In April 2019, motorists had to reduce their speed from 90 to 70 km / h on the Lyon ring road. At the same time, nitrogen dioxide pollution has decreased. But it is still difficult to establish with certainty that it is indeed this measure that has made it possible to improve air quality. In some cases, an increase in the concentration of certain pollutants has even been observed. Another study is expected to refine the results. We will tell you more in our dossier on progres.fr that will be published on Saturday morning.
17:41 | Updated at 17:42 – Reading time: