Evaluation of PM2.5 Emitted in Environmental Contingency in the urban area of Tijuana, B.C. (Mexico)
Ma. Cristina Castañón Bautista, José Chávez Carvayar, Ghiraldo Murillo, Gerardo Cesar Díaz Trujillo

Abstract
From October 22 to 29, 2007, there was an environmental contingency in the city of Tijuana. This contingency generated environmental conditions that did not allow citizens to have a clear sky. With the purpose of identifying elemental contents and morphological composition of PM2.5 particulate material, which was generated during such period, a sampling was carried out in two areas of the city: one with constant traffic activity and a residential area. Particle Induced X-Ray Emission (PIXE) techniques was applied for the quantitative determination of micro-elemental contents, while Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to study the morphology. Based on the results obtained, it is estimated that the analyzed particulate material comes from different generating sources, mainly from mineral and soil, as well as that resulting from biomass burning and traffic activity. Regarding PM2.5 and in compliance with the Mexican Official Regulation, the limit allowed was not surpassed.

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