High-resolution mapping of NO2 population exposure in China from satellite observations

Nitrogen dioxide (NO₂) exposure in urban China poses severe health risks, yet conventional assessments relying on chemical transport models face uncertainties from vertical NO₂ profiling and emission inventories. This study overcomes these limitations by directly integrating satellite-derived NO₂ vertical column density (VCD) data from Ozone Monitoring Instrument (OMI) and TROPOspheric Monitoring Instrument (TROPOMI) with 1 km population data, generating the first high-resolution (1 km × 1 km) annual exposure dataset for China (2005–2020). Our approach eliminates error-prone vertical modeling, achieving strong consistency with satellite data (R² = 0.92) while enhancing spatial resolution 62.5 × over OMI and 10 × over TROPOMI. The results expose striking disparities: urban cores (e.g. Shanghai) exhibit exposure levels 310 × higher than rural regions (e.g. Tibet), driven by overlapping pollution and population density. Unlike raw satellite observations, our 1 km resolution maps pinpoint localized hotspots previously obscured by coarse pixels. By bridging atmospheric science and public health, this work provides a scalable framework for targeting air quality interventions where they matter most–high-density urban areas. Policymakers can leverage these insights to prioritize emission reductions in traffic corridors and industrial zones, maximizing health benefits for vulnerable populations.