Estudio de la concentración de compuestos orgánicos volátiles, óxidos de nitrógeno y ozono en el núcleo urbano de la ciudad de Cartagena y evaluación de la exposición de la población

Abstract

ABSTRACT This thesis presents the methodology and results of an environmental study conducted in the city of Cartagena. Firstly, the levels of benzene, toluene, ethylbenzene, xylenes, c-hexane, n-hexane, ozone and nitrogen dioxide in the urban air of Cartagena have been evaluated. Secondly, the personal exposure of the population and the extra cancer risk from exposure to benzene has also been assessed. Determining the concentration of chemicals in the air was performed using a radial passive sensor as sampling system previously evaluated by the European Reference Laboratory of the Joint Research Centre and subsequent laboratory analysis. Sampling took place during a week (from July 15 to July 22, 2009) and consisted of a uniform and strategic distribution around the city of 44 passive samplers to capture VOC, 13 of which can also measure the nitrogen dioxide and ozone levels. This allows the possibility to calculate both the background concentration in the city and the hot spots. This information, along with weather data collected during the campaign, has served as a basis for isoconcentration maps of each pollutant in the city. The results have been contrasted with those from network stations monitoring the atmosphere that the Autonomous Region of Murcia has established in Cartagena. These results have been discussed based on the law. A significantly higher concentration of NO2 has been observed which could indicate the existence of other sources of pollutants other than vehicular traffic. The systematic study and representation of the relations between VOCs concentrations, considering their reactivity and therefore their average lifetime in the atmosphere, have allowed the classification of Cartagena in areas where the horizontal dispersion of pollutants is favoured and areas where it is impeded (where the accumulation of contaminants occurs). By analyzing the graphs, it was possible to visually identify areas where there are additional traffic sources to any of the VOC studied. The study of personal exposure to VOCs and the extra leukaemia risk estimation of Cartagena's population from exposure to benzene has been conducted from the behaviour patterns, studied by analyzing a personal survey of 590 citizens over 16 years of age and non-smokers. Determining the mean concentration values of each microenvironment was performed combining the experimental results of this study with a series of ratios obtained by both the treatment of our experimental data and bibliographical analysis. The main conclusions include that the concentration of the 8 studied organic compounds is higher in indoor environments than outdoors due to the existence of other sources and that the extra leukaemia risk derived from exposure to benzene in Cartagena is 1.71 cases annually.