India: Recent research into the air quality of cities worldwide, conducted by the Health Effects Institute’s (HEI) State of Global Air Initiative revealed that the Indian metropolitan cities of Delhi and Kolkata are the two most polluted cities in the world, as per average annual-population weighted PM 2.5 exposure.
The report entitled ‘Air Pollution and Health in Cities’ further ranks Mumbai at 14, making this metropolitan triad to be the only three Indian cities in the top 20. According to the disease burden proportion associated with PM 2.5-related illness, Kolkata ranked eighth with 99 deaths per 100,000 while Delhi came in sixth with 106 deaths.
Incidentally, Beijing bagged the top spot with a shocking 124 attributable deaths per 100,000 persons. Five Chinese cities took their spots in the top 20.
The research involved the statistical data of 7,000 cities in total but only 103 of the most populous ones from six regions were selected for the final ranking.
No other Indian city took a spot in the top 20 for NO2 exposure, with Shanghai having the worst average exposure. Cities all across the globe had levels of PM 2.5 and NO2 numbers way higher than the World Health Organization (WHO) guidelines.
The average PM 2.5 exposure in Delhi was 110 micrograms per cubic metre in 2019, which is reportedly 22 times higher than the WHO standard of 5 micrograms per cubic metre. Kolkata swooped in to secure the second spot with 84 micrograms per cubic metre, nearly 17 times higher than the WHO designated threshold.
As per the study’s results, exposure to PM 2.5 was responsible for 29,900 deaths in Delhi, 21,380 in Kolkata and 16,020 in Mumbai in 2019. In contrast, Beijing witnessed nearly 26,270 fatalities in 2019.
Meanwhile, the average NO2 exposure was 41.6 micrograms per cubic metre in Russia which established its second spot on the grade board. The WHO recommended threshold for average NO2 exposure is 10 micrograms per cubic metre.
According to the research, 86% of the more than 7,000 cities it covered in 2019, had pollution levels over the WHO guidelines, adversely affecting about 2.6 billion people.
Moreover, the data compiled from 2010 to 2019 also discovered notable differences between global patterns for the two main air pollutants, NO2 and PM 2.5.
While cities in low and middle-income nations suffered from higher exposure to fine particulate matter, cities in high and middle-income nations had higher exposure to NO2 or nitrogen dioxide. The case is such because NO2 is an air pollutant resulting from power plants and automobile emissions.
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