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Tropical Cities Account for 180,000 Excess Deaths Due to Air Pollution

A study directed by scientists at the University College London (UCL) and the University of Birmingham has exposed that approximately 180,000 avoidable fatalities spanning 14 years in rapidly expanding tropical cities were caused by a swift increase in emerging air pollution,

Tropical Cities Account for 180,000 Excess Deaths Due to Air Pollution.

Image Credit: iStock/Balaji Srinivasan.

The international team of researchers was keen to resolve data gaps in air quality for 46* future megacities in Asia, Africa and the Middle East making use of space-based observations from instruments onboard and European Space Agency (ESA) and NASA satellites from 2005 to 2018.

Details of the study have been published recently in the journal Science Advances. The research shows fast degradation in the quality of air and increases in urban exposure to air pollutants dangerous to health.

Through all the cities, the researchers discover major yearly increases in pollutants that are dangerous to health with up to 14% of nitrogen dioxide (NO2) and up to 8% of fine particles (PM2.5), as well as a rise in precursors of PM2.5 of up to 11% for reactive volatile organic compounds and up to 12% for ammonia.

The team connected this fast deterioration in air quality to newly upcoming industries and residential sources such as waste burning, road traffic, and extensive use of fuelwood and charcoal.

Open burning of biomass for land clearance and agricultural waste disposal has in the past overwhelmingly dominated air pollution in the tropics. Our analysis suggests we’re entering a new era of air pollution in these cities, with some experiencing rates of degradation in a year that other cities experience in a decade.

Dr. Karn Vohra, Study Lead Author, Department of Geography, UCL

Dr. Karn Vohra completed this study as a Ph.D. student at the University of Birmingham.

The researchers also discovered a 1.5- to 4- fold increase in city population exposure to air pollution throughout the study period in 40 of the 46 cities for NO2 and 33 of the 46 cities for PM2.5. was caused by a mixture of population explosion and rapid decline in air quality.

According to the research, the rise in the number of people dying ahead of time from being exposed to air pollution was highest in South Asian cities, especially Dhaka, Bangladesh (totaling 24,000 people), and the Indian cities of Chennai, Mumbai, Kolkata, Bangalore, Hyderabad, Pune, Surat, and Ahmedabad (totaling 100,000 people).

The scientists state that while the number of fatalities in tropical cities in Africa is at present lower because of new developments in healthcare throughout the continent resulting in a decrease in general premature mortality, the worst impacts of air pollution on health will probably happen in the near future.

We continue to shift air pollution from one region to the next, rather than learning from errors of the past and ensuring rapid industrialisation and economic development don’t harm public health. We hope our results will incentivise preventative action in the tropics.

Dr. Eloise Marais, Study Co-Author, Department of Geography, UCL

The research was sponsored by the University of Birmingham’s Global Challenges Ph.D. Studentship, which was bestowed to Dr. Vohra, and a NERC/EPSRC grant, which was bestowed to Dr. Marais.

*The cities scrutinized in the research include:

South Asia – Ahmedabad, Bangalore, Chittagong, Chennai, Dhaka, Hyderabad, Kolkata, Karachi, Mumbai, Pune, Surat.

Africa - Abuja, Abidjan, Antananarivo, Addis Ababa, Blantyre, Bamako, Conakry, Dar es Salaam, Dakar, Ibadan, Kampala, Kaduna, Kano, Kigali, Khartoum, Kinshasa, Lilongwe, Lagos, Luanda, Lusaka, Lubumbashi, Mombasa, Nairobi, N’Djamena, Niamey, Ouagadougou.

Middle East – Riyadh, Sana’a.

Southeast Asia – Bangkok, Ho Chi Minh City, Hanoi, Jakarta, Manila, Phnom Penh, Yangon.

Journal Reference:

Vohra, K., et al. (2022) Rapid rise in premature mortality due to anthropogenic air pollution in fast-growing tropical cities from 2005 to 2018. Science Advances.


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