Air pollution in tropical cities led to 470,000 premature deaths in 2018

Cities in the tropics have a growing air pollution problem that has led to an estimated 62 percent increase in premature deaths since 2005


April 8, 2022

Mumbai, India, a tropical city with a growing population

Ivaylo Daskalov/Alamy

According to an analysis in 2018, around 470,000 people in cities near the equator died prematurely from air pollution. With cities expected to grow rapidly in this century, the problem could get worse without new measures to reduce pollution.

Karn Vohra of University College London and his colleagues analyzed the increase in particulate matter pollution in 46 tropical cities, including Mumbai, Dhaka and Lagos, which are each expected to have more than 10 million inhabitants by 2100. Researchers examined satellite data collected between 2005 and 2018 by NASA and the European Space Agency.

They were able to decipher the long-term trends in particulate matter pollution in the air over each city by studying how sunlight was scattered by the particles. From this, they found that for 33 of the cities, this pollution increased by 1.5 to 4 times during the study period.

According to Vohra, this increase is likely due to increases in road traffic, waste incineration and the use of charcoal in households.

The team then fitted the data into a health risk model that links increases in particulate matter exposure to premature mortality. According to Vohra, the results suggest that more than 30 percent of known premature deaths in Asia are caused in part by this pollution.

“This [particles] penetrate deep into our lungs and have been shown to affect almost every organ in our body,” he says.

The research shows that Dhaka, the capital of Bangladesh, saw the largest increase in premature deaths from air pollution during the study period. Between 2005 and 2018, around 24,000 more people in the city are believed to have died prematurely from air pollution.

The problem is getting worse, both as more pollution is generated and as cities grow. The study suggests that the number of premature deaths from air pollution in the tropics increased by 62 percent between 2005 and 2018.

Vohra says more people will die prematurely if solutions are not found. “Even assuming no change in air quality, urban populations are increasing in all cities in the tropics, so urban pollution will inevitably increase,” he says.

“I think this study gives a good overview of recent air pollution trends in fast-growing cities across Africa, South and Southeast Asia,” says Miranda Loh of the Institute of Occupational Medicine.

“Satellite data and models – as used in the article – are useful for this type of global analysis, especially when there is a lack of ground surveillance data. But if we want to better track population exposure, it’s important to improve ground-level surveillance around the world,” she says.

Magazine reference: scientific advancesDOI: 10.1126/sciadv.abm4435

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