Preliminary work confirmed the important contribution of regional scale processes on pollutant concns. obsd. at local scales. For Grenoble, France, the model domain for simulations discussed, was selected considering the topog., urban area distribution, boundary conditions, and possible constraints in terms of computing time. The nesting technique used involved calcns. over a larger domain which contained the smaller domain. Two of the most important components of these models are the chem. mechanism and transport algorithm. The field campaign objective was to develop the necessary database to use for initial model conditions. Lidar and differential optical absorption spectroscopy observations provided essential inputs to develop the appropriate models. Results showed that even in very complex topog. areas, atm. models can be used to assess air pollution abatement strategy.