Three decades ago, an insalubrious mix of industrial emissions and car exhaust made breathing Mexico City’s air roughly the equivalent of smoking two packs of cigarettes a day. One of the biggest problems was—and is—traffic: each day, around 4.5 million cars clog the city’s streets and emit about 45 percent of its greenhouse gas (GHG). In fact, the average commuter spends nearly 230 hours a year in traffic jams.
Hoy non circula
The government responded by imposing stricter emission testing (which forced the oldest smoke-belching cars from the streets) and a program called Hoy non circula (“Today [your car] doesn’t drive”). Most cars are banned from the city for two Saturdays a month, and those with worse emissions have to stay parked one additional day a week. Emission thresholds for industrial facilities were tightened as well. It’s working: Mexico City now ranks just 461st in particulate-matter emissions.
One of those who helped guide Mexico City’s green transformation was Tanya Müller García, who grew up in southwest Germany and earned a master’s degree in International Agriculture Economics and Management from Humboldt University in Berlin. In the early 2000s she served as a city planner and helped organize the rehabilitation of Mexico City’s urban parks. In 2012 she was appointed Secretary for the Environment. Her main task was to oversee the implementation of the city’s Plan Verde.
More bikes and buses
Mexico City itself has about 5 million registered vehicles; the greater metropolitan area, 9.6 million. To lure drivers out of them, the government has invested more than the equivalent of €3 billion to expand public transport and bicycle infrastructure. Studies commissioned by Müller García’s department showed that more than half of the 20 million car trips made daily in Mexico City are shorter than 8 kilometers (about 5 miles). One response is ECOBICI, a public bike-sharing program that now has more than 6,000 bikes and over 100,000 active users. The city has also added bicycle lanes to major thoroughfares. They enable cyclists to safely peddle past motorists during rush hour, when the average speed is barely more than a walking pace.
Müller García see streets not just as routes for cars but rather as public spaces for pedestrians, bicycles, and public transport. Cars are banned entirely from the city center on Sundays, to give walkers, joggers, and cyclists space and air to breathe.
Roofs and roads: from grey to green
Müller García’s efforts to make the city greener encountered a typical problem faced by urban planners: a lack of space. Although Mexico City has parks, the floating gardens of Xochimilco (a UNESCO World Heritage Site), and tree-lined avenues, these don’t suffice to absorb the city’s 50 million metric tons of annual GHG emissions. The World Health Organization (WHO) estimates that 9 square meters of greenery per inhabitant are needed to prevent chronic respiratory diseases. Mexico City, which has just 5.3, plans to add 30 million square meters by 2030. But where?
With little space available on the ground, Müller García looked upward: to the city’s roofs. Her department made available over €1.3 million in funding in 2015 alone to transform unused roofs into gardens where residents can grow fruits, herbs, and vegetables. The program has given rise to an increasingly popular urban gardening movement.
Müller García’s department also supported Vía Verde, a privately funded initiative conducted in 2016. It involved encircling the more than 1,000 support columns of the freeway that rings the inner city with 10-meter-high trellises on which grow a variety of creepers and succulents. The plants, which are irrigated exclusively with rainwater and other unpotable sources, produce oxygen and may go some way toward helping purify the air. The idea isn’t new. Other densely populated cities like London, São Paulo, and Beirut have vertical gardens as well. China is going a step further and building Liuzhou Forest City in Guangxi Province. Designed for about 30,000 residents, it will have almost 1 million plants and 40,000 trees.
A new flagbearer with ambitious goals
Mexico City’s environmental transformation has another decade to go. Although Müller García resigned as the city's Secretary for the Environment in 2018, that same year its new mayor, Claudia Sheinbaum Pardo, took office. Sheinbaum, who has a PhD in physics from the National Autonomous University of Mexico, served on the United Nations’ Intergovernmental Panel on Climate Change when it was awarded the Nobel Peace Prize in 2007. Under her leadership Mexico City recently put in place a comprehensive package air-quality measures that aims to GHG emissions by 30 percent within five years.
Air pollution has several sources: industry, transport, agriculture, energy production, and nature itself. According to the WHO, air pollution is (after tobacco use) the second-most frequent cause of death from noncommunicable diseases. It contributes to 4.2 million deaths annually, most commonly from strokes, lung cancer as well as cardiovascular and respiratory diseases.