This investigation was made by the National University of Colombia in agreement with the Metropolitan Area of the Aburra Valley. The principal objective was to enforcing the monitoring of the quality of the air of the Aburra valley by means of the passive testers of sulfur dioxide, nitrogen dioxide, ozone, volatile organic compounds (BTX) and the rate of particle sedimentation in main road routes. Testers were settled in 15 Stations of the Metropolitan Area for a year. In gas measurement passive tubes of diffusion were used. Settleable particle measurement uses the principle of the gravity and the samples are analyzed by means of total solids. The results of sulfur dioxide and nitrogen do not exceed the Annual Colombian Norm, but in 12 stations of testing the value is surpassed guides of the WHO for nitrogen dioxide. The ozone levels show formation of this one polluting agent in the zones of slope. In 9 stations the Annual Colombian Norm for benzene is exceeded and all the stations the WHO Norm was not fulfilled. The greater rates of particle sedimentation are obtained in the sites of testing influenced by activities of construction and maintenance of ways. The use of passive measurers allows to identify critic zones and to evaluate of simple way the tendencies of atmospheric contamination. We suggest that in Colombia this technique for the measurement of the quality of the air is approved.