Air pollution in Madrid has become so bad that steps have been taken to reduce it.
A 70km/h speed limit has been imposed on the M-30 ring road and only residents are allowed to park in public places.
On Thursday things were stepped up further with a ban on cars with number plates ending in an even number entering the city. This would alternate with numbers ending in odd numbers banned on other days. The plan was to allow all vehicles back into the city on Fridays and Saturdays.
Initially the idea was to set up police checks at the main access points to the city. However that plan was abandoned when they realised the chaos it would cause. Added to which, stopping cars would actually increase pollution.
Exceptions to the scheme include hybrid cars, those carrying three of more people and disabled drivers. Taxis and delivery vehicles are also exempt.