Determining VOCs Reactivity for Ozone Forming Potential in the Megacity of São Paulo

Débora Souza Alvim; Luciana Vanni Gatti; Sergio Machado Corrêa; Júlio Barboza Chiquetto; Guaciara Macedo Santos; Carlos de Souza Rossatti; Angélica Pretto; José Roberto Rozante; Silvio Nilo Figueroa; Jayant Pendharkar; Paulo Nobre

doi:10.4209/aaqr.2017.10.0361

Determining VOCs Reactivity for Ozone Forming Potential in the Megacity of São Paulo

Aerosol and Atmospheric Chemistry South America

Débora Souza Alvim ¹^,6, Luciana Vanni Gatti²^,6, Sergio Machado Corrêa³, Júlio Barboza Chiquetto⁴, Guaciara Macedo Santos⁵, Carlos de Souza Rossatti⁶, Angélica Pretto⁶, José Roberto Rozante², Silvio Nilo Figueroa², Jayant Pendharkar², Paulo Nobre²

¹Center of Natural Sciences and Humanities (CCNH), Federal University of ABC (UFABC), Santo André, SP, Brazil
²Center for Weather Forecasting and Climate Studies (CPTEC), and Earth System Science Center (CCST), National Institute for Space Research, Cachoeira Paulista, SP, Brazil|
³Faculty of Technology, Rio de Janeiro State University (UERJ), Resende, RJ, Brazil
⁴Department of Geography, University of Sao Paulo (USP), São Paulo, SP, Brazil
⁵Department of Earth System Science, University of California, Irvine, CA 92697, USA
⁶Chemistry and Environment Center, Institute of Nuclear Energy Research (IPEN), São Paulo, SP, Brazil

Received: December 22, 2017
Revised: March 1, 2018
Accepted: March 3, 2018
Download Citation: ||https://doi.org/10.4209/aaqr.2017.10.0361

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Cite this article:
Alvim, D.S., Gatti, L.V., Corrêa, S.M., Chiquetto, J.B., Santos, G.M., de Souza Rossatti, C., Pretto, A., Rozante, J.R., Figueroa, S.N., Pendharkar, J. and Nobre, P. (2018). Determining VOCs Reactivity for Ozone Forming Potential in the Megacity of São Paulo. Aerosol Air Qual. Res. 18: 2460-2474. https://doi.org/10.4209/aaqr.2017.10.0361

HIGHLIGHTS

During 2016, the 1-hour national standard for ozone was exceeded on 76 days.
Carbonyls VOCs emissions will increase worldwide due to the increase in ethanol use.
Aldehydes were 35.3 % of total VOCs mass, ethanol was 22.6% and aromatics 15.7%.
Ozone forming potential: 74% from aldehydes (61.2% acetaldehyde), aromatics 14.5%.
The most effective solution to limit the O₃ levels is to reduce the oxygenated VOCs.

ABSTRACT

High ozone (O₃) concentrations are a major concern about air quality in the São Paulo Metropolitan Area (SPMA). During 2016, the 8-hour state standard of 140 µg m^–3 was exceeded on 32 days, whereas the 1-hour national standard of 160 µg m^–3 was exceeded on 76 days. Exposure to such unhealthy O₃ levels and other pollutants can lead to respiratory disease. The focus of this study is to determine the main O₃ precursor in terms of the volatile organic compounds (VOCs) in order to provide a scientific basis for controlling this pollutant. In this work, 66 samples of hydrocarbons, 62 of aldehydes and 42 of ethanol were taken during the period from September 2011 to August 2012 from 7:00 to 9:00 a.m. The OZIPR trajectory model and SAPRC atmospheric chemical mechanism were used to determine the major O₃ precursors. During the studied period, aldehydes represented 35.3% of the VOCs, followed by ethanol (22.6%), aromatic compounds (15.7%), alkanes (13.5%), ketones (6.8%), alkenes (6.0%) and alkadienes (less than 0.1%). Considering the concentration of VOCs and their typical reactivity, the simulation results showed that acetaldehyde contributed 61.2% of the O₃ formation. The total aldehydes contributed 74%, followed by aromatics (14.5%), alkenes (10.2%), alkanes (1.3%) and alkadienes (e.g., isoprene; 0.03%). Simulation results for the SPMA showed that the most effective alternative for limiting the O₃ levels was reducing the VOC emissions, mainly the aldehydes.