This dataset accompanies the paper "Urban hotspots reveal hidden inequality in global PM₂.₅ improvement" and contains two files: SupplementaryData_202606.xlsx provides country-level results for 191 countries across five time points (2000, 2005, 2010, 2015, 2020), including population-weighted PM2.5 exposure for hotspot (HS) and non-hotspot (NHS) areas, absolute and relative HS–NHS disparities, temporal coupling metrics, quadrant classifications, and a parallel urban–rural disparity analysis for 145 countries. Global_hotspot_shp.zip contains global urban hotspot boundary polygons in Shapefile format (WGS 1984, EPSG:4326) for the same five time points. Hotspots were delineated from nighttime-light imagery using a head/tail breaks procedure based on Zipf's law, requiring no country-specific urban definition. Detailed methodology is provided in Note S2 of the supplementary information.