## 2 Related Works  
Previous concepts for conducting subject studies during a pandemic are usually very short, undetailed and only outline some aspects that are necessary for the safe conduct of the studies. A concept of the TU Dresden [2] formulates only rough conditions of participation, hygiene and distance rules. Furthermore, it only mentions the disinfection and ventilation measures. Aerosols and droplet cores, in contrast to droplets, follow the movement of indoor air. Their movement in enclosed spaces is also dependent on heat sources, ventilation and the movement of persons and objects in the room [3]. Aerosols and droplet cores are able to fully distribute in a room [4], so that infections can occur despite social distancing [5]. The concentration of aerosols and droplet cores in the air depends on a number of factors: the number of people present, their activities and total time in the room as well as the room's size and ventilation. [6].A study by [PERSON] [4] demonstrates that the concentration of infectious particles increases the longer an infected person is in an unventilated room. The number of infectious particles increases significantly more in a smaller room than in a larger room. At the same time, the number of indented particles loaded by viruses increases exponentially. Through ventilation, the concentration of infectious particles can be significantly reduced. Here the air change rate, i.e., the time period in which the room air is exchanged for fresh air [7], plays a role. Even a rate of 2.8 air changes per hour leads to a significantly lower number of infectious particles in the room and decreases further with a higher air change rate. The number of indented particles loaded with viruses also decreases significantly through an increased rate of air change and avoids the exponential growth found in an unventilated room. Studies in vehicles require special measures. A study by [PERSON] [8] for simulations of droplet and aerosol spread in a room shows that conversations between two people sitting in close proximity increase the risk of infection. The study also shows that they can't pick up drops directly from the air if they do not face each other while speaking. Another study by [PERSON] [9] simulates the distribution of aerosols and droplet cores in the air of an unventilated vehicle. It established that aerosols and droplet cores are distributed almost homogeneously in the entire interior air of the vehicle very quickly. Due to the low interior volume of vehicles, the concentration of aerosols and droplet cores increases faster than indoors, which can lead to an aerogenic infection even after a short exposure. Due to the geometric properties of the interior of a vehicle, it is usually not possible to maintain a recommended distance of at least 1.5 m between the driver and the passenger [10]. Based on trigonometric calculations, this distance can only be achieved in a diagonal seating arrangement if there are no more than two persons in the vehicle [11]. To prevent viral infections in vehicles, it is recommended to attach partitions that can fully prevent both direct contact and droplet infections while limiting aerogenic infections [12]. Such protective walls can be installed, either as a barrier between the front and rear part of the vehicle, or between the driver and the passenger. A study by [PERSON] [9] shows the distribution of aerosols and droplet cores in a vehicle three seconds after the driver coughs with a slightly open window on the driver's side and built-in partition wall. It is clear from this that a partition successfully avoids a homogeneous distribution of the particles, as they remain mostly in the front area of the vehicle. Most aerosols and droplet cores that enter the rear of the vehicle flow with the air below the protective wall. A slightly open window can also allow many particles to escape from the vehicle. Similar to as in stationary venues, ventilation of the vehicle interior can prevent aerogenic infections [9].