Abstract A methodology based on CFD-RANS simulations (WA CFD-RANS, Weighted Averaged Computational Fluid Dynamic-Reynolds–Averaged Navier–Stokes simulations) which includes appropriate modifications, has been applied to compute the annual, seasonal, and hourly average concentration of NO 2 and NO X throughout the city of Pamplona (Spain) at pedestrian level during 2016. The results have been evaluated using measurements provided both by the city's network of air quality monitoring stations and by a network of mobile microsensors carried around by cyclists during their daily commutes, obtaining a maximum relative error lower than 30% when computing NO 2 annual average concentrations. The model has taken into account the actual city layout in three dimensions, as well as the traffic emissions. The resulting air pollution maps provided information critical for studying the traffic-related health effects of NO 2 and their associated external costs in the city of Pamplona and the spatial representativeness of the current network of air quality monitoring stations (it has not been carried out for an entire city to date). The developed methodology can be applied to similar cities, providing useful information for the decision-makers. Graphical abstract Unlabelled Image Highlights • CFD modelling of annual average NO 2 and NO X maps throughout an entire city • Evaluation of modelled annual average concentrations with network station data • Comparison against average data recorded by mobile microsensors • Computation of spatial representativeness of monitoring stations of the city network • Assessment of health externalities arising from NO 2 in the whole city [ABSTRACT FROM AUTHOR]