Resumo

JAIMES-LOPEZ, José Luis; SANDOVAL-FERNANDEZ, Julio  e  ZAMBRANO-GARCIA, Angel. Exploring the Liquefied Petroleum Gas - Ozone Relation in Guadalajara, Mexico, by Smog Chamber Experiments. J. Mex. Chem. Soc [online]. 2005, vol.49, n.3, pp.292-297. ISSN 1870-249X.

It has been hypothesized that liquefied petroleum gas (LPG) emissions can increase substantially the formation of ozone (O₃) in the ambient air. We tested experimentally such hypothesis in Guadalajara's downtown by captive-air irradiation (CAI) techniques. During November 1997-January, 1998, morning ambient air samples were confined in outdoor smog chambers and subjected to the following treatments: 35% addition of commercial LPG or one out of two mixtures of major LPG compounds (propane/butane: 70/30% or 60/40%), 50% dilution of total volatile hydrocarbons (VOCs), and 50% dilution of LPG associated VOCs (C2-C4). Captive and untreated morning ambient air served as experimental control. This experiment ran under ambient sunlight and temperature. Chamber O₃ was measured hourly from 08:00-18:00h, and the maximum O₃ concentration (O_3max) was used for treatment comparisons. Daily O₃ profiles within the control chambers and in open ambient air were fairly similar, though O_3max was consistently higher in the chambers. Only the 50% dilution of total volatile hydrocarbons (VOCs) had a significant effect on O_3max, which decreased by 16% on average. These results indicate that high O₃ levels in Guadalajara can not be explained by LPG emissions. A supplementary experiment with captive clean air added with commercial LPG or the same propane/butane mixtures showed that O₃ formation was less favoured by the 70/30% mixture.

Palavras-chave : Smog chamber experiments; ozone; air quality and liquefied petroleum gas.

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