北京PM2.5来源，本地排放占比降至43%

Core Insights - The latest research on PM2.5 sources in Beijing indicates a significant shift in the contribution of local and regional sources, with regional transmission now accounting for 57% and local emissions for 43% [1][2][4] Group 1: PM2.5 Source Analysis - The fourth round of PM2.5 source analysis shows that local sources contribute 43% to the current PM2.5 levels in Beijing, with mobile sources being the largest contributor at 50% [2][5] - The analysis has improved monitoring techniques and data accuracy, achieving a level of detail that is internationally leading [2][4] - Compared to 2020, the absolute contribution from local sources has significantly decreased, with mobile and life sources increasing their relative contributions [2][5] Group 2: Regional Air Quality Improvement - Collaborative efforts in the Beijing-Tianjin-Hebei region have led to substantial improvements in air quality, with PM2.5 annual concentrations dropping over 60% since 2013 [4] - The increase in regional transmission's contribution to PM2.5 levels highlights the importance of coordinated regional pollution control efforts [4][5] - Experts recommend enhancing regional cooperation and focusing on local emission reduction potential to further improve air quality [4][5]