a b s t r a c tParticle composition data for PM 10 samples collected at an urban background location in Elche in southeastern Spain from December 2004 to November 2005 were analysed to provide source identification and apportionment. A total of 120 samples were collected and analysed by Particle Induced X-ray Emission (PIXE) and ion chromatography. Positive matrix factorization (PMF) was used to estimate sources profiles and their mass contributions. The PMF modelling identified six sources: PM 10 mass was apportioned to secondary nitrate (26%), secondary sulphate (22%), local soil dust (21%), traffic (13%), seasalt (11%) and African dust (7%). It is worth noting that PMF was able to identify a Saharan dust source even in the presence of a weighty local dust source, and to quantitatively estimate the contributions of these two sources. The African dust contribution varies, depending on the intrusion days, within a range of 5-40% of the total PM 10 concentration. Without the contribution of Saharan dust, 50% of the total exceedances of the PM 10 50 mg m À3 EC limit during the studied period would not have taken place.

PM2.5 and PM10 samples were collected in the urban atmosphere of Elche (southeastern Spain) between December 2004 and November 2005. The samples were analyzed for mass and water-soluble inorganic ions (Na + , NH þ 4 , K + , Ca 2+ , Mg 2+ , Cl − , NO À 3 and SO 2À 4 ) with the aim of investigating the influence of the climatic and geographic features of a coastal semiarid area on the contribution of these species to PM levels. Secondary inorganic ions (SO 2À 4 , NO À 3 , NH þ 4 ) were the major components in the fine fraction (PM2.5), accounting for 40% of the total mass. The relationship between non-marine SO 2À 4 and NH þ 4 indicated that fine sulfate particles were completely neutralized by ammonium. In the coarse fraction (PM10-2.5), nitrate (as NaNO 3 and Ca(NO 3 ) 2 ), together with crustal (CaCO 3 ) and marine species (NaCl) accounted for almost 50% of the total mass. Fine sulfate and coarse nitrate showed summer maximums. In contrast, the concentrations of fine NO À 3 were lowest in the warm period. Ammonium presented both winter and summer maximums. The levels of marine ions, except for coarse Cl − , were highest in summer when the dominant wind flow is from the sea. No significant seasonal variations were observed for coarse Ca 2+ and SO 2À 4 . The concentrations of all inorganic ions increased during Saharan dust events, in particular, fine NH þ 4 and SO 2À 4 and coarse NO À 3 . Coarse calcium was proved not to be a good tracer for this type of episode in our region since the average levels of this cation are elevated and the relative increase in its concentrations during African events was not as high as expected.

h i g h l i g h t sStreaker/Dekati/PIXE are suitable to study high-intensity short-lived firework events. Fireworks related elements showed >80% elemental mass in the submicrometric region. Resuspended soil dust is an important source of atmospheric particles in these shows. a r t i c l e i n f o b s t r a c tTypical of festivals in Eastern Spain, mascletàs are high-intensity pyrotechnic events where thousands of firecrackers are burnt in an intense, rapid episode that generates short-lived heavy aerosol clouds. High temporal resolution and size distribution characterisation of aerosol components were performed to evaluate the effects of the brief (<30 min) and acute exposure on the spectators present. Very high concentrations of firework specific elements, especially in the fine fraction, were reached during mascletàs, with values of about 500 g/m 3 for K and 300 g/m 3 for Cl. Sr, Al, Mg, Ba, Cu, Co, Zn, and Pb concentration increase factors of more than 100 (1000 for Sr and Ba) were observed in the fine fraction with respect to background levels. Crustal origin elements, like Ca, Fe, Si, Ti, also showed an important concentration rise (∼10 times above background levels) but this is due to dust resuspension by pyrotechnic explosions. The crustal components are mainly in the coarse mode (>90% elemental mass), between 2 and 3 m. Most firework related metals are concentrated in the submicrometric region (>80%) with a trimodal size distribution. This may be interesting to epidemiologists given the toxic effects that such fine, metal-rich particles can have on human health.

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