Mexico was dubbed the most polluted city in 1992 by the United Nations. It now houses almost 22 million people making it the seventh largest city in the world. With this, has come industrial and economical developments which have increased the levels of pollution massively.

Mexico’s geographical situation does not help matters either as it is surrounded by mountains creating a sort of bowl which traps pollution. But since the 1990s, Mexico has put in place some significant changes and initiatives to tackle the effects and sources of pollution.

The most polluting factories were closed and the circulation of cars and traffic is limited by a system called ‘Hoy No Circula’. As part of this initiative, private vehicles are forbidden from driving one day a week. This was put in place on a rotatory basis and has significantly lowered air pollution levels. Other plans include the implementation of a Metrobus system which now is the longest in Latin America. The launch of EcoBici in 2010 with thousands of bicycles available to the public also had a positive impact with levels of carbon monoxide and sulphur dioxide decreasing year on year. 

Berlin is another example of a city which has been able to respond to the threat air pollution poses to its population. With its 3,4 million inhabitants, it has become one of the cleanest cities in Europe coming fourth in the 2015 list of ‘Soot Free Cities’. It came just after Zurich, Copenhagen, Vienna and Stockholm.

As of March 2015, Berlin set aside 4 million euros to develop new cycle routes and improve those that already exist. To this is added an excellent public transport system which boasts trams, buses and a metro. Most memorably, Berlin has cordoned off a ‘Low Emission Zone’, an area spanning over 85 square metres. Since 2010, this zone is a permanent 24h no-go area for cars that do not reach the necessary standards of particle emissions. A third of Berlin’s residents are affected by this zone and it has lead to rapid results with soot emissions from cars cut by half. 

But these are a couple of the rare expections, cities that have managed to respond to the issue. Many have not been so successful. 

A couple of case studies: What is being done? 

Watch an interactive interview with Sandra Cavalieri