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Measurements of aerosol scattering properties obtained during the period from March 2006 to December 2010 at Valencia (Spain) have been analyzed. The total aerosol scattering (sigma(sp)) and backscattering (sigma(bsp)) coefficients were measured using a TSI Model 3563 three-wavelength integrating nephelometer. From the measurements of sigma(sp) and sigma(bsp), it was possible to determine also the scattering Angstrom exponent (alpha(s)). For the entire measurement period, the mean values (+/- standard deviation) at 550 nm are: 80 +/- 50 Mm(-1) for sigma(sp); 8 +/- 5 Mm(-1) for sigma(bsp); and 1.6 +/- 0.3 for alpha(s). These results indicate a moderate polluted atmosphere characterized by fine particles. The daily variation for all seasons shows clear patterns in the scattering properties of the atmospheric aerosols, due to the traffic and the evolution of the boundary layer throughout the day. This influence of traffic was analyzed, observing different daily patterns for weekdays (Monday-Friday) and weekends (Saturday and Sunday). (C) 2011 Elsevier Ltd. All rights reserved.