There has been little data on air pollution in Wuppertal to date. Tobias Gerbracht (19) wanted to change that - he built a measuring station with the help of a special lamp. The lamp shines on a distant reflector, which in turn sends the light to a telescope. The light travels up to two kilometers through the atmosphere. The incoming light spectrum can then be used to calculate the concentration of nitrogen oxide in the air, because every pollutant in the atmosphere absorbs light in a characteristic way. Gerbracht was thus able to prove that the nitrogen oxide content of Wuppertal's city air at times significantly exceeds the EU limit value. For his development, he received the prize for the best interdisciplinary work at Jugend forscht 2017 and the prize for a work on climate protection.