Open Data BCN portal publish for first time data related to air quality of the city of Barcelona. One of them is the dataset with the locations, codes and main features of the Air quality measure stations of the city of Barcelona and the other one is the Air quality of the city of Barcelona with the real-time data of O3 (tropospheric Ozone), NO2 (Nitrogen dioxide), and PM10 (suspended particles). The source of this information is the Direcció General de Qualitat Ambiental i Canvi Climàtic de la Generalitat de Catalunya, reason why you  also can find  data of all the stations located in Catalonia.