Road dust resuspension: A review

In the last decades, emissions from road traffic saw a significant drop due to the stricter regulations for the motor vehicles' exhaust and cleaner technologies for fleets. Therefore, non-tailpipe emissions should be increasingly held responsible for traffic-related emissions, including brake-, tyre- and road-wear particles, as well as vehicleinduced resuspension of road dust deposited on the surface. Nevertheless, the quantification of road dust resuspension is still lacking a standardised sampling procedure, leading to a doubtful integration in emission inventories. This article aims at presenting the various methodologies that were so far developed to collect road dust, ranging from the most rudimental scoop sweeping until more sophisticated devices with size-selective inlets to capture the more worrisome fraction: the inhalable resuspended particulate matter. The different methodologies for sampling and calculating emission factors are critically reviewed. Sources that contribute to the road dust and their implications on the particle size distributions and chemical composition are discussed. Easily applicable indexes to quantify the magnitude of pollution of road dust are presented. Emission factors and physicochemical profiles of road dust are necessary towards a more accurate inclusion of this specific nonexhaust category in emission inventories, receptor modelling and health protection programmes by policymakers.