Urbanization and the challenges in the characterization of air quality

Abstract

The increase in urbanization, as well as the changes in consumption patterns, lead to an increase in the use of resources, waste generation, water pollution and a degradation in air quality since the 20th century. Air Quality monitoring and control have become a huge challenge, mainly in major cities. The physical and chemical processes in urban atmosphere are very complex and include ozone and other secondary pollutants formation. The relation between primary pollutants and ozone concentrations are nonlinear and depends on very complex chemical mechanisms and the atmospheric conditions, mainly temperature and solar radiation. In this work the most used methods for the determination of volatile organic compounds, which are ozone precursors and are not determined by automatic monitoring stations, it is also presented as well as an air quality model of simple implementation. Using the trajectory model OZIPR (Ozone Isopleth Package for Research), from US Environmental Protection Agency, together with SAPRC mechanism (Air Pollution Research Center), the ozone isopleths, curves with the maximum ozone concentrations, can be calculated for different initial concentrations of volatile organic compounds (VOCs) and nitrogen oxides (NOx = NO + NO2). From the obtained results it is possible to infer the main characteristics of ozone forming processes in urban ambient. The results also show the importance of obtaining all the meteorological and concentrations parameters, mainly CO, NO, NO2 and O3, in a monitoring station as well as the concentration and VOCs speciation's in order to understand and explain ozone levels.