Spatiotemporal Evolution of Anthropogenic Emissions and Their Impact on Air Pollution in Guangdong Province from 2006 to 2020

Air quality in Guangdong Province has improved in recent years, but progress varies across different provincial sub-regions, particularly between Pearl River Delta (PRD) and non-PRD (NPRD) regions. To unveil possible causes of this, this study established a high-resolution gridded emission inventory for Guangdong (2006–2020) by integrating multi-year Point of Interest (POI) data and road network information. The spatiotemporal evolutions of anthropogenic sulfur dioxide (SO2), nitrous oxide (NOX), and particulate matter (PM10 and PM2.5) emissions were analyzed, with a focus on their impacts on PM2.5 pollution using the CMAQ model. Spatial shifts in emission sources were quantified using spatial statistical methods, including the average nearest neighbor index (ANNI), kernel density analysis (KDA), standard deviational ellipse (SDE), and mean center (MC). From 2006 to 2020, emissions decreased significantly for SO2 (88%), NOX (26%), PM10 (64%), and PM2.5 (68%). Emission hotspots shifted toward NPRD regions, driven by stricter environmental policies and industrial restructuring, lowering PRD-to-NPRD emission ratios for SO2 (from 1.25 to 0.87), NOX (1.67–1.51), and PM10 (0.94–0.89). The spatial evolution of emissions varied across sources. For example, the emission share of industrial sources in the PRD declined despite an increase in enterprises, whereas vehicle emissions remained concentrated in the PRD. CMAQ modeling results revealed that overall emission reductions from 2012 to 2020 lowered provincial PM2.5 concentrations by 9.2–10.5 μg/m3. Accounting for spatial evolution further enhanced PM2.5 reductions in the PRD by 1.4 μg/m3 (April) and 1.1 μg/m3 (October). Conversely, PM2.5 improvements in NPRD regions weakened, with reductions declining by 0.2–3.2 μg/m3 (April) and 0.1–1.4 μg/m3 (October). These findings provide guidance for formulating region-specific strategies, aiming for more equitable air quality improvements across Guangdong.