Characterization of airborne gaseous BTEX and aldehydes from populated Brazilian cities as representative atmospheres of typical urban areas from the Southern Hemisphere

This work evaluated BTEX, HCHO, and CH3COH concentrations in the 5 most populated Brazilian urban centers. We investigated contributing sources in both dry and rainy periods, together with the ozone formation potential (OFP) and the possibly related health risk. Six simultaneous campaigns by passive sampling were carried out from August/2017 to June/2018, for periods of 14 days. The compounds were quantified by GC-FID (BTEX) and HPLC-UV/Vis (aldehydes). Atmospheric concentrations varied within 0.97 mu g m(-3) (m, p-xylene) to 28 mu g m(-3) (benzene). The HCHO and CH3COH concentration levels exceeded international recommendations in all the studied urban centers. Benzene concentrations were above 1.7 mu g m(-3), which is associated with a higher probability of individuals that may develop leukemia. Toluene/Benzene, Xylenes/Benzene, m,p-Xylene/Ethylbenzene, and Formaldehyde/Acetaldehyde ratios indicated vehicle emissions are the main sources of these volatile organic compounds. In addition, the Formaldehyde/Acetaldehyde ratios demonstrate the changes generated in the urban atmosphere of Brazilian cities due to the decrease in the consumption of ethanol fuel. Multivariate analysis separated two groups. CH3COH and benzene were the compounds that most contributed to the clustering of the Sao Paulo and Belo Horizonte centers, while HCHO, Toluene, Ethylbenzene, and xylenes contributed to the clustering of Salvador, Rio de Janeiro, and Londrina. The HQ data for the BTEX and aldehydes levels were below 1 (HQ < 1). Lifetime carcinogenic risk (LCR) values for HCHO and benzene due to exposure to the atmosphere were above the acceptable USEPA limit (1.0 x 10(-6)). HCHO, CH3COH, and toluene were the main contributors to the OFP.