To increase the knowledge of the particle composition in Bogota, 70 samples of PM were collected during 3 mo in an industrial and non-attainment PM area. A large variation within all PM components was observed. The carbonaceous fraction accounts for 10-60% of the total PM fraction. The organic carbon (OC) and elemental carbon (EC) ratio varied between 0.2:1 and 2.2:1. A very weak correlation between PM and the OC-EC fractions was found. There was a good correlation between NH and SO and NH and NO , which explained a secondary formation of aerosol in Bogota. Given the current sulfur content in diesel, the combustion conditions at high altitude and the presence of man-made agricultural sources around the city, the permanently presence of SO , NO , their atmospheric oxidation products, and NH in Bogota's atmosphere could be expected. Preliminary analysis of the PM composition in Bogota provided an indication of the sources of primary particles, i.e., automobiles, industry, and unpaved roads. This is an abstract of a paper presented at the 101st AWMA Annual Conference and Exhibition (Portland, OR 6/24-27/2008). 10 10 10 10 4 4 4 3 2 x 3 10