Delineation of air-quality basins utilizing multivariate statistical methods in Taiwan

This study analyzed time-series data of air pollutants, O-3 and PM10, to de termine the division of air-quality basins in Taiwan by employing multivari ate statistical methods, Varimax rotational method and cluster analysis. Th e databases of air pollutants, daily maximum l-h O-3 and daily mean PM10 co ncentrations, were obtained from the ROC Environmental Protection Administr ation (ROC EPA) for the period from 1 July 1993 to 30 June 1998. The Varima x rotational method allowed us to delineate five homogenous PM10 subregions that cumulatively accounted for 85.6% of the total variance. The time-seri es analysis of rotated component scores associated with the PM10 subregions revealed that all divided subregions presented a strong seasonal cycle. Fo ur of five subregions had higher component scores and PM lo concentrations from November to January. One subregion experienced higher values from Marc h to May. The use of Varimax approach and cluster analysis on the O-3 and P M10 confirmed that O-3 was more demonstrative of the air-quality basins in Taiwan. Both the Varimax rotational method and the cluster analysis have sp ecific advantages for the division of air-quality basins. This study also p roposes a delineation of five air-duality basins having homogenous O-3 feat ures as an alternative assignment of atmospheric carrying capacity control regions. (C) 2001 Elsevier Science Ltd. All rights reserved.