The Stick’Air sticker introduced in Geneva four years ago has been only used twice in that time, and then only affecting the worst polluting vehicles.
The idea that all cars must have a sticker, determining how polluting they are – ranging from zero to 5.
When air pollution hits certain levels, the dirtiest cars are banned from the city centre.
The canton says its good news that the system is not often used as it shows the city is getting cleaner.