The "Votre Air" project: development of a modelling tool to assess the real atmospheric exposure in Paris

International audienceTraffic generates about 60% of the Paris nitrogen dioxide and particles emissions, and the levels of these pollutants are a major concern, in particular nearby the road traffic. Therefore, the realistic characterization of the population exposure draws special attention from the concerned actors. Nowadays, high resolution modelling tools like Urban'Air well reproduce the spatial distribution of atmospheric pollutants concentrations at the city scale. One limitation of these new modelling tools is that they are most of the time provided with "standard temporal profiles" of emissions data (weekly and monthly profiles), instead of real-time traffic data. Moreover, the pollution measured at the monitoring stations is not generally taken into account in the computations. The "Votre Air" project's aim was to develop a numerical tool to provide realistic and real-time estimation of the air quality at the scale over Paris Center. In this paper, we especially detail how the real-time concentration observations are assimilated in order to better reproduce the chemical state of the atmosphere. The results are illustrated with nitrogen dioxide