Particulate matter, especially PM2.5, is associated with increased morbidity and mortality from respiratory diseases. Studies that focus on the chemical composition of the material are frequent in the literature, but those that characterize the biological fraction are rare. The objectives of this study were to characterize samples collected in Sao Paulo, Brazil on the quantity of fungi and endotoxins associated with PM2.5, correlating with the mass of particulate matter, chemical composition and meteorological parameters. We did that by Principal Component Analysis (PCA) and multiple linear regressions. The results have shown that fungi and endotoxins represent significant portion of PM2.5, reaching average concentrations of 772.23sporesμg-1 of PM2.5 (SD: 400.37) and 5.52EUmg-1 of PM2.5 (SD: 4.51EUmg-1), respectively. Hyaline basidiospores, Cladosporium and total spore counts were correlated to factor Ba/Ca/Fe/Zn/K/Si of PM2.5 (p andlt; 0.05). Genera Pen/Asp were correlated to the total mass of PM2.5 (p andlt; 0.05) and colorless ascospores were correlated to humidity (p andlt; 0.05). Endotoxin was positively correlated with the atmospheric temperature (p andlt; 0.05). This study has shown that bioaerosol is present in considerable amounts in PM2.5 in the atmosphere of Sao Paulo, Brazil. Some fungi were correlated with soil particle resuspension and mass of particulate matter. Therefore, the relative contribution of bioaerosol in PM2.5 should be considered in future studies aimed at evaluating the clinical impact of exposure to air pollution.
