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Clearer skies, cleaner air in Mexico City

Air pollution has been a serious environmental and health problem in Mexico City for many years. The city’s rapid growth and urban expansion generates high ozone levels, and its topography and climate contribute to trapping the pollution across the broad valley that surrounds the capital.

In 1990, there were a total of 333 days (or 92.2% of the entire year) in which the ozone level was above the Mexican national standard, which is 0.110 parts per million. In 2009, the number of days in which the ozone level was above the standard fell to 180, or 49.3% of total days. In addition, the number of average hours per day that the ozone standard is above the norm has also fallen over the same period – from an average of 4.9 hours per day in 1990, to 1.5 hours per day in 2009. Other pollutants, including carbon dioxide and lead, have also fallen significantly.

The trend of clearer skies has continued this year. In the first three months of 2010, there were 24 days when the ozone level was above the standard (just 26.7% of total days), with the average hours per day level falling to just 0.8 hours.

Mayor Marcelo Ebrard’s government in Mexico City has made improving air quality an important priority of his administration. The city has put in place a comprehensive 15-year Green Plan designed to reduce GHG emissions by 7 million metric tonnes between 2008 and 2012. In the plan’s first year, emissions fell by 2%, or by more than 750,000 metric tonnes. The city is investing in a new Metro (subway) line, a clean-fuel Metrobus system, and replacing old taxi and microbus vehicles with newer, cleaner models. There are private vehicle restrictions on certain days and cargo transportation in certain high-traffic zones. Businesses and citizens are being encouraged to adopt more climate-friendly behavior.

The result is clearer, healthier air for Mexico City’s 20 million residents and visitors. On many days, the magnificent volcanoes of Popocatépetl and Iztaccihuatl can be seen in the distance.