1. Hebei Province Key Laboratory of Occupational Health and Safety for Coal Industry, School of Public Health, North China University of Science and Technology, Tangshan, Hebei, P.R. China;
2. Tangshan Center of Disease Control and Prevention, Tangshan, Hebei, P.R. China;
3. Tangshan Gongren Hospital, Tangshan, Hebei, P.R. China;
4. Department of Environmental and Chemical Engineering, Tangshan College, Tangshan, Hebei, P.R. China;
5. College of Psychology, North China University of Science and Technology, Tangshan, Hebei, P.R. China