Fossil fuel pollution causes 1 in 5 global deaths

More than 8 million people died in 2018 worldwide from breathing air polluted with particulate matter from burning fuels such as coal, petrol or diesel, a significantly higher figure than previous research had suggested.

This is the main conclusion of a study by Harvard University, in collaboration with the University of Birmingham, the University of Leicester and University College London, published in the journal Environmental Research.

The researchers estimated that 1 in 5 deaths (18 to 21.5%) each year can be attributed to fossil fuel pollution, a much higher figure than previously thought.

Thus, regions with the highest concentrations of fossil fuel-related air pollution - including eastern North America, Europe and Southeast Asia - have the highest death rates.

According to a press release from Harvard's John A. Paulson School of Engineering and Applied Sciences (SEAS), the largest and most comprehensive study of the causes of global mortality - the Global Burden of Disease Study - put the total number of deaths worldwide from outdoor airborne particles - including dust, smoke from forest fires and agricultural burning - at 4.2 million.

Now, fossil fuel emissions alone are estimated to be responsible for the deaths of 8.7 million people.

How have researchers arrived at such a high number of deaths caused by fossil fuels?

Previous research, according to Harvard, relied on satellite and surface observations to estimate annual average concentrations of airborne particulate matter, PM2.5.

The problem is that satellite and surface observations cannot distinguish between particles from fossil fuel emissions and those from dust, smoke from forest fires or other sources, the authors say.

"With satellite data, you only see pieces of the puzzle," says Loretta J. Mickley, a Harvard scientist and author of the new study, who points out that it is challenging for satellites to distinguish between particle types, "and there can be gaps in the data".

To overcome this, the researchers turned to GEOS-Chem, a global 3D model of atmospheric chemistry run at SEAS; thanks to its high spatial resolution, the researchers were able to divide the globe into a grid and study each of its tiny squares.

"Rather than relying on averages across large regions, we wanted to map where the pollution is and where people live, so we know more accurately what they are breathing," explains Karn Vohra of the University of Birmingham.

To model PM2.5 from fossil fuel combustion, the researchers used estimates of emissions from multiple sectors, including energy, industry, shipping, aircraft and land transport, as well as meteorological data.

Specifically, the scientists used data primarily from 2012 because it was a year that was not influenced by El Niño, which can make air pollution worse or better, and updated it to reflect "the significant change" in China's fossil fuel emissions, which roughly halved between 2012 and 2018, according to the authors.

Thus, this new model, which links particulate matter concentration levels from fossil fuel emissions to health outcomes, found a higher mortality rate from long-term exposure to fossil fuels, even at lower concentrations.

The study notes that, globally, exposure to particulate matter from these emissions accounted for 21.5% of all deaths in 2012, and in 2018 this fell to 18% due to tightening air quality measures in China.

Burning fossil fuels produces fine particles laden with toxins, which are small enough to penetrate deep into the lungs, and the risks of inhaling these PM2.5 particles are well documented.

"Our study adds to the growing evidence that air pollution from continued reliance on fossil fuels is detrimental to global health," says Eloise Marais of University College London, who stresses: "We cannot in good conscience continue to rely on fossil fuels when we know there are such severe health effects and viable, cleaner alternatives.