NEW YORK, March 11:  A new study has revealed that all but one of the world's top 20 most polluted cities last year were located in Asia. The report highlights the alarming air quality in many of the world's most populous nations, particularly India, which accounted for 13 of the cities on the list. India’s rapid economic growth, fueled by coal, and the dense traffic in its megacities have significantly contributed to pollution levels.

Other countries in the region with high pollution levels include Pakistan, which has four cities on the list, and China and Kazakhstan, which each have one city included. The only city outside of Asia to appear on the list is N'Djamena, the capital of Chad, in Central Africa, which was noted for having the worst air pollution in the country.

In North America, cities in California, such as Ontario, Bloomington, and Huntington Park, were among the worst for pollution, according to the report.

The study, conducted by IQAir, a Swiss company that tracks global air quality, focused on fine particulate matter (PM2.5), a particularly harmful pollutant. These tiny particles, which are about 1/20th the width of a human hair, can penetrate deep into the lungs and bloodstream, causing serious health issues like respiratory problems, cancer, heart disease, stroke, and even affecting mental health, with links to depression and anxiety.

The World Health Organization (WHO) recommends that the average annual concentration of PM2.5 should not exceed 5 micrograms per cubic meter. However, many cities on the list far exceeded this threshold. Byrnihat, an industrial town in northeast India, recorded a PM2.5 concentration of 128.2, more than 25 times the WHO limit.

Suman Momin, a 26-year-old Byrnihat resident, expressed frustration over the situation, blaming nearby factories, construction, and deforestation for the pollution. “The pollution is particularly bad right now, visibility is not great, there is dust everywhere, my eyes also burn,” she told CNN. She added that she never leaves home without a mask.

India’s capital, New Delhi, once again topped the list as the world’s most polluted capital, with a PM2.5 concentration of 91.8. This marks the sixth consecutive year the city has held this title. Other cities in India, such as Faridabad, Loni, and Gurugram, also made the top 20. In November, a thick layer of smog blanketed Delhi, leading to disrupted flights and prompting the city's chief minister to declare a “medical emergency.”

Despite the troubling numbers, India has made progress, with the report noting that the country moved from third to fifth place in the global rankings for air pollution. However, air pollution continues to significantly affect public health, reducing life expectancy by an estimated 5.2 years.

The report also highlighted pollution in India’s neighboring countries. Bangladesh and Pakistan ranked second and third, respectively, in terms of PM2.5 concentrations.

China, which has long been a major contributor to global air pollution, saw a slight improvement in its air quality. The report revealed a small decrease in the national average PM2.5 concentration, from 32.5 to 31 micrograms per cubic meter, with improvements in cities like Beijing, Shanghai, and Guangzhou. China has been investing heavily in renewable energy sources such as solar and wind power to reduce its carbon footprint. However, concerns have been raised regarding plans to build new coal plants in the country, which could undermine its progress in combating air pollution.

All 20 cities on the list of the most polluted last year exceeded the WHO’s recommended PM2.5 guidelines by more than 10 times, underscoring the severity of the global air pollution crisis. IQAir’s Global CEO, Frank Hammes, emphasized that air pollution remains a critical threat to human health and the environment. "Air pollution remains a critical threat to both human health and environmental stability, yet vast populations remain unaware of their exposure levels," Hammes said.

In addition, many countries in Southeast Asia, including Cambodia, are facing challenges in air quality monitoring, with nearly half of the region’s cities lacking government monitoring stations. This issue is expected to worsen following the U.S. decision to stop sharing air quality data collected from its embassies and consulates worldwide due to funding constraints.

The report revealed that only 17% of the 8,954 cities analyzed globally met the WHO’s air quality guidelines. To address this, the report calls for increased investment in renewable energy and stricter emission limits for vehicles and industrial activities.

Suman Momin expressed a sense of hopelessness but urged the government to take more action to protect her city from pollution. "People around have developed breathing issues over the years as well. This is my birthplace. I am a local. I do not want to leave this area. We want the governments to do more, come together, and work for us," Momin said.