1. Department of Occupational and Environmental Health, Peking University School of Public Health, No. 38 Xueyuan Road, Haidian District, Beijing 100191, China
2. Peking University Institute of Environmental Medicine, Beijing 100191, China
3. Key Laboratory of Molecular Cardiovascular Sciences of Ministry of Education, Peking University, Beijing 100191, China
4. Institute of Atmospheric Physics, Chinese Academy of Sciences, No. 40 Huayanli, Beichen West Road, Chaoyang District, Beijing 100029, China
5. Division of Respiration, Peking University Third Hospital, Beijing 100191, China
6. Institute for Risk Assessment Sciences, University Medical Centre Utrecht, University of Utrecht, P.O. Box 80125, Utrecht 3508 TC, The Netherlands
7. Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Copenhagen K 1353, Denmark
8. State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Ecological Effect and Risk Assessment of Chemicals, Chinese Research Academy of Environmental Sciences, Beijing 100012, China