10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Evaluation and Sampling Efficiency of the Wet Dust Sampler (WDS) - a Water-based Method for Road Dust Sampling
JOACIM LUNDBERG, Göran Blomqvist, Mats Gustafsson, Sara Janhäll, Ida Järlskog, VTI
Abstract Number: 1690 Working Group: Instrumentation
Abstract Emissions of PM is a well-known problem, with great impact on human health. One of the largest contributors is the road traffic. Due to stricter regulations for exhaust emissions, the relative importance of non-exhaust emissions is increasing. Abrasion wear of both pavements, tyres and brakes contribute to non-exhaust emissions. These particles are both directly emitted but also accumulated on the road surface as road dust load. This road dust is suspended through the road surface and tyre interaction as well as the turbulence introduced by the vehicle.
To allow for studies of the emission potential for road dust, the road dust load must be quantified. To quantify the total available dust load, a measurement device, the Wet Dust Sampler (WDS) [1] was developed. The WDS has since its development been used extensively for measurements in Sweden and has since then been updated. This updated version has also recently been exported to Norway and Finland.
The WDS basic principle of operation is to perform high pressure washing of a defined road surface area. This washing can be performed using regular water, or to allow for chemical analyses, distilled water. The sample is transferred into a storage container by the means of compressed air.
Studies of how the machine and the settings used impact on the cleaning and sampling efficiency include several tests of the performance of the newest version. Features tested have been e.g. the repeatability of flushed water, the repeatability of collected water, the cleaning efficiency and the retention of dust in the system.
One of the initial studies focused on the cleaning efficiency in which repeated sampling was performed in the same point. This was done for three different pavements of type Stone Mastic Asphalt (SMA) with maximum nominal aggregate size of 16, 8 and 6 mm. These pavements were selected based on common usage in Sweden (mainly larger sizes) due to their resistance against abrasion from studded tyres. This study was performed in a laboratory setting with laboratory manufactured slabs of pavement. The road surface texture was then filled with a well characterised dust of known source.
The initial, limited results show indications of a high cleaning efficiency, all having less than 10% retained material after the first sampling.
Further results regarding
References [1] P. Jonsson, G. Blomqvist, and M. Gustafsson, "Wet Dust Sampler: Technological Innovation for Sampling Particles and Salt on Road Surface.," Seventh International Symposium on Snow Removal and Ice Control Technology, Transportation Research Circular vol. E-C126, pp. 102-111, 2008.