Over the course of the corona pandemic, a considerable reduction in road traffic has occurred and, as a result, nitrogen dioxide (NO2) emissions have fallen sharply. Since the end of the first lockdown in mid-April 2020, significant increases have already been recorded. Looking back to the year 2019, the annual average limit value for NO2 of 40 µg/m³ air was exceeded at around 20 percent of the measuring stations in Germany which are located close to traffic – despite the fact that diesel driving bans were already in force and environmental zones had been established. In comparison, in 2018 this figure was still 42 percent of the stations. The Fraunhofer IST has extensive experience in the development of surfaces which, when equipped with photocatalytic activity, can contribute to the reduction of air pollutants. Particularly in urban environments, large built-up areas are available for this purpose. In collaboration with the Ostfalia University of Applied Sciences in Wolfenbüttel, a study was therefore initiated within the framework of a master's thesis with the aim of applying numerical simulation to determine the degradation potential of photocatalytically equipped surfaces for nitrogen oxide reduction. For this purpose, the model of a real street canyon on the premises of the Fraunhofer IST was selected, as, firstly, the pollutants are poorly removed here under certain wind conditions and, secondly, sufficient surfaces are available which can potentially be equipped with photocatalytic properties.