This study investigates the sources and pathways of microplastics in urban environments, focusing on atmospheric fallout as a potential vector. Microplastics, defined as particles smaller than 5 mm, are collected and analyzed from two sites: an urban area and a sub-urban area. The results show that fibers, primarily synthetic, account for almost all the microplastics collected. The atmospheric fallout of microplastics ranges from 2 to 355 particles/m²/day, with higher fluxes observed in urban areas. Chemical characterization reveals that 29% of the fibers are made of synthetic materials or a mixture of natural and synthetic materials. Extrapolation of the collected fibers suggests that between 3 and 10 tons of synthetic fibers are deposited annually in the Parisian agglomeration. The study highlights the importance of considering atmospheric fallout as a source of microplastics and calls for further research to understand the mechanisms and factors contributing to their transport and deposition.This study investigates the sources and pathways of microplastics in urban environments, focusing on atmospheric fallout as a potential vector. Microplastics, defined as particles smaller than 5 mm, are collected and analyzed from two sites: an urban area and a sub-urban area. The results show that fibers, primarily synthetic, account for almost all the microplastics collected. The atmospheric fallout of microplastics ranges from 2 to 355 particles/m²/day, with higher fluxes observed in urban areas. Chemical characterization reveals that 29% of the fibers are made of synthetic materials or a mixture of natural and synthetic materials. Extrapolation of the collected fibers suggests that between 3 and 10 tons of synthetic fibers are deposited annually in the Parisian agglomeration. The study highlights the importance of considering atmospheric fallout as a source of microplastics and calls for further research to understand the mechanisms and factors contributing to their transport and deposition.