India’s cities hold 15 of the top 20 spots in the ‘world’s most polluted cities’ list for 2018, as per a report released by Greenpeace and IQAir AirVisual, a software company that tracks air-quality data. Leading the way is Gurugram followed by Ghaziabad, Faridabad, Bhiwadi and Noida. Faisalabad in neighbouring Pakistan is in the third spot. The full rankings can be found here.

South Asia is easily the most polluted region in the world. Both Lahore and Dhaka, two of the world’s most populous cities, are in the top 20. Delhi is in the 11th place. Most of the top 50 rankings are dominated by cities in India, China, Pakistan and Bangladesh. When weighted by population, Bangladesh is the most polluted country, closely followed by Pakistan and India, with Middle-Eastern countries, Afghanistan and Mongolia rounding up the top 10.

The 2018 World Air Quality report looked at data from more than 3,000 cities around the world. It focused on PM2.5 air-quality data as aggregated through the IQAir AirVisual platform in 2018, measured from ground-based stations with high data availability. The sources included government monitoring networks as well as validated data from air-quality monitors operated by individuals and organisations. PM2.5 is regarded as the particulate matter with the most adverse and toxic health impact of all commonly measured air pollutants. It can penetrate deep into the lungs and enter the bloodstream and cause all kinds of serious health effects.

The levels of PM2.5 were largely unchanged from 2017 to 2018 in many Indian cities. Among capital cities, Delhi had the highest average yearly PM2.5 concentration of 113.5, followed by Dhaka, Bangladesh (97.1). Of the 84 cities monitored in South Asia, 99 per cent failed to meet the WHO guidelines for PM2.5 concentration with an average of 60 μg/m³, six times the recommended limit of 10 μg/m³. Gurugram’s average was a whopping 135.8. The main contributors towards this level of pollution in the region are vehicle exhaust, open crop and biomass burning, industrial emissions, and coal combustion.

Last year a report from the United Nations Environment Program, Air Pollution in Asia and the Pacific: Science-based Solutions, found that every year approximately 7 million people die prematurely from air pollution-related diseases, with about 4 million of these deaths occurring in Asia-Pacific. Currently, 92 per cent of Asia and the Pacific’s population, that is about 4 billion people, are exposed to toxic levels of air pollution that can cause significant health problems.