A qualidade do ar na região metropolitana de Fortaleza – CE sob a perspectiva do sistema clima urbano

Abstract

This study aimed at evaluating the air quality in the Metropolitan Region of Fortaleza. It was based on the physicochemical channel of the Urban Climate System by Monteiro (1976). It also attempted to check the influence of climate dynamics in the detected polluting concentrations. Breathable Particulate Matter (PM) samples and Carbonyl Compounds (CCs) were collected, after being detected by the air samplers. These concentrations were analyzed during the day and the night, on representative week days and on Sundays, in contrasting annual seasons - the rainy and dry seasons. The work was carried out in three areas: Meireles neighborhood, Messejana neighborhood and Maracanaú Industrial District. Samplings occured in triplicate, with three spots in each collecting area, which had distinguished urban dynamics and geoecologic features. After quantification of such pollutants, the Cancer Risk (CR)to which the population in these areas would be exposed was estimated. In addition to the measurement of pollutants, other aspects such as the flow of vehicles, climate dynamics ,and the climate elements were also verifyed. From the results it was verifyed that the Maracanaú Industrial District showed the highest PM and CC’s concentrations, followed by Messejana neighborhood and Meireles neighborhood. The highest concentrations of pollutants in the study areas were detected during the week, due to the increased flow of vehicles and industrial activity, and there was a decrease of these concentrations on Sundays. The influence of photochemical effect resulted in the transformation of primary to secondary pollutants, generating a higher concentration of CCs during the day, comparing with the night. The highest PM concentrations were also detected during daytime. The Industrial District showed the highest CR rating. Both atmospheric system and climate elements were very important for the dispersion and / or concentration of pollutants in the analyzed areas. After analyzing all these results, it was concluded that the highest concentrations of CCs were found in the rainy season. The PM, on the other hand, showed the highest concentrations during the dry period. Such situations have occurred possibly due to the climate elements and the urban dynamics.