The aim of this study was to evaluate redundant measurements in the air quality monitoring network (AQMN) of Lisbon and Tagus Valley (LTV). With this purpose, the minimum number of monitoring sites that should operate was achieved using principal component analysis (PCA). The air pollution data was collected in twenty monitoring sites during the period from January to December 2006. The air pollutants analysed were CO, NO2, PM10 and O3.In this study, a different criterion for selection of the number of principal components (PCs) was applied. The PCs were selected representing at least 95% of the original data variance. Using this criterion, the PCs have more information about the air pollution data, increasing the confidence in the PCA results.The PCA results showed that, from twenty studied monitoring sites, only ten for CO, eleven for NO2, five for O3 and nine for PM10 were needed to characterize the region. The air pollutant analysers corresponding to the redundant measurements can be installed in non-monitored regions, allowing the enlargement of the air quality monitoring network.
©2011 Walter de Gruyter GmbH & Co. KG, Berlin/Boston