We consider the problem of real-time reconstruction of urban air pollution maps. The task is challenging due to the heterogeneous sources of available data, the scarcity of direct measurements, the presence of noise, and the large surfaces that need to be considered. In this work, we introduce different reconstruction methods based on posing the problem on city graphs. Our strategies can be classified as fully data-driven, physics-driven, or hybrid, and we combine them with super-learning models. The performance of the methods is tested in the case of the inner city of Paris, France.
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Figure 6. Pollution map for the ensemble model at $ 8 $am on March 1st, 2023. Based on the predictions on the node, one can linearly extrapolate pollution values even outside of the graph edges. Note that the fine variations in pollutant concentration (between 45 and 55 $ \mu \text{g/m}^3 $) seem to trace the main circulation axes
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Cropped Google Map screenshot of Paris and the
Raw data from Google Maps: the image contains the city with its main landmarks, and some streets are highlighted with one of the four colors corresponding to traffic
The metric graph downloaded from Open Street Maps, with the edges that never had Google Traffic activation in red, and the edges remaining after filtration in yellow
Correlation between stations as a function of the distance. The vertical slashed red line marks the maximal separation between vertex and station (165m) which still lays in the zone of high correlation
Root mean square error on tested stations for the different proposed methods
Pollution map for the ensemble model at