The particulate matter (PM) is comprised of two kinds of particles, classified after their dimensions, the PM2.5 which encompasses particles with sizes smaller than 2.5 µm and the PM10 with particles ranging in size from 2.5 µm to 10 µm. As previous studies have shown, PMs have an undeniable influence, dependent on the exposure time, upon the health of the human cardiopulmonary system. In this study we focused on the dimensional distribution of PMs and the influence of altitude on their numbers. Our detailed investigation lead us to the conclusion that the particle number is increasing at higher altitudes and also that PM2.5, which represents a greater health risk factor, is much more abundant than PM10