2020-03-20T11: 21 + 0300
Experts talked about the proper ventilation of rooms with COVID-19
The authors recommend turning on the ventilation system two hours before the start of the working day and not turning it off immediately after it ends. It’s better to generally maintain ventilation 24/7 with reduced ventilation to remove particles of the virus from the building when people are absent, experts say.
“Our document considers the risk of transmission of airborne infection through small particles – less than 5 micrometers, which can remain in the air for several hours and can be transported over long distances,” the words of one of the authors of the recommendations, chairman of the Scientific REHVA Technical Committee, Professor Jarek Kurnitski of Tallinn University of Technology – These small particles form when coughing and talking and do not disappear from the air as quickly as ie large droplets, which settle and dry up. This mechanism means that the increase in ventilation is useful for removing large amounts of particles. “
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The authors note that the risk of infection increases in crowded and poorly ventilated rooms. The particle size of the coronavirus is 80-160 nanometers, and they remain active under normal conditions for up to 3 hours in indoor air and up to 2-3 days on internal surfaces and objects.
The drafters of the document pay particular attention to the ventilation of toilets, where a flush containing small drops forms when flushing. “Therefore, it’s important to flush with a closed toilet lid,” says Kournitsky.
In addition, in order to avoid fecal-oral transmission of the toilet exhaust ventilation systems in areas of outbreak, COVID-19 should operate 24/7, and maintenance engineers should regularly check the negative air pressure in the systems.
In buildings without artificial ventilation, it is recommended to open windows for active ventilation for 15 minutes before starting work or during a shift of personnel. But you should not open the windows in the toilets where ventilation works, as this can lead to a reverse flow of air from the toilet to other rooms.
Another recommendation is not to use the air recirculation mode, because viral particles, passing through the return channels of centralized ventilation units, can re-enter the building. During an outbreak, the recirculation flaps must be closed through the control system or manually.
If possible, decentralized systems using local recirculation, such as fan coils, should also be disabled. In rotary heat exchangers of such systems, virus particles settle on the return air side of the heat exchanger, after which they can be returned to the system when the heat exchanger turns to the supply air side.
The recommendations also provide examples of actions that are devoid of practical meaning. For example, keeping the room temperature high in the hope that it will protect against the virus. There is no need to create high humidity. SARS-CoV-2 virus is resistant to environmental changes and is susceptible only to very high relative humidity above 80 percent and temperatures above 30 degrees Celsius, which are unacceptable in work or public premises. Therefore, heating or cooling systems do not need any adjustment.
There is also no need to replace the external air filters of the ventilation system, which in this particular context are not sources of pollution, and in special cleaning of the interior ventilation ducts.
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