1. State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Cooperative Laboratory for Atmospheric Environment-Health Research, Nankai University, Tianjin, P. R. China
2. Department of Civil, Environmental, and Construction Engineering, University of Central Florida, Orlando, Florida, USA
3. School of Geography Earth and Environment Sciences, University of Birmingham, Birmingham, UK
4. China National Environmental Monitoring Centre, Beijing, China