With background concentrations having reached phytotoxic levels, ozone (O3) has become a key agent in climate change. For risk assessment, the O3 flux-based approach relies on dose-response functions. However, the assessment of effective O3 flux leading to adverse effects forms a main knowledge gap, with a view to O3 dose modeling. The main objective in this project is to link the spatiotemporal development of injury in foliage with the cellular responses. Using a phytotron facility at the EEF, France, foliage of micropropagated hybrid poplars exposed to O3 is being sampled sequentially, with a view to integrative ecophysiological, biochemical, molecular and structural analyses. As expected results, the several plant responses to ozone stress should be disentangled and related to the corresponding effective O3 dose, thus shedding light into the black box of detoxification processes. This project is being performed in collaboration with the INRA-Lorraine University (co-PIs: Yves Jolivet1, Pierre Vollenweider2, Team: Dany Afif1, Mireille Cabané1, Anthony Gandin1, Didier Le Thiec1, Marcus Schaub2, Marie Noëlle Vaultier1; 1: UMR 1137 Ecology and Forest Ecophysiology (EEF), Lorraine University‐INRA, 2: WSL).