In this work, the structure and protein profile of Chenopodium alba pollen samples collected in rural and urban environments were compared. Pollen structure was studied using light and scanning electron microscopy and the soluble protein profile was investigated by means of biochemical analyses (SDS-PAGE). The rural pollen has the opercules well defined while in the urban pollen there is a fine film covering its wall, and opercules are deformed. A decrease in the protein content in the urban pollen and different protein profiles were observed. Micro-Raman spectroscopic studies allowed the identification of carbon-containing particles in the urban pollen wall as well as its morphology and size. The results of this study indicate that the particles present in the urban air are diesel exhaust particles that are adsorbed and accumulated on the Chenopodium alba pollen. These particles can contribute for modifying their structure and protein content. (C) 2008 Elsevier Ltd. All rights reserved.