We made our way to Mariakliniken, a hospital situated in the heart of Stockholm, where we met up with Daniel Schlesinger, former PhD student at the Department of Environmental Science and current Air Quality Officer, Post-Doc Jean Froment, Stefano Papazian, Head of the National Facility for Exposomics at ScilifeLab, and Master’s student Foteini Raptopoulou. Our mission was to visit the air quality monitoring station of SLB-analys, a unit within the Environmental Administration in Stockholm City, on behalf of the East Sweden Air Quality Management Association (Östra Sveriges Luftvårdsförbund), perched on the rooftop of the building. After navigating a dimly lit corridor and ascending a metal staircase, we arrived at three mushroom-shaped passive samplers arranged in the form of a crown. Jean had inserted a single silicone foam-based disc into each of the sampler housings, designed to collect gases and particles from the air.