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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 pattern is little known. Here we developed an innovative index model called the road dust index ( RI < 105 μm ) and it combines source and transport factors for road dust particles < 105 μm in diameter. It could quantify and differentiate 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 < 105 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 < 105 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. [ABSTRACT FROM AUTHOR]

Abstract: The proper evaluation of pollutant strength and loads associated with road-deposited sediment (RDS) is crucial for controlling diffuse pollution in urban areas. A new index model, which combines source and transport factors and is called the RDS index, was developed using RDS characteristics (e.g., the amount, grain size, mobility, and metal concentrations) and used in a case study in the Beijing region. The observed and weighted RDS characteristics along an urban–rural gradient, which included central urban (UCA), urban village (UVA), central suburban county (CSA), rural town (RTA), and rural village (RVA) areas, were used to calculate the RDS index for the pollutant load (RDSindex,load) and the pollutant strength (RDSindex,strength). Our results demonstrated that the RDSindex,load and RDSindex,strength values both changed significantly along the urban–rural gradient. RDSindex,strength increased along the urban–rural gradient and the RDSindex,load value along the main roads decreased in the order RVA > UCA > CSA > RTA. The method offers a new way of assessing metal pollution in RDS and provides an important scientific basis for controlling pollution caused by RDS washoff. [Copyright &y& Elsevier]