Air Pollution: The World's Most Polluted Cities

Air pollution is a pressing global issue, causing millions of premature deaths annually and triggering asthma attacks, harming lung development in children, and more. The primary sources of air pollution are the burning of fossil fuels in power plants and vehicles, with nitrogen oxide emissions reacting with UV rays to form smog. In 2024, only 17% of cities met the WHO's PM2.5 guideline, indicating that urban populations worldwide are at risk. This text will explore the cities with the worst air pollution, focusing on the role of particulate matter and the efforts to combat this deadly issue.

India: Home to 11 of the top 20 most polluted cities in 2024

Air pollution is a deadly environmental threat, causing millions of premature deaths each year. In 2024, only 17% of cities worldwide met the World Health Organization's annual PM2.5 guideline of less than 5 µg/m3. This means that the vast majority of urban populations are exposed to unhealthy air.

India is home to some of the world's most polluted cities, with 11 of the top 20 most polluted cities in 2024. Byrnihat, a city in northeastern India, recorded the worst air pollution globally in 2024, with a PM2.5 concentration of 128.2 micrograms per cubic meter—over 25 times higher than the World Health Organization's recommended limit. Other Indian cities with poor air quality include New Delhi, which was ranked as the capital with the worst air quality in the world in 2021. On average, Indian cities exceed WHO guidelines for PM2.5 in the atmosphere by 10 times.

Air pollution in India is caused by various factors, including vehicular traffic fumes, diesel generators, and the burning of fossil fuels for cooking by poorer families. The country has been making efforts to improve air quality, with the National Clean Air Programme aiming to reduce air pollution levels by up to 30% by 2024. India is also planning the world's largest expansion of renewable energy by 2022 and has seen some promising progress in this regard. However, the impact of these initiatives remains to be seen in the coming years.

It is worth noting that other countries, such as China, have also been facing significant air pollution issues. Chinese officials reported that Beijing met state air quality standards for the first time in 2020, ahead of schedule. China has been investing heavily in solar energy, reducing coal consumption, and addressing emissions from transportation. By 2024, China is expected to generate twice as much power from solar as the US.

Byrnihat: A city in northeastern India with the worst air pollution in 2024

Air pollution is one of the most significant environmental threats, causing millions of premature deaths each year. In 2024, only 17% of cities worldwide met the World Health Organization's annual PM2.5 guideline of less than 5 µg/m3. This indicates that a large majority of the global population is exposed to poor air quality.

India is home to some of the world's most air-polluted cities, with 11 of the top 20 polluted cities in 2024. Byrnihat, a city in northeastern India, recorded the worst air pollution globally in 2024, with a PM2.5 concentration of 128.2 µg/m3. This figure is over 25 times higher than the World Health Organization's recommended limit.

The high levels of air pollution in Byrnihat and other cities in India are attributed to various factors, including burning fossil fuels, agricultural practices, vehicle emissions, and rapid urbanization. These activities contribute to dangerous chemical reactions in the atmosphere, leading to hazardous air quality.

The effects of air pollution on human health are significant. Exposure to unsafe air quality is linked to increased mortality rates and various health issues. These include respiratory and viral infections, asthma, cancer, stroke, and lung disease. It can also impair children's cognitive development and exacerbate mental health issues and pre-existing conditions such as diabetes.

The Indian government and local authorities have implemented measures to combat air pollution and mitigate its impacts. However, the severity of the pollution in Byrnihat and other Indian cities underscores the urgent need for more comprehensive solutions and sustainable practices to improve air quality and protect public health.

China: The world's biggest polluter, but investing heavily in solar energy

China has long been regarded as the world's biggest polluter, with 1.25 million Chinese people dying prematurely each year from air pollution. However, in recent years, the country has made significant efforts to reduce pollution, particularly in major cities. Since 2005, there has been a notable decline in the number of homes cooking with coal or wood, dropping from 61% in 2005 to 32% in 2017. Beijing, for instance, has banned coal heating, opting instead for natural gas, and clean energy initiatives have been promoted countrywide.

