6. Effect of Covid-19 sanitary containment on air quality

The health confinement linked to the Covid-19 pandemic, from March 17 to May 11, 2020, was an extraordinary opportunity to confirm the modeling results relating to the drastic reduction of road transport on air quality based on air quality measurements.

In Île-de-France, during the months of March 2018 and 2019, the air had been qualified as "average" for 35% of the time (Citeair European air quality index between 50 and 75 on a scale of 100 and above), due to high measured concentrations of NO ₂ or PM ₁₀ . On other days, air quality was good and qualified as "low" (index between 25 and 50) (figure 46 ).