To define urban morphology parameters, which could explain the spatial variability of particles concentration in Parisian street. Using GIS analysis to study what urban morphology indexes affect the spatial distribution of particle concentration at local scale. OBJECTIVES Particle is one of the most important megacities' air pollution problems, with public health issues. To assess personal exposure in Paris, we made few measurements of particles concentrations by foot and by bike. The results show that particles concentration and size distribution are spatially highly variable due to different emissions and air mass movements. At the scale of the city, street geometry (orientation, width…), the built-up environment (density, color, materials…) and the green spaces also strongly affect the spatial distribution of pollutant concentrations. sara.