Despite these improvements, China recognizes the urgency of addressing its air pollution crisis, which continues to claim lives and adversely affect the health of its citizens. Notably, China has emerged as a global leader in solar energy investment, currently accounting for 45% of all global investments in this sector. This commitment to solar energy is expected to yield significant results, with projections indicating that by 2024, China will be generating twice as much power from solar sources as the United States.

China's transition toward renewable energy sources is not limited to solar power alone. The country is also planning the world's largest expansion of renewable energy by 2022, encompassing a diverse range of clean energy sources. This ambitious undertaking reflects China's recognition of the imperative to reduce its reliance on fossil fuels and mitigate the devastating environmental and health impacts of air pollution.

While China's efforts to curb pollution and invest in renewable energy are commendable, it is essential to acknowledge that the country still has a long way to go in combating this issue. The air pollution problem in China remains a pressing concern, and continued dedication to implementing and enforcing sustainable practices is vital. Nonetheless, China's recent initiatives offer a glimmer of hope in the global fight against air pollution and its devastating consequences.

Beijing: Banned coal heating in favour of natural gas and clean energy

Air pollution is a significant environmental threat, causing millions of premature deaths annually. In 2024, India was home to some of the world's most air-polluted cities, with 11 of the top 20 cities. However, Beijing, China, has also been notorious for its poor air quality, largely due to coal-fired power plants and stoves used for heating in the winter.

Recognizing the health and environmental impacts of coal, Beijing has taken significant steps to address this issue by banning coal heating in favor of natural gas and clean energy. In March 2017, the city shut down its last coal-fired power plant, marking a pivotal moment in its transition to cleaner energy sources.

The Chinese government's coal-to-clean heating policy (CHP), implemented in 2015, played a crucial role in this transformation. The CHP banned household coal burning and provided subsidies for clean electric or gas-powered heating for millions of households. This policy not only improved air quality but also had potential cardiovascular benefits for the population, as suggested by a study on the incidence of acute myocardial infarction in Beijing townships.

However, the transition to natural gas and clean energy in Beijing was not without challenges. In 2017, China faced a natural gas shortage as a result of the coal ban. The surge in demand for natural gas, particularly for heating, outpaced the available supply. This disruption highlighted the complexities of shifting away from coal, as it forced some chemical plants and factories to shut down and even led to heating shortages in certain areas.

Despite these initial setbacks, Beijing remains committed to promoting clean energy for winter heating in its northern region. China is investing in the development of shale gas and other clean energy sources, aiming to increase natural gas's contribution to the country's total energy supply. Beijing's efforts to reduce coal consumption and improve air quality are ongoing, demonstrating the city's dedication to creating a healthier and more sustainable environment for its residents.

N'Djamena: The only non-Asian city in the top 20 most polluted cities in 2024

Air pollution is a major environmental threat, causing millions of premature deaths each year. In 2024, only 17% of cities worldwide met the World Health Organization's annual PM2.5 guideline of less than 5 µg/m3. This means that the vast majority of urban populations are exposed to unhealthy air.

India is home to some of the world's most air-polluted cities, with 11 of the top 20 most polluted cities in 2024. Byrnihat, a city in northeastern India, recorded the worst air pollution globally in 2024, with a PM2.5 concentration of 128.2 µg/m3—over 25 times higher than the World Health Organization's recommended limit.

However, N'Djamena, the capital of Chad, was the only non-Asian city to rank among the top 20 most polluted cities in 2024. The main pollutant in N'Djamena is PM2.5, with a concentration of 80 µg/m3, which is 16 times higher than the World Health Organization's annual PM2.5 guideline value.

The high levels of air pollution in N'Djamena can be attributed to various factors, including dust storms, vehicle emissions, and industrial activities. The city is also located in a region that experiences frequent sandstorms, which can worsen the air quality.

The effects of air pollution in N'Djamena are severe, with potential impacts on the health and well-being of its residents. Particulate matter, such as PM2.5, can have harmful effects when inhaled, as the particles are small enough to bypass the body's natural defenses. This can lead to an increased risk of respiratory and cardiovascular problems, as well as other adverse health outcomes.

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