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Mask on and okay?
No: adequate ventilation is very important
like the right mask
A Swiss calculation model and a Spanish one show that you can still get infected without fresh air if you wear a mask in rooms.
The mask alone is not enough. Classrooms and other rooms should be well ventilated.
The pediatrician had been wearing a mask in the hospital for months. And he had internalized how to deal with it properly. He only took them off during breaks inside to eat and drink. And he quickly fell ill with Covid-19. He had severely restricted his leisure life, in recent weeks he had hardly had contact with other people. Several co-workers also tested positive.
Was it enough not to wear the mask in the break room? Probably. However, in most cases of infection, it is not clear where the transmission took place. It would be particularly important to know now where, despite the masks, there is still infection with Sars Cov-2. Can’t expect help from contact trackers. Whether in St. Gallen, Lucerne, Basel or Aargau, in all the cantons it is said that they do not really have the ability to provide information.
Cantons only list general transmission locations. In Basel-Stadt in October, a known or suspected source of infection could only be determined in 27 percent of new infections. Of these, 25 percent were infected in the family, 6 percent when meeting friends or relatives, 24 percent in their free time, 20 percent at work, and 7 percent on the plane or while was traveling.
Some fall asleep with a false sense of security
The danger is that one feels in a false sense of security when wearing a mask. Because community masks do not provide sufficient protection in all situations, especially those that are not certified.
This is indicated by a model for calculating Covid-19 aerosol transmission situations, developed by researchers from José Luis Jiménez’s team from the University of Colorado in America. The model has been tested by other scientists. In each case, the researchers assumed that infected people spoke loudly, that everyone kept their distance, and that no one was immune. In terms of virus payload, they also assumed a single size. Therefore, the model does not take into account that the factors influencing an airborne infection may also be distributed differently.
In the long term, the effect is greatly diminished
But under the alleged circumstances, the results show an astonishingly low long-term effect of community masks. The Spanish newspaper El País described the calculated scenarios.
Private: Six people stay in a room for four hours, one person is contagious. Without a mask or ventilation, everyone else becomes infected. According to the calculation, only one person will not be infected with a mask in the same situation. Infections only decrease significantly when ventilation is on (or regularly ventilated) and the length of stay is reduced to two hours. So, on average, less than one person is infected.
School: There are 24 students in a classroom for two hours, the teacher is infected. Without a mask or ventilation, 12 students are infected. If everyone in the room wears a mask, there are still five infected schoolchildren. Only when the room is also ventilated (by opening the window regularly or by ventilating it) and after an hour it is also fully ventilated, the infection rate also drops below 1 depending on the model.
Swiss aerosol expert Michael Riediker says: “When I see people walking around with single or double layer cotton towels in front of their faces, the calculation can be absolutely correct. I get similar results with my model. “(Download to calculate the probability of infection in rooms: https://scoeh.ch/en/tools-en/)
The federal government looks for good ventilation ideas
Ernest Weingartner, a particle expert at the Northwestern Swiss University of Applied Sciences, notes that there are also good products for community masks. «Test certificates for this should be studied when buying. But even shabby or ill-fitting masks help contain the spread of the virus. “
However, if an infected person wearing a community mask spends hours in a poorly ventilated room, the air is still enriched with aerosols containing viruses. Weingartner says:
«Correct ventilation is
a neuralgic point “.
His team at the Swiss Northwestern University of Applied Sciences now wants to investigate on behalf of the federal government how intelligent ventilation could be installed in critical places, for example in an elevator.
