AIR QUALITY MONITORING OF BTXs IN THEVALLEY OF ABURRA WITH DIFFUSIVE TUBES

摘要

The main objective was to optimize the monitoring process of the air quality in the urban zones of the valley using passive diffusive tubes for the concentrations of the volatile organic compounds (BTXs) Benzene, Toluene, Xylene, in 15 sites of the metropolitan area during one year time. The study was conducted in the Aburra Valley, a narrow valley with thermal inversion problems, located in the Colombian Andean Mountains. It was made by the National University of Colombia (UNAL), Medellin Campus, through of an agreement with the Environmental Authority of the Metropolitan Area of the Valley of Aburra (AMVA). The passive diffusive tubes were used to measure the concentration of these gases in the atmosphere. The tubes contained an absorbent substance for each type of gas and were exposed to the atmosphere during periods of 2 to 4 weeks. The absorbed amount of polluting agent was proportional to its concentration in the atmosphere. In 9 of the 15 stations, the Annual Colombian Standard of Air Quality for Benzene was exceeded. All the stations it exceeded the guidelines of the World Health Organization (WHO). The main conclusion is that the human population of the Aburra Valley is chronically exposed to levels of Benzene over 5 g/m~ 3. The WHO does not recommend a safe value of exposure to Benzene as it considers it to be a carcinogenic substance; therefore, in the 15 monitored sites, regarding Benzene, there is no compliance with the WHO guidelines for the protection of the public health. The use of passive monitors also helped to identify critical zones of contamination and to evaluate a simple method for monitoring contaminants in the air. The result of this research has started the process for the official sanction of the use of the technique of diffusive tubes in Colombia for monitoring air quality.