Source apportionment and health impact assessment of atmospheric particulate matter in the city of São Carlos, Brazil.

In this study, positive matrix factorization method was used for source apportionment of PM in the city of São Carlos from 2015 to 2018. The annual mean concentrations of PM, 15 PAHs, 4 oxy-PAHs, 6 nitro-PAHs, 21 saccharides, and 17 ions in these samples were in the ranges 18.1 ± 6.99 to 25.0 ± 11.3 μg m for PM, 9.80 × 10 ± 2.06 to 2.03 ± 8.54 × 10 ng m for ΣPAHs, 83.9 ± 35.7 to 683 ± 521 pg m for Σoxy-PAHs, 1.79 × 10 ± 1.23 × 10 to 7.12 ± 4.90 ng m for Σnitro-PAHs, 83.3 ± 44.7 to 142 ± 85.9 ng m for Σsaccharides, and 3.80 ± 1.54 to 5.66 ± 4.52 μg m for Σions. For most species, the concentrations were higher in the dry season than in the rainy. This was related not only to the low rainfall and relative humidity characteristic of the dry season but also to an increase in fire spots recorded in the region between April and September every year from 2015 to 2018. A 4-factor solution provided the best description of the dataset, with the four identified sources of PM being soil resuspension (28%), biogenic emissions (27%), biomass burning (27%), and vehicle exhaust together with secondary PM (18%). Although the PM concentrations were not above the limit established by local legislation, the epidemiological study showed that by reducing PM concentrations to the level recommended by the WHO, approximately 35 premature deaths per 100,000 population could be avoided annually. The results revealed that biomass burning continues to be one of the main anthropic sources of emissions to the atmosphere in the region, so it needs to be incorporated into the existing guidelines and policies to reduce the concentration of particulate matter to within the limits recommended by the WHO, in order to avoid premature deaths.