Particles of anthropogenic and biological origin, minerals and gaseous elements are the major constituents of the aerosol. Pollen is a biological component of the aerosol, found in suspension with other pollutants. In recent years, research has been conducted on the crossed effects between non-biological and biological pollutants on allergy worsening in susceptible individuals or on the development of symptoms in non-symptomatic ones. Platanus spp pollen is abundantly present in the atmosphere of Porto in early spring and is known to promote allergic respiratory symptoms. The aim of this study was to characterize possible alterations of the main elements present on the Platanus spp. pollen wall under different atmospheric conditions in the coastal city of Porto, Portugal, using EPMA.