Characteristics and health risks assessment of PM2.5-bound heavy metals during winter in urban areas of northern China: A case study in Kaifeng

Qi Xin, Yan Han, Hanxiong Che, Jiawei Zhou, Chao Peng, Zhier Bao, Yiliang Liu, Lingshuo Meng, Shumin Zhang, Fumo Yang, Wenbo Xue, Yu Lei, Weiling Wu, Xi Wu, Jinxin Yang, Xin Long, Yang Chen