Air pollution-related fatalities in Mumbai, Bengaluru, Kolkata, Hyderabad, Chennai, Surat, Pune and Ahmedabad from 2005-2018
Bengaluru, Hyderabad, Kolkata and Pune recorded the highest number of such deaths — 93.9, 96.4, 82.1 and 73.6 per 100,000 population, respectively, during this period, the analysis published in Science Advances April 8 noted.
Mumbai, Surat, Chennai and Ahmedabad saw 65.5, 58.4, 48 and 47.7 premature deaths per 100,000 population, respectively, the report showed.
The study, however, did not cover Delhi, Noida and Faridabad, which featured in the World Health Organization’s list of the top 20 most polluted cities in the world.
“We wanted to evaluate fast-growing cities in the tropics, which are projected to transform into megacities by 2100, and eight of these cities are in India,” Karn Vohra, lead author and research fellow from the University College London, told Down To Earth.
The team wanted to quantify long-term changes in air quality in cities which lack extensive surface monitoring networks, he added.
Vohra and his colleagues relied on instruments aboard United State’s National Aeronautics and Space Administration (NASA) and the European Space Agency satellites to gather data on air pollutants in the tropical regions between 2005 and 2018.
The scientist said:
The tropics are the next frontier in air pollution. They are experiencing population growth at an unprecedented pace. Also, most countries in the tropics are yet to implement policies and set up infrastructure to mitigate air pollution.
Their analysis observed significant yearly increases in pollutants worldwide. In tropical cities, nitrogen dioxide (NO2) concentration in the atmosphere rose up to 14 per cent and that of fine particles (particulate matter or PM 2.5) rose 8 per cent, the report showed.
PM 2.5 are tiny particles or droplets that are 2.5 micrometres or less in width that are linked to a host of diseases and premature death.
Ammonia and reactive volatile organic compounds, which aid the formation of PM2.5, rose up to 12 per cent and 11 per cent respectively.
The researchers studied exposure to pollutants in 46 cities. Exposure to NO2 and PM2.5 rose 1.5-4 fold in 40 and 33 cities respectively, they found.
Population growth combined with rapid deterioration in air quality due to road traffic, waste burning and widespread use of charcoal and fuelwood drive this increase in exposure to pollutants, the researchers wrote in their study.
Next, the team turned to a health risk assessment model to calculate premature deaths due to exposure to PM 2.5. They also gathered country-level age-specific mortality rates and population data for each city included in the study.
In 2005, Kolkata had recorded 39,200 premature deaths, Ahmedabad 10,500, Surat 5,800, Mumbai 30,400, Pune 7,400, Bengaluru 9,500, Chennai 11,200 and Hyderabad 9,900, the team observed.
The figures rose to 54,000 for Kolkata, 18,400 for Ahmedabad, 15,000 for Surat, 48,300 for Mumbai, 15,500 for Pune, 21,000 for Bengaluru, 20,800 for Chennai and 23,700 for Hyderabad in 2018.
Overall, India had 123,900 premature deaths from long-term exposure to PM 2.5 in 2005, which increased to 223,200 in 2018, Vohra said.
Tropical countries will continue to bear the brunt of poor air quality, the researchers said in the study. The COVID-19 pandemic also revealed the vulnerability of healthcare systems in these countries, the authors wrote.
“We continue to shift air pollution from one region to the next, rather than learning from errors of the past,” Eloise Marais, co-author and associate professor in physical geography at the University College London, said. He pressed on the need to ensure that rapid industrialisation and economic development don’t harm public health.
These nations should implement immediate and strict policy measures to improve air quality and prevent further damage, the report said.
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