A new study led by researchers from the Aerospace Information Research Institute (AIR) of the Chinese Academy of Sciences has for the first time mapped the long-term, large-scale transport pathways of PM2.5 pollution across China spanning from 2000 to 2021, providing scientific support for refining national air quality management strategies.

Published in the journal Geoscience Frontiers, the study introduces a novel data-driven framework built on the Dynamic Time Warping (DTW) method. This approach enables the researchers to trace the cross-regional movement of air pollutants over the two-decade period—a breakthrough that sheds new light on how PM2.5 transport patterns have evolved across China.

An analysis of the data reveals distinct regional variations in PM2.5 transport activity. Northwest China accounts for the highest share of identified pathways at 34%, followed by the Southwest (22%) and North (21%) regions. The Northeast contributes 10% of pathways, while isolated cases were recorded in other areas.

Notably, the number of PM2.5 transport pathways dropped significantly after 2013—a trend that aligns with a sharp reduction in annual average PM2.5 concentrations during the same period.

Unlike conventional chemical transport models, which rely on complex meteorological and emission datasets to function, the DTW-based framework is purely data-driven. Despite its simplified data requirements, the method effectively captures PM2.5 transport pathways and demonstrates strong spatiotemporal consistency with established modeling techniques.

This advantage makes the DTW approach particularly valuable for regions with sparse air quality monitoring infrastructure, such as Northwest China. In these areas, the method can identify potential pollution sources and transport routes that were previously difficult to detect using traditional tools.

"This work showcases how Big Earth Data can uncover long-term pollution transport patterns that often elude traditional methods," said LIU Yiming from AIR, the study's first author. "By gaining a clearer understanding of how pollutants move across regions, we can develop more targeted and effective strategies to protect air quality and public health."