An index for estimating the potential metal pollution contribution to atmospheric particulate matter from road dust in Beijing Hongtao Zhao a , Yaping Shao b , Chengqing Yin c , Yan Jiang a , Xuyong Li a, ⁎ a State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China b Institute for Geophysics and Meteorology, University of Cologne, Cologne 50923, Germany c State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China HIGHLIGHTS • An innovative road dust index was developed. • Road dust characteristics were ranked and weighted in the index model. • Source and transport factors were both considered in the index model. • The index can indicate risks of road dust causing atmospheric particulate pollution. GRAPHICAL ABSTRACT abstract article info Article history: Received 17 September 2015 Received in revised form 18 January 2016 Accepted 18 January 2016 Available online 24 January 2016 Editor: D. Barcelo The resuspension of road dust from street surfaces could be a big contributor to atmospheric particulate pollution in the rapid urbanization context in the world. However, to date what its potential contribution to the spatial pat- tern is little known. Here we developed an innovative index model called the road dust index (RI b105 μm ) and it combines source and transport factors for road dust particles b 105 μm in diameter. It could quantify and differ- entiate the impact of the spatial distribution of the potential risks posed by metals associated with road dust on atmospheric suspended particles. The factors were ranked and weighted based on road dust characteristics (the amounts, grain sizes, and mobilities of the road dust, and the concentrations and toxicities of metals in the road dust). We then applied the RI b105 μm in the Beijing region to assess the spatial distribution of the potential risks posed by metals associated with road dust on atmospheric suspended particles. The results demonstrated that the road dust in urban areas has higher potential risk of metal to atmospheric particles than that in rural areas. The RI b105 μm method offers a new and useful tool for assessing the potential risks posed by metals associated with road dust on atmospheric suspended particles and for controlling atmospheric particulate pollution caused by road dust emissions. © 2016 Elsevier B.V. All rights reserved. Keywords: Road dust particle Risk assessment methods Metal pollution Urban–rural gradient Atmospheric particulate pollution Science of the Total Environment 550 (2016) 167–175 ⁎ Corresponding author. E-mail address: xyli@rcees.ac.cn (X. Li). http://dx.doi.org/10.1016/j.scitotenv.2016.01.110 0048-9697/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv