Fourteen of the twenty most polluted cities in the world are in India, according to the World Health Organisation (WHO). Not surprisingly, these include Kanpur, Faridabad, Varanasi and New Delhi. The maximum particulate matter under 2.5 micrograms, or PM2.5, was recorded in Kanpur (173 micrograms per cubic metre) followed by Faridabad at 172. The ranking has been done based on toxic air quality in the cities.
Major sources of air pollution from particulate matter include inefficient use of energy by households, industry, agriculture and transport sectors, and coal-fired power plants.
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This may be read with the rider that air quality data for 2016 has a smaller sample size of 859 cities compared to previous years, . For 2015, air quality has been updated for 2,481 cities; for 2014 about 2,545 cities; and for 2013 about 2,291 cities.
Delhi’s with ranking (at 143 micrograms per cubic metre of PM2.5) has improved from 4th in 2015 to 6th in 2016 but that is not because the pollution levels have improved but because more Indian cities have become more polluted than Delhi.
Improvement in air quality monitoring has led to new additions in the list. Cities like Gaya (149 micrograms per cubic metre ), Patiala(101 micrograms per cubic metre), Srinagar (113 micrograms per cubic metre ), Gurgaon (113 micrograms per cubic metre) and Jaipur (105 micrograms per cubic metre) which were hitherto not there in the top 20 list are now a part of the list.
Some others have also gone off the top 20 list. These include Dhanbad, Khurja, Howrah, Dehradun, Amritsar, Khanna, Gwalior (which topped the list in 2012 with 176 micrograms per cubic metre of PM2.5) and Raipur.
WHO also said:
- Other Indian cities that have high levels of PM2.5 are Agra (131 micrograms per cubic metre), Patna (144 micrograms per cubic metre), Muzaffarpur (120 micrograms per cubic metre) and Varanasi (151 micrograms per cubic metre).
- Nine out of 10 people on the planet breathe polluted air and it kills 7 million people each year, most of them in Asian countries and African countries. About a quarter of deaths from heart disease, stroke and lung cancer can be attributed to air pollution.
- Chinese cities such as Xingtai and Shijiazhuang and the Saudi refining hub at Jubail were also highly polluted, but the data for those places was 4-5 years old. It said China had made big improvements that India should follow.
- The report provides air quality data from more than 4,300 cities and towns in 108 countries, constituting the world’s biggest database of ambient, or outdoor, air pollution. The UN agency’s assessment is based on satellite data and modelling overlaid on the database of cities.
(Editor’s Note: The story published on May 2 stated that Gwalior was the most polluted city in the world with 176 micron per cubic metre of particulate matter under 2.5. After a reader pointed out that this is incorrect, we ran a fact check. Gwalior was indeed the most polluted city with the stated PM2.5 levels but in 2012. The 2016 WHO data says that Kanpur is the most polluted city. We corrected the story with the latest data on May 4)