Air Pollution's Impact On Mexico City

Mexico City was once labelled the most polluted city in the world by the United Nations in 1992. This was due to a combination of factors, including industrial growth, a sharp increase in population, and the proliferation of vehicles. However, in recent years, Mexico City's ranking has dropped significantly, falling to 917th in 2021. While the city's air quality has improved, it still faces challenges, with pollution levels exceeding the World Health Organization's guidelines. In 2023, Mexico City did not make it to the top 25 most polluted capital cities, and Xonacatlán was ranked as the most polluted city in Mexico based on fine air particulate matter concentration (PM2.5).

Mexico City's air pollution history

Mexico City's air pollution has been a concern for decades. In the 20th century, Mexico City's population rapidly increased as industrialization brought thousands of migrants from all over the world. This rapid and unexpected growth led to a population boom, which, in turn, caused a proliferation of vehicles and rapid industrial growth.

The city's high altitude of 7382 feet above sea level also contributed to the problem, as it caused oxygen levels to be 25% lower, and carbon-based fuels did not combust completely. The topography of Mexico City did not favour its industrialisation, as it is located in a basin where air pollutants tend to be trapped.

In 1992, the United Nations named Mexico City "the most polluted city on the planet". Air pollution in Mexico City reached its peak in the 80s and 90s, as ground-level ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide, and airborne particles, all five major air pollutants, were at their record levels. These air pollutants were mostly generated from human activities such as burning fossil fuels in power plants and vehicle emissions. In the 80s, there were about 124 cars per 1000 residents, and these cars were made of poor quality and ran on very toxic fuel. At the same time, non-regulated and highly polluting factories, power plants, and oil refineries were operating all over the city.

Recognising the severity of air pollution in the 80s and 90s, the city’s government implemented a range of policies to combat the issue. The most notable among these policies was the “Hoy No Circula”, which was first introduced in 1989. This policy required that all vehicles go through emissions testing every six months, with underperforming vehicles only allowed to circulate on certain days.

In recent years, Mexico City has seen a significant improvement in air quality, dropping to the 917th most polluted city in the world in 2021. This improvement is due to various factors, including the Mexican government's requirement that gasoline be reformulated, that polluting factories be closed or moved, and that drivers be prohibited from using their cars one day a week. The government has also invested in sustainable, non-motor mobility, such as cycling, and has expanded public transportation, with the introduction of electric buses and electric heavy-duty vehicles. Mexico City has also joined the global Breathe Cities initiative, which aims to reduce air pollution by 30% on average across its participating cities by 2030.

Current air quality and rank

Mexico City's air pollution has been a concern for its population and health officials for decades. In 1992, the United Nations named it the "most polluted city on the planet". This was due to a combination of factors, including the city's high altitude, which lowers its oxygen levels, the incomplete combustion of carbon-based fuels, rapid industrial growth, a booming population, and a proliferation of vehicles.

The severity of air pollution in Mexico City was at its peak in the 1980s and 1990s, with ground-level ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide, and airborne particles all at record levels. The air quality was described as so severe that birds were found dead from its toxicity. The Mexican government has since implemented policies to combat air pollution, such as "Hoy No Circula", which restricts vehicular circulation based on emissions testing.

The air quality in Mexico City has improved significantly since the 1980s and 1990s. In 2021, Mexico City was ranked as the 917th most polluted city in the world by IQAir, a Swiss company that tracks global air quality. However, it is important to note that Mexico City's concentration of airborne particles (PM2.5) still exceeds the guidelines set by the World Health Organization. In 2023, Mexico City did not make it to the top 25 most polluted capital cities, and its ranking among countries with the highest PM2.5 concentration was 46th.

The Mexican government continues to prioritize the reduction of emission levels through various active plans. These plans include citizen participation, vehicular restrictions, increasing green areas, and promoting bicycle accessibility. While Mexico City's air pollution has improved, it still faces challenges in meeting air quality standards, and the health risks associated with air pollution remain a concern.

The impact of industrialisation

Mexico City's air pollution has been a concern for its population and health officials for decades. In the 20th century, the city's population rapidly increased as industrialization brought thousands of migrants from around the world. This rapid growth led to the UN declaring Mexico City the most polluted city globally in 1992.

The industrialization era in Mexico City was responsible for emitting over 11,000 tons of waste material into the atmosphere daily. The burning of fossil fuels in power plants, vehicle emissions, and industrial processes all contributed significantly to air pollution. In the 1980s, there were about 124 cars per 1000 residents, and these vehicles were of poor quality, running on highly toxic fuel. The topography of Mexico City also did not favour its industrialization, as the city is located in a basin where air pollutants are trapped.

The Mexican government has implemented various policies and plans to reduce emission levels, including vehicular restrictions, increasing green areas, and expanding bicycle accessibility. These efforts have led to significant improvements, with Mexico City dropping to the 917th most polluted city in the world in 2021, according to IQAir. However, the city still exceeds the World Health Organization's guidelines for airborne particle concentrations (PM 2.5).

Despite the improvements, Mexico City continues to face air quality issues. Ground-level ozone, a significant concern, reached about 1.9 times the acceptable limit in the spring of 2016. The interaction of nitrogen oxides (NOx) with volatile organic compounds (VOCs) and ultraviolet (UV) radiation from the sun contributes to the formation of ground-level ozone.

