Air pollution is now recognized as one of the biggest killers in the world, yet the relative contribution of different types of emissions has until now been difficult to calculate. However, after combining data from numerous atmospheric chemistry models and satellite-derived emissions estimates, researchers have now concluded that 1.05 million deaths were attributable to fossil fuel combustion in 2017, with coal accounting for more than half of this figure.
Given that the largest number of air pollution-related deaths occurred in China and India, the study authors calculate that eliminating coal and oil and natural gas combustion in these two countries could decrease the global death rate from fossil fuel emissions by 20 percent.
Presenting their findings in the journal Nature Communications, the researchers note that “roughly 1 million deaths could be avoided by the global elimination of fossil-fuel combustion, with 20% of this burden associated with fossil-fuel use in China and India alone.”
The study authors used updated emissions datasets in order to calculate the level of microscopic particles called PM2.5 in 204 countries around the world. Measuring less than 2.5 micrometers, these particles are able to make their way into the human lungs and cardiovascular system, causing respiratory and heart illnesses.
Overall, the team found that the burning of fossil fuels accounted for 27.3 percent of all PM2.5-related deaths in 2017, while the use of solid biofuels, such as wood and charcoal, contributed another 20 percent.
“The use of solid biofuel was a primary source of emissions from the residential sector and was the dominant contributing combustible fuel in 78 countries, especially throughout the tropics,” wrote the researchers. Generally used for cooking and heating in residential settings, biofuel combustion was found to account for up to 40 percent of the PM2.5 disease burden in countries such as Guatemala, Nepal, and Rwanda.
Globally, residential emissions led to 740,000 deaths in 2017, while air pollution generated by the industrial and energy sectors caused 450,000 and 390,000 deaths, respectively. Agriculture and transport, meanwhile, both contributed roughly eight percent of worldwide PM2.5 deaths.
To conduct their research, the study authors combined their enhanced global emissions data with the Global Burden of Disease, thereby attaining an unprecedented level of detail on the health impact of PM2.5 in different regions around the world.
"PM2.5 is the world's leading environmental risk factor for mortality. Our key objective is to understand its sources," explained study author Randall Martin in a statement. Doing so will enable scientists and policymakers to develop targeted mitigation strategies for the reduction of air pollution across different regions, thereby providing a roadmap to a healthier environment and fewer deaths.