title: Effect of liquefied petroleum gas on ozone formation in Guadalajara and Mexico City.
abstract: Leakages of liquefied petroleum gas (LPG) are suspected to contribute greatly to ozone (O3) formation in Mexico City. We tested such a hypothesis by outdoor captive-air irradiation (CAI) experiments in the two largest Mexican metropolitan areas: Guadalajara (GMA) in 1997 and Mexico City (MCMA) in 2000. O3 was monitored in each city for 20 days (8:00 a.m.-6:00 p.m.) in smog chambers containing unaltered morning air or morning air enriched with either commercial LPG or LPG synthetic mixture 60/40 (propane and butane). Tested additions of both components were 35% (by volume) in GMA and 60% (by volume) in MCMA. The addition effects on O3 (max) were compared with effects from diluting LPG components or total nonmethane hydrocarbons (tNMHCs) by 50%. Diluting tNMHCs had the greatest absolute effect at both cities: it lowered O3 (max) by 24% in GMA and 55% in MCMA. Adding commercial LPG increased O3 (max) by 6% in GMA and 28% in MCMA; whereas adding LPG synthetic mixture 60/40 caused a similar increase in O3 (max), 4 and 21% in GMA and MCMA, respectively. Compared with dilution of tNMHCs, dilution of LPG-associated compounds had a smaller decreasing effect on O3 (max), only 4% in GMA and 15% in MCMA. These results show that commercial LPG and LPG synthetic mixture 60/40 affect O3 formation to a lesser extent than estimated previously.
authors: Programa de Investigación en Medio Ambiente y Seguridad, Dirección Ejecutiva de Investigación, Instituto Mexicano del Petróleo, Mexico City, Mexico. jjaimes@imp.mx
authors: J Luis
authors: JL
authors: Jaimes-López
authors: Julio
authors: J
authors: Sandoval-Fernández
authors: Emmanuel
authors: E
authors: González-Ortíz
authors: Marcos
authors: M
authors: Vázquez-García
authors: Uriel
authors: U
authors: González-Macías
authors: Angel
authors: A
authors: Zambrano-García
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000475:Alkenes / Q000737:chemistry; D002947:Cities; D004784:Environmental Monitoring; D008800:Mexico; D010083:Oxidants, Photochemical / Q000032:analysis*; D010126:Ozone / Q000032:analysis*; D010578:Petroleum; D010777:Photochemistry
chemical_list: D000393:Air Pollutants; D000475:Alkenes; D010083:Oxidants, Photochemical; D010578:Petroleum; D010126:Ozone