Aims: In the present work, health risk from inhalation of PM2.5 pollutants in both areas was assessed spatially Place and Duration of Study: The metropolitan areas of the Toluca (MATV) and Mexico Valleys (MAMV), between September and November 2009. Methodology: A simultaneous sampling campaign was conducted in the Toluca and Mexico Valleys on alternate days from September-22 to November-29, 2009. From the samples collected, their gravimetric concentration was obtained, and S, Cl, K, Ca Ti, V, Mn, Fe, Ni, Cu, Zn, and Pb were determined using the particle-induced X-ray emission technique (PIXE). Results: The health risk by inhalation of PM2.5 with a higher result for the metropolitan area of the Toluca Valley (2.09 for adults, 6.25 for children from 6-12 years old, and 6.58 for children from 2-6 years old) in contrast with that of the metropolitan area of the Mexico Valley (1.67 for adults, 5.20 for children from 6-12 years old, and 5.28 for children from 2-6 years old). Conclusion: These results are perhaps due to the higher concentration of Cl and Mn for the MATV. Additionally, the air parcels from sampling site MAMV go to MATV and thus contributes to an increased health risk from inhalation of PM2.5. There are health risks for the inhalation of PM2.5 in the MATV and MAMV study areas. The risk only considers the elemental risk. There are no similar studies for this comparison between MATV and MAMV in the literature.