Main ozone-forming VOCs in the city of Sao Paulo: observations, modelling and impacts

• Published in: Air quality, atmosphere and health Vol. 10; no. 4; pp. 421 - 435
• Main Authors: Alvim, Débora Souza, Gatti, Luciana Vanni, Corrêa, Sergio Machado, Chiquetto, Júlio Barboza, de Souza Rossatti, Carlos, Pretto, Angélica, Santos, Maria Helena dos, Yamazaki, Amélia, Orlando, João Paulo, Santos, Guaciara Macedo
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.05.2017; Springer Nature B.V
• Subjects: Air pollution; Air quality; Aldehydes; Alkenes; Atmospheric chemistry; Atmospheric Protection/Air Quality Control/Air Pollution; Earth and Environmental Science; Emissions; Environment; Environmental Health; Ethanol; Gasohol; Gasoline; Health Promotion and Disease Prevention; International; Ionization; Mass spectrometry; Metropolitan areas; Motorcycles; Organic compounds; Outdoor air quality; Ozone; Pollution studies; Studies; Urban areas; VOCs; Volatile organic compounds; Xylene; Brazil; Sao Paulo Brazil; Brazil, Sao Paulo; Volatile organic compounds; Atmospheric chemistry; Incremental reactivity; Ozone-forming potential
• ISSN: 1873-9318; 1873-9326
• DOI: 10.1007/s11869-016-0429-9

High-ozone concentrations currently represent the main air pollution problem in the city of São Paulo, Brazil. To elucidate the main volatile organic compounds (VOCs), which act as ozone precursors, samples from air quality monitoring stations were evaluated. Thirty-five samples were collected in August–September of 2006 and 43 in July–August of 2008, when the consumption of ethanol was about 50 % of the total fuel used in the São Paulo Metropolitan Area. Samples were collected using electropolished stainless canisters. Chemical analyses were performed on pre-concentrated samples followed by gas chromatograph with flame ionization and mass spectrometry detection. The incremental reactivity scale was used to rank the ozone precursors using the Ozone Isopleth Package for Research (OZIPR) trajectory model coupled with chemical mechanism Statewide Air Pollution Research Center (SAPRC). Sixty-nine species of VOCs were quantified, and the ten main ozone precursors identified in 2008 were as follows: formaldehyde (42.8 %), acetaldehyde (13.9 %), ethene (12.2 %), propene (5.1 %), 1-methylcyclopentene (3.0 %), p-xylene (2.4 %), 1-butene (2.1 %), trans-2-pentene (1.9 %), 2-methyl 2-butene (1.7 %) and trans-2-butene (1.6 %). Volatile organic compound mass distribution showed that in 2008 alkanes represented 46 % of the total VOCs, alkenes 27 %, aromatics 14 %, alkadienes 1 % and aldehydes 12 %.