Burning fossil fuels has created a massive, global problem: climate change. New research from Washington University finds these fuel sources also have serious health consequences.
The study found more than 1 million people died worldwide in 2017 related to air pollution from burning coal, oil and natural gas. When inhaled, the microscopic particles, known as PM 2.5, cause a variety of serious illnesses.
Because these particles are so small — about one-third the size of a red blood cell — they can penetrate deep into the lungs and even enter the bloodstream.
Many studies have documented the long- and short-term effects of breathing polluted air, which can be linked to other illnesses. A recent analysis, for instance, found people living in U.S. counties with higher levels of particulate pollution had higher death rates due to COVID-19, compared to counties with cleaner air.
Fine particulates are a “critical air pollutant,” according to the U.S. Environmental Protection Agency, which sets air quality standards to limit the maximum amount in outdoor air. The average concentration of PM 2.5 across the U.S. has dropped by 41% since 2000, and in the central U.S., which includes Missouri, it has decreased by 51%.
Still, most of the on-the-ground monitoring for this type of air pollution is based in the U.S. and Europe. As of 2019, only 40% of countries monitored their air for the dust-like particles.
“It's remarkable that for a pollutant as important as PM 2.5, many countries in the world have no monitoring at all,” said Randall Martin, a professor of engineering at Washington University and study co-author.
Further complicating matters is the fact that PM 2.5 is a dizzyingly complex form of pollution created by human activity, natural sources and chemical interactions in our atmosphere. “Pretty much any activity that humans do on Earth emits compounds that can end up forming fine particulate matter,” said atmospheric scientist and lead author Erin McDuffie.
To fill in the gaps, the study examined 20 different sources, such as agriculture and forest fires, and estimated how much specific fuel types are contributing to poor air quality.
Using global air pollution emissions data, high-resolution NASA satellite images and mathematical modeling, McDuffie and her colleagues mapped concentrations of the airborne pollutant across more than 200 countries — and added mortality data for six of the most commonly associated illnesses.
Air pollution from burning fossil fuels was linked to just over 1 million deaths, half of which were specifically related to coal combustion. Other major sources included residential energy use, industrial processes and energy generation, linked to about 1.5 million deaths overall.
But the specific causes of air pollution sometimes varied enormously between regions — and even within individual countries.
In parts of sub-Saharan Africa, windblown dust made up about 75% of all particulate pollution in 2017, far above the 16% global average. In comparison, in Southeast Asia, contributions from home cookstoves and heating were a major contributor.
Because the U.S. is “geographically diverse," McDuffie said, the sources of air pollution varied between regions. “Wildfires were the dominant source in much of the western U.S. in 2017, but as you started moving east, you saw contributions from agriculture in heartland America and energy generation.”
Providing this fine-scale information not only fills in large gaps in our understanding of these common air pollutants, she added, it can also help decision-makers who are looking to improve air quality.
The team has made its data public and created an interactive tool that allows users to explore air quality and health effects in their own region.
“Solutions are largely going to come from national or even local-scale policies, and sources of PM 2.5 vary depending where you are around the world,” McDuffie said. “Being aware of what the major sources are where you live is important to start prioritizing mitigation approaches.”
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