Air Pollution: Worst Areas In Latin America

Air pollution is a pressing issue in Latin America and the Caribbean, with the region experiencing a boom in urbanisation and industrialisation. In Mexico, air pollution has been a major concern in Mexico City, which was once named the world's most polluted city. The city's high altitude, rapid population growth, proliferation of vehicles, and industrial activities have contributed to poor air quality. While Mexico City's air pollution ranking has improved in recent years, it still exceeds the World Health Organization's guidelines for airborne particle concentration. Other cities in Latin America and the Caribbean, such as Santiago, Bogotá, Medellín, and Lima, have also faced challenges with air quality and have implemented various initiatives to address the issue.

Mexico City's air pollution

The rapid growth in population, the increase in manpower and human activities, and the proliferation of vehicles have resulted in severely poor air quality. In the 1980s, there were about 124 cars per 1,000 residents, and by 2010, this number had doubled. Although this number might not seem particularly high, 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. The topography of Mexico City also does not favour its industrialization, as it is located in a basin where air pollutants tend to be trapped. The city is surrounded by mountains, almost forming a bowl-like container, and is at a considerable height, which also explains why historically it has been a place where pollution is trapped.

In 1992, Mexico City was labelled by the United Nations as the world's most polluted city. Air pollution in Mexico City reached its peak in the 1980s and 1990s, as ground-level ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide, and airborne particles, all five major air pollutants, were at their record levels. The air quality in Mexico City at that time was described as just as severe as India's today, where birds fell out of the sky and were found dead because of air pollution's toxicity.

Recognizing the severity of air pollution in the 1980s and 1990s, the city's government understood the importance of reducing air pollution as it posed a huge threat to public health and hindered further economic development. As such, the government implemented a range of policies to combat air pollution in the country's capital. The most notable among these policies was the "Hoy No Circula", meaning "today, (these vehicles) don't circulate", which was first introduced in 1989. In Mexico City and the state of Mexico, all vehicles are required to go through emissions testing every six months and are issued a verification according to their performance in the test. The Mexican government has several active plans to reduce emission levels, which require citizen participation, vehicular restrictions, an increase in green areas, and expanded bicycle accessibility.

In recent years, there has been an expansion of public transportation. The government has also required the reformulation of gasoline, the closure or relocation of polluting factories, and the prohibition of driving one day per week. These actions have resulted in an 86% decrease in CO, a 53% decrease in ozone, and a 32% decrease in particulate matter over a 20-year span. According to IQAir, a Swiss company that tracks the air quality of cities worldwide, Mexico City has dropped to the 917th most polluted city in the world in 2021. While its concentration of airborne particles (PM 2.5) still exceeds the World Health Organization (WHO) guidelines, the improvement in air quality in Mexico City is undeniable.

Population growth and industrialization

Mexico City has been a hub of industrialization and urbanization since the 20th century. The population of the metropolitan area of the valley of Mexico, also called Greater Mexico City, grew significantly from 3.1 million in the 1950s to 14 million in the 1980s and 22 million in the present day. This rapid population growth, coupled with an increased workforce and human activity, has resulted in severely poor air quality.

Industrial growth has been responsible for emitting over 11,000 tons of waste material into the atmosphere daily. The economy boomed, and so did the proliferation of vehicles. In 1980, there were 124 cars and light-duty trucks per 1000 residents, and by 2010, this number had increased to 267. As of 2022, there are around 55 million vehicles in the country, with over 4 million in Mexico City alone. The burning of fossil fuels in power plants and automobile exhausts has led to the emission of greenhouse gases like carbon monoxide, sulfur dioxide, nitrogen oxides, and ozone, which are the main sources of air pollution in the city.

Mexico City's topography does not favour its industrialization. Located in a basin, air pollutants tend to be trapped, and the warm air over the valley, known as the "inversion layer," further traps pollutants over the city. The city's high altitude of 7382 feet above sea level results in oxygen levels that are 25% lower, causing carbon-based fuels to not combust completely and leading to increased emissions. The surrounding mountains also prevent pollutants from escaping.

The Mexican government has recognized the severity of air pollution and has implemented various policies and programs to reduce emissions and improve air quality. Some of these include the “Hoy No Circula” program, which restricts certain vehicles from circulating on certain days, vehicular restrictions, the increase of green areas, expanding bicycle accessibility, and promoting public transportation. The government has also worked on removing lead from gasoline, implementing catalytic converters, reducing sulfur content in diesel fuel, and substituting fuel oil with natural gas in industries and power plants. While these efforts have shown some success, citizen participation is crucial for their effectiveness, and more stringent emissions standards and non-fossil fuel alternatives are needed to combat the issue effectively.

LAC region's anti-pollution efforts

Mexico City has been a significant source of concern for air pollution in the Latin America and Caribbean (LAC) region. In 1992, the United Nations named Mexico City "the most polluted city on the planet". The city's air pollution was caused by a combination of factors, including population growth, increasing motorization, industrial activities, and the city's constrained basin topography, which traps pollutants.

Over the years, the Mexican government has implemented various policies and programs to combat air pollution in Mexico City. For example, in 1989, the "Hoy No Circula" policy was introduced, which requires vehicles to undergo emissions testing every six months and restricts their circulation based on their performance. The government has also taken steps such as removing lead from gasoline, implementing catalytic converters, reducing sulphur content in diesel fuel, and substituting fuel oil with natural gas in industries and power plants. These efforts have led to a significant improvement in air quality, with Mexico City dropping to the 917th most polluted city in the world in 2021.

