Mexico City's Air Pollution: A Critical Concern

Mexico City has long struggled with air pollution, with the metropolis once being named the world's most polluted city. The air quality in the Mexican capital has been described as so severe that birds were found dead from the toxicity of the air. However, in recent years, the city has seen a colossal improvement in its air quality, dropping to the 917th most polluted city in the world in 2021. This improvement is largely due to the Mexican government's efforts to reduce air pollution, including requiring gasoline to be reformulated, closing polluting factories, and prohibiting cars on certain days. Despite this progress, air pollution in Mexico City still exceeds the World Health Organization's guidelines, and the city continues to implement initiatives to further improve air quality.

Mexico City was the world's most polluted city in 1992

Mexico City has long struggled with air pollution, and in 1992, the United Nations declared it to be "the most polluted city on the planet". This was due to a combination of factors, including the city's high altitude, rapid industrialization, a population boom, and the proliferation of vehicles.

Located 7382 feet above sea level, Mexico City's high altitude meant that its oxygen levels were 25% lower than at sea level. This, in turn, meant that carbon-based fuels did not combust completely, leading to higher levels of pollution. The city's industrialization and population boom, which began in the 1950s, also contributed to the problem. As the population grew from three million in 1950 to twenty million by 2015, the demand for jobs and services increased, leading to rapid industrial growth and the emission of over 11,000 tons of waste material into the atmosphere daily.

The proliferation of vehicles was another significant factor. By 1980, there were 124 cars and light-duty trucks per 1000 residents, and the number of vehicles continued to grow in the following decades. These cars were often of poor quality and ran on very toxic fuel. The topography of Mexico City also did not favour its industrialization, as the city is located in a basin where air pollutants tend to be trapped.

The severe air pollution in Mexico City during the 1980s and 1990s posed a significant threat to public health and the economy. Thousands of people were hospitalized every year, and around 1,000 premature deaths annually were attributed to airborne pollutants. Birds were also found dead due to the toxicity of the air. Recognizing the severity of the problem, the city's government implemented a range of policies to combat air pollution, including the "Hoy No Circula" program, which was introduced in 1989 and required vehicles to be taken off the road for one day a week.

In recent years, Mexico City has seen significant improvements in air quality. The Mexican government mandated the reformulation of gasoline, the closure or relocation of polluting factories, and the implementation of low-sulphur standards. The use of fuel ethers has also contributed to an 86% decrease in CO, a 53% decrease in ozone, and a 32% decrease in particulate matter between 1992 and 2012. As a result of these efforts, Mexico City has dropped to the 917th most polluted city in the world as of 2021, according to IQAir, a Swiss company that tracks global air quality.

The city's topography makes it prone to poor air quality

The combination of geographical factors and human activities has led to historically high levels of air pollution in Mexico City. The city's constrained basin and intense solar radiation further contribute to the poor air quality. As the city industrialized, the proliferation of vehicles and industrial activities emitted significant amounts of pollutants into the atmosphere.

Over the past two decades, authorities have made efforts to improve air quality by relocating factories outside the capital, tightening regulations on fuel and vehicles, and implementing air quality management programs like Proaire. These measures have shown some success, with ozone levels gradually decreasing below government limits. However, the city's unique topography still poses a challenge in ensuring effective dispersion of pollutants.

The Mexican government has also introduced the Management Programme to Improve Air Quality (Proaire), which has helped reduce air pollution levels. This program has restricted vehicle use, improved fuel quality, and limited greenhouse gas emissions from factories. Despite these efforts, the city's topography, with its surrounding mountains and high altitude, continues to hinder the dispersion of pollutants, making it prone to poor air quality.

To address the issue, Mexico has set a goal of achieving zero deforestation by 2030 and is working to prioritize public and active transport, such as electric transportation, cycling, and walking, to reduce emissions from the transport sector, which is currently the main cause of air pollution in the city centre.

Air pollution causes 5.9% of deaths in Mexico

Mexico City, the capital of Mexico, was once labelled the world's most polluted city. In 1992, the United Nations named Mexico City "the most polluted city on the planet". The city's air quality has improved since, dropping to the 917th most polluted city in the world in 2021. However, air pollution remains a significant issue, causing about 5.9% of all deaths in the country.

Mexico City's air quality is measured by the Índice Metropolitano de la Calidad del Aire (IMECA) (Metropolitan Index of Air Quality). The air-quality monitor system (IMECA) is the tool used by Mexican authorities to measure air quality. IMECA uses five index categories to report air quality: Good, Fair, Poor, Very Poor, and Extremely Poor. The system takes into account the levels of six main pollutants in the atmosphere: O3, PM10, PM2.5, CO, NO2, and SO2.

