Study links 135 million premature deaths from 1980 to 2020 to PM2.5 exposure

Changes in climate patterns like El Nino-Southern Oscillation, Indian Ocean Dipole can make air pollution worse, finds paper

By Nandita Banerji
Published: Tuesday 11 June 2024
Air pollution in Hong Kong. China saw 49 million premature deaths due to air pollution between 1980 and 2020. Photo: iStock

Silent killers fine particulate matter (PM 2.5) led to a staggering 135 million premature deaths worldwide between 1980 and 2020, a new study has found. The research has also highlighted the role of climate variability phenomena like El Nino-Southern Oscillation, Indian Ocean Dipole and North Atlantic Oscillation in exacerbating PM2.5 pollution levels. 

The study by researchers from Nanyang Technological University in Singapore was published in the peer-reviewed journal Environment International. The scientists analysed 40 years of data to provide new insights into the complex relationship between climate and air quality by examining how specific climate patterns affect air pollution in different regions.

Read more: India was third-most polluted country globally in 2023, right behind top-ranking Bangladesh and Pakistan

The researchers analysed satellite data from the United States’ National Aeronautics and Space Administration on PM2.5 levels in the Earth’s atmosphere. They also utilised data from Institute for Health Metrics and Evaluation in US on global deaths and occurrences of pollution-linked diseases, which include lower respiratory infections, tracheal, bronchus and lung cancer, chronic obstructive pulmonary disease, stroke and ischemic heart disease.

The study estimated that from 1980 to 2020, a third of premature deaths were associated with stroke (33.3 per cent), another third with ischemic heart disease (32.7 per cent) and the remaining deaths were due to chronic obstructive pulmonary disease, lower respiratory infections and lung cancer.

Premature deaths, as defined in the paper, referred to fatalities that occur earlier than expected based on average life expectancy. These deaths are often caused by preventable or treatable illnesses triggered or exacerbated by environmental factors like air pollution. 

The study found a significant geographical disparity in the burden of air pollution-related deaths. Asia stands out as the most affected region, with an estimated 98.1 million premature deaths attributed to PM2.5 pollution during the study period. China and India led the pack at 49 million and 26.1 million deaths, respectively. 

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Other South Asian nations like Pakistan, Bangladesh, Indonesia and Japan also suffered significant losses due to PM2.5 exposure.

The researchers identified 363 major air pollution episodes worldwide over the past four decades, averaging nine episodes per year. These episodes lasted between two and nine months, with 2002 experiencing the highest number of episodes (15), followed by 2004 and 2006 (14 each). 

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They estimate that the three weather phenomena collectively caused approximately 7,000 additional premature deaths annually. The Indian Ocean Dipole had the largest impact on the number of deaths, followed by the North Atlantic Oscillation and then El Nino.

Our findings show that changes in climate patterns can make air pollution worse, underlined lead researcher Associate Professor Steve Yim from NTU Singapore, in a statement. 

“When certain climate events happen, like El Nino, pollution levels can go up, which means more people might die prematurely because of PM2.5 pollution. This highlights the need to understand and account for these climate patterns when tackling air pollution to protect the health of the global population,” he said. Yim is also principal investigator at NTU’s Earth Observatory of Singapore. 

The effects of climate change and the environment on human health are not lesser than those of genomics and lifestyle patterns and they have been increasing over the past decades, said study co-author Joseph Sung, who is also NTU’s senior vice president (health and life sciences) and dean of NTU’s LKCMedicine. 

Read more: Winter pollution 2023-24: North & east India most polluted; air quality in north worsened significantly

“By recognising these patterns, healthcare providers can better prepare for potential increases in patients seeking treatment for pollution-related ailments. Additionally, this knowledge underscores the importance of proactive measures to reduce pollution and mitigate its health impacts, ultimately helping healthcare systems manage and alleviate the burden of pollution-related illnesses on communities,” he said in the statement. 

PM2.5 are microscopic pollutant particles. These particles come from a variety of sources, including vehicle emissions, industrial processes and agricultural burning. Once inhaled, PM2.5 can penetrate deep into the lungs and even enter the bloodstream, causing respiratory problems, heart disease and other health complications.

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