Associations of short-term exposure to air pollution with outpatient visits and treatment costs for chronic obstructive pulmonary disease in Xinxiang, China (2016–2021) - Huijun Li; Fei Zhai; You Ma; Yongbin Wang; Rongrong Gu; Chenlong Cao; Lei Wang; Beilei Ge; Wei Wu; Chengkai Zhai; Weidong Wu (Science of The Total Environment, 2025)