The Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) activity consists of a series of 4 airborne campaigns held in Romania (September 2014, August 2015, May–June 2016) and Germany (April 2016). These campaigns were supported by ESA in the framework of the preparation of future spaceborne missions and focused on studying air quality in urban areas (Bucharest, Berlin) and polluted rural areas (the Jiu Valley in Romania, where several large power plants are located). Different airborne platforms (balloons,Unmanned Aerial Vehicle (UAV), ultralight and more traditional aircraft) carried remote sensing and in-situ instruments and were operated in synergy with ground-based instruments. The campaign dataset is thus interesting not only from a geophysical perspective but also in its information contents regarding the instrument characterization aspect. The AROMAT Special Issue is dedicated to the findings related to the AROMAT activity and open to all submissions within this scope.