Corona direct: drugs, no masks – the police celebrate a party with 24 people

The risk of infection varies in different rooms

The length of stay in closed rooms is especially critical in the spread of the Coronavirus. The longer you stay in the room, the more aerosols are inhaled and thus the risk of infection increases. This was shown by scientists from TU Berlin with the Robert Koch Institute and Charity Berlin in a study. They investigated an area where the microscopic particles, which are mainly emitted when sneezing and coughing, as well as when breathing, speaking and singing, are particularly common.

Scientists led by ventilation expert Martin Kriegel wanted to know how these aerosols were distributed in closed rooms. From this, they deduced how uninfected people are at risk of infection, for example in schools, when visiting a hairdresser, at the cinema, or when shopping in the supermarket. For the study, researchers developed a model of infection risk and extracted a condition-related reproductive value, R for short. In R-1, exactly another person is infected with the Coronavirus. The different positions in the closed rooms were examined.

Hence, the crucial duration of the stay in the room, the type of activities such as sports, speaking, and the airflow distribution. From this they were able to derive the value of R accordingly. The AHA-L rules were taken into account (keep distance, maintain hygiene, wear a daily mask and ventilate regularly).

They found that in an office where half of the regular staff worked for eight hours, an average of eight people were infected. In a supermarket that requires a mask, on the other hand, if you spend an average of one hour shopping, only one person will be infected with the Coronavirus. The risk of infection is lower with a 2-hour visit to the hairdresser with a mask, here the R-value is 0.6. Even if you visit a cinema with an occupancy rate of 30 percent of the seats, the risk of contracting the Coronavirus is very low (R1 value), as is the case in a restaurant that occupies half the seats possible with guests (R 2.3 value). In fitness studios, the situation is different (50% occupancy without a mask): here the R-value is 3.4, so more than three other people could be injured.

Scientists also see a relatively high risk of infection in high school. If alternative lessons are taught without a mask, then the value of R is 5.8. However, by using the mask, the risk of infection is reduced by half. “The risk of infection in offices and schools is very high,” says ventilation expert Kriegel.