A Swiss company that tracks global air quality has named Delhi as the world’s most polluted national capital for the sixth straight year. Thirteen of the world’s 20 most polluted cities are in India, according to the World Air Quality Report for 2024 released by IQAir on Tuesday. The most polluted city in the world is Byrnihat on the border of Assam and Meghalaya, according to the report. IQAir examined data collected from 40,000 air quality monitoring stations in 138 countries. The report looked specifically at concentrations of fine particulate matter, or PM2.5, one of the smallest but most dangerous of pollutants. PM2.5 comes from sources such as the combustion of fossil fuels, and can cause respiratory problems, chronic kidney disease, cancer, and stroke or heart attacks. A global problem In 2024, most of the global population was breathing dirty air, the report shows. Only 12 countries, regions, and territories recorded PM2.5 concentrations below the World Health Organization’s (WHO) recommended average annual limit of 5 µg Most of these countries were in Latin America, the Caribbean, or the Oceania region. The five most polluted countries, according to the report, were Chad, Bangladesh, Pakistan, Congo, and India, with annual average PM2.5 concentrations of 91.8 µg/m3, 78 µg/m3, 73.7 µg/m3, 58.2 µg/m3, and 50.6 µg/m3 respectively. Only 17% of the 8,954 cities around the world recorded air quality that met WHO PM2.5 guidelines. The 20 most polluted cities – located in India, Kazakhstan, Chad, Pakistan, and China – exceeded these guidelines by more than 10 times. Pollution in India At 50.6 µg/m3, India’s average PM2.5 concentration last year was 7% lower than in 2023 (54.4 µg/m3). However, six Indian cities made it to the list of the world’s 10 most polluted. Byrnihat, the most polluted city in the world, had an annual average PM2.5 concentration of 128.2 µg Delhi continued to see high levels of pollution, with an annual average of 91.6 µg/m3 in 2024, which was almost unchanged from the 92.7 µg/m3 recorded in 2023. India’s northern states, particularly, witnessed severe pollution episodes in 2024, the report noted. For instance, “January air quality was especially poor in Delhi and Himachal Pradesh.” Extreme levels of pollution were seen in November in Delhi, Punjab, Chandigarh, Haryana, and Himachal Pradesh. Crop stubble-burning remained the major contributor to PM2.5 levels, accounting for 60% of pollution during peak periods. Other major sources of pollution in the country included vehicular emissions, industrial discharges, and construction dust, the report said.
