, (2) is a slightly acidic hypochlorous acid water atomization device, and (3) is a virus capture and detection device. The gas flow rate in the device was 35 L/min. At the same time, in order to prove that the killing effect occurred in the air rather than the virus trap, two different aerosol atomization methods were also used in this experiment to remove system interference.
Figure 5 Inactivation effect of slightly acidic hypochlorous acid water on virus aerosols
The results of this study show that when the aerosol in the air is treated with the available chlorine concentration of 300ppm and 500ppm slightly acid hypochlorous acid water, within a few seconds of the contact between the aerosol particles and the slightly acid hypochlorous acid water droplets, The virus titers were reduced by 1.16 and 1.67 orders of magnitude, respectively, and the reduction rates reached 93.1% and 97.9%, respectively. The killing effect was very significant.
Note: According to previous researches, hypochlorous acid water with low effective chlorine concentration (50-100ppm) is also effective in removing biological aerosols in the air, but the treatment time is relatively longer.
At the same time, the team has also confirmed in previous research projects that slightly acidic hypochlorous acid water can completely kill the Newcastle disease virus within 5s; , the virus-positive detection rate of oropharyngeal swabs from live poultry samples was 0.
On the whole, the slightly acidic hypochlorous acid water has a good treatment effect on the high-speed moving virus aerosol in the air, and the virus can be effectively killed within a few seconds after the droplet is in contact with the aerosol. Therefore, the use of slightly acidic hypochlorous acid water for the disinfection of indoor environments can effectively and effectively prevent the spread of viruses from person to person through aerosols, which has a very positive impact on the current epidemic prevention and control situation.
