Daily Estimation of Ground-Level PM2.5 Concentrations over Beijing Using 3 km Resolution MODIS AOD

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• 作者：Yuanyu Xie ; Yuxuan Wang ; Kai Zhang ; Wenhao Dong ; Baolei Lv ; Yuqi Bai
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：October 20, 2015
• 年：2015
• 卷：49
• 期：20
• 页码：12280-12288
• 全文大小：529K
• ISSN：1520-5851

文摘

Estimating exposures to PM_2.5 within urban areas requires surface PM_2.5 concentrations at high temporal and spatial resolutions. We developed a mixed effects model to derive daily estimations of surface PM_2.5 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-PM_2.5 relationships and shows good performance in model predictions (R² of 0.81鈥?.83) and cross-validations (R² of 0.75鈥?.79). Satellite derived population-weighted mean PM_2.5 for Beijing was 51.2 渭g/m³ over the study period (Mar 2013 to Apr 2014), 46% higher than China鈥檚 annual-mean PM_2.5 standard of 35 渭g/m³. We estimated that more than 19.2 million people (98% of Beijing鈥檚 population) are exposed to harmful level of long-term PM_2.5 pollution. During 25% of the days with model data, the population-weighted mean PM_2.5 exceeded China鈥檚 daily PM_2.5 standard of 75 渭g/m³. Predicted high-resolution daily PM_2.5 maps are useful to identify pollution 鈥渉ot spots鈥?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 PM_2.5 monitoring sites and more are still needed in Beijing.