This chapter describes the physicochemical mechanisms that formulate the air quality over the Mediterranean region and the resulted impacts on the regional climate. At first, a detailed description of the teleconnections and regional flow patterns that dominate in the region is provided. The dominant flow patterns during the different seasons of the year determine the transport paths of air pollutants and aerosols towards and across the study area. The analysis on the characteristics of the air pollution transport is separated for the different parts of the Mediterranean region (eastern, western and entire), since the sources of pollutants that reach at different points in the region vary, while specific pollutant transport paths may influence the wider Mediterranean area. Similarities and differences in patterns are discussed. The air quality over the region, as recorded from black/organic carbon, ozone, aerosol observations, is extensively discussed, along with seasonal variabilities and annual trends. There is particular discussion on the suspension of naturally-produced aerosols and especially desert dust particles in the region and their spatial influence on the aerosol levels. At the last part of the chapter, the major impacts of the transport and transformation processes (natural and anthropogenic pollutants) on the regional climate are discussed. The impacts of aerosols are distinguished in direct (the impacts on radiation budget), health (the amounts of inhaled particles and impacts on health) and indirect effects (impacts on clouds and precipitation), are discussed on qualitative and quantitative way.