Mexico's Air Pollution Crisis: Reasons And Solutions

Mexico has been facing an air pollution crisis for decades, with Mexico City being labelled the world's most polluted city in 1992. The country's industrialisation and urbanisation, coupled with a lax regulatory framework, have led to a significant decline in air quality. The situation is especially dire in Mexico City due to its topography, which traps pollutants in a basin surrounded by mountains. Various factors contribute to Mexico's air pollution, including industrial growth, vehicle emissions, population growth, and the use of biomass fuels for cooking. The government has implemented policies to address the issue, but citizen participation is crucial in reducing emission levels and improving air quality.

Population growth and industrialisation

Mexico City, the country's capital, has long been known for its poor air quality. From 1950 to 2015, the population of Mexico City increased from three million to twenty million. This population boom was largely due to migrants seeking better opportunities, and it triggered an era of industrialisation. This industrial growth emitted over 11,000 tons of waste material into the atmosphere every day.

The metropolitan area of the valley of Mexico, also called Greater Mexico City, saw its population grow from 3.1 million in the 1950s to 14 million in the 1980s. This rapid growth in population, together with the increase in manpower and human activities, resulted in severely poor air quality.

The proliferation of vehicles is another factor that has contributed to the air pollution in Mexico City. In 1980, there were 124 cars and light-duty trucks per 1000 residents. By 2010, this number had increased to 267. The number of vehicles in the city continues to increase annually, and as the city spreads out, automobile trips become longer. As of 2022, there were around 55 million vehicles in the country, with a rate of 358 vehicles per 1000 people.

Industrial activities are also a major contributor to Mexico City's air pollution. Non-regulated and highly polluting factories, power plants, and oil refineries operated all over the city. The topography of Mexico City did not favour its industrialisation, as the city is located in a basin where air pollutants tend to be trapped.

The Mexican government has recognised the severity of the air pollution issue and has implemented various policies and regulations to address it. In 1989, the government introduced the "Hoy No Circula" policy, which required vehicles to undergo emissions testing every six months and prohibited underperforming vehicles from being driven on certain days. In the early 1990s, the government reduced leaded gasoline production and closed noncompliant industrial plants. The government has also implemented air quality management programs to reduce emissions, such as removing lead from gasoline and substituting fuel oil in industry and power plants with natural gas.

Poor regulatory framework

One of the critical factors contributing to Mexico's worsening air pollution is the country's inadequate regulatory framework. The country's air quality policies and regulations are characterized by a lack of stringent measures, ineffective enforcement, and a failure to address key sources of pollution comprehensively.

Mexico's air quality management has been traditionally characterized by a sectoral approach, with separate regulations for industries, vehicles, and other sources.

Vehicle emissions

One of the main issues is the proliferation of vehicles. In 1980, there were 124 cars and light-duty trucks per 1,000 residents in Mexico City. By 2010, this number had almost doubled to 267 vehicles per 1,000 residents. The increase in the number of vehicles, coupled with the city's high altitude and geographical basin, has led to a significant rise in air pollutants. Mexico City's elevation of 7,382 feet above sea level means that its oxygen levels are 25% lower than at sea level, exacerbating the effects of vehicle emissions.

The type of vehicles on the road is also a factor. In the 1980s, many of the cars in Mexico City were of poor quality and ran on highly toxic fuel. While the Mexican government has since implemented policies to improve fuel quality and vehicle emissions standards, the rapid increase in the number of vehicles continues to outpace these efforts.

In addition to private vehicles, public transportation vehicles also contribute to emissions. It has been found that public transportation vehicles in Mexico City have largely ineffective catalytic converters, which are essential for reducing gaseous emissions. This is particularly concerning given the high population density and heavy traffic in the city, with over 120 million people in the country today, up from 3 million in 1950.

To combat vehicle emissions, the Mexican government has implemented various policies and programs. These include the "Hoy No Circula" program, which restricts driving based on license plate numbers, and the Mandatory Inspection and Maintenance (I/M) Program, which measures carbon monoxide and hydrocarbon exhaust emission levels. However, these programs have had limited success, with residents continuing to choose private vehicles over public transportation.

Wildfires

The combination of wildfires and agricultural burns, coupled with persistent southerly winds, has resulted in air quality issues along the Gulf Coast, from Texas through Florida. The smoke from these fires has been visible on satellite imagery, and the high levels of haze have impacted visibility.

Mexico's topography and climate also play a role in the impact of wildfires on air quality. The country's drought conditions, with 82% of the country experiencing unusually dry weather and nearly 70% under drought conditions, provide the perfect fuel for fires to burn. The dry vegetation and forests, coupled with poor forest management and deforestation, have exacerbated the scale and severity of the fires.

The effects of wildfires on air quality are particularly concerning for public health. The smoke from wildfires contains particulate matter (PM2.5) and volatile organic compounds, which can have detrimental effects on human health, especially for those with pre-existing respiratory diseases. The increase in the intensity and frequency of wildfires in Mexico, driven by climate change, contributes to a vicious cycle of global warming and air pollution.

In addition to the immediate impacts on air quality, wildfires also have long-term consequences. They destroy valuable land, displace communities, and eliminate entire habitats. The Mexican government's recent decision to cut budget funds to CONAFOR, the agency responsible for forest conservation and restoration, may hinder mitigation and recovery efforts.

Topography and climate

The topography and climate of Mexico City play a significant role in the city's air pollution issues. The city is located in a basin surrounded by mountains, which creates a bowl-like structure. This geographic characteristic prevents the dispersion of air pollutants, trapping them within the city. The high altitude of Mexico City, at 7382 feet (2300 meters) above sea level, further contributes to the air quality problems. The oxygen levels at this altitude are 25% lower, impacting the combustion of carbon-based fuels and leading to the release of incomplete combustion byproducts.

The climate in Mexico City also influences air pollution levels. The spring season, which is typically hot and dry, provides favourable conditions for the formation of ground-level ozone, a significant air pollutant. Ozone is formed through the interaction of nitrogen oxides (NOx) with volatile organic compounds (VOCs), and the high levels of ultraviolet (UV) radiation from the sun during this season accelerate the reaction. Additionally, the dry season in Mexico City, from November to May, experiences high-pressure systems centered around 20°N, which further contribute to poor air quality.

The basin-like topography of Mexico City, coupled with the surrounding higher mountains, creates a natural barrier that prevents the ventilation of polluted air. This results in the accumulation of industrial, economic, and transport-related air pollutants. The city's constrained basin geography and intense solar radiation further exacerbate the air quality problems, leading to a mix of primary and secondary pollutants.

Mexico City's unique topography and climate have significant implications for air quality. The combination of geographic characteristics and meteorological conditions creates an environment where air pollutants are trapped and concentrated, posing challenges to the city's efforts to improve air quality and protect public health. The interaction between topography and climate highlights the complexity of addressing air pollution in Mexico City and underscores the need for comprehensive solutions that take into account the city's natural environment.

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