Visual Pollution In Mexico City: An Unseen Crisis

Mexico City has been notorious for its air pollution, which has been a concern for the city's population and health officials for decades. The city's high altitude, rapid industrialization, and proliferation of vehicles have all contributed to poor air quality. While it was once named the world's most polluted city, Mexico City has since dropped to the 917th most polluted city in the world as of 2021. Despite this improvement, the city still faces challenges in reducing air pollution, and it continues to be an issue that affects the health and quality of life of its residents. With a focus on reducing emissions, modifying mobility systems, and prioritizing public and active transport, there is hope that Mexico City can further improve its air quality and create a healthier environment for its citizens.

Air pollution in Mexico City: causes and effects

Mexico City was once labelled the world's most polluted city by the United Nations in 1992. The metropolis's high altitude of 7382 feet above sea level results in oxygen levels that are 25% lower than at sea level. In addition, carbon-based fuels do not combust completely at this altitude, leading to further air quality issues. The city's topography, located in a basin, also means that air pollutants are trapped. The combination of these natural factors with human activities such as industrialization, population growth, vehicle emissions, and the burning of fossil fuels has resulted in poor air quality.

During the 20th century, Mexico City underwent rapid industrialization and urbanization, resulting in a substantial increase in population. The number of residents in the metropolitan area, also known as Greater Mexico City, grew from 3.1 million in the 1950s to 14 million in the 1980s and further to 20 million by 2015. This population boom was driven by migrants seeking better opportunities. The industrialization era that followed this population growth emitted over 11,000 tons of waste material into the atmosphere daily.

Air pollution in Mexico City is primarily caused by human activities, with ground-level ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide, and airborne particles (PM 2.5 and PM10) being the major pollutants. These pollutants are generated from burning fossil fuels in power plants, vehicle emissions, and industrial processes. The proliferation of vehicles, especially those running on toxic fuel, has contributed significantly to the city's air pollution. In the 1980s, there were about 124 cars per 1,000 residents, and these vehicles were made with poor-quality standards. Additionally, unregulated and highly polluting factories, power plants, and oil refineries were operating throughout the city.

The effects of air pollution in Mexico City are severe, with about one in seventeen (5.9%) of all deaths in the country attributed to poor air quality. It is the eighth leading cause of death in Mexico, after factors such as diet, overweight, high blood pressure, alcohol and drug use, smoking, and lack of exercise. The pollutants in the air can lead to chronic lung disease, acute respiratory infections, lung cancer, heart disease, and strokes. The most harmful airborne particles are known as PM2.5, which are less than 2.5 thousandths of a millimetre across and can penetrate deep into the lungs. The World Health Organization (WHO) has set a limit for average outdoor ambient air pollution of 10 micrograms of PM2.5 per cubic metre of air (10 µg/m3). However, Mexico City's annual concentration of PM10 has been above the limit for over a decade, with the highest levels recorded in November 2019, exceeding 110 µg/m3.

To address air pollution, the Mexican government has implemented several plans to reduce emission levels. These plans include citizen participation, vehicular restrictions, increasing green areas, and expanding bicycle accessibility. Additionally, the activation of policies like the ACEP during the spring season has become necessary due to the seasonal high levels of air pollution from climate change. While Mexico City has made significant improvements, dropping to the 917th most polluted city in the world in 2021, it still exceeds the WHO's guidelines for PM 2.5 concentrations.

The impact of air pollution on human health

Mexico City has long struggled with air pollution, previously earning the title of the world's most polluted city. While it has since dropped to 917th place in global rankings, air pollution in the city still exceeds World Health Organization guidelines. The causes of this pollution include industrialization, urbanization, vehicle emissions, and the burning of fossil fuels.

Air pollution has been identified as a significant threat to human health, causing millions of deaths each year. It is a mix of hazardous substances from both human-made and natural sources. Human-made sources include vehicle emissions, fuel oils, and natural gases used to heat homes, as well as by-products of manufacturing and power generation. Natural sources include smoke from wildfires, ash and gases from volcanic eruptions, and gases emitted from decomposing organic matter in soils.

The main pathway of exposure to air pollution is through the respiratory tract. Pollutants can cause inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout the body, impacting the lungs, heart, brain, and other organs. Fine particulate matter, such as PM2.5, is of particular concern as it can be inhaled deeply into the lungs, enter the bloodstream, and travel to other organs, causing systemic damage to tissues and cells. This can lead to a range of health issues, including respiratory illnesses, cardiovascular disease, neurological problems, and cancer.

The health impacts of air pollution vary depending on the types, sources, and concentrations of pollutants, as well as individual factors such as age, pre-existing health conditions, and socioeconomic status. Children, older people, and those with pre-existing health conditions are generally more vulnerable to the negative effects of air pollution. Additionally, individuals with lower socioeconomic status often face increased exposure due to their proximity to busy roads or industrial areas.

In Mexico City, the IMECA index is used to assess the level of pollution and the associated health risks. The index categorizes air quality as "good," "fair," or "poor," with corresponding recommendations for protecting public health. Despite efforts to reduce air pollution, it continues to pose a risk to the health of residents, with 15.5% of respondents in one study reporting respiratory illnesses in their households.

