title: Daily Estimation of Ground-Level PM2.5 Concentrations over Beijing Using 3 km Resolution MODIS AOD.
abstract: Estimating exposures to PM2.5 within urban areas requires surface PM2.5 concentrations at high temporal and spatial resolutions. We developed a mixed effects model to derive daily estimations of surface PM2.5 levels in Beijing, using the 3 km resolution satellite aerosol optical depth (AOD) calibrated daily by the newly available high-density surface measurements. The mixed effects model accounts for daily variations of AOD-PM2.5 relationships and shows good performance in model predictions (R(2) of 0.81-0.83) and cross-validations (R(2) of 0.75-0.79). Satellite derived population-weighted mean PM2.5 for Beijing was 51.2 μg/m(3) over the study period (Mar 2013 to Apr 2014), 46% higher than China's annual-mean PM2.5 standard of 35 μg/m(3). We estimated that more than 19.2 million people (98% of Beijing's population) are exposed to harmful level of long-term PM2.5 pollution. During 25% of the days with model data, the population-weighted mean PM2.5 exceeded China's daily PM2.5 standard of 75 μg/m(3). Predicted high-resolution daily PM2.5 maps are useful to identify pollution "hot spots" and estimate short- and long-term exposure. We further demonstrated that a good calibration of the satellite data requires a relatively large number of ground-level PM2.5 monitoring sites and more are still needed in Beijing.
authors: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University , Beijing 100084, China.
authors: Yuanyu
authors: Y
authors: Xie
authors: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University , Beijing 100084, China.|Department of Marine Science, Texas A&M University at Galveston , Galveston, Texas 77553, United States.|Department of Atmospheric Science, Texas A&M University , College Station, Texas 77853, United States.
authors: Yuxuan
authors: Y
authors: Wang
authors: Department of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health , Houston, Texas 77030, United States.
authors: Kai
authors: K
authors: Zhang
authors: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University , Beijing 100084, China.
authors: Wenhao
authors: W
authors: Dong
authors: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University , Beijing 100084, China.
authors: Baolei
authors: B
authors: Lv
authors: Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Tsinghua University , Beijing 100084, China.
authors: Yuqi
authors: Y
authors: Bai
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000068476:Beijing; D002138:Calibration; D006801:Humans; D016014:Linear Models; D008962:Models, Theoretical; D055620:Optical Phenomena; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012044:Regression Analysis; D015203:Reproducibility of Results; D013057:Spectrum Analysis; D013997:Time Factors; D035501:Uncertainty
chemical_list: D000336:Aerosols; D052638:Particulate Matter