The impact of industrialization on Mexico City's air pollution has been significant, and the city continues to grapple with the environmental consequences. While there have been notable improvements, further efforts and aggressive policies are needed to address the root causes of air pollution and ensure a sustainable future for the city's residents. International pressure and aid may also play a role in helping Mexico City combat air pollution.

Government policies and their effects

Mexico City, the capital of Mexico, was once named the world's most polluted city by the United Nations in 1992. The city's administration and the Metropolitan Environmental Commission (MEC) have implemented several policies and programs to combat air pollution.

• Hoy No Circula ('Today, don't circulate'): First introduced in 1989, this policy requires all vehicles in Mexico City and the State of Mexico to undergo emissions testing every six months. Vehicles are then issued a verification based on their performance: "0" for those that meet the requirements, and "1" or "2" for underperforming vehicles. While vehicles with a "0" rating are exempt from the "Hoy No Circula" program, those with "1" or "2" ratings are prohibited from being driven on one weekday per week and two Saturdays per month. Despite this, the effectiveness of this policy has been questioned, as air pollution levels did not significantly decrease after its implementation.
• No-Drive Days: The Mexican government introduced "No-Drive Days" or "Hoy No Circula" in 1989, prohibiting drivers from using their vehicles on one weekday per week. In 2008, this was extended to include Saturdays as well.
• Alternatives to driving: The government also promotes alternatives to driving, such as bus rapid transit lines and bike-sharing systems.
• Comprehensive Programme Against Air Pollution (PICCA): Launched in 1990, this program aimed to improve the air quality in the Metropolitan Area of Mexico City.
• ProAire: First introduced in 1995, ProAire has since been updated to ProAire IV, which addresses eight themes, including the reduction of energy consumption and the creation of a permanent program for ecosystem analysis of Mexico City.
• IMECA (Índice Metropolitano de la Calidad del Aire): The Mexican authorities use this air quality monitoring system to measure the levels of six main pollutants in the city: O3, PM10, PM2.5, CO, NO2, and SO2. IMECA uses five index categories to report air quality, ranging from "Good" to "Hazardous."
• Other initiatives: The Mexican government has also proposed plans to reduce emission levels through citizen participation, vehicular restrictions, increasing green areas, and expanding bicycle accessibility. However, these plans require greater citizen involvement to be effective.

While Mexico City has made significant improvements in reducing air pollution, dropping to the 917th most polluted city in the world in 2021, it still exceeds the World Health Organization's guidelines for airborne particle concentrations (PM 2.5). Experts believe that emissions from vehicles significantly contribute to air pollution, and new rules and regulations are needed to tighten controls and reduce the number of polluting vehicles on the roads.

Future goals and targets

Mexico City's air pollution has been a concern for its population and health officials for decades. In 1992, the United Nations named Mexico City the "most polluted city on the planet". The city's high altitude, industrialization, vehicle proliferation, and rapid population growth have contributed to poor air quality. While Mexico City's air pollution ranking has improved significantly, dropping to 917th in 2021, future goals and targets are essential to sustain and further enhance air quality.

• Strengthening Inspection and Surveillance Systems: To address the issue of illegal changes in land use, which contributes to deforestation, Mexico aims to strengthen inspection and surveillance systems. The goal is to achieve zero deforestation by 2030, tackling the pollution problem at its source.
• Mobility Systems Modification: Mexico City aims to prioritize public transport, electric mobility, and active transport (cycling and walking), and reduce emissions from vehicles, which are currently the main cause of air pollution within the city center.
• Reducing Vehicle Emissions: The Mexican government's plans include vehicular restrictions and mandatory emissions testing for all vehicles every six months. Underperforming vehicles are identified, and citizen participation in emission reduction is encouraged.
• Increase in Green Areas and Bicycle Accessibility: The government aims to expand green spaces and promote bicycle use by improving bicycle infrastructure.
• Addressing Industrial Pollution: With industrial growth being a significant contributor to air pollution, the government should focus on regulating and reducing emissions from factories, power plants, and oil refineries.
• Public Health and Economic Development: Reducing air pollution is crucial for public health and the region's economic development. The government should continue to prioritize policies that protect public health and support sustainable economic growth.
• Education and Awareness: Educating the public about the causes and impacts of air pollution, as well as promoting individual actions to reduce emissions, can help achieve air quality goals.
• Collaboration with International Organizations: Working with organizations like the World Health Organization (WHO) and collaborating with other cities facing similar challenges can provide valuable insights and best practices to further improve air quality.
• Real-time Air Quality Monitoring and Data Transparency: Mexico City can benefit from continued investment in real-time air quality monitoring systems, ensuring data transparency, and providing accessible information to the public.
• Policy Advocacy and Implementation: Local and national governments should advocate for policies that address the root causes of air pollution and ensure effective implementation and enforcement of existing and future regulations.

These goals and targets aim to address the diverse factors contributing to air pollution in Mexico City, prioritizing public health, environmental sustainability, and economic development. By learning from past successes and challenges, Mexico City can continue to improve its air quality and create a healthier and more sustainable future for its residents.

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