Scientific research shows that the main foci of infection are in confined spaces. What precautions should be taken - tells InoPressa.
Summer came, it became warmer, and again the question arose about the use of air conditioning during a pandemic. Especially since enclosed spaces appear to be particularly conducive to the spread of Sars-CoV-2, as has already been observed with other coronaviruses, such as Sras.
Thus, a study conducted in China showed that of the 318 cluster outbreaks of coronavirus infection detected in 120 cities, only one occurred in the open air, that is, it is assumed that the joint use of the internal space poses a serious risk of infection.
Many cases confirm the hypothesis that in a limited space, airflow can contribute to the spread of the virus. The virus can be transmitted not only through the large droplets that we secrete when we sneeze, but also by spraying the smallest particles that we emit when we speak or simply breathe. They are more volatile and able to travel long distances.
Today, the subject of debate is the transmission of Sars-CoV-2 over the air. According to The New York Times, at the beginning of July, 239 scientists in an open letter called on the World Health Organization to change their position on this issue to recognize the possibility of transmission of the virus through the smallest particles in the air. So far, WHO has argued that such evidence is insufficient.
In a document released on June 22, the European Center for Disease Prevention and Control (ECDC) recalls that although the risk is limited, “indoors, the airflow generated by air conditioning can spread the droplets that infected people excrete over longer distances” ... and that “these ventilation / air conditioning systems can play an additional role in reducing the transmission of the virus by increasing the rate of air renewal”.
Thus, such infection chains require prudence: the health authorities, as well as specialists in this sector made several recommendations on the use of air conditioners and fans.
What safety measures should be followed
Namely, whether at home or in the office, to refresh the air, it is recommended to “regularly ventilate by opening the sashes or windows wide open for at least 10-15 minutes twice a day”. It is recommended to continue ventilation also during periods of unoccupied buildings.
The personal fans of the house do not cause any concern. On the other hand, in small collective spaces it is not recommended to use a fan when several people are present, because they help to spread the smallest particles, mixing the air.
Regarding individual home air conditioning systems, we can say that “most of them have standard, rather coarse filters that do not trap bacteria or viruses,” explains Christelle Molle, president of the strategic committee for refrigeration and air conditioning Uniclima, a union of thermal industries. hydraulic and refrigeration industry. Therefore, it is necessary to remember the need for regular ventilation.
There are several options for collective air conditioning systems, as Christelle Molle explains: “Tall buildings that are over 30 meters in height have diffusers placed on suspended ceilings that suck in or blow the air in, and the current recommendation is to adjust them completely for fresh air supply.
How virus particles behave in public transport
There is a major advantage in airplanes: the use - as in medical institutions - of more expensive HEPA filters (high efficiency particle retention), they are effective against coronaviruses like Sars-CoV-2. In the cabin, the air often changes, blown out from top to bottom towards the feet of passengers. “Air circulation and filtration level are optimal.
In trains, everything depends on the model, but in high-speed trains there are systems that allow you to supply fresh air (except when the train passes through the tunnel. In the subway, diffusers are often placed on the ceiling in the middle of the train, and suction is done from the side. Thus, logically, it is better not to cling to the glass so as not to be at the end of the air flow circulation.
In all cases, the health authorities recall that wearing a confined space wearing a mask can limit the release of infectious drops.