The movement is spreading to other areas of the country with major cities and départments signing up to the "lower emissions zones" (LEZ) idea.
Essentially the idea is that when the air becomes bad, and it is usually in summer when the warmer air holds the smog in the air, that they can close areas of the city, and open them to lower emissions classes of vehicles. And that is determined by the CO2 output of the vehicle.
Every vehicle accessing the city must carry the crit-air sticker on the windscreen/shield on the right side lower. On the bike it goes on the upper right of the fork leg. They even produced a video on how to affix it!
Pepé is Cat 2.
As we intend to go to France in the summer, I have applied for a sticker at a cost of €4.21 including postage.
There is also an app that you can download for Apple or Android phones. It will give you the traffic light system and access categories when the zones are active. Amazingly there are lots of them! It would seem that from the last few zone activations that Cat 2 gets through.
So lots of information for you and a photo to follow when the sticker arrives.