Government initiatives to combat air pollution

Mexico City has been ranked as the world's most polluted city. However, it has successfully managed to reduce air pollution and is now ranked 917th. The Mexican government has implemented various initiatives and policies to combat air pollution, which still poses a significant threat to public health.

One notable initiative is the Breathe Cities initiative, which Mexico City recently joined. This global partnership, which includes 14 cities, aims to tackle urban air pollution by sharing data, community engagement strategies, and knowledge among city leaders. The initiative is delivered by Bloomberg Philanthropies, the Clean Air Fund, and C40 Cities. Mexico City's participation in the Breathe Cities initiative underscores its commitment to tackling toxic air and improving public health.

The Mexican government has also taken several active measures to reduce emission levels. These include vehicular restrictions, such as the "Hoy No Circula" program, which restricts driving on certain days of the week, and the expansion of public transportation. The government has also closed or moved polluting factories and required the reformulation of gasoline. In addition, Mexico City has implemented programs to promote bicycle accessibility and increase green spaces.

Another initiative is the Mexican Atmospheric Environmental Contingency Plan (AECP), which includes further restrictions on vehicle use and limits on greenhouse gas emissions from factories. This plan is activated during seasons with high levels of air pollution, such as spring.

While Mexico has made significant progress in reducing air pollution, it still faces challenges. The country has yet to set a net-zero target, and current environmental policies lack sufficient financial and political backing from the federal government. As Mexico continues to address air pollution, these initiatives and policies are crucial steps toward creating a healthier and more sustainable environment for its citizens.

The role of topography in trapping air pollutants

Mexico City has been dubbed the "most polluted city in the world" by the UN in 1992. The city's high altitude, industrialization, vehicle emissions, and population growth have all contributed to its poor air quality. Notably, Mexico City's topography has played a significant role in trapping air pollutants.

Topography plays a crucial role in influencing wind patterns, which, in turn, affect the dispersion of air pollutants. The shape of the land, including mountains, valleys, and hills, can either accelerate or hinder wind speed and direction. For example, mountains can act as barriers to wind movement, leading to the formation of wind shadows on the leeward side. In contrast, valleys and low-lying areas can experience reduced air circulation, causing pollutants to become trapped and resulting in higher pollution levels.

In the case of Mexico City, its location in a basin has contributed to the trapping of air pollutants. The surrounding mountain ranges can block the horizontal transport of smog and other pollutants, causing them to accumulate on one side. This effect is exacerbated when wind speeds are insufficient to carry the pollutants over the ridges, leading to higher concentrations of pollutants in the basin.

Additionally, temperature inversions can occur in certain topographic settings, such as valleys or basins surrounded by mountains. A temperature inversion happens when a layer of warm air acts as a lid, trapping a layer of cooler air and pollutants close to the surface. This phenomenon can further contribute to the trapping of air pollutants in low-lying areas like Mexico City.

The complex interaction between topography and wind patterns influences the dispersion and concentration of air pollutants. By understanding these relationships, we can develop effective strategies to mitigate air pollution and protect public health and the environment.

In summary, topography plays a significant role in trapping air pollutants, and this effect is particularly relevant in the case of Mexico City due to its specific geographic characteristics.

Strategies for reducing visual pollution in Mexico City

Mexico City has been ranked as one of the most polluted cities in the world. The city's high altitude, topography, and industrialization have contributed to its poor air quality. While there has been a significant improvement in recent years, the concentration of airborne particles still exceeds the World Health Organization's guidelines. To address this issue, the following strategies can be implemented to reduce visual pollution in Mexico City:

• Promote the use of public transport and active transport: The Mexican government should prioritize the development and improvement of public transportation systems, such as electric buses, trains, and subways. Additionally, investing in infrastructure that encourages active transport, such as cycling and walking, can help reduce vehicle emissions, a major source of air pollution in the city centre.
• Restrict vehicular circulation: Implementing vehicular restrictions, such as limiting the number of cars circulating in the city and enforcing stricter emission standards, can effectively reduce emissions and improve air quality. The current vehicle verification process in Mexico City allows cars to transit on certain days of the week based on their emission levels.
• Expand green areas: Increasing the number of parks, gardens, and green spaces in the city can help absorb pollutants and improve air quality. Green areas also provide spaces for recreation and contribute to the overall well-being of residents.
• Educate the population: Raising awareness about air pollution and its health implications is crucial. Educational campaigns can encourage citizens to take individual actions, such as reducing vehicle usage, switching to cleaner energy sources, and adopting sustainable practices, ultimately contributing to a collective effort to improve air quality.
• Strengthen inspection and surveillance systems: Illegal changes in land use, particularly for agricultural expansion, have contributed to deforestation, which further exacerbates air pollution. By strengthening inspection and surveillance, the government can better regulate land use practices and work towards achieving its goal of zero deforestation by 2030.
• Address indoor air pollution: The use of organic fuels for cooking and heating is a significant source of indoor air pollution. Promoting cleaner and more sustainable alternatives, such as electric or solar power, can help reduce indoor air pollution and improve the overall air quality in the city.

By implementing these strategies and continuing to prioritize environmental initiatives, Mexico City can effectively reduce visual pollution and improve the health and well-being of its residents.

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