Valle de Aburrá is a valley located in the Andes mountain range, and it is characterized for being a geographically narrow valley with thermal inversion problems.The environmental authority (Área Metropolitana del Valle de Aburrá), has established an Air Quality Monitoring network with stations in nine of the ten municipalities forming the valley.The network is operated by the National University of Colombia.Although the air quality network monitors particulate material (PST, PM 10 , PM 2.5 and PM 1 ), nitrogen dioxide, sulphur dioxide, carbon monoxide and ozone, apart from meteorological variables, the problematics concerning air quality in Valle de Aburrá has historically been associated with the breathable particulate matter PM 10 and the inhalable particulate matter PM 2.5 .Results obtained from the monitoring of PM 10 and PM 2.5 for the period July-December 2013 are presented in this study, for the stations measuring both of the pollutants.Additionally, the PM 2.5 /PM 10 , relationship is reported, which can be used as a parameter for decision-making concerning health protection of the inhabitants of Valle de Aburrá, as well as the correlation coefficients for each station.According to the results, the PM 2.5 /PM 10 relationship in the MED-UNFM station was 0.501, in the MED_PJIC station this relationship was of 0.380, and in the ITA_CONC station, it was 0.496.