Urban populations are nowadays overexposed to extreme heat and pollution episodes, degrading their life quality and affecting their health. CoolPath project aims to provide communities and residents with knowledge and recommendations for identifying, quantifying, and reducing their exposure to overheating and pollution risks, in particular by proposing alternative pedestrian itineraries in urban areas. The aim of the proposed work is, on the one hand, to enhance knowledge of the spatial practices and lifestyles of residents in "real-life" situations. On the other hand, it will deepen our understanding of people's response and adaptation to overheating and pollution, depending on the frequency and the severity of their exposures. New models, adapted to rapid changes in physical and physiological variables over time, at different spatial scales and for different environments, will emerge from this work. To achieve the project's objective, a reproducible, multi-scale and multi-physics methodology will be implemented. This interdisciplinary methodology, combining human and social sciences, physiology and urban physics, will be based on interviews, modeling and field measurements. The results will highlight new interdisciplinary indicators of exposure and adapted discomfort thresholds, making it possible to better assess the vulnerability of different population profiles on different urban itineraries and scales ranging from the pedestrian to the city, via the building and the neighborhood. Promoting an interdisciplinary approach, this project involves academic and applied research centers, specialized in the urban environment, an air quality monitoring association, the local authority of Nantes and the French national agency of health.