The poor air quality in Mexico City is attributed to various factors, including industrialization, urbanisation, population growth, vehicle emissions, and the burning of fossil fuels. The city's high altitude of 7382 feet above sea level also contributes to the problem, as it causes oxygen levels to be 25% lower. In addition, carbon-based fuels do not combust completely, further adding to the pollution. The topography of the city exacerbates the issue, as it is located in a basin where air pollutants tend to be trapped.

To address the air pollution problem, the Mexican government has implemented several measures. These include requiring the use of reformulated gasoline, closing or relocating polluting factories, prohibiting driving one day per week, and expanding public transportation. The government has also introduced vehicular restrictions, increased green areas, and promoted bicycle accessibility. Despite these efforts, air pollution continues to pose a threat to public health, and further improvements are needed to meet the World Health Organization's air quality standards.

The health effects of air pollution in Mexico City are significant, with about one in seventeen (5.9%) of all deaths in the country attributed to air pollution. The most dangerous airborne particles, known as PM2.5 (particulates less than 2.5 thousandths of a millimetre across), can penetrate deep into the lungs and cause respiratory and cardiovascular issues, including lung cancer, heart disease, and stroke. Reducing outdoor ambient PM2.5 concentrations to the WHO's target of 15µg/m3 could save at least 10,000 lives per year.

The Mexican government has implemented policies to improve air quality

Mexico City was once labelled the world's most polluted city by the United Nations in 1992. In the years since, the Mexican government has implemented a variety of policies to improve the air quality of the city.

In 1989, the "Hoy No Circula" policy was introduced, which required vehicles to go through emissions testing every six months and prohibited certain vehicles from driving on particular days of the week. This policy is still in place today, with vehicles issued a verification number based on their performance in the test.

In 1990, the Comprehensive Programme Against Air Pollution (PICCA) was launched, followed by ProAire in 1995. The purpose of each was to improve the air quality of the metropolitan area of Mexico City. ProAire is now in its fourth phase, ProAire IV, which addresses eight themes, including the reduction of energy consumption and the creation of a permanent program of ecosystem analysis of Mexico City. In 2013, ProAire IV won the C40 and Siemens Climate Leadership Awards’ Air Quality category.

In 2012, the Mexican government passed the General Law on Climate Change, creating a legal obligation to address Short-Lived Climate Pollutants (SLCPs). This was followed by a commitment in 2015 to reduce Black Carbon emissions by 25% by 2030, with a potential increase to 40% with international support. In 2019, Mexico launched a National Strategy to Reduce Short-Lived Climate Pollutants, which aims to achieve local air quality benefits while reducing near-term temperature increases.

In addition to these policies, the Mexican government has also taken steps to improve air quality by requiring the reformulation of gasoline, closing or moving polluting factories, and expanding public transportation options. Mexico City has also joined the BreatheLife network, implementing a variety of clean energy efforts, including removing lead from gasoline, reducing sulphur content in diesel fuel, and introducing electric taxis.

As a result of these efforts, Mexico City's air quality has improved significantly. In 2021, it was ranked as the 917th most polluted city in the world, and between 1990 and 2015, the average life expectancy of citizens increased by 3.2 to 3.4 years, saving an estimated 22,500-28,000 lives.

Mexico City has joined the Breathe Cities initiative to combat air pollution

Mexico City has long struggled with air pollution. In the 20th century, the city's population rapidly increased as industrialization brought thousands of migrants from around the world. This population boom, coupled with the proliferation of vehicles and rapid industrial growth, led to a severe decline in air quality. In 1992, the United Nations declared Mexico City the "most polluted city in the world".

Since then, Mexico City has made significant strides in improving its air quality. The Mexican government has implemented several plans to reduce emission levels, including citizen participation, vehicular restrictions, the expansion of green areas, and increased bicycle accessibility. These efforts have borne fruit, with Mexico City dropping to the 917th most polluted city in the world in 2021, according to IQAir.

Despite this progress, Mexico City's concentration of airborne particles (PM 2.5) still exceeds the World Health Organization's guidelines. Determined to tackle this issue, Mexico City has joined the Breathe Cities initiative, a global partnership that supports cities in cutting air pollution and climate emissions. Breathe Cities, announced in 2023 by Michael R. Bloomberg and Sadiq Khan, brings together air quality data, communities, and city leaders to share learnings and scale local impact. The initiative aims to reduce air pollution by 30% on average across its participating cities by 2030.

As part of Breathe Cities, Mexico City will gain support in strengthening air quality data, community engagement, and technical capacity building. The city will also be able to share knowledge with other cities in the network, including Accra, Bangkok, Bogotá, Brussels, Jakarta, Johannesburg, London, Milan, Nairobi, Paris, Rio de Janeiro, Sofia, and Warsaw. By joining this initiative, Mexico City demonstrates its commitment to creating healthier and more sustainable urban environments for its residents.

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