More broadly, the LAC region has taken steps to combat air pollution and improve clean air. In 2022, the region launched the Actions on Air Quality in Latin America and the Caribbean 2022–2025 and the Regional Strategy for Climate Change for the Central America Region (2021-2025). Several LAC national and sub-national governments have formulated and implemented initiatives such as air quality monitoring, solid waste management, cleaner production, energy efficiency in industry, and sustainable transport. Additionally, at least eight LAC countries have national air quality management strategies, frameworks, or action plans.

However, there is still a need for long-term, sustainable solutions to air pollution in the LAC region. According to UNEP, some countries lack current frameworks to reduce air pollution, and there are delays in implementing existing policies and regulations. Collective responsibility and cooperation across national and regional borders are crucial for addressing air quality challenges in the LAC region, as air pollution does not respect geographical boundaries.

Some specific efforts in the LAC region include:

• DOI-ITAP's work in the LAC region supports energy independence in Argentina, environmental offsets in Colombia, protection of archaeological sites in Guatemala, climate change adaptation in Panama, and counter wildlife trafficking in Central America, the Dominican Republic, Colombia, and Chile.
• Protected Area Management and Environmental Governance in the Selva Maya (Guatemala, Belize, and Mexico), where DOI-ITAP works with partners and specialists to strengthen protected area management, environmental governance, and local community empowerment, promoting community-based tourism and empowering Indigenous women and youth as conservation leaders.
• Climate Action LAC, which promotes climate action in line with the long-term objectives of adaptation, mitigation, transparency, and financing of the Paris Agreement.

Health impacts of air pollution

Air pollution is a mix of hazardous substances from both human-made and natural sources. It is a major threat to global health and prosperity, causing more than 6.5 million deaths each year worldwide. Almost every organ in the body can be impacted by air pollution.

In Mexico, Central America, and the Caribbean, air pollution is a significant issue, particularly in Mexico City, which was once named the world's most polluted city. The basin-like topography of Mexico City, surrounded by mountains, traps air pollutants, and its high altitude causes oxygen levels to be 25% lower. The city's rapid population growth, industrialization, and proliferation of vehicles have resulted in severely poor air quality. However, Mexico City has made notable improvements, dropping to the 917th most polluted city in the world in 2021.

The health impacts of air pollution are far-reaching and affect multiple organ systems. The main pathway of exposure is through the respiratory tract, leading to inflammation, oxidative stress, immunosuppression, and mutagenicity in cells. Fine particulate matter, such as PM2.5, can penetrate deep into the lungs, enter the bloodstream, and travel to various organs, causing systemic damage to tissues and cells. Short-term exposure to high levels of particulate matter can lead to reduced lung function, respiratory infections, and aggravated asthma. Long-term exposure increases the risk of non-communicable diseases, including stroke, heart disease, chronic obstructive pulmonary disease, and cancer.

Maternal exposure to air pollution during pregnancy is associated with adverse birth outcomes, such as low birth weight, pre-term birth, and intrauterine inflammation, which can disrupt fetal growth and development. Air pollution may also affect neurological development in children and increase the risk of neurological disorders. Additionally, air pollution contributes to respiratory diseases, diabetes mellitus, obesity, reproductive disorders, and immune system dysfunction.

The impacts of air pollution are not limited to physical health. Psychosocial stress, such as poverty and racial discrimination, can amplify the harmful effects of air pollution. Disadvantaged communities of color are disproportionately affected by air pollution due to the placement of pollution sources, such as power plants and industrial facilities, in their neighborhoods.

Pollution from wildfires

Mexico, Central America, and the Caribbean have all experienced air pollution from wildfires. In 2019, the Ministry of Environment and Natural Resources reported that at least 66 fires had broken out in the capital, with another 130 in the State of Mexico, bordering Mexico City. The topographical location of Mexico City—in a basin surrounded by mountains—has contributed to the trapping of air pollutants. The city's substantial increase in population, manpower, and human activities during the 20th century also played a role in its poor air quality.

Mexico City was once named the world's most polluted city. Although its air quality has improved, with the city dropping to 917th place in 2021, its concentration of airborne particles (PM 2.5) still exceeds World Health Organization guidelines. The frequent activity of the nearby volcano Popocatépetl has also been linked to increased contamination levels in the city.

Wildfires in Central and Southern Chile in early 2023 resulted in at least 23 deaths and significantly impacted air quality. More than 400 fires, many of them intentional, burned large areas of plantations and woods. The combination of high temperatures, winds, and an ongoing drought fuelled the fires. The National Air Quality Information System recorded increased levels of all air pollutants, leading to a drastic rise in short-term ozone exposure.

Wildfires can release a mix of chemicals that affect air quality, human health, plants, ecosystems, and crops, ultimately contributing to more carbon emissions and greenhouse gases in the atmosphere. Climate change can indirectly increase the frequency and intensity of heatwaves and prolong droughts, creating conditions that heighten the risk of wildfires and further degrade air quality.

Countries in the Latin America and Caribbean (LAC) region, including Mexico, Chile, and Colombia, have taken steps to address air pollution through initiatives such as the Actions on Air Quality in Latin America and the Caribbean 2022-2025 and the Regional Strategy for Climate Change for the Central America Region (2021-2025). However, long-term, sustainable solutions are still needed to achieve cleaner air in the region.

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