Airparif is an independent non-profit organisation monitoring the air quality in Île de France, the region of France containing Paris. On their website they have maps showing the average air pollution for different pollutants, starting in 2007. From these I created the following animation, which shows the evolution of PM2.5, fine particles with a diameter of 2.5 μm or less:

PM25 concentrations from 2007 to 2021 in Paris