Assessment of the impact of the bus fleet and transportation infrastructure works on the air quality in Rio de Janeiro (Olympic Games 2016)

Samples of PM 2.5 , PM 10 SO 2 , and NO 2 were collected in the Metropolitan Area of Rio de Janeiro (MARJ), Brazil, between 2016 and 2017. The annual emissions of NO x , PM 10 , and SO x emitted from buses running on roads near the monitoring stations were estimated using a bottom-up methodology in some sites. In most stations, the results showed an increase in PM 2.5 and PM 10 due to urban activities carried out before and during the Olympic Games in 2016. In all sites, the inorganic species reflected the influence of secondary aerosol and marine contributions. The species Fe and Cu were the most abundant elements found in the particles. The elements Cu, As, Mo, Cd, and Pb were the most enriched ones in the samples collected at all sites, suggesting an important anthropogenic influence. The source apportionment was obtained with Positive Matrix Factorization; four aerosol sources were identified at the sites: vehicular, marine spray, secondary formation, and a mix of industrial and soil resuspension. During the entire period, the average oxidation ratio of sulfur (SOR) value indicated that sulfate was mainly produced by the secondary oxidation of SO 2 . On the other hand, the average oxidation ratio of nitrogen (NOR) indicated a weak secondary conversion of nitrate. From the calculation of nitrogen and sulfur oxides (NO X and SO X ) and PM 10 pollutants in buses on certain avenues, NO X presented a relatively higher concentration, and it was strongly related to diesel oil burning from heavy vehicles. Thereby, the city’s improvement works contributed to aggravating the air quality in Rio de Janeiro since it was possible to observe a decrease in the particulate matter after the Olympic Games, despite weather conditions. In addition, the results suggested that diesel fuel burning mainly formed NO 3 - , since, in Brazil, this fuel is used in buses.