This study focuses on fully discriminating the origins of particulates by tackling specific secondary organic aerosol (SOA) sources that are difficult to resolve using traditional datasets, especially at a city scale. This is done through the use of additional fit-for-purpose tracers in the Positive Matrix Factorization (PMF) model, which can be obtained using simpler and more targeted techniques, and the comparison of the PMF models from sites in close range but with different urban typologies.