The world’s 100 most polluted cities are in Asia, and 83 of them are in just one country.

All but one of the cities with the world’s worst air pollution last year were in Asia, according to a new report, with the climate crisis playing a central role in poor air quality that endangers people’s health. billion people around the world.

The vast majority of these cities – 83 – were in India and all exceeded the World Health Organization’s air quality guidelines by more than 10 times, according to the report from IQAir, which tracks quality air around the world.

The study focused specifically on fine particles, or PM2.5, which are the smallest pollutant but also the most dangerous. Only 9% of the more than 7,800 cities analyzed worldwide recorded air quality that met the WHO standard, according to which average annual PM2.5 levels should not exceed 5 micrograms per cubic meter.

“We see that air pollution impacts every aspect of our lives,” said Frank Hammes, CEO of IQAir Global. “And generally, in some of the most polluted countries, it probably reduces between three and six years of life. And before that, it will lead to many years of suffering that would be entirely avoidable if air quality were better.”

When inhaled, PM2.5 penetrates deep into the lung tissues where it can enter the bloodstream. It comes from sources such as fossil fuel burning, dust storms and wildfires, and has been linked to asthma, heart and lung disease, cancer and other respiratory illnesses, as well as cognitive disorders in children.

Begusarai, a city of half a million people in the northern Indian state of Bihar, was the world’s most polluted city last year with an average annual concentration of PM2, 5 of 118.9, or 23 times the WHO guidelines. It was followed in the IQAir ranking by the Indian cities of Guwahati, Assam; Delhi; and Mullanpur, Punjab.

Across India, 1.3 billion people, or 96% of the population, live with air quality seven times higher than WHO guidelines, the report said.

Central and South Asia were the worst-performing regions in the world, home to the four most polluted countries last year: Bangladesh, Pakistan, India and Tajikistan.

South Asia is particularly worrying, with 29 of the 30 most polluted cities in India, Pakistan or Bangladesh. The report ranks the major population centers of Lahore at 5th, New Delhi at 6th and Dhaka at 24th.

Hammes said no significant improvement in pollution levels in the region was likely without “major changes in energy infrastructure and agricultural practices.”

“What is also worrying in many parts of the world is that the things that cause outdoor air pollution are sometimes also the things that cause indoor air pollution,” he added. “So cooking with dirty fuel will create indoor exposures that could be several times greater than what you see outdoors.”

A global problem

IQAir found that 92.5% of 7,812 sites in 134 countries, regions and territories where average air quality was analyzed last year exceeded WHO guidelines on PM2.5.

Only 10 countries and territories had “healthy” air quality: Finland, Estonia, Puerto Rico, Australia, New Zealand, Bermuda, Grenada, Iceland, Mauritius and French Polynesia.

Millions of people die each year from health problems linked to air pollution. Air pollution from fossil fuels kills 5.1 million people worldwide each year, according to a study published in the BMJ in November. Meanwhile, the WHO says that 6.7 million people die each year from the combined effects of ambient and household air pollution.

The man-made climate crisis, caused by the burning of fossil fuels, plays a “crucial” role in influencing air pollution levels, the IQAir report said.

The climate crisis is altering weather patterns, leading to changes in winds and precipitation, which affects the dispersion of pollutants. Climate change will only make pollution worse as extreme heat becomes more severe and more frequent, he said.

The climate crisis is also leading to more severe wildfires in many regions and longer, more intense pollen seasons, which exacerbate health problems linked to air pollution.

“We have a very strong overlap between what is causing our climate crisis and what is causing air pollution,” Hammes said. “Anything we can do to reduce air pollution will have a huge long-term impact on also improving our climate gas emissions, and vice versa. »

Regional rankings

North America was hit hard by the wildfires that raged in Canada from May to October last year. In May, Alberta’s monthly air pollution average was nine times higher than the same month in 2022, the report said.

And for the first time, Canada has overtaken the United States in regional pollution rankings.

Wildfires have also affected U.S. cities like Minneapolis and Detroit, where annual pollution averages have increased 30 to 50 percent from the previous year. The most polluted major U.S. city in 2023 was Columbus, Ohio, for the second year in a row. But major cities like Portland, Seattle and Los Angeles saw significant declines in average annual pollution levels, the report said.

In Asia, however, pollution levels have rebounded across much of the region.

China has reversed a five-year trend of falling pollution levels, the report said. Chinese cities once dominated global rankings for the world’s worst air quality, but a series of air quality policies over the past decade have transformed the situation for the better.

A study last year found the campaign meant the average lifespan of the Chinese citizen was now 2.2 years longer. But thick smog returned to Beijing last year, where citizens experienced a 14% increase in average annual PM2.5 concentration, according to the IQAir report. Hotan, the most polluted city in China, ranks 14th in the IQAir ranking.

In Southeast Asia, only the Philippines recorded a decline in annual pollution levels compared to the previous year, the report said.

Indonesia was the most polluted country in the region, with an increase of 20% compared to 2022. Indonesia, Vietnam and Thailand all had cities that exceeded WHO guidelines by more than 10 times on PM2.5, according to the report.

Last month, Thai authorities ordered government employees to work from home due to unhealthy pollution levels in the capital Bangkok and surrounding areas, according to Reuters. Tourism hotspot Chiang Mai was the world’s most polluted city on Friday as toxic smog brought by seasonal agricultural fires blanketed the northern city.

Inequalities… and a positive point

The report also highlights a worrying inequality: the lack of monitoring stations in countries in Africa, South America and the Middle East, leading to a shortage of air quality data in these regions.

Although Africa saw an improvement in the number of countries included in this year’s report compared to previous years, the continent remains largely the most underrepresented. According to IQAir, only 24 of 54 African countries had sufficient data from their monitoring stations.

Seven African countries were among the new sites included in the 2023 ranking, including Burkina Faso, the fifth most polluted country in the world, and Rwanda, 15th.

Several countries that were high on the list of most polluted countries last year were not included for 2023 due to lack of available data. Among them, Chad, which was the most polluted country in 2022.

“There is still so much hidden air pollution on the planet,” Hammes said.

One bright spot is growing pressure and civic engagement from communities, NGOs, businesses and scientists to monitor air quality.

“At the end of the day, it’s great because it really shows governments that people care,” Hammes said.

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