The world’s most polluted cities rank among the top 20 highest. All except one person are in Asia

All of these are in Asia except for the world’s most polluted cities last year, a new study shows.

Most of these cities (13) are the most populous country in India, where economic growth is largely expelled from coal and hundreds of millions of people live in large cities with congested traffic and crowded.

The other four are in neighboring Pakistan, in China and Kazakhstan.

The only city outside Asia on the list is n’djamena, the capital of Chad in Central Africa, which is named the worst air pollution.

Meanwhile, the most polluted cities in North America are all in California.

A report by Swiss company IQAIR, which tracks global air quality, specializes in fine particulate matter, or PM2.5 is one of the smallest but most dangerous pollutants.

PM2.5 comes from sources such as fossil fuels, dust storms and wildfires. It is so small – 1/20th the width of human hair, that it can enter your lungs or blood through the body’s usual defense.

Granules can cause irritation and inflammation and are associated with respiratory problems and chronic kidney disease. Exposure can cause cancer, stroke, or heart attack and is associated with a higher risk of depression and anxiety.

The World Health Organization (WHO) said that the average annual level of PM2.5 should not exceed 5 micrograms per cubic meter.

Byrnihat, an industrial town in northeastern India, had a PM2.5 concentration of 128.2 last year, more than 25 times the World Health Organization standard.

“Byrnihat has been leading the list, which makes me feel very sad and helpless,” Suman Momin, 26, who lives in a city of about 70,000 people, told CNN.

She accused the factories around the town, as well as the thriving construction industry and the contribution of the trees to the toxic air.

“The pollution is particularly bad at the moment, the visibility is not very good, there is dust everywhere, and my eyes are burning,” she said.

“I won’t leave home without a mask.”

The other twelve cities in the top 20 are in India.

Its capital, New Delhi, has become the world’s most polluted capital for the sixth consecutive year, with a concentration of PM2.5 of 91.8. The report also lists six satellite cities – Faridabad, Loni, Delhi, Gurugram, Noida and Greater Noida – on the list.

Just last November, a pile of throat smoke shrouded Delhi’s smoke, damaging flights, blocking buildings and prompting the city’s chief minister to declare a “medical emergency.”

But overall, India is the most populous country in the world, with 1.4 billion people falling from third to fifth from the previous year.

But the report said air pollution “stills a significant health burden…reduces life expectancy by about 5.2 years.”

India’s neighbors Bangladesh and Pakistan (with about 400 million people) are second and third in the world to pollute PM2.5 molecules, the report said.

China, which has ranked globally in the world’s worst air in the past, pointed out that China’s progress is small.

The report said its national annual PM2.5 concentration dropped from 32.5 micrograms per cubic meter to 31, with air quality improving in major cities such as Beijing, Shanghai, Chengdu, Guangzhou, Guangzhou and Shenzhen.

China is the world’s largest carbon dioxide emitter, but in recent years a campaign against air pollution has been launched, especially in cities that drive its economic growth and has driven a massive expansion of solar and wind energy.

But last month, what the two clean energy groups said to them was the plan of China’s power industry, which lasted nearly 100 GW of new coal-fired power plants last year.

The IQ Aviation report shows that among all the most polluted cities in the world last year, the world’s worst cities exceeded the WHO PM2.5 guidelines by more than 10 times.

Data gap

“Air pollution still poses a critical threat to human health and environmental stability, but large populations remain unaware of its exposure levels,” said Frank Hammes, global CEO of IQAIR.

Iran and Afghanistan did not appear in this year’s report due to lack of data availability.

The report found that air quality monitoring in Southeast Asia is also a problem, with almost all countries having “a big gap in government-led initiatives.”

It said that in 2024, 173 of the 392 cities in the region lacked government monitoring stations, while Cambodia did not.

The problems could be exacerbated after the U.S. announced earlier this month that the U.S. would stop sharing air quality data from embassy and collected air quality data worldwide, as reported by the Associated Press.

“Air quality data saved lives,” Hams said.

“It creates much-needed awareness, provides information for policy decisions, guides public health interventions, and empowers communities to take action to reduce air pollution and protect future generations.”

The worst city in North America

The report said that of the 8,954 cities around the world involving air quality, only 17% comply with the WHO pollution guidelines.

The report says the most air pollution cities in North America are Ontario, Bloomington and Huntington Park – both in California.

Overall, the PM2.5 level in the United States dropped significantly last year, with an annual average dropping by 22% from 2023.

North America has long had a powerful air quality monitoring system, accounting for 56% of the total number of ground air quality monitoring stations included in the IQ air report – helping scientists continue to study air quality and help makers to determine public health.

Only 12 countries, regions and regions recorded PM2.5 concentrations below WHO guidelines, most of which were in Latin America, the Caribbean or Oceania.

The report calls on government funds specifically for renewable energy projects and “strengthening emission restrictions on vehicle and industrial activities”.

Suman is advised to wish Byrnihat’s authorities to save her city again next year at the top of the most polluted list.

“For years, people around them have had breathing problems, too,” she told CNN.

“This is my birthplace. I am a local. I don’t want to leave this area. We want the government to do more and work together for us.”

Aishwarya S Iyer contributed the report

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