Abstract: Background: Air quality in cities is an important health factor. Several studies have shown that poor outdoor air quality is related to a wide range of discomforts and health problems. Cities in France are used to measuring air quality through a small number of fixed air monitoring stations provided by reference local organizations such as ATMO and virtual modelling. An alternative is to densify the air sensor network, thus dispatching the air monitoring micro - stations in the territory to obtain a finer mesh and a better view of air quality at a regional or local level. Methods: A network of thirty - four air monitoring micro - stations was installed in Annecy agglomeration community in France. These air monitoring micro - stations were lightweight and mobile to be easily hung on poles or other city infrastructures. Air quality data was retrieved and compared in order to detect any event or phenomena that would affect air quality and that would not be detected by local fixed air monitoring ATMO stations, which are reference stations. The air micro - station network granted permission to install a fine mesh in the city, in relation to air quality. Data was compared between each air monitoring micro - station in order to highlight local phenomenon (when only a few numbers of air micro - stations detected it) or global phenomenon (when every air micro - station detected it). Results & conclusions: This study highlighted and brought an understanding of the impact of several events and habits of the air quality in the agglomeration community. For example, the impact of a local fire in the town hall or the impact of traffic near a school.