In terms of average annual population-weighted PM 2.5 exposure, Delhi and Kolkata are the two most polluted cities in the world, according to a recent report, Air Pollution and Health in Cities, published by the Health Effects Institute’s (HEI) State of Global Air Initiative.
Mumbai came in at number 14. There are no other Indian cities in the top 20. Beijing had the highest disease burden associated with a PM 2.5-related illness, with 124 attributable deaths per 100,000 people. Kolkata ranked eighth with 99 deaths per 100,000, while Delhi came in sixth with 106 deaths. In the top 20, there were five Chinese cities.
The study covered 7,000 cities in total, but only 103 of the most populous ones from six regions were taken into account for the ranking.
18 of the 20 cities in the world where PM2.5 levels rose at the fastest rate between 2010 and 2019 are located in India.
The top 10 most polluted cities according to exposure to PM2.5 were Delhi, Kolkata, Kano (Nigeria), Lima (Peru), Dhaka (Bangladesh), Jakarta (Indonesia), Lagos (Nigeria), Karachi (Pakistan), Beijing (China), and Accra (Ghana), while the top 10 most polluted cities according to exposure to NO2 were Shanghai, Moscow, Tehran (Iran), St. Petersburg (Russia), Beijing (China), Beijing appeared on both lists of the top 10.
The Health Effects Institute (HEI) report, which was released on August 17, 2022, focuses on fine particulate matter (PM2.5) and nitrogen dioxide as two of the most dangerous pollutants (NO2).
Cities all over the world had levels of PM 2.5 and NO2 that were 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 22 times higher than the WHO benchmark of 5 micrograms per cubic metre, according to the report. The average exposure in Kolkata was 84 micrograms per cubic metre.
Moscow in Russia came in second with an average NO2 exposure of 41.6 micrograms per cubic metre (40.2 micrograms per cubic metre). The WHO recommended exposure level for NO2 is 10 micrograms per cubic metre. According to the report, 86% of the more than 7,000 cities it covered in 2019 had pollution exposure levels above the WHO standard, which had an effect on about 2.6 billion people.
According to the study, 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, PM 2.5 exposure caused 26,270 fatalities in Beijing in 2019.
The study, which examined data from 2010 to 2019, also discovered remarkably different global exposure patterns for NO2 and PM 2.5, the two main air pollutants. Although exposure to fine particulate matter was found to be higher in cities in low- and middle-income countries, exposure to nitrogen dioxide, or NO2, was high in both high- and middle-income cities. In order to release NO2, vehicles and power plants primarily emit emissions.
