Megacities, like Sao Paulo, Brazil, are increasingly receiving attention as strong pollution hotspots. Located in South America,the Sao Paulo Metropolitan Area has 19 million inhabitants and 7.4 million vehicles. During winter (dry season), the average concentration of inhalable particles (i.e., PM10, particulate matter with aerodynamic diameter 10 mm) can be as high as 150 mg m3. A major known source of pollutants are vehicular emissions; however, in addition to traffic there are also contributions from biomass burning. Previous studies showed that there is a link between particulate concentrations and adverse health effects, more specifically, respiratory problems