The Federal Environment Agency of Germany(UBA) collects official data on air pollution in Germany and makes it publicly available. This data contains information on the amount of air pollutants and dust in the atmosphere from anthropogenic (man-made) and natural sources.
daily
hourly to daily
5647 Stations 24406 Sensors
Data provided by: Umweltbundesamt (UBA) Deutschland under GeoNutzV (http://www.geodatenzentrum.de/docpdf/geonutzv.pdf)
https://www.umweltbundesamt.de/daten/luft/luftdaten/stationen