A survey that ranks the efforts of 23 major European cities to improve air quality has just been released.

This is different to other pollution surveys, which mostly analyse the actual quality of the air. The rankings are part of a campaign called Soot-free for the climate, produced by Friends of the Earth Germany and supported by members of the European Environmental Bureau.

Zurich came out on top, closely followed by Copenhagen, Vienna and Stockholm. Berlin, top of the last survey in 2012, came fifth this time around.

Luxembourg, Lisbon, Rome, Madrid and Glasgow are in the bottom five.