Mexico Vs. Us: Who's More Polluted?

Mexico City has been a source of concern for its citizens and health officials due to its high levels of air pollution. The city was once named the world's most polluted city, but it has since dropped to the 917th most polluted city in the world. Despite this improvement, the city still faces challenges in reducing air pollution, with issues such as industrial growth, population increase, and vehicle emissions contributing to the problem. The Mexican government has implemented plans to reduce emission levels, but the country's ambition to fight climate change is considered insufficient due to the lack of a concrete decarbonization plan. The effects of air pollution are felt disproportionately by the poor, with informal workers suffering worse health and income losses than those in more privileged positions.

Mexico City's air pollution

Mexico City has long struggled with air pollution, which has been a concern for the city's population and health officials for decades. In 1992, the United Nations declared Mexico City the most polluted city in the world. 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, and a proliferation of vehicles.

The population of Mexico City grew substantially in the 20th century, with migrants from all over the world seeking better opportunities. This rapid and unexpected growth, coupled with industrialization, led to a significant decline in air quality. By the 1980s, the city's air pollution had reached its peak, with ground-level ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide, and airborne particles all at record levels. The topography of the city, located in a basin, also meant that air pollutants were trapped, further worsening the situation.

The Mexican government has implemented various measures to combat air pollution in recent decades. These include requiring the reformulation of gasoline, closing or relocating polluting factories, and restricting vehicle usage to one day per week. More recently, there has been an expansion of public transportation, with the government investing heavily in this area. The government has also incentivized the purchase of cleaner vehicles, built bike lanes, and curbed heavy industry in the city.

While these efforts have led to improvements, air pollution remains a significant issue in Mexico City. In 2016, ozone and suspended matter pollution reached levels detrimental to human health. Ground-level ozone, formed by the interaction of nitrogen oxides and volatile organic compounds, is currently the air pollutant of greatest concern. The climate in Mexico during the spring season, which is typically hot and dry, creates ideal conditions for ozone formation.

The impact of air pollution in Mexico City is felt disproportionately by the poor, with informal workers suffering worse health and income effects. A 2019 survey of lower-income neighbourhoods revealed that nearly 95% viewed air pollution as a significant problem. On days with high levels of PM contamination, informal workers tend to work more than those in formal employment, and they have less ability to compensate for lost hours. This results in serious health implications, with higher hospital admissions for respiratory diseases in areas with large numbers of informal workers.

Population growth and industrial activities

Mexico City has experienced a substantial population increase since the 1950s. The population grew from 3.1 million in the 1950s to 14 million in the 1980s, and currently stands at around 22 million. This rapid population growth has been driven by industrialization, which attracted thousands of migrants from across the globe. The industrialization of Mexico City has resulted in severe air pollution, with over 11,000 tons of waste material being emitted into the atmosphere daily.

The proliferation of vehicles has been a significant contributor to the poor air quality in Mexico City. The number of vehicles in the city has increased over the years, with 267 cars and light-duty trucks per 1,000 residents in 2010, up from 124 in 1980. The increase in vehicles has led to higher emissions, with vehicle exhaust being the source of 75% of emissions in the city. In addition to vehicles, industrial activities such as factories, power plants, and oil refineries have emitted large amounts of pollutants into the atmosphere. The topography of Mexico City, located in a basin, further exacerbates the problem as air pollutants tend to be trapped.

The Mexican government has implemented various measures to combat air pollution, including driving restrictions, incentives for purchasing cleaner vehicles, investments in public transport, and the development of bike lanes. Additionally, there have been efforts to regulate emissions from industries and promote the use of non-polluting energy sources such as natural gas. The government has also mandated the removal of lead from gasoline and the implementation of catalytic converters in automobiles. 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, according to IQAir.

However, despite these improvements, air pollution remains a pressing issue in Mexico City. The concentration of airborne particles (PM 2.5) still exceeds the guidelines set by the World Health Organization (WHO). The city's unique climate, with hot and dry springs, contributes to the formation of ground-level ozone, which is the air pollutant of biggest concern. The interaction of nitrogen oxides (NOx) with volatile organic compounds (VOCs) and ultraviolet (UV) radiation from the sun accelerates the formation of ozone.

The pollution has had significant impacts on the health and income of residents, particularly affecting the poor and informal workers. Studies have shown that recent increases in hospital admissions for respiratory diseases are driven by municipalities with large shares of informal workers, who tend to work more on days with high pollution levels. The economic impact of pollution is also substantial, with approximately $430 million lost in a year due to reduced productivity on days with very high PM contamination.

Vehicle emissions

In Mexico City, the country's capital, air pollution reached alarming levels in the 1980s and 1990s, with ground-level ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide, and airborne particles at record highs. The topography of the city, located in a basin, traps air pollutants, exacerbating the issue. The proliferation of vehicles during this period, coupled with poor vehicle quality and the use of toxic fuel, contributed significantly to the city's air pollution crisis.

To address this, the Mexican government implemented various plans and policies over the years. In 1989, the "Hoy No Circula" program was introduced, restricting vehicles from driving on certain days of the week based on their emissions performance. While this program has undergone adjustments, its effectiveness in improving air quality has been questioned. More recently, the government has focused on promoting public transportation, regulating fuel consumption, and closing or relocating polluting factories.

