Evaluating Fine-Scale Winter Nighttime PM2.5 Concentrations and Population Exposure Using SDGSAT-1 Glimmer Imagery

A comprehensive understanding of fine particulate matter (PM_2.5) distribution is vital for addressing health concerns related to deteriorating air quality. While remotely sensed nighttime light (NTL) observations have proven effective in monitoring PM_2.5 concentrations, their coarse resolution limits their ability to capture the fine-scale spatial variations within urban environments. To address this limitation, an improved simple spatial random forest model was employed to estimate PM_2.5 concentrations using SDGSAT-1 Glimmer NTL data. The resultant PM_2.5 concentration maps, with a resolution of 300 m, were generated for the winter of 2021 (R² = 0.81) and cover four urban agglomerations (UAs) in China. Two population-weighted indicators were utilized to assess the nighttime population exposure to PM_2.5. The findings suggest that population exposure to PM_2.5 is highest in the Beijing-Tianjin-Hebei UA (66.84 μg/m³), followed by Chengdu-Chongqing (CC) (62.66 μg/m³), Yangtze River Delta (52.04 μg/m³), and Guangdong-Hong Kong-Macao Greater Bay Area (33.74 μg/m³). Notably, the CC UA exhibits the highest levels of exposure among children ($ \leq $ 5 years) and the elderly ($ \geq $ 65 years). These findings provide valuable insights for policymakers to prioritize pollution control strategies and measures.