This book describes tropospheric ozone concentrations observed in the Sao Paulo Metropolitan Area (SPMA), Brazil, between 1996 and 2005, and different climatic patterns possibly linked to them. Ozone hourly data was used to calculate different time scale averages. Seasonal cycles were observed, with a spring maximum and an autumn minimum. Stations located in areas away from the main urban centre showed higher concentrations, somewhat linked to the predominant land use in their surroundings. In the monthly and daily analysis of ozone concentrations and atmospheric behaviour, higher ozone concentrations were related to higher solar radiation and lesser relative humidity, both resulting from the predominance of systems such as high-latitude anticyclones, the Southern Atlantic semipermanent anticyclone and Upper Level Cyclonic Vortexes from Northeastern Brazil. For months of lower ozone concentations, more intense or frequent frontal systems were observed, with higher cloudiness and increased rainfall, sometimes linked to the Southern Atlantic Convergence Zone. It was also observed that generally, less polluted months were preceded by other months with better dispesion conditions.