Characteristics and Causes of PM2.5 Changes in the Fenwei Plain from 2013 to 2020

• • Cumulative PM2.5 reduction of 19% from 2013 to 2020, with phase-specific annual declines of 3% (first phase) and 16% (second phase), demonstrating accelerated policy effectiveness. • • Emission reductions contributed −8 μg·m−3 in the second phase, outweighing adverse meteorological effects (+3.5 μg·m−3), underscoring the dominance of control measures. • • Winter showed the most significant improvement in the first phase, while spring and autumn improved notably in the second phase, indicating seasonal shifts in policy impact. • • Residential emissions became as important as industrial sources during winter heating, necessitating targeted controls for future PM2.5 mitigation.