Representative photo: iStock
Representative photo: iStock

Climate change to trigger mortality risks from air pollution, flooding: Researchers warn ahead of COP28

More than 6.5 million deaths a year globally are attributable to air pollution
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Health “can be the engine” and “it can be the ultimate motivation for combatting climate change and doing something more fundamental,” World Health Organization Director Maria Neira recently said in an interview with the BMJ medical journal, published by the British Medical Association.

Neira indicated that talking about climate change from the health perspective in terms of reducing asthma, lung cancer and cost to the health system can “completely change the speed and the ambition in our negotiations on climate change.”

For the first time in history, the 28th Conference of Parties (COP28) to the United Nations Framework Convention on Climate Change will have an entire day committed to health on December 3, 2023. This dedicated day will focus on the need to adapt health systems worldwide in response to climate change and the financial burden resulting from climate and health crises.

Two months ahead of COP28, the latest edition of the medical journal by the British Medical Association highlighted the intersection between climate change and health to shed light on this crucial linkage with several new studies on this theme.

Ozone contributes to the warming climate, and coal combustion releases particulate matter, which in turn increases mortality risk.

One particular paper focused on establishing the synergistic interaction between air pollution and mortality. To accomplish this, researchers analysed significant associations of exposure to particulate matter (PM 2.5) and ozone with total mortality in 372 cities across 19 countries and regions between 1994 and 2020.

The analysis included 19.3 million deaths attributed to all causes. It was found that overall, 5.3 million and 1.9 million deaths were attributed to cardiovascular and respiratory diseases, respectively. The median annual mean concentrations of PM2.5 and Ozone across the 372 cities were 11.4 μg/m3.

A significant synergistic interaction was also identified between PM2.5 and ozone for total mortality, with a synergy index of 1.93. Generally, an indication >1 denotes a synergistic interaction, whereas a number <1 indicates an antagonistic interaction, the researchers added. These are measures to establish the interaction between air pollution and mortality risk.

Another article published in the same edition made a case for listing pollution on death certificates to enable policies that could reduce air pollution.

“It is important that a major source of preventable death should appear in our national statistics as this underpins decision making. Death certification is a key way data on cause of death are collected.”

More than 6.5 million deaths a year globally are attributable to air pollution, the Lancet Commission on Pollution and Health said. This number is increasing because of the rise in fossil fuel usage.

As action on air pollution has failed to keep pace with evidence, perhaps attributing death to air pollution might spur some action in the right direction, the authors proposed.

Another study, published in the journal, focused on mortality risks with flooding associated with climate change. The study found cardiovascular and respiratory deaths, mortality risks increased and persisted for up to 60 days (50 days for cardiovascular mortality) after a flooded day.

About 761 communities from 35 countries or territories were included in the analyses.

“Communities with the most flood days per year during the study period were located in the areas along the Mississippi in the United States, the Pacific coast of Latin America, Lake Victoria and the Volta in Africa, South East Asia, the coastal areas of mainland China and the eastern coast of Australia,” the study said.

“From 2000-2019, 47.6 million all-cause deaths (8.5 million causes of death in 142 communities from six countries or territories were non-external), 11.1 million cardiovascular deaths, and 4.9 million respiratory deaths were included in analyses,” the study added.

According to a 2022 study by the University of Hawai and the University of Wisconsin-Madison, from the 375 known infectious pathogenic diseases in circulation worldwide, about 58 per cent can be aggravated by climate change. Hazards include warming, droughts, wildfires, extreme precipitation, floods, rise in sea levels and land cover changes.

“Heatwaves and persistent heavy rainfalls were associated with amplified transmission of vectorborne diseases such as dengue, chikungunya, Zika, and West Nile virus,” the latest edition of the BMJ journal emphasised further.

“At present an ongoing outbreak of dengue is putting tremendous pressure on the health systems in Bangladesh. Rising temperatures, increased flood events, storms, and droughts were linked with heightened incidences of waterborne, respiratory, and skin diseases,” the journal added.

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