The LIDAR principle for air quality and meteorol. measurements is presented, followed by different examples of vertical O3 profiles and time series obtained with a new optical layout of the EPFL-LPAS DIAL system using dual telescope detection. These data were obtained during the summer 96 field campaign in the Geneva area. Results are compared with the meso-scale Eulerian model calcns. The results provide new insight into air pollution dynamics in the Geneva area and calcns. are under way, using the model adjusted by the measurements, to optimize air pollution abatement strategies under certain atm. conditions in this part of Switzerland.