From 27.11.2017 on it will be possible to announce an emergency low emission zone in Toulouse. Certain vehicles won't be allowed to circulate.

You need a Crit'Air sticker to be allowed to circulate when the emergency low emission zone is active. More details when available.

See here for other French emergency schemes and where to get the Crit'Air sticker:

Grenoble, Lille, Lyon, Paris, Strasbourg 

Picture source pixabay.