Concentrations of Cd, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V, and Zn in particulate matter (PM) 10 ambient air samples were determined for the urban zone of Tampico, Mexico every 6 days during 2004. A Wedding and Associates PM 10 high-volume sampler was used to collect the particles on quartz and glass fiber filters. A Thermo Jarrel Ash inductively coupled plasma-optical emission spectrometer (ICP-OES) was used to identify and quantify metals in PM 10 according to the USEPA-IO 3.1 method. A scanning electron microscope with an energy dispersive spectrometer (SEM-EDS) was used to analyze the elemental composition, size, and morphology of atmospheric particles. Principal component factor analysis (PCFA) was used to study the sources of PM 10 and metals. PM 10 and Pb concentrations in Tampico did not exceed the Mexican standard value of 120 and 1.5 μg m −3 in 24 h, respectively. PM 10 concentrations ranged from 12 to 47 μg m −3 . The results for Cd, Cr, and Cu are associated to the presence of an industrial source near the sampling site. V and Zn and likely Pb and Ni are related to a refinery. Fe and Ti are associated to natural sources, whereas Cu, Fe, Ni, Pb, and Zn are associated to the storage and transportation of minerals near the sampling zone. Mn is associated to a ferromanganese manufacturing industry and to the refinery. The SEM-EDS micrographs show porous spherical particles rich in V and Ni and smooth spherical particles rich in C and O.