Road Dust and Air Quality in Sweden

During the last years it has become evident that wear particles from road pavements, tires, brakes, and road maintenance strongly contribute to episodes with very high concentration of inhalable particles (PM10) in outdoor air. These episodes normally occur during dry periods in winter and spring when accelerated wear and particle production occurs due to the use of studded tires and winter gritting. A lot of new knowledge about wear particles is needed in order to develop cost-efficient measures to deal with them. A great advantage is the possibility to study aerosols from each source both separately and in different combination in a controlled environment. At VTI (Swedish National Road and Transport Research Institute) a road simulator, previously used for pavement and tire wear studies, is used as a wear particle generator. Measurements of PM10 in the road simulator hall have been used to study the influence of pavement properties, tire type, and vehicle speed on pavement wear. In several cities in Sweden, different winter maintenance chemicals (e.g., calcium magnesium acetate and magnesium chloride) have recently started to be used as dustbinders in springtime in order to abate the dust problem. Also other measures aiming at abating road dust concentrations are under way, including reduced studded tire use and speed reductions. In this paper compilations of results from several recent research projects and field case studies will be presented. Different pavements, tires, winter maintenance abrasive material, as well as measures like reduced studded tire wear and chemical dustbinding are discussed.