The Saclay observatory, 20 km southwest of Paris, monitored greenhouse and reactive gases, as well as aerosols, over 10 years to assess the impact of urban emissions. By comparing downwind and background conditions, the study revealed significant reductions in pollutants linked to traffic: -35.6 % for CO, -52.3 % for NOₓ, -56.7 % for eBC, and -15 % for CO₂. These trends align with emission decrease estimates from AIRPARIF inventories over the same period.