Changes in elemental composition and mass of atmospheric aerosol pollution between 1996 and 2002 in a Central European city Imre Salma a, * , Willy Maenhaut b a Environmental Chemistry, Eo ¨tvo ¨s University, P.O. Box 32, H-1518 Budapest, Hungary b Institute for Nuclear Sciences, Ghent University, Proeftuinstraat 86, B-9000 Ghent, Belgium Received 14 September 2005; received in revised form 10 November 2005; accepted 29 November 2005 Non-exhaust traffic emission particles and coarse-mode particles are increasing in Budapest, Hungary. Abstract Median atmospheric concentrations of Pb, Br, S, As, Se, and particulate matter (PM) decreased, and median concentrations of Sb, Cu, Zn, Fe, Ca, Cr and Ba increased in urban aerosol in downtown Budapest between 1996 and 2002. The changes in Pb and Br concentrations were un- ambiguously attributed to the phasing out of leaded gasoline. The increments were mainly related to and explained by non-exhaust vehicular emissions. The mechanical wear of asbestos-free brake linings of road vehicles contributed to the concentration of Cu and Sb on average by 69% and 66%, respectively in the PM10 size fraction. Tire rubber abrasion was a major source for atmospheric Zn; on average, non-crustal sources accounted for 67% of Zn in the PM10 size fraction. Contribution of the tire wear component to the PM10 mass was estimated to be 6% at most, while its contribution to organic aerosol was of the order of 15%. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Urban aerosol; Road traffic; Non-exhaust vehicle emissions; Brake wear; Tire rubber wear 1. Introduction Several Central and Eastern European countries changed their economy and political system in the beginning of the 1990s. In the period of transition, the economic productivity decreased (which also meant that emissions from industrial plants were usually reduced), and society experienced, quite suddenly, the achievements of the free market economy. In ad- dition to the industrial recession, the structure of the economy changed; services and trade sector gained over heavy and chemical industry, some contemporary industrial and domestic (heating) technologies were adopted on a large scale, and the number of road vehicles and traffic densities increased. For instance, the number of passenger cars (including jeeps and microbuses) registered in Budapest combined with Pest County, Hungary was about 800,000 in 1996 and 918,000 in 2002. Diesel-powered vehicles shared 8.5% of the national passenger car fleet in 1996, and 11.2% in 2002; the mean life- time of passenger cars registered in Budapest was 10.6 years in 1996, and 9.6 years in 2002 (GKM, 1997, 2003). The changes affected the air qualitydin particular in cities where road traffic belongs to the main emission sources of particulate matter (PM). Aerosol particles are emitted directly from the incomplete combustion of fossil fuel and from friction acting on individual components (mainly on brakes and tire rubber), or are produced indirectly through chemical reactions. The principal aerosol components emitted by unleaded gasoline and diesel-fueled vehicles are organic carbon (OC) and ele- mental carbon (EC). Abundances of sulfates and nitrates are also significant (up to several percents by mass); concentration of other elements in the exhaust aerosol is quite small (most being <1% by mass; US EPA, 2004). Relative abundance of the components varies with individual fuel type and exact composition (including lubricants and additives), as well as * Corresponding author. E-mail address: salma@para.chem.elte.hu (I. Salma). 0269-7491/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2005.11.042 Environmental Pollution 143 (2006) 479e488 www.elsevier.com/locate/envpol