Ambient fine particulate matter (PM2.5) is the world’s leading environmental health risk factor. At only 2.5 micrometers or smaller, these particles are small enough to be inhaled and cause respiratory problems, such as asthma and bronchitis, and cardiovascular issues, including heart attacks and high blood pressure. For children, PM2.5 can cause lifelong developmental issues, and for the general population, PM2.5 is associated with premature death.
To ameliorate these wide-ranging negative impacts resulting from exposure to PM2.5, which is produced largely through traditional energy sources such as burning fossil fuels or wood, several countries have taken steps to reduce exposure to PM2.5. But how effective have these mitigation efforts been, and what region or regions are most responsible for driving global PM2.5 reduction?
Researchers working with Randall Martin, the Raymond R. Tucker Distinguished Professor in the McKelvey School of Engineering at Washington University in St. Louis, examined PM2.5 data from 1998-2019 to find out.
“The importance of PM2.5 as a leading risk factor for human health motivates assessment of its long-term changes,” Martin said. “We sought to analyze our satellite-derived PM2.5 estimates for insight into global and regional changes in PM2.5 exposure and its health effects.”The team’s analysis, published Sept. 2 in Nature Communications, showed that global, population-weighted PM2.5 exposure, related to both pollution levels and population size, increased from 1998 to a peak in 2011, then decreased steadily from 2011 to 2019, largely driven by exposure reduction in China and slower growth in other regions.
The team’s analysis, published Sept. 2 in Nature Communications, showed that global, population-weighted PM2.5 exposure, related to both pollution levels and population size, increased from 1998 to a peak in 2011, then decreased steadily from 2011 to 2019, largely driven by exposure reduction in China and slower growth in other regions.
“Before this work, there was a knowledge gap regarding quantitative local/regional contributions to global population exposure to PM2.5 and its changes,” said Chi Li, first author on the study and a staff scientist in Martin’s research group. “We developed a new regional decomposition approach that jointly considered pollution level and population size, and from that we depicted the first-ever time series of regional contributions to global PM2.5 air pollution.”
Li found that many regions exhibited decreasing exposure since 2011, including continuous reductions in North America and western Europe. He described recent emerging decreases in China as particularly striking.