A study published by the Health Impact Institute (HEI) of the Global Air Initiative states that Delhi continues to rank the world’s most polluted cities in terms of population-weighted average annual concentrations of PM2.5. Another city in the west of India, Kolkata, ranked second in the list of the most polluted cities in the world. Meanwhile, Mumbai is the 14th most polluted city in the world.
According to the City Air Pollution and Health Report, the city of Kano in Nigeria is ranked third and Lima in Peru is fourth. Dhaka, Bangladesh, and Jakarta, Indonesia came in fifth and sixth respectively. In addition to India, the list of the 20 most polluted cities in the world includes three Chinese cities (Beijing, Shanghai and Chengdu).
Two cities in India have official ground air surveillance bases
The report says, “Local air quality data are not available in many cities around the world. According to the WHO Air Quality Database 2022, of the 20 cities with the highest increases in PM2.5 exposure in the data, only Satna in Madhya Pradesh and Varanasi in Uttar Pradesh of India have formal ground-based monitoring stations, “This fact highlights the need to improve the regional infrastructure for global air quality monitoring.”
Air pollution in cities comes from local and regional sources, and the relative importance of these sources can vary from city to city. The predominant sources of PM2.5 at a given location often depend on the local environment, domestic customs, and agricultural and industrial activities taking place nearby.