Evaluating Fine-Scale Winter Nighttime PM_2.5 Concentrations and Population Exposure using SDGSAT-1 Glimmer Imagery

A comprehensive understanding of fine particulate matter (PM2.5) distribution is vital for addressing health concerns related to deteriorating air quality. While remotely sensed nighttime light 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 spatial random forest (ISSRF) model was employed to estimate PM_2.5 concentrations using SDGSAT-1 Glimmer nighttime light data. The resultant PM_2.5 concentration maps, with a resolution of 300 meters, 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 (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 Chengdu-Chongqing UA exhibits the highest levels of exposure among children (≤ 5 years) and the elderly (≥ 65 years). These findings provide valuable insights for policymakers to prioritize pollution control strategies and measures.