10.1021/acs.est.5b02776.s001 Ying Li Ying Li Changqing Lin Changqing Lin Alexis K. H. Lau Alexis K. H. Lau Chenghao Liao Chenghao Liao Yongbo Zhang Yongbo Zhang Wutao Zeng Wutao Zeng Chengcai Li Chengcai Li Jimmy C. H. Fung Jimmy C. H. Fung Tim K. T. Tse Tim K. T. Tse Assessing Long-Term Trend of Particulate Matter Pollution in the Pearl River Delta Region Using Satellite Remote Sensing American Chemical Society 2015 PM 10 trend 1 km control measures PRD region Pearl River Delta Region Particulate Matter Pollution ambient PM pollution Pearl River Delta PM pollution PM 10 pollution pollution problems Satellite Remote SensingSerious PRD area PM 10 concentrations estimate PM concentrations PM measurements health effects air pollution future policies 2015-10-06 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Assessing_Long_Term_Trend_of_Particulate_Matter_Pollution_in_the_Pearl_River_Delta_Region_Using_Satellite_Remote_Sensing/2125360 Serious particulate matter (PM) pollution problems in many polluted regions of China have been frequently reported in recent years. Long-term exposure to ambient PM pollution is significantly associated with adverse health effects. Characterizing the long-term trends and variation in PM pollution is a basic requirement for evaluating long-term exposure and for guiding future policies to reduce the effects of air pollution on health. However, long-term, ground-based PM measurements are only available at a few fixed stations. In this study, an algorithm is developed and validated to estimate PM concentrations based on the satellite atmospheric optical depth with 1 km spatial resolution. The long-term trends of PM<sub>10</sub> concentrations in the entire Pearl River Delta (PRD) region and different cities are quantified and discussed. From 2001 to 2013, the PM<sub>10</sub> pollution of the entire PRD region was dominated by a decreasing trend of −0.15 ± 0.23 μg/m<sup>3</sup>·yr. This decreasing PM<sub>10</sub> trend was apparent over 75% of the PRD area, with the most significant decreases observed in the center of the region. However, the remaining 25%, mostly located in the outskirts of the region, showed an increasing PM<sub>10</sub> trend. This overall decreasing trend indicates the effectiveness of the control measures applied in the past decade for the primary pollutants.