In 2022, a study by Mogro and Huertas compared vehicle emissions in Los Angeles, Chicago, Mexico City, and Monterrey. They found that the difference in emissions between Mexican and US cities was due to the presence of obsolete technology in Mexico and the lack of mandatory I/M programs. The study also highlighted the impact of older vehicles, with those registered before 2005 accounting for only 7% of the sampled fleet but contributing up to 42% of total emissions across pollutants.

To reduce emissions from the highest-emitting vehicles, local policymakers in Mexico City have recommended strengthening inspection and maintenance programs and providing incentives for replacing high-emitting taxis with lower- or zero-emitting models. The city has also set goals for future emissions reduction by implementing low-emission zones and accelerating the transition to battery-electric vehicles.

While Mexico's vehicle emissions regulations are based on US regulations, the country has historically struggled with higher mean emissions. The discrepancy in emissions between the two countries highlights the need for updated regulatory frameworks, stringent emission standards, and the implementation of sustainable transportation options to improve air quality and protect public health.

Government initiatives

Mexico has made significant strides in reducing air pollution in recent years, dropping from the most polluted city in the world to the 917th in 2021. However, air pollution still exceeds the World Health Organization's (WHO) guidelines, and the country faces challenges such as industrial growth, a growing vehicle population, and frequent wildfires.

• Nationally Determined Contribution (NDC): Mexico has committed to reducing greenhouse gas emissions by 22% by 2030 compared to a business-as-usual scenario. This target is part of the country's climate change commitment and aims to reduce the impact of climate change and improve air quality.
• Integrated SLCP Strategy: Mexico launched its Integrated Short-Lived Climate Pollutants (SLCPs) strategy in December 2019. The strategy, developed by the National Institute of Ecology and Climate Change (INECC), aims to reduce SLCPs, including black carbon, methane, tropospheric ozone, and hydrofluorocarbons (HFCs). The strategy outlines nine mitigation measures across eight key source sectors to achieve these targets.
• General Law on Climate Change (Ley General de Cambio Climático): This law, last updated in 2018, serves as Mexico's national guide for climate change policy. It outlines the federal government's responsibilities in formulating, conducting, and evaluating national waste management policies and programs.
• ProAire Programs: Mexico has 29 ProAire programs that cover 27 federal entities and aim to address air pollution challenges. These programs promote collaboration between different levels of government, industry, academia, and civil society to find solutions, identify emission sources, and implement measures to reduce emissions and improve environmental education.
• National Water Plan (Programa Nacional Hídrico or PNH): The federal government has implemented the National Water Plan for 2020-2024 to address water challenges such as over-exploitation, inadequate infrastructure, drought, and water resource contamination. The plan includes initiatives to modernize infrastructure and improve water management in urban and agricultural areas.
• Mexican Atmospheric Environmental Contingency Plan (AECP): Reactivated in 2016, the AECP includes restrictions on vehicle use, such as the "Hoy No Circula" program, which forbids driving on two days a week to reduce traffic emissions.

• Clean Air Act: This act calls for collaboration between state, local, federal, and tribal governments to implement measures to reduce air pollution. The Environmental Protection Agency (EPA) plays a crucial role in providing guidance, establishing health-based national air quality standards, and reviewing state plans to ensure compliance with the Act.
• Congressional Initiatives: Congress has mandated the phasing out of ozone-depleting chemicals and the implementation of a federal acid rain program to reduce acid rain-forming emissions from power plants that cross state lines.
• Climate and Clean Air Coalition: The US is part of this international partnership hosted by the UN Environment Programme (UNEP), aiming to protect the climate and improve air quality by reducing short-lived climate pollutants.

Health and economic impacts

Mexico has made significant strides in reducing its air pollution levels, dropping from the most polluted city in the world in 1992 to the 917th in 2021. However, air pollution remains a pressing issue with health and economic repercussions.

Health Impacts

Air pollution is linked to various adverse health outcomes in Mexico, including asthma, bronchitis, respiratory infections, and even cancer. It is the eighth-highest cause of death in the country, causing approximately 33,000 premature deaths annually. The concentration of airborne particles, particularly PM2.5, poses the greatest health risk. Exposure to PM2.5 can lead to coughing, shortness of breath, bronchitis, respiratory infections, and heart problems. Children, the elderly, and poorer groups are especially vulnerable to the detrimental effects of air pollution. Studies indicate that individuals from lower-income backgrounds work 20% more on days with hazardous air quality as they cannot afford to take time off, exacerbating their exposure and health risks.

Economic Impacts

Air pollution also inflicts economic losses on Mexico. In Mexico City, high levels of PM2.5 cause workers to lose an average of 7.5% of their working hours, resulting in economic losses of over USD 8 billion in 2020. Air pollution also harms agriculture, with pollutants like ozone damaging crops and reducing yields. The treatment of pollution-related diseases imposes a substantial financial burden on the country's healthcare system, further straining economic resources.

To summarize, while Mexico has shown improvement in reducing air pollution, it continues to grapple with the adverse health and economic consequences. The country needs to address emissions and implement further policies to mitigate these impacts effectively.

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