NO2 Concentration Analysis in Urban Area of Catania

The recent scientific researches have revealed principal causes and trend of Nitrogen dioxide (NO2), a chemical gas very dangerous for the human respiratory apparatus. The generation of this gas is principally associated to the high temperature combustion processes such as those in internal combustion engines and thermal power plants. In the urban area of Catania there are not thermal power plants so, the most important NO2 generation is related to the increasing use of vehicles. It is also demonstrated that NO2 is correlated with other pollutants such as PM10 and PM2,5. The city of Catania is provided by an air quality monitoring network made up of five fixed stations. The principal monitored pollutants are: NO2, CO, BTX, PM10, O3, SO2. This paper focuses on the analysis of the big amount of NO2 data recorded by instrument “Philips model 42” in the urban area of Catania. This data has been validated and analysed in order to conduct a multivariate statistical analysis. The Principal Component Analysis (PCA) and Cluster Analysis (CA), have been developed related to the atmospheric parameters (Wind velocity, Air Temperature, Precipitation, Relative humidity, Global Solar Radiation) in the period between 2009 and 2012. This multivariate analysis has been applied to the investigation process about the linear dependence of NO2 to these parameters. Another important aim of this paper has been to study the trend of NO2 concentration and the number of times this value has overtook the limits imposed by the Air Quality Directive 2008/50/EC.