Spatiotemporal Dynamics and Exposure Analysis of Daily PM2.5 Using a Remote Sensing-based Machine Learning Model and Multi-time Meteorological Parameters
Abstract Background Identifying spatiotemporal characteristics of daily fine particulate matter (PM2.5) concentrations is essential for assessing air quality. Exposure analysis can help understand the environmental health impact on human beings and provide basic information for appropriate decision making. This study aimed to estimate daily PM2.5 concentrations and analyze the resident exposure level in the economically developed Yangtze River Delta (YRD) from 2016–2018. Methods An integrated method incorporating satellite-based aerosol optical depth (AOD), machine learning models and multi-time meteorological parameters were developed. Ten-fold cross validation (CV) was implemented to evaluate the model performance. Results Compared to the models with daily means of meteorological fields, the models with multi-time meteorological parameters had higher CV R2 and lower CV root mean square error (RMSE) values. The model with the best performance achieved sample- (site-) based CV R2 values of 0.88 (0.88) and RMSE values of 10.33 (10.35) µg/m3. The YRD region is seriously polluted (exceeding the World Health Organization (WHO) Interim Targets (IT)-1 standard of 35 µg/m3) during our study period, especially in Jiangsu Province, but with an improving trend. The residents in Zhejiang Province suffered the least from exposure, with 39 days (4% of the total days) characterized as over polluted (daily average > 75 µg/m3) in our study period. Air pollution in Shanghai Municipality mitigated the most from 2016 to 2018. Conclusions With the advantages of high-accuracy and high-resolution (daily and 0.01°×0.01° resolutions), the proposed method can help explore the effect of air pollution to human health spatiotemporally and guide for environmental policy planning.