Regional Disparities in Air Pollution Control: A Comparative Analysis of Beijing-Tianjin-Hebei, Yangtze River Delta, Pearl River Delta, and Fenwei Plain, China.

China has achieved significant progress in air pollution control over the past decade, yet regional disparities persist due to varying industrial structures, energy consumption patterns, and policy enforcement. This study examines air quality trends in four key regions-Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), Pearl River Delta (PRD), and Fenwei Plain (FWP)-from 2015 to 2023, focusing on particulate matter (PM2.5 and PM10), ozone (O3), sulfur dioxide (SO2), and nitrogen dioxide (NO2). Using government monitoring data, emission inventories, and statistical modeling, we assess the effectiveness of national policies and identify persistent challenges. Results show that while PM2.5 levels have declined significantly in BTH and YRD, O3 pollution has worsened across all regions, particularly in FWP. The PRD has achieved the cleanest air, with PM2.5 concentrations meeting EU standards. However, rising VOC emissions threaten further O3 increases. We recommend region-specific emission controls, stricter industrial regulations, and enhanced inter-regional cooperation to sustain air quality improvements.