The air quality around Geneva is improving.
For the first time since measurements began in 1998, nitrogen dioxide levels remained within acceptable levels throughout the region.
In addition, the amount of particulate matter pollution has decreased – although there were jumps during the passage of a cloud of dust from the Sahara Desert in February last year.
Even ozone levels are falling – peaks at the lower level recorded over the past 10 years.
Canton says the closure only partially explains the best figures. It says that improvements in car technology and cleaner heating systems are largely to blame.