Spatial variations in nitrogen dioxide concentrations in urban Ljubljana, Slovenia

Ambient nitrogen dioxide (NO₂) concentrations are regularly measured at only two monitoring stations in the city centre of Ljubljana, and such scanty data are inadequate for drawing conclusions about spatial patterns of pollution within the city, or to decide on effective measures to further improve air quality. In order to determine the spatial distribution of NO₂ concentrations in different types of urban space in Ljubljana, two measuring campaigns throughout the city were carried out, during the summer of 2013 and during the winter of 2014. The main source of NO₂ in Ljubljana is road transport. Accordingly, three types of urban space have been identified (urban background, open space along roads, and street canyon), and their NO₂ pollution level was measured using Palmes diffusive samplers at a total of 108 measuring spots. This article analyses the results of both measuring campaigns and compares the pollution levels of different types of urban space.