Assessing Provincial PM_2.5 Trends in China from 2001 to 2015 Using High-Resolution Satellite Remote Sensing

Given the vast territory of China, control efforts for air pollution and the long-term PM2.5 trends may substantially differ among the provinces. In this study, we aim to assess the provincial PM2.5 trends in China during the past few Five-Year Plan (FYP) periods. The lack of long-term PM2.5 measurements, however, makes such assessment difficult. Satellite remote sensing of PM2.5 concentration is an important step toward filling this data gap. In this study, a PM2.5 data set was built over China at a resolution of 1 km from 2001 to 2015 using satellite remote sensing. Analyses show that the national average of PM2.5 concentration increased by 0.11 µg·m-3·yr-1 during the 10th FYP period (2001 to 2005) and started to decline by -0.75 µg·m-3·yr-1 and -2.20 µg·m-3·yr-1 during the 11th (2006 to 2010) and the 12th (2011 to 2015) FYP period, respectively. In addition, substantial differences in the PM2.5 trends were observed among the provinces. Although PM2.5 concentrations remained steady or worsened in most provinces during the 10th FYP period, PM2.5 concentrations substantially declined for provinces in the Beijing-Tianjin-Hebei (BTH) region, suggesting that these provinces were the most successful in their control efforts during this period. The most substantial decline in provincial PM2.5 concentration during the 12th FYP period was also observed in the BTH region. In contrast, PM2.5 concentrations remained steady for provinces in eastern and southeastern China (e.g., Shanghai) during the 12th FYP period, suggesting that these provinces have been less successful in controlling PM2.5 concentrations since 2011 and therefore require more efforts to effectively reduce the PM2.5 concentrations in future.