References：
[1] Chen, H., Kwong, J. C., Copes, R., et al. Exposure to ambient air pollution and the incidence of dementia: a population-based cohort study [J]. Environment International, 2017, 108: 271-277.
[2] Guo, Y., Zeng, H., Zheng, R., et al. The association between lung cancer incidence and ambient air pollution in China: a spatiotemporal analysis [J]. Environmental Research, 2016, 144: 60-65.
[3] Maji, K. J., Dikshit, A. K., Arora, M., et al. Estimating premature mortality attributable to PM2.5 exposure and benefit of air pollution control policies in China for 2020 [J]. Science of the Total Environment, 2018, 612: 683-693.
[4] Ministry of Environmental Protection, General Administration of Quality Supervision, Inspection and Quarantine. Ambient air quality standard: GB 3095—2012 (3rd ed.) [S]. Beijing: China Environmental Science Press, 2012: 3.
[5] Collins, T. W., Grineski, S. E., Shaker, Y., et al. Communities of color are disproportionately exposed to long-term and short-term PM2.5 in metropolitan America [J]. Environmental Research, 2022, 214: 114038.
[6] Ouyang, W., Gao, B., Cheng, H., et al. Exposure inequality assessment for PM2.5 and the potential association with environmental health in Beijing [J]. Science of the Total Environment, 2018, 635: 769-778.
[7] Bravo, M. A., Anthopolos, R., Bell, M. L., et al. Racial isolation and exposure to airborne particulate matter and ozone in understudied US populations: environmental justice applications of downscaled numerical model output [J]. Environment International, 2016, 92: 247-255.
[8] Chen, Z. Y., Zhang, T. H., Zhang, R., et al. Extreme gradient boosting model to estimate PM2.5 concentrations with missing-filled satellite data in China [J]. Atmospheric Environment, 2019, 202: 180-189.
[9] Danesh Yazdi, M., Kuang, Z., Dimakopoulou, K., et al. Predicting fine particulate matter (PM2.5) in the Greater London Area: an ensemble approach using machine learning methods [J]. Remote Sensing, 2020, 12(6): 914.
[10] Sun, J., Gong, J., Zhou, J. Estimating hourly PM2.5 concentrations in Beijing with satellite aerosol optical depth and a random forest approach [J]. Science of the Total Environment, 2021, 762: 144502.
[11] Zou, H., Hastie, T. Regularization and variable selection via the elastic net [J]. Journal of the Royal Statistical Society Series B: Statistical Methodology, 2005, 67(2): 301-320.
[12] Shao, Z. J. Study on indoor PM2.5 pollution and its impact on human health [D]. Nanjing: Nanjing University, 2019.
[13] Jbaily, A., Zhou, X., Liu, J., et al. Air pollution exposure disparities across US population and income groups [J]. Nature, 2022, 601(7892): 228-233.
[14] Josa, I., Aguado, A. Measuring unidimensional inequality: practical framework for the choice of an appropriate measure [J]. Social Indicators Research, 2020, 149(2): 541-570.
[15] Saunders, P. Social Class and Stratification [M]. London: Routledge, 2006.