Air quality mexican regulations about atmospheric aerosols refer to particle sizes and to the total suspended particle. None of these norms establishes the allowed values based on the particulate chemical composition. Mexican environmental legislation also considers as critical zones those with high concentration of contaminants in the atmosphere. One of these zones is the Tula-Vito-Apasco corridor where no chemical composition characterization in terms of trace metal associated to the air particulate matter has been made. Along this corridor near Tlaxcoapan there are important contaminant sources as petrochemical and electric power plants, metal-mechanical industry, limestone quarry and contaminated soils. In this work PIXE and SEM-EDS were applied to the PM10 fraction collected on filters. The trace element values thus determined were compared with those of a similar critical zone. It was found that most of the coarse particles come from limestone quarry as fugitive dusts while V, Ni, Cr and Pb values are moderately high and seems to be associated to industrial activities and contaminated soil as well.