It’s a simple system. If you are entering one of the restricted zones you need to buy a sticker, which will be a specific colour depending on the emissions level of your vehicle. Crit’Air 0/E: ...

Vehicles not registered in France must also display the ecological Crit'Air sticker in order to travel on French roads. In Paris, it is compulsory for drivers to have the sticker within the ...

You can purchase one here. Failing to display a Crit'Air sticker in a ZFE, or not complying with the restrictions, can lead to a fine of €68 for a light-weight vehicle, or a fine of €135 for a ...