The risk of infection is so different in different rooms
The length of stay in closed rooms is particularly decisive in the spread of the corona virus. The longer you stay in a room, the more aerosols are inhaled and thus the risk of becoming infected increases. This was shown by scientists from the TU Berlin together with the Robert Koch Institute and the Charité Berlin in a study. They investigated in which area the microscopic particles, which are mainly emitted when sneezing and coughing, but also when breathing, speaking and singing, are particularly common.
The scientists led by ventilation expert Martin Kriegel wanted to know how these aerosols are distributed in closed rooms. From this, they derived how strongly non-infected people are exposed to an infection risk, for example in schools, when visiting the hairdresser or cinema or when shopping in the supermarket. For the study, the researchers developed an infection risk model and derived a situation-dependent reproductive value, R for short. At R-1, exactly one other person is infected with the corona virus. Different situations in closed rooms were examined.
The length of stay in the room, the type of activities such as sport and speaking, and the distribution of the air flow are decisive. From this they were able to derive the R value accordingly. It was taken into account that the AHA-L rules (keep your distance, observe hygiene, wear an everyday mask and regular ventilation) were observed.
The researchers found that in an office where half of the usual employees work for eight hours, an average of eight people are infected. In a supermarket that requires a mask, on the other hand, if you spend an average of one hour shopping, only one other person will be infected with the corona virus. The risk of infection is even lower with a two-hour visit to the hairdresser with a mask, here the R value is 0.6. Even if you visit a cinema with 30 percent occupancy of the seats, the risk of contracting the coronavirus is quite low (R value 1), as is the case in a restaurant that occupies half of the possible seats with guests (R- value 2.3). The situation is different in fitness studios (50 percent occupancy without wearing a mask): Here the R value is 3.4, so more than three other people can become infected.
The scientists also see a relatively high risk of infection in secondary schools. If the alternating lessons are taught without a mask, the R value is 5.8. With a mask, however, the risk of infection is halved. Ventilation expert Kriegel says: “In offices and schools, the risk of infection is very high.”
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