Fighting increasing air pollution in cities in a concentrated manner requires an extensive amount of data. For the first time, as part of a pilot project in Nuremberg, an innovative method has been developed to enable the analysis of traffic flows and, subsequently, air quality, by using anonymised mobile network data. The project is a collaboration between sustainability experts South Pole Group, Telefónica NEXT, the data analysis expert Teralytics and the city of Nuremberg. Supported by the EU programme Low Carbon City Lab (LoCaL) under the Climate-KIC, the new methodology will be further developed in a